Merge branch 'master' of ssh://crater.dragonflybsd.org/repository/git/dragonfly

[dragonfly.git] / usr.bin / make / var.c

/*-
 * Copyright (c) 2002 Juli Mallett.
 * Copyright (c) 1988, 1989, 1990, 1993
 *      The Regents of the University of California.  All rights reserved.
 * Copyright (c) 1989 by Berkeley Softworks
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Adam de Boor.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * @(#)var.c    8.3 (Berkeley) 3/19/94
 * $FreeBSD: src/usr.bin/make/var.c,v 1.83 2005/02/11 10:49:01 harti Exp $
 * $DragonFly: src/usr.bin/make/var.c,v 1.224 2005/09/24 07:37:38 okumoto Exp $
 */

/**
 * var.c --
 *      Variable-handling functions
 *
 * Interface:
 *      Var_Set         Set the value of a variable in the given
 *                      context. The variable is created if it doesn't
 *                      yet exist. The value and variable name need not
 *                      be preserved.
 *
 *      Var_Append      Append more characters to an existing variable
 *                      in the given context. The variable needn't
 *                      exist already -- it will be created if it doesn't.
 *                      A space is placed between the old value and the
 *                      new one.
 *
 *      Var_Value       Return the value of a variable in a context or
 *                      NULL if the variable is undefined.
 *
 *      Var_Subst       Substitute named variable, or all variables if
 *                      NULL in a string using
 *                      the given context as the top-most one. If the
 *                      third argument is non-zero, Parse_Error is
 *                      called if any variables are undefined.
 *
 *      Var_Parse       Parse a variable expansion from a string and
 *                      return the result and the number of characters
 *                      consumed.
 *
 *      Var_Delete      Delete a variable in a context.
 *
 *      Var_Init        Initialize this module.
 *
 * Debugging:
 *      Var_Dump        Print out all variables defined in the given
 *                      context.
 *
 * XXX: There's a lot of duplication in these functions.
 */

#include <assert.h>
#include <ctype.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <regex.h>

#include "buf.h"
#include "config.h"
#include "globals.h"
#include "GNode.h"
#include "job.h"
#include "lst.h"
#include "make.h"
#include "parse.h"
#include "str.h"
#include "targ.h"
#include "util.h"
#include "var.h"

/**
 *
 */
typedef struct VarParser {
        const char      *const input;   /* pointer to input string */
        const char      *ptr;           /* current parser pos in input str */
        GNode           *ctxt;
        bool            err;
        bool            execute;
} VarParser;

typedef struct Var {
        char            *name;  /* the variable's name */
        struct Buffer   *val;   /* its value */
        int             flags;  /* miscellaneous status flags */

#define VAR_IN_USE      1       /* Variable's value currently being used.
                                 * Used to avoid recursion */

#define VAR_JUNK        4       /* Variable is a junk variable that
                                 * should be destroyed when done with
                                 * it. Used by Var_Parse for undefined,
                                 * modified variables */

#define VAR_TO_ENV      8       /* Place variable in environment */
} Var;

typedef struct {
        struct Buffer   *lhs;   /* String to match */
        struct Buffer   *rhs;   /* Replacement string (w/ &'s removed) */

        regex_t                 re;
        int                     nsub;
        regmatch_t              *matches;

        int     flags;
#define VAR_SUB_GLOBAL  0x01    /* Apply substitution globally */
#define VAR_SUB_ONE     0x02    /* Apply substitution to one word */
#define VAR_SUB_MATCHED 0x04    /* There was a match */
#define VAR_MATCH_START 0x08    /* Match at start of word */
#define VAR_MATCH_END   0x10    /* Match at end of word */
} VarPattern;

typedef bool VarModifyProc(const char [], bool, struct Buffer *, void *);

static char *VarParse(VarParser *, bool *);

/*
 * This is a harmless return value for Var_Parse that can be used by Var_Subst
 * to determine if there was an error in parsing -- easier than returning
 * a flag, as things outside this module don't give a hoot.
 */
char    var_Error[] = "";

/*
 * Similar to var_Error, but returned when the 'err' flag for Var_Parse is
 * set false. Why not just use a constant? Well, gcc likes to condense
 * identical string instances...
 */
static char     varNoError[] = "";

/*
 * Internally, variables are contained in four different contexts.
 *      1) the environment. They may not be changed. If an environment
 *         variable is appended-to, the result is placed in the global
 *         context.
 *      2) the global context. Variables set in the Makefile are located in
 *         the global context. It is the penultimate context searched when
 *         substituting.
 *      3) the command-line context. All variables set on the command line
 *         are placed in this context. They are UNALTERABLE once placed here.
 *      4) the local context. Each target has associated with it a context
 *         list. On this list are located the structures describing such
 *         local variables as $(@) and $(*)
 * The four contexts are searched in the reverse order from which they are
 * listed.
 */
static GNode    *VAR_ENV;       /* variables from the environment */
GNode           *VAR_GLOBAL;    /* variables from the makefile */
GNode           *VAR_CMD;       /* variables defined on the command-line */

bool            oldVars;        /* variable substitution style */
bool            checkEnvFirst;  /* -e flag */

/**
 * Create a Var object.
 *
 * @param name          Name of variable.
 * @param value         Value of variable.
 * @param flags         Flags set on variable.
 */
static Var *
VarCreate(const char name[], const char value[], int flags)
{
        Var *v;

        v = emalloc(sizeof(Var));
        v->name = estrdup(name);
        v->val  = Buf_Init(0);
        v->flags        = flags;

        if (value != NULL) {
                Buf_Append(v->val, value);
        }
        return (v);
}

/**
 * Destroy a Var object.
 *
 * @param v     Object to destroy.
 * @param f     true if internal buffer in Buffer object is to be
 *              removed.
 */
static void
VarDestroy(Var *v, bool f)
{

        Buf_Destroy(v->val, f);
        free(v->name);
        free(v);
}

/**
 * Remove the tail of the given word and place the result in the given
 * buffer.
 *
 * Results:
 *      true if characters were added to the buffer (a space needs to be
 *      added to the buffer before the next word).
 *
 * Side Effects:
 *      The trimmed word is added to the buffer.
 */
static bool
VarHead(const char word[], bool addSpace, Buffer *buf, void *dummy __unused)
{
        char *slash;

        slash = strrchr(word, '/');
        if (slash != NULL) {
                if (addSpace) {
                        Buf_AddByte(buf, ' ');
                }
                Buf_AppendRange(buf, word, slash);
        } else {
                /*
                 * If no directory part, give . (q.v. the POSIX standard)
                 */
                if (addSpace) {
                        Buf_Append(buf, " .");
                } else {
                        Buf_AddByte(buf, '.');
                }
        }
        return (true);
}

/**
 * Remove the head of the given word and place the result in the given
 * buffer.
 *
 * Results:
 *      true if characters were added to the buffer (a space needs to be
 *      added to the buffer before the next word).
 *
 * Side Effects:
 *      The trimmed word is added to the buffer.
 */
static bool
VarTail(const char word[], bool addSpace, Buffer *buf, void *dummy __unused)
{
        const char *slash;

        if (addSpace) {
                Buf_AddByte(buf, ' ');
        }

        slash = strrchr(word, '/');
        if (slash != NULL) {
                slash++;
                Buf_Append(buf, slash);
        } else {
                Buf_Append(buf, word);
        }
        return (true);
}

/**
 * Place the suffix of the given word in the given buffer.
 *
 * Results:
 *      true if characters were added to the buffer (a space needs to be
 *      added to the buffer before the next word).
 *
 * Side Effects:
 *      The suffix from the word is placed in the buffer.
 */
static bool
VarSuffix(const char word[], bool addSpace, Buffer *buf, void *dummy __unused)
{
        const char *dot;

        dot = strrchr(word, '.');
        if (dot != NULL) {
                if (addSpace) {
                        Buf_AddByte(buf, ' ');
                }
                dot++;
                Buf_Append(buf, dot);
                addSpace = true;
        }
        return (addSpace);
}

/**
 * Remove the suffix of the given word and place the result in the
 * buffer.
 *
 * Results:
 *      true if characters were added to the buffer (a space needs to be
 *      added to the buffer before the next word).
 *
 * Side Effects:
 *      The trimmed word is added to the buffer.
 */
static bool
VarRoot(const char word[], bool addSpace, Buffer *buf, void *dummy __unused)
{
        char *dot;

        if (addSpace) {
                Buf_AddByte(buf, ' ');
        }

        dot = strrchr(word, '.');
        if (dot != NULL) {
                Buf_AppendRange(buf, word, dot);
        } else {
                Buf_Append(buf, word);
        }
        return (true);
}

/**
 * Place the word in the buffer if it matches the given pattern.
 * Callback function for VarModify to implement the :M modifier.
 * A space will be added if requested.  A pattern is supplied
 * which the word must match.
 *
 * Results:
 *      true if a space should be placed in the buffer before the next
 *      word.
 *
 * Side Effects:
 *      The word may be copied to the buffer.
 */
static bool
VarMatch(const char word[], bool addSpace, Buffer *buf, void *pattern)
{

        if (Str_Match(word, pattern)) {
                if (addSpace) {
                        Buf_AddByte(buf, ' ');
                }
                addSpace = true;
                Buf_Append(buf, word);
        }
        return (addSpace);
}

/**
 * Place the word in the buffer if it matches the given pattern.
 * Callback function for VarModify to implement the System V %
 * modifiers.  A space is added if requested.
 *
 * Results:
 *      true if a space should be placed in the buffer before the next
 *      word.
 *
 * Side Effects:
 *      The word may be copied to the buffer.
 */
static bool
VarSYSVMatch(const char word[], bool addSpace, Buffer *buf, void *patp)
{
        int             len;
        const char      *ptr;
        VarPattern      *pat = (VarPattern *)patp;

        if (addSpace)
                Buf_AddByte(buf, ' ');

        addSpace = true;

        if ((ptr = Str_SYSVMatch(word, Buf_Data(pat->lhs), &len)) != NULL)
                Str_SYSVSubst(buf, Buf_Data(pat->rhs), ptr, len);
        else
                Buf_Append(buf, word);

        return (addSpace);
}

/**
 * Place the word in the buffer if it doesn't match the given pattern.
 * Callback function for VarModify to implement the :N modifier.  A
 * space is added if requested.
 *
 * Results:
 *      true if a space should be placed in the buffer before the next
 *      word.
 *
 * Side Effects:
 *      The word may be copied to the buffer.
 */
static bool
VarNoMatch(const char word[], bool addSpace, Buffer *buf, void *pattern)
{

        if (!Str_Match(word, pattern)) {
                if (addSpace) {
                        Buf_AddByte(buf, ' ');
                }
                addSpace = true;
                Buf_Append(buf, word);
        }
        return (addSpace);
}

/**
 * Perform a string-substitution on the given word, placing the
 * result in the passed buffer.  A space is added if requested.
 *
 * Results:
 *      true if a space is needed before more characters are added.
 */
static bool
VarSubstitute(const char word[], bool addSpace, Buffer *buf, void *patternp)
{
        size_t          wordLen;        /* Length of word */
        const char      *cp;            /* General pointer */
        VarPattern      *pattern = patternp;

        wordLen = strlen(word);
        if (1) { /* substitute in each word of the variable */
                /*
                 * Break substitution down into simple anchored cases
                 * and if none of them fits, perform the general substitution
                 * case.
                 */
                if ((pattern->flags & VAR_MATCH_START) &&
                   (strncmp(word, Buf_Data(pattern->lhs),
                    Buf_Size(pattern->lhs)) == 0)) {
                        /*
                         * Anchored at start and beginning of word matches
                         * pattern.
                         */
                        if ((pattern->flags & VAR_MATCH_END) &&
                            (wordLen == Buf_Size(pattern->lhs))) {
                                /*
                                 * Also anchored at end and matches to the end
                                 * (word is same length as pattern) add space
                                 * and rhs only if rhs is non-null.
                                 */
                                if (Buf_Size(pattern->rhs) != 0) {
                                        if (addSpace) {
                                                Buf_AddByte(buf, ' ');
                                        }
                                        addSpace = true;
                                        Buf_AppendBuf(buf, pattern->rhs);
                                }

                        } else if (pattern->flags & VAR_MATCH_END) {
                                /*
                                 * Doesn't match to end -- copy word wholesale
                                 */
                                goto nosub;

                        } else {
                                /*
                                 * Matches at start but need to copy in
                                 * trailing characters.
                                 */
                                if ((Buf_Size(pattern->rhs) + wordLen -
                                    Buf_Size(pattern->lhs)) != 0) {
                                        if (addSpace) {
                                                Buf_AddByte(buf, ' ');
                                        }
                                        addSpace = true;
                                }
                                Buf_AppendBuf(buf, pattern->rhs);
                                Buf_AddBytes(buf, wordLen -
                                    Buf_Size(pattern->lhs),
                                    (word + Buf_Size(pattern->lhs)));
                        }

                } else if (pattern->flags & VAR_MATCH_START) {
                        /*
                         * Had to match at start of word and didn't -- copy
                         * whole word.
                         */
                        goto nosub;

                } else if (pattern->flags & VAR_MATCH_END) {
                        /*
                         * Anchored at end, Find only place match could occur
                         * (leftLen characters from the end of the word) and
                         * see if it does. Note that because the $ will be
                         * left at the end of the lhs, we have to use strncmp.
                         */
                        cp = word + (wordLen - Buf_Size(pattern->lhs));
                        if ((cp >= word) && (strncmp(cp, Buf_Data(pattern->lhs),
                            Buf_Size(pattern->lhs)) == 0)) {
                                /*
                                 * Match found. If we will place characters in
                                 * the buffer, add a space before hand as
                                 * indicated by addSpace, then stuff in the
                                 * initial, unmatched part of the word followed
                                 * by the right-hand-side.
                                 */
                                if ((cp - word) + Buf_Size(pattern->rhs) != 0) {
                                        if (addSpace) {
                                                Buf_AddByte(buf, ' ');
                                        }
                                        addSpace = true;
                                }
                                Buf_AppendRange(buf, word, cp);
                                Buf_AppendBuf(buf, pattern->rhs);

                        } else {
                                /*
                                 * Had to match at end and didn't. Copy entire
                                 * word.
                                 */
                                goto nosub;
                        }
                } else {
                        /*
                         * Pattern is unanchored: search for the pattern in the
                         * word using strstr(3), copying unmatched portions and
                         * the right-hand-side for each match found, handling
                         * non-global substitutions correctly, etc. When the
                         * loop is done, any remaining part of the word (word
                         * and wordLen are adjusted accordingly through the
                         * loop) is copied straight into the buffer.
                         * addSpace is set false as soon as a space is added
                         * to the buffer.
                         */
                        bool done;
                        size_t origSize;

                        done = false;
                        origSize = Buf_Size(buf);
                        while (!done) {
                                cp = strstr(word, Buf_Data(pattern->lhs));
                                if (cp != NULL) {
                                        if (addSpace && (((cp - word) +
                                            Buf_Size(pattern->rhs)) != 0)) {
                                                Buf_AddByte(buf, ' ');
                                                addSpace = false;
                                        }
                                        Buf_AppendRange(buf, word, cp);
                                        Buf_AppendBuf(buf, pattern->rhs);
                                        wordLen -= (cp - word) +
                                            Buf_Size(pattern->lhs);
                                        word = cp + Buf_Size(pattern->lhs);
                                        if (wordLen == 0 || (pattern->flags &
                                            VAR_SUB_GLOBAL) == 0) {
                                                done = true;
                                        }
                                } else {
                                        done = true;
                                }
                        }
                        if (wordLen != 0) {
                                if (addSpace) {
                                        Buf_AddByte(buf, ' ');
                                }
                                Buf_AddBytes(buf, wordLen, word);
                        }

                        /*
                         * If added characters to the buffer, need to add a
                         * space before we add any more. If we didn't add any,
                         * just return the previous value of addSpace.
                         */
                        return ((Buf_Size(buf) != origSize) || addSpace);
                }
                /*
                 * Common code for anchored substitutions:
                 * addSpace was set true if characters were added to the buffer.
                 */
                return (addSpace);
        }
  nosub:
        if (addSpace) {
                Buf_AddByte(buf, ' ');
        }
        Buf_AddBytes(buf, wordLen, word);
        return (true);
}

/**
 * Print the error caused by a regcomp or regexec call.
 *
 * Side Effects:
 *      An error gets printed.
 */
static void
VarREError(int err, regex_t *pat, const char str[])
{
        char   *errbuf;
        int     errlen;

        errlen = regerror(err, pat, 0, 0);
        errbuf = emalloc(errlen);
        regerror(err, pat, errbuf, errlen);
        Error("%s: %s", str, errbuf);
        free(errbuf);
}


/**
 * Perform a regex substitution on the given word, placing the
 * result in the passed buffer.  A space is added if requested.
 *
 * Results:
 *      true if a space is needed before more characters are added.
 */
static bool
VarRESubstitute(const char word[], bool addSpace, Buffer *buf, void *patternp)
{
        VarPattern      *pat;
        int             xrv;
        const char      *wp;
        char            *rp;
        int             added;
        int             flags = 0;

#define MAYBE_ADD_SPACE()                       \
        if (addSpace && !added)                 \
                Buf_AddByte(buf, ' ');  \
        added = 1

        added = 0;
        wp = word;
        pat = patternp;

        if ((pat->flags & (VAR_SUB_ONE | VAR_SUB_MATCHED)) ==
            (VAR_SUB_ONE | VAR_SUB_MATCHED)) {
                xrv = REG_NOMATCH;
        } else {
  tryagain:
                xrv = regexec(&pat->re, wp, pat->nsub, pat->matches, flags);
        }

        switch (xrv) {
          case 0:
                pat->flags |= VAR_SUB_MATCHED;
                if (pat->matches[0].rm_so > 0) {
                        MAYBE_ADD_SPACE();
                        Buf_AddBytes(buf, pat->matches[0].rm_so, wp);
                }

                for (rp = Buf_Data(pat->rhs); *rp; rp++) {
                        if ((*rp == '\\') && ((rp[1] == '&') || (rp[1] == '\\'))) {
                                MAYBE_ADD_SPACE();
                                Buf_AddByte(buf, rp[1]);
                                rp++;

                        } else if ((*rp == '&') ||
                            ((*rp == '\\') && isdigit((unsigned char)rp[1]))) {
                                int     n;
                                const char *subbuf;
                                int     sublen;
                                char    errstr[3];

                                if (*rp == '&') {
                                        n = 0;
                                        errstr[0] = '&';
                                        errstr[1] = '\0';
                                } else {
                                        n = rp[1] - '0';
                                        errstr[0] = '\\';
                                        errstr[1] = rp[1];
                                        errstr[2] = '\0';
                                        rp++;
                                }

                                if (n > pat->nsub) {
                                        Error("No subexpression %s",
                                            &errstr[0]);
                                        subbuf = "";
                                        sublen = 0;

                                } else if ((pat->matches[n].rm_so == -1) &&
                                    (pat->matches[n].rm_eo == -1)) {
                                        Error("No match for subexpression %s",
                                            &errstr[0]);
                                        subbuf = "";
                                        sublen = 0;

                                } else {
                                        subbuf = wp + pat->matches[n].rm_so;
                                        sublen = pat->matches[n].rm_eo -
                                            pat->matches[n].rm_so;
                                }

                                if (sublen > 0) {
                                        MAYBE_ADD_SPACE();
                                        Buf_AddBytes(buf, sublen, subbuf);
                                }
                        } else {
                                MAYBE_ADD_SPACE();
                                Buf_AddByte(buf, *rp);
                        }
                }
                wp += pat->matches[0].rm_eo;
                if (pat->flags & VAR_SUB_GLOBAL) {
                        flags |= REG_NOTBOL;
                        if (pat->matches[0].rm_so == 0 &&
                            pat->matches[0].rm_eo == 0) {
                                MAYBE_ADD_SPACE();
                                Buf_AddByte(buf, *wp);
                                wp++;
                        }
                        if (*wp)
                                goto tryagain;
                }
                if (*wp) {
                        MAYBE_ADD_SPACE();
                        Buf_Append(buf, wp);
                }
                break;

          default:
                VarREError(xrv, &pat->re, "Unexpected regex error");
                /* fall through */

          case REG_NOMATCH:
                if (*wp) {
                        MAYBE_ADD_SPACE();
                        Buf_Append(buf, wp);
                }
                break;
        }
        return (addSpace || added);
}

/**
 * Find a variable in a variable list.
 */
static Var *
VarLookup(Lst *vlist, const char name[])
{
        LstNode *ln;

        LST_FOREACH(ln, vlist)
                if (strcmp(((const Var *)Lst_Datum(ln))->name, name) == 0)
                        return (Lst_Datum(ln));
        return (NULL);
}

/**
 * Expand a variable name's embedded variables in the given context.
 *
 * Results:
 *      The contents of name, possibly expanded.
 */
static char *
VarPossiblyExpand(const char name[], GNode *ctxt)
{
        Buffer  *buf;

        if (strchr(name, '$') != NULL) {
                buf = Var_Subst(name, ctxt, 0);
                return (Buf_Peel(buf));
        } else {
                return estrdup(name);
        }
}

/**
 * If the variable name begins with a '.', it could very well be
 * one of the local ones.  We check the name against all the local
 * variables and substitute the short version in for 'name' if it
 * matches one of them.
 */
static const char *
VarLocal(const char name[])
{
        if (name[0] == '.') {
                switch (name[1]) {
                case 'A':
                        if (!strcmp(name, ".ALLSRC"))
                                return (ALLSRC);
                        if (!strcmp(name, ".ARCHIVE"))
                                return (ARCHIVE);
                        break;
                case 'I':
                        if (!strcmp(name, ".IMPSRC"))
                                return (IMPSRC);
                        break;
                case 'M':
                        if (!strcmp(name, ".MEMBER"))
                                return (MEMBER);
                        break;
                case 'O':
                        if (!strcmp(name, ".OODATE"))
                                return (OODATE);
                        break;
                case 'P':
                        if (!strcmp(name, ".PREFIX"))
                                return (PREFIX);
                        break;
                case 'T':
                        if (!strcmp(name, ".TARGET"))
                                return (TARGET);
                        break;
                default:
                        break;
                }
        }
        return (name);
}

/**
 * Find the given variable in the given context and the environment.
 *
 * Results:
 *      A pointer to the structure describing the desired variable or
 *      NULL if the variable does not exist.
 */
static Var *
VarFindEnv(const char name[], GNode *ctxt)
{
        Var     *var;

        name = VarLocal(name);

        if ((var = VarLookup(&ctxt->context, name)) != NULL)
                return (var);

        if ((var = VarLookup(&VAR_ENV->context, name)) != NULL)
                return (var);

        return (NULL);
}

/**
 * Look for the variable in the given context.
 */
static Var *
VarFindOnly(const char name[], GNode *ctxt)
{

        return (VarLookup(&ctxt->context, VarLocal(name)));
}

/**
 * Look for the variable in all contexts.
 */
static Var *
VarFindAny(const char name[], GNode *ctxt)
{
        bool    localCheckEnvFirst;
        LstNode *ln;
        Var     *var;

        name = VarLocal(name);

        /*
         * Note whether this is one of the specific variables we were told
         * through the -E flag to use environment-variable-override for.
         */
        localCheckEnvFirst = false;
        LST_FOREACH(ln, &envFirstVars) {
                if (strcmp(Lst_Datum(ln), name) == 0) {
                        localCheckEnvFirst = true;
                        break;
                }
        }

        /*
         * First look for the variable in the given context. If it's not there,
         * look for it in VAR_CMD, VAR_GLOBAL and the environment,
         * in that order, depending on the FIND_* flags in 'flags'
         */
        if ((var = VarLookup(&ctxt->context, name)) != NULL)
                return (var);

        /* not there - try command line context */
        if (ctxt != VAR_CMD) {
                if ((var = VarLookup(&VAR_CMD->context, name)) != NULL)
                        return (var);
        }

        /* not there - try global context, but only if not -e/-E */
        if (ctxt != VAR_GLOBAL && (!checkEnvFirst && !localCheckEnvFirst)) {
                if ((var = VarLookup(&VAR_GLOBAL->context, name)) != NULL)
                        return (var);
        }

        if ((var = VarLookup(&VAR_ENV->context, name)) != NULL)
                return (var);

        /* deferred check for the environment (in case of -e/-E) */
        if ((ctxt != VAR_GLOBAL) && (checkEnvFirst || localCheckEnvFirst)) {
                if ((var = VarLookup(&VAR_GLOBAL->context, name)) != NULL)
                        return (var);
        }

        return (NULL);
}

/**
 * Add a new variable of name name and value val to the given context.
 *
 * Side Effects:
 *      The new variable is placed at the front of the given context
 *      The name and val arguments are duplicated so they may
 *      safely be freed.
 */
static void
VarAdd(const char name[], const char val[], GNode *ctxt)
{

        Lst_AtFront(&ctxt->context, VarCreate(name, val, 0));
        DEBUGF(VAR, ("%s:%s = %s\n", ctxt->name, name, val));
}

/**
 * Remove a variable from a context.
 *
 * Side Effects:
 *      The Var structure is removed and freed.
 */
void
Var_Delete(const char name[], GNode *ctxt)
{
        LstNode *ln;

        DEBUGF(VAR, ("%s:delete %s\n", ctxt->name, name));
        LST_FOREACH(ln, &ctxt->context) {
                if (strcmp(((const Var *)Lst_Datum(ln))->name, name) == 0) {
                        VarDestroy(Lst_Datum(ln), true);
                        Lst_Remove(&ctxt->context, ln);
                        break;
                }
        }
}

/**
 * Set the variable name to the value val in the given context.
 *
 * Side Effects:
 *      If the variable doesn't yet exist, a new record is created for it.
 *      Else the old value is freed and the new one stuck in its place
 *
 * Notes:
 *      The variable is searched for only in its context before being
 *      created in that context. I.e. if the context is VAR_GLOBAL,
 *      only VAR_GLOBAL->context is searched. Likewise if it is VAR_CMD, only
 *      VAR_CMD->context is searched. This is done to avoid the literally
 *      thousands of unnecessary strcmp's that used to be done to
 *      set, say, $(@) or $(<).
 */
void
Var_Set(const char name[], const char val[], GNode *ctxt)
{
        Var    *v;
        char   *n;

        /*
         * We only look for a variable in the given context since anything
         * set here will override anything in a lower context, so there's not
         * much point in searching them all just to save a bit of memory...
         */
        n = VarPossiblyExpand(name, ctxt);
        v = VarFindOnly(n, ctxt);
        if (v == NULL) {
                VarAdd(n, val, ctxt);
                if (ctxt == VAR_CMD) {
                        /*
                         * Any variables given on the command line
                         * are automatically exported to the
                         * environment (as per POSIX standard)
                         */
                        if (setenv(n, val, 1) == -1)
                                Punt( "setenv: %s: can't allocate memory", n);
                }
        } else {
                Buf_Clear(v->val);
                Buf_Append(v->val, val);

                if (ctxt == VAR_CMD || (v->flags & VAR_TO_ENV)) {
                        /*
                         * Any variables given on the command line
                         * are automatically exported to the
                         * environment (as per POSIX standard)
                         */
                        char *exp_value;

                        exp_value = Buf_Peel(Var_Subst(val, ctxt, false));
                        if (setenv(n, exp_value, 1) == -1)
                                Punt( "setenv: %s: can't allocate memory", n);
                        free(exp_value);
                }

        }

        DEBUGF(VAR, ("%s:%s = %s\n", ctxt->name, n, val));
        free(n);
}

/**
 * Set the a global name variable to the value.
 */
void
Var_SetGlobal(const char name[], const char value[])
{

        Var_Set(name, value, VAR_GLOBAL);
}


/**
 * Set the VAR_TO_ENV flag on a variable
 */
void
Var_SetEnv(const char name[], GNode *ctxt)
{
        Var    *v;

        v = VarFindOnly(name, VAR_CMD);
        if (v != NULL) {
                /*
                 * Do not allow .EXPORT: to be set on variables
                 * from the command line or MAKEFLAGS.
                 */
                Error(
                    "Warning: Did not set .EXPORTVAR: on %s because it "
                    "is from the command line or MAKEFLAGS", name);
                return;
        }

        v = VarFindAny(name, ctxt);
        if (v == NULL) {
                Lst_AtFront(&VAR_ENV->context,
                    VarCreate(name, NULL, VAR_TO_ENV));
                if (setenv(name, "", 1) == -1)
                        Punt( "setenv: %s: can't allocate memory", name);
                Error("Warning: .EXPORTVAR: set on undefined variable %s", name);
        } else {
                if ((v->flags & VAR_TO_ENV) == 0) {
                        char *value;

                        value = Buf_Peel(Var_Subst(Buf_Data(v->val), ctxt, false));
                        v->flags |= VAR_TO_ENV;
                        if (setenv(v->name, value, 1) == -1)
                                Punt( "setenv: %s: can't allocate memory", v->name);    
                        free(value);
                }
        }
}

/**
 * The variable of the given name has the given value appended to it in
 * the given context.
 *
 * Side Effects:
 *      If the variable doesn't exist, it is created. Else the strings
 *      are concatenated (with a space in between).
 *
 * Notes:
 *      Only if the variable is being sought in the global context is the
 *      environment searched.
 *      XXX: Knows its calling circumstances in that if called with ctxt
 *      an actual target, it will only search that context since only
 *      a local variable could be being appended to. This is actually
 *      a big win and must be tolerated.
 */
void
Var_Append(const char name[], const char val[], GNode *ctxt)
{
        Var     *v;
        char    *n;

        n = VarPossiblyExpand(name, ctxt);
        if (ctxt == VAR_GLOBAL) {
                v = VarFindEnv(n, ctxt);
        } else {
                v = VarFindOnly(n, ctxt);
        }
        if (v == NULL) {
                VarAdd(n, val, ctxt);
        } else {
                Buf_AddByte(v->val, ' ');
                Buf_Append(v->val, val);
                DEBUGF(VAR, ("%s:%s = %s\n", ctxt->name, n, Buf_Data(v->val)));
        }
        free(n);
}

/**
 * Return the value of the named variable in the given context
 *
 * Results:
 *      The value if the variable exists, NULL if it doesn't.
 */
const char *
Var_Value(const char name[], GNode *ctxt)
{
        Var     *v;
        char    *n;

        n = VarPossiblyExpand(name, ctxt);
        v = VarFindAny(n, ctxt);
        free(n);
        if (v == NULL) {
                return (NULL);
        } else {
                return (Buf_Data(v->val));
        }
}

/**
 * Modify each of the words of the passed string using the given
 * function. Used to implement all modifiers.
 *
 * Results:
 *      A string of all the words modified appropriately.
 */
static char *
VarModify(const char str[], VarModifyProc *modProc, void *datum)
{
        ArgArray        aa;
        Buffer          *buf;           /* Buffer for the new string */
        int             i;
        bool            addSpace;       /*
                                         * true if need to add a space to
                                         * the buffer before adding the
                                         * trimmed word
                                         */

        brk_string(&aa, str, false);

        addSpace = false;
        buf = Buf_Init(0);
        for (i = 1; i < aa.argc; i++)
                addSpace = (*modProc)(aa.argv[i], addSpace, buf, datum);

        ArgArray_Done(&aa);
        return (Buf_Peel(buf));
}

/**
 * Sort the words in the string.
 *
 * Input:
 *      str             String whose words should be sorted
 *      cmp             A comparison function to control the ordering
 *
 * Results:
 *      A string containing the words sorted
 */
static char *
VarSortWords(const char str[], int (*cmp)(const void *, const void *))
{
        ArgArray        aa;
        Buffer          *buf;
        int             i;

        brk_string(&aa, str, false);
        qsort(aa.argv + 1, aa.argc - 1, sizeof(char *), cmp);

        buf = Buf_Init(0);
        for (i = 1; i < aa.argc; i++) {
                Buf_Append(buf, aa.argv[i]);
                Buf_AddByte(buf, ((i < aa.argc - 1) ? ' ' : '\0'));
        }

        ArgArray_Done(&aa);
        return (Buf_Peel(buf));
}

static int
SortIncreasing(const void *l, const void *r)
{

        return (strcmp(*(const char* const*)l, *(const char* const*)r));
}

/**
 * Pass through the tstr looking for 1) escaped delimiters,
 * '$'s and backslashes (place the escaped character in
 * uninterpreted) and 2) unescaped $'s that aren't before
 * the delimiter (expand the variable substitution).
 * Return the expanded string or NULL if the delimiter was missing
 * If pattern is specified, handle escaped ampersands, and replace
 * unescaped ampersands with the lhs of the pattern.
 *
 * Results:
 *      A string of all the words modified appropriately.
 *      If length is specified, return the string length of the buffer
 *      If flags is specified and the last character of the pattern is a
 *      $ set the VAR_MATCH_END bit of flags.
 */
static Buffer *
VarGetPattern(VarParser *vp, int delim, int *flags, VarPattern *patt)
{
        Buffer          *buf;

        buf = Buf_Init(0);

        /*
         * Skim through until the matching delimiter is found; pick up
         * variable substitutions on the way. Also allow backslashes to quote
         * the delimiter, $, and \, but don't touch other backslashes.
         */
        while (*vp->ptr != '\0') {
                if (*vp->ptr == delim) {
                        return (buf);

                } else if ((vp->ptr[0] == '\\') &&
                    ((vp->ptr[1] == delim) ||
                     (vp->ptr[1] == '\\') ||
                     (vp->ptr[1] == '$') ||
                     (vp->ptr[1] == '&' && patt != NULL))) {
                        vp->ptr++;              /* consume backslash */
                        Buf_AddByte(buf, vp->ptr[0]);
                        vp->ptr++;

                } else if (vp->ptr[0] == '$') {
                        if (vp->ptr[1] == delim) {
                                if (flags == NULL) {
                                        Buf_AddByte(buf, vp->ptr[0]);
                                        vp->ptr++;
                                } else {
                                        /*
                                         * Unescaped $ at end of patt =>
                                         * anchor patt at end.
                                         */
                                        *flags |= VAR_MATCH_END;
                                        vp->ptr++;
                                }
                        } else {
                                VarParser       subvp = {
                                        vp->ptr,
                                        vp->ptr,
                                        vp->ctxt,
                                        vp->err,
                                        vp->execute
                                };
                                char   *rval;
                                bool rfree;

                                /*
                                 * If unescaped dollar sign not
                                 * before the delimiter, assume it's
                                 * a variable substitution and
                                 * recurse.
                                 */
                                rval = VarParse(&subvp, &rfree);
                                Buf_Append(buf, rval);
                                if (rfree)
                                        free(rval);
                                vp->ptr = subvp.ptr;
                        }
                } else if (vp->ptr[0] == '&' && patt != NULL) {
                        Buf_AppendBuf(buf, patt->lhs);
                        vp->ptr++;
                } else {
                        Buf_AddByte(buf, vp->ptr[0]);
                        vp->ptr++;
                }
        }

        Buf_Destroy(buf, true);
        return (NULL);
}

/**
 * Make sure this variable is fully expanded.
 */
static char *
VarExpand(Var *v, VarParser *vp)
{
        char    *value;
        char    *result;

        if (v->flags & VAR_IN_USE) {
                Fatal("Variable %s is recursive.", v->name);
                /* NOTREACHED */
        }

        v->flags |= VAR_IN_USE;

        /*
         * Before doing any modification, we have to make sure the
         * value has been fully expanded. If it looks like recursion
         * might be necessary (there's a dollar sign somewhere in the
         * variable's value) we just call Var_Subst to do any other
         * substitutions that are necessary. Note that the value
         * returned by Var_Subst will have been
         * dynamically-allocated, so it will need freeing when we
         * return.
         */
        value = Buf_Data(v->val);
        if (strchr(value, '$') == NULL) {
                result = strdup(value);
        } else {
                Buffer  *buf;

                buf = Var_Subst(value, vp->ctxt, vp->err);
                result = Buf_Peel(buf);
        }

        v->flags &= ~VAR_IN_USE;

        return (result);
}

/**
 * Select only those words in value that match the modifier.
 */
static char *
modifier_M(VarParser *vp, const char value[], char endc)
{
        char    *patt;
        char    *ptr;
        char    *newValue;
        char    modifier;

        modifier = vp->ptr[0];
        vp->ptr++;      /* consume 'M' or 'N' */

        /*
         * Compress the \:'s out of the pattern, so allocate enough
         * room to hold the uncompressed pattern and compress the
         * pattern into that space.
         */
        patt = estrdup(vp->ptr);
        ptr = patt;
        while (vp->ptr[0] != '\0') {
                if (vp->ptr[0] == endc || vp->ptr[0] == ':') {
                        break;
                }
                if (vp->ptr[0] == '\\' &&
                    (vp->ptr[1] == endc || vp->ptr[1] == ':')) {
                        vp->ptr++;      /* consume backslash */
                }
                *ptr = vp->ptr[0];
                ptr++;
                vp->ptr++;
        }
        *ptr = '\0';

        if (modifier == 'M') {
                newValue = VarModify(value, VarMatch, patt);
        } else {
                newValue = VarModify(value, VarNoMatch, patt);
        }
        free(patt);

        return (newValue);
}

/**
 * Substitute the replacement string for the pattern.  The substitution
 * is applied to each word in value.
 */
static char *
modifier_S(VarParser *vp, const char value[], Var *v)
{
        VarPattern      patt;
        char            delim;
        char            *newValue;

        patt.flags = 0;

        vp->ptr++;              /* consume 'S' */

        delim = *vp->ptr;       /* used to find end of pattern */
        vp->ptr++;              /* consume 1st delim */

        /*
         * If pattern begins with '^', it is anchored to the start of the
         * word -- skip over it and flag pattern.
         */
        if (*vp->ptr == '^') {
                patt.flags |= VAR_MATCH_START;
                vp->ptr++;
        }

        patt.lhs = VarGetPattern(vp, delim, &patt.flags, NULL);
        if (patt.lhs == NULL) {
                /*
                 * LHS didn't end with the delim, complain and exit.
                 */
                Fatal("Unclosed substitution for %s (%c missing)",
                    v->name, delim);
        }

        vp->ptr++;      /* consume 2nd delim */

        patt.rhs = VarGetPattern(vp, delim, NULL, &patt);
        if (patt.rhs == NULL) {
                /*
                 * RHS didn't end with the delim, complain and exit.
                 */
                Fatal("Unclosed substitution for %s (%c missing)",
                    v->name, delim);
        }

        vp->ptr++;      /* consume last delim */

        /*
         * Check for global substitution. If 'g' after the final delimiter,
         * substitution is global and is marked that way.
         */
        if (vp->ptr[0] == 'g') {
                patt.flags |= VAR_SUB_GLOBAL;
                vp->ptr++;
        }

        /*
         * Global substitution of the empty string causes an infinite number
         * of matches, unless anchored by '^' (start of string) or '$' (end
         * of string). Catch the infinite substitution here. Note that flags
         * can only contain the 3 bits we're interested in so we don't have
         * to mask unrelated bits. We can test for equality.
         */
        if (Buf_Size(patt.lhs) == 0 && patt.flags == VAR_SUB_GLOBAL)
                Fatal("Global substitution of the empty string");

        newValue = VarModify(value, VarSubstitute, &patt);

        /*
         * Free the two strings.
         */
        free(patt.lhs);
        free(patt.rhs);

        return (newValue);
}

static char *
modifier_C(VarParser *vp, char value[], Var *v)
{
        VarPattern      patt;
        char            delim;
        int             error;
        char            *newValue;

        patt.flags = 0;

        vp->ptr++;              /* consume 'C' */

        delim = *vp->ptr;       /* delimiter between sections */

        vp->ptr++;              /* consume 1st delim */

        patt.lhs = VarGetPattern(vp, delim, NULL, NULL);
        if (patt.lhs == NULL) {
                Fatal("Unclosed substitution for %s (%c missing)",
                     v->name, delim);
        }

        vp->ptr++;              /* consume 2st delim */

        patt.rhs = VarGetPattern(vp, delim, NULL, NULL);
        if (patt.rhs == NULL) {
                Fatal("Unclosed substitution for %s (%c missing)",
                     v->name, delim);
        }

        vp->ptr++;              /* consume last delim */

        switch (*vp->ptr) {
        case 'g':
                patt.flags |= VAR_SUB_GLOBAL;
                vp->ptr++;              /* consume 'g' */
                break;
        case '1':
                patt.flags |= VAR_SUB_ONE;
                vp->ptr++;              /* consume '1' */
                break;
        default:
                break;
        }

        error = regcomp(&patt.re, Buf_Data(patt.lhs), REG_EXTENDED);
        if (error) {
                VarREError(error, &patt.re, "RE substitution error");
                free(patt.rhs);
                free(patt.lhs);
                return (var_Error);
        }

        patt.nsub = patt.re.re_nsub + 1;
        if (patt.nsub < 1)
                patt.nsub = 1;
        if (patt.nsub > 10)
                patt.nsub = 10;
        patt.matches = emalloc(patt.nsub * sizeof(regmatch_t));

        newValue = VarModify(value, VarRESubstitute, &patt);

        regfree(&patt.re);
        free(patt.matches);
        free(patt.rhs);
        free(patt.lhs);

        return (newValue);
}

static char *
sysVvarsub(VarParser *vp, char startc, Var *v, const char value[])
{
        /*
         * This can either be a bogus modifier or a System-V substitution
         * command.
         */
        char            endc;
        VarPattern      patt;
        bool            eqFound;
        int             cnt;
        char            *newStr;
        const char      *cp;

        endc = (startc == OPEN_PAREN) ? CLOSE_PAREN : CLOSE_BRACE;

        patt.flags = 0;

        /*
         * First we make a pass through the string trying to verify it is a
         * SYSV-make-style translation: it must be: <string1>=<string2>)
         */
        eqFound = false;
        cp = vp->ptr;
        cnt = 1;
        while (*cp != '\0' && cnt) {
                if (*cp == '=') {
                        eqFound = true;
                        /* continue looking for endc */
                } else if (*cp == endc)
                        cnt--;
                else if (*cp == startc)
                        cnt++;
                if (cnt)
                        cp++;
        }

        if (*cp == endc && eqFound) {
                /*
                 * Now we break this sucker into the lhs and rhs.
                 */
                patt.lhs = VarGetPattern(vp, '=', &patt.flags, NULL);
                if (patt.lhs == NULL) {
                        Fatal("Unclosed substitution for %s (%c missing)",
                              v->name, '=');
                }
                vp->ptr++;      /* consume '=' */

                patt.rhs = VarGetPattern(vp, endc, NULL, &patt);
                if (patt.rhs == NULL) {
                        Fatal("Unclosed substitution for %s (%c missing)",
                              v->name, endc);
                }

                /*
                 * SYSV modifications happen through the whole string. Note
                 * the pattern is anchored at the end.
                 */
                newStr = VarModify(value, VarSYSVMatch, &patt);

                free(patt.lhs);
                free(patt.rhs);
        } else {
                Error("Unknown modifier '%c'\n", *vp->ptr);
                vp->ptr++;
                while (*vp->ptr != '\0') {
                        if (*vp->ptr == endc && *vp->ptr == ':') {
                                break;
                        }
                        vp->ptr++;
                }
                newStr = var_Error;
        }

        return (newStr);
}

/**
 * Quote shell meta-characters in the string
 *
 * Results:
 *      The quoted string
 */
static char *
Var_Quote(const char str[])
{
        Buffer *buf;
        /* This should cover most shells :-( */
        static char meta[] = "\n \t'`\";&<>()|*?{}[]\\$!#^~";

        buf = Buf_Init(MAKE_BSIZE);
        for (; *str; str++) {
                if (strchr(meta, *str) != NULL)
                        Buf_AddByte(buf, '\\');
                Buf_AddByte(buf, *str);
        }

        return (Buf_Peel(buf));
}


/*
 * Now we need to apply any modifiers the user wants applied.
 * These are:
 *      :M<pattern>
 *              words which match the given <pattern>.
 *              <pattern> is of the standard file
 *              wildcarding form.
 *      :S<d><pat1><d><pat2><d>[g]
 *              Substitute <pat2> for <pat1> in the value
 *      :C<d><pat1><d><pat2><d>[g]
 *              Substitute <pat2> for regex <pat1> in the value
 *      :H      Substitute the head of each word
 *      :T      Substitute the tail of each word
 *      :E      Substitute the extension (minus '.') of
 *              each word
 *      :R      Substitute the root of each word
 *              (pathname minus the suffix).
 *      :lhs=rhs
 *              Like :S, but the rhs goes to the end of
 *              the invocation.
 *      :U      Converts variable to upper-case.
 *      :L      Converts variable to lower-case.
 *
 * XXXHB update this comment or remove it and point to the man page.
 */
static char *
ParseModifier(VarParser *vp, char startc, Var *v, bool *freeResult)
{
        char    *value;
        char    endc;

        value = VarExpand(v, vp);
        *freeResult = true;

        endc = (startc == OPEN_PAREN) ? CLOSE_PAREN : CLOSE_BRACE;

        vp->ptr++;      /* consume first colon */

        while (*vp->ptr != '\0') {
                char    *newStr;        /* New value to return */

                if (*vp->ptr == endc) {
                        return (value);
                }

                DEBUGF(VAR, ("Applying :%c to \"%s\"\n", *vp->ptr, value));
                switch (*vp->ptr) {
                case 'N':
                case 'M':
                        newStr = modifier_M(vp, value, endc);
                        break;
                case 'S':
                        newStr = modifier_S(vp, value, v);
                        break;
                case 'C':
                        newStr = modifier_C(vp, value, v);
                        break;
                default:
                        if (vp->ptr[1] != endc && vp->ptr[1] != ':') {
#ifdef SUNSHCMD
                                if ((vp->ptr[0] == 's') &&
                                    (vp->ptr[1] == 'h') &&
                                    (vp->ptr[2] == endc || vp->ptr[2] == ':')) {
                                        const char      *error;

                                        if (vp->execute) {
                                                newStr = Buf_Peel(
                                                    Cmd_Exec(value, &error));
                                        } else {
                                                newStr = estrdup("");
                                        }

                                        if (error)
                                                Error(error, value);
                                        vp->ptr += 2;
                                } else
#endif
                                {
                                        newStr = sysVvarsub(vp, startc, v, value);
                                }
                                break;
                        }

                        switch (vp->ptr[0]) {
                        case 'L':
                                {
                                const char      *cp;
                                Buffer          *buf;
                                buf = Buf_Init(MAKE_BSIZE);
                                for (cp = value; *cp; cp++)
                                        Buf_AddByte(buf, tolower((unsigned char)*cp));

                                newStr = Buf_Peel(buf);

                                vp->ptr++;
                                break;
                                }
                        case 'O':
                                newStr = VarSortWords(value, SortIncreasing);
                                vp->ptr++;
                                break;
                        case 'Q':
                                newStr = Var_Quote(value);
                                vp->ptr++;
                                break;
                        case 'T':
                                newStr = VarModify(value, VarTail, NULL);
                                vp->ptr++;
                                break;
                        case 'U':
                                {
                                const char      *cp;
                                Buffer          *buf;
                                buf = Buf_Init(MAKE_BSIZE);
                                for (cp = value; *cp; cp++)
                                        Buf_AddByte(buf, toupper((unsigned char)*cp));

                                newStr = Buf_Peel(buf);

                                vp->ptr++;
                                break;
                                }
                        case 'H':
                                newStr = VarModify(value, VarHead, NULL);
                                vp->ptr++;
                                break;
                        case 'E':
                                newStr = VarModify(value, VarSuffix, NULL);
                                vp->ptr++;
                                break;
                        case 'R':
                                newStr = VarModify(value, VarRoot, NULL);
                                vp->ptr++;
                                break;
                        default:
                                newStr = sysVvarsub(vp, startc, v, value);
                                break;
                        }
                        break;
                }

                DEBUGF(VAR, ("Result is \"%s\"\n", newStr));
                if (*freeResult) {
                        free(value);
                }

                value = newStr;
                *freeResult = (value == var_Error) ? false : true;

                if (vp->ptr[0] == ':') {
                        vp->ptr++;      /* consume colon */
                }
        }

        return (value);
}

static char *
ParseRestModifier(VarParser *vp, char startc, Buffer *buf, bool *freeResult)
{
        const char      *vname;
        size_t          vlen;
        Var             *v;
        char            *value;

        vname = Buf_Data(buf);
        vlen = Buf_Size(buf);

        v = VarFindAny(vname, vp->ctxt);
        if (v != NULL) {
                value = ParseModifier(vp, startc, v, freeResult);
                return (value);
        }

        if ((vp->ctxt == VAR_CMD) || (vp->ctxt == VAR_GLOBAL)) {
                size_t  consumed;
                /*
                 * Still need to get to the end of the variable
                 * specification, so kludge up a Var structure for the
                 * modifications
                 */
                v = VarCreate(vname, NULL, VAR_JUNK);
                value = ParseModifier(vp, startc, v, freeResult);
                if (*freeResult) {
                        free(value);
                }
                VarDestroy(v, true);

                consumed = vp->ptr - vp->input + 1;
                /*
                 * If substituting a local variable in a non-local context,
                 * assume it's for dynamic source stuff. We have to handle
                 * this specially and return the longhand for the variable
                 * with the dollar sign escaped so it makes it back to the
                 * caller. Only four of the local variables are treated
                 * specially as they are the only four that will be set when
                 * dynamic sources are expanded.
                 */
                if (vlen == 1 ||
                    (vlen == 2 && (vname[1] == 'F' || vname[1] == 'D'))) {
                        if (strchr("!%*@", vname[0]) != NULL) {
                                value = emalloc(consumed + 1);
                                strncpy(value, vp->input, consumed);
                                value[consumed] = '\0';

                                *freeResult = true;
                                return (value);
                        }
                }
                if (vlen > 2 &&
                    vname[0] == '.' &&
                    isupper((unsigned char)vname[1])) {
                        if ((strncmp(vname, ".TARGET", vlen - 1) == 0) ||
                            (strncmp(vname, ".ARCHIVE", vlen - 1) == 0) ||
                            (strncmp(vname, ".PREFIX", vlen - 1) == 0) ||
                            (strncmp(vname, ".MEMBER", vlen - 1) == 0)) {
                                value = emalloc(consumed + 1);
                                strncpy(value, vp->input, consumed);
                                value[consumed] = '\0';

                                *freeResult = true;
                                return (value);
                        }
                }

                *freeResult = false;
                return (vp->err ? var_Error : varNoError);
        } else {
                /*
                 * Check for D and F forms of local variables since we're in
                 * a local context and the name is the right length.
                 */
                if (vlen == 2 &&
                    (vname[1] == 'F' || vname[1] == 'D') &&
                    (strchr("!%*<>@", vname[0]) != NULL)) {
                        char    name[2];

                        name[0] = vname[0];
                        name[1] = '\0';

                        v = VarFindOnly(name, vp->ctxt);
                        if (v != NULL) {
                                value = ParseModifier(vp, startc, v, freeResult);
                                return (value);
                        }
                }

                /*
                 * Still need to get to the end of the variable
                 * specification, so kludge up a Var structure for the
                 * modifications
                 */
                v = VarCreate(vname, NULL, VAR_JUNK);
                value = ParseModifier(vp, startc, v, freeResult);
                if (*freeResult) {
                        free(value);
                }
                VarDestroy(v, true);

                *freeResult = false;
                return (vp->err ? var_Error : varNoError);
        }
}

static char *
ParseRestEnd(VarParser *vp, Buffer *buf, bool *freeResult)
{
        const char      *vname;
        size_t          vlen;
        Var             *v;
        char            *value;

        vname = Buf_Data(buf);
        vlen = Buf_Size(buf);

        v = VarFindAny(vname, vp->ctxt);
        if (v != NULL) {
                value = VarExpand(v, vp);
                *freeResult = true;
                return (value);
        }

        if ((vp->ctxt == VAR_CMD) || (vp->ctxt == VAR_GLOBAL)) {
                size_t  consumed = vp->ptr - vp->input + 1;

                /*
                 * If substituting a local variable in a non-local context,
                 * assume it's for dynamic source stuff. We have to handle
                 * this specially and return the longhand for the variable
                 * with the dollar sign escaped so it makes it back to the
                 * caller. Only four of the local variables are treated
                 * specially as they are the only four that will be set when
                 * dynamic sources are expanded.
                 */
                if (vlen == 1 ||
                    (vlen == 2 && (vname[1] == 'F' || vname[1] == 'D'))) {
                        if (strchr("!%*@", vname[0]) != NULL) {
                                value = emalloc(consumed + 1);
                                strncpy(value, vp->input, consumed);
                                value[consumed] = '\0';

                                *freeResult = true;
                                return (value);
                        }
                }
                if (vlen > 2 &&
                    vname[0] == '.' &&
                    isupper((unsigned char)vname[1])) {
                        if ((strncmp(vname, ".TARGET", vlen - 1) == 0) ||
                            (strncmp(vname, ".ARCHIVE", vlen - 1) == 0) ||
                            (strncmp(vname, ".PREFIX", vlen - 1) == 0) ||
                            (strncmp(vname, ".MEMBER", vlen - 1) == 0)) {
                                value = emalloc(consumed + 1);
                                strncpy(value, vp->input, consumed);
                                value[consumed] = '\0';

                                *freeResult = true;
                                return (value);
                        }
                }
        } else {
                /*
                 * Check for D and F forms of local variables since we're in
                 * a local context and the name is the right length.
                 */
                if (vlen == 2 &&
                    (vname[1] == 'F' || vname[1] == 'D') &&
                    (strchr("!%*<>@", vname[0]) != NULL)) {
                        char    name[2];

                        name[0] = vname[0];
                        name[1] = '\0';

                        v = VarFindOnly(name, vp->ctxt);
                        if (v != NULL) {
                                char    *val;
                                /*
                                 * No need for nested expansion or anything,
                                 * as we're the only one who sets these
                                 * things and we sure don't put nested
                                 * invocations in them...
                                 */
                                val = Buf_Data(v->val);

                                if (vname[1] == 'D') {
                                        val = VarModify(val, VarHead, NULL);
                                } else {
                                        val = VarModify(val, VarTail, NULL);
                                }

                                *freeResult = true;
                                return (val);
                        }
                }
        }

        *freeResult = false;
        return (vp->err ? var_Error : varNoError);
}

/**
 * Parse a multi letter variable name, and return it's value.
 */
static char *
VarParseLong(VarParser *vp, bool *freeResult)
{
        Buffer          *buf;
        char            startc;
        char            endc;
        char            *value;

        buf = Buf_Init(MAKE_BSIZE);

        startc = vp->ptr[0];
        vp->ptr++;              /* consume opening paren or brace */

        endc = (startc == OPEN_PAREN) ? CLOSE_PAREN : CLOSE_BRACE;

        /*
         * Process characters until we reach an end character or a colon,
         * replacing embedded variables as we go.
         */
        while (*vp->ptr != '\0') {
                if (*vp->ptr == endc) {
                        value = ParseRestEnd(vp, buf, freeResult);
                        vp->ptr++;      /* consume closing paren or brace */
                        Buf_Destroy(buf, true);
                        return (value);

                } else if (*vp->ptr == ':') {
                        value = ParseRestModifier(vp, startc, buf, freeResult);
                        vp->ptr++;      /* consume closing paren or brace */
                        Buf_Destroy(buf, true);
                        return (value);

                } else if (*vp->ptr == '$') {
                        VarParser       subvp = {
                                vp->ptr,
                                vp->ptr,
                                vp->ctxt,
                                vp->err,
                                vp->execute
                        };
                        char    *rval;
                        bool    rfree;

                        rval = VarParse(&subvp, &rfree);
                        if (rval == var_Error) {
                                Fatal("Error expanding embedded variable.");
                        }
                        Buf_Append(buf, rval);
                        if (rfree)
                                free(rval);
                        vp->ptr = subvp.ptr;
                } else {
                        Buf_AddByte(buf, *vp->ptr);
                        vp->ptr++;
                }
        }

        /* If we did not find the end character, return var_Error */
        Buf_Destroy(buf, true);
        *freeResult = false;
        return (var_Error);
}

/**
 * Parse a single letter variable name, and return it's value.
 */
static char *
VarParseShort(VarParser *vp, bool *freeResult)
{
        char    vname[2];
        Var     *v;
        char    *value;

        vname[0] = vp->ptr[0];
        vname[1] = '\0';

        vp->ptr++;      /* consume single letter */

        v = VarFindAny(vname, vp->ctxt);
        if (v != NULL) {
                value = VarExpand(v, vp);
                *freeResult = true;
                return (value);
        }

        /*
         * If substituting a local variable in a non-local context, assume
         * it's for dynamic source stuff. We have to handle this specially
         * and return the longhand for the variable with the dollar sign
         * escaped so it makes it back to the caller. Only four of the local
         * variables are treated specially as they are the only four that
         * will be set when dynamic sources are expanded.
         */
        if ((vp->ctxt == VAR_CMD) || (vp->ctxt == VAR_GLOBAL)) {

                /* XXX: It looks like $% and $! are reversed here */
                switch (vname[0]) {
                case '@':
                        *freeResult = true;
                        return (estrdup("$(.TARGET)"));
                case '%':
                        *freeResult = true;
                        return (estrdup("$(.ARCHIVE)"));
                case '*':
                        *freeResult = true;
                        return (estrdup("$(.PREFIX)"));
                case '!':
                        *freeResult = true;
                        return (estrdup("$(.MEMBER)"));
                default:
                        *freeResult = false;
                        return (vp->err ? var_Error : varNoError);
                }
        }

        /* Variable name was not found. */
        *freeResult = false;
        return (vp->err ? var_Error : varNoError);
}

static char *
VarParse(VarParser *vp, bool *freeResult)
{

        vp->ptr++;      /* consume '$' or last letter of conditional */

        if (vp->ptr[0] == '\0') {
                /* Error, there is only a dollar sign in the input string. */
                *freeResult = false;
                return (vp->err ? var_Error : varNoError);

        } else if (vp->ptr[0] == OPEN_PAREN || vp->ptr[0] == OPEN_BRACE) {
                /* multi letter variable name */
                return (VarParseLong(vp, freeResult));

        } else {
                /* single letter variable name */
                return (VarParseShort(vp, freeResult));
        }
}

/**
 * Given the start of a variable invocation, extract the variable
 * name and find its value, then modify it according to the
 * specification.
 *
 * Results:
 *      The value of the variable or var_Error if the specification
 *      is invalid.  The number of characters in the specification
 *      is placed in the variable pointed to by consumed.  (for
 *      invalid specifications, this is just 2 to skip the '$' and
 *      the following letter, or 1 if '$' was the last character
 *      in the string).  A bool in *freeResult telling whether the
 *      returned string should be freed by the caller.
 */
char *
Var_Parse(const char input[], GNode *ctxt, bool err,
        size_t *consumed, bool *freeResult)
{
        VarParser       vp = {
                input,
                input,
                ctxt,
                err,
                true
        };
        char            *value;

        value = VarParse(&vp, freeResult);
        *consumed += vp.ptr - vp.input;
        return (value);
}

/*
 * Given the start of a variable invocation, determine the length
 * of the specification.
 *
 * Results:
 *      The number of characters in the specification.  For invalid
 *      specifications, this is just 2 to skip the '$' and the
 *      following letter, or 1 if '$' was the last character in the
 *      string.
 */
size_t
Var_Match(const char input[], GNode *ctxt)
{
        VarParser       vp = {
                input,
                input,
                ctxt,
                false,
                false
        };
        char            *value;
        bool            freeResult;

        value = VarParse(&vp, &freeResult);
        if (freeResult) {
                free(value);
        }
        return (vp.ptr - vp.input);
}

static int
match_var(const char str[], const char var[])
{
        const char      *start = str;
        size_t          len;

        str++;                  /* consume '$' */

        if (str[0] == OPEN_PAREN || str[0] == OPEN_BRACE) {
                str++;          /* consume opening paren or brace */

                while (str[0] != '\0') {
                        if (str[0] == '$') {
                                /*
                                 * A variable inside the variable. We cannot
                                 * expand the external variable yet.
                                 */
                                return (str - start);
                        } else if (str[0] == ':' ||
                                   str[0] == CLOSE_PAREN ||
                                   str[0] == CLOSE_BRACE) {
                                len = str - (start + 2);

                                if (var[len] == '\0' && strncmp(var, start + 2, len) == 0) {
                                        return (0);     /* match */
                                } else {
                                        /*
                                         * Not the variable we want to
                                         * expand.
                                         */
                                        return (str - start);
                                }
                        } else {
                                ++str;
                        }
                }
                return (str - start);
        } else {
                /* Single letter variable name */
                if (var[1] == '\0' && var[0] == str[0]) {
                        return (0);     /* match */
                } else {
                        str++;  /* consume variable name */
                        return (str - start);
                }
        }
}

/**
 * Substitute for all variables in the given string in the given
 * context If err is true, Parse_Error will be called when an
 * undefined variable is encountered.
 *
 * Results:
 *      The resulting string.
 *
 * Side Effects:
 *      None. The old string must be freed by the caller
 */
Buffer *
Var_Subst(const char str[], GNode *ctxt, bool err)
{
        bool    errorReported;
        Buffer *buf;            /* Buffer for forming things */

        /*
         * Set true if an error has already been reported to prevent a
         * plethora of messages when recursing. XXXHB this comment sounds
         * wrong.
         */
        errorReported = false;

        buf = Buf_Init(0);
        while (str[0] != '\0') {
                if ((str[0] == '$') && (str[1] == '$')) {
                        /*
                         * A dollar sign may be escaped with another dollar
                         * sign.  In such a case, we skip over the escape
                         * character and store the dollar sign into the
                         * buffer directly.
                         */
                        str++;
                        Buf_AddByte(buf, str[0]);
                        str++;

                } else if (str[0] == '$') {
                        /* Variable invocation. */
                        VarParser subvp = {
                                str,
                                str,
                                ctxt,
                                err,
                                true
                        };
                        char    *rval;
                        bool    rfree;

                        rval = VarParse(&subvp, &rfree);

                        /*
                         * When we come down here, val should either point to
                         * the value of this variable, suitably modified, or
                         * be NULL. Length should be the total length of the
                         * potential variable invocation (from $ to end
                         * character...)
                         */
                        if (rval == var_Error || rval == varNoError) {
                                /*
                                 * If performing old-time variable
                                 * substitution, skip over the variable and
                                 * continue with the substitution. Otherwise,
                                 * store the dollar sign and advance str so
                                 * we continue with the string...
                                 */
                                if (oldVars) {
                                        str = subvp.ptr;
                                } else if (err) {
                                        /*
                                         * If variable is undefined, complain
                                         * and skip the variable. The
                                         * complaint will stop us from doing
                                         * anything when the file is parsed.
                                         */
                                        if (!errorReported) {
                                                Parse_Error(PARSE_FATAL,
                                                            "Undefined variable \"%.*s\"", subvp.ptr - subvp.input, str);
                                        }
                                        errorReported = true;
                                        str = subvp.ptr;
                                } else {
                                        Buf_AddByte(buf, str[0]);
                                        str++;
                                }
                        } else {
                                /*
                                 * Copy all the characters from the variable
                                 * value straight into the new string.
                                 */
                                Buf_Append(buf, rval);
                                if (rfree) {
                                        free(rval);
                                }
                                str = subvp.ptr;
                        }
                } else {
                        Buf_AddByte(buf, str[0]);
                        str++;
                }
        }

        return (buf);
}

/**
 * Substitute for all variables except if it is the same as 'var',
 * in the given string in the given context.  If err is true,
 * Parse_Error will be called when an undefined variable is
 * encountered.
 *
 * Results:
 *      The resulting string.
 *
 * Side Effects:
 *      None. The old string must be freed by the caller
 */
Buffer *
Var_SubstOnly(const char var[], const char str[], bool err)
{
        GNode *ctxt = VAR_GLOBAL;
        bool    errorReported;
        Buffer  *buf;           /* Buffer for forming things */

        /*
         * Set true if an error has already been reported to prevent a
         * plethora of messages when recursing. XXXHB this comment sounds
         * wrong.
         */
        errorReported = false;

        buf = Buf_Init(0);
        while (str[0] != '\0') {
                if (str[0] == '$') {
                        int     skip;

                        skip = match_var(str, var);
                        if (skip > 0) {
                                Buf_AddBytes(buf, skip, str);
                                str += skip;
                        } else {
                                /* Variable invocation. */
                                VarParser       subvp = {
                                        str,
                                        str,
                                        ctxt,
                                        err,
                                        true
                                };
                                char    *rval;
                                bool    rfree;

                                rval = VarParse(&subvp, &rfree);

                                /*
                                 * When we get down here, rval should either
                                 * point to the value of this variable, or be
                                 * NULL.
                                 */
                                if (rval == var_Error || rval == varNoError) {
                                        /*
                                         * If performing old-time variable
                                         * substitution, skip over the
                                         * variable and continue with the
                                         * substitution. Otherwise, store the
                                         * dollar sign and advance str so we
                                         * continue with the string...
                                         */
                                        if (oldVars) {
                                                str = subvp.ptr;
                                        } else if (err) {
                                                /*
                                                 * If variable is undefined,
                                                 * complain and skip the
                                                 * variable. The complaint
                                                 * will stop us from doing
                                                 * anything when the file is
                                                 * parsed.
                                                 */
                                                if (!errorReported) {
                                                        Parse_Error(PARSE_FATAL,
                                                                    "Undefined variable \"%.*s\"", subvp.ptr - subvp.input, str);
                                                }
                                                errorReported = true;
                                                str = subvp.ptr;
                                        } else {
                                                Buf_AddByte(buf, str[0]);
                                                str++;
                                        }
                                } else {
                                        /*
                                         * Copy all the characters from the
                                         * variable value straight into the
                                         * new string.
                                         */
                                        Buf_Append(buf, rval);
                                        if (rfree) {
                                                free(rval);
                                        }
                                        str = subvp.ptr;
                                }
                        }
                } else {
                        Buf_AddByte(buf, str[0]);
                        str++;
                }
        }

        return (buf);
}

/**
 * Initialize the module
 *
 * Side Effects:
 *      The VAR_CMD and VAR_GLOBAL contexts are created
 */
void
Var_Init(char **env)
{
        char    **ptr;

        VAR_CMD = Targ_NewGN("Command");
        VAR_ENV = Targ_NewGN("Environment");
        VAR_GLOBAL = Targ_NewGN("Global");

        /*
         * Copy user environment variables into ENV context.
         */
        for (ptr = env; *ptr != NULL; ++ptr) {
                char            *tmp = estrdup(*ptr);
                const char      *name = tmp;
                char            *sep = strchr(name, '=');

                if (sep != NULL) {
                        const char      *value = sep + 1;

                        *sep = '\0';
                        VarAdd(name, value, VAR_ENV);
                }
                free(tmp);
        }
}

/**
 * Print all variables in global and command line contexts.
 */
void
Var_Dump(void)
{
        const LstNode   *ln;
        const Var       *v;

        printf("#*** Global Variables:\n");
        LST_FOREACH(ln, &VAR_GLOBAL->context) {
                v = Lst_Datum(ln);
                printf("%-16s = %s\n", v->name, Buf_Data(v->val));
        }

        printf("#*** Command-line Variables:\n");
        LST_FOREACH(ln, &VAR_CMD->context) {
                v = Lst_Datum(ln);
                printf("%-16s = %s\n", v->name, Buf_Data(v->val));
        }
}

/**
 * Print the values of any variables requested by
 * the user.
 */
void
Var_Print(Lst *vlist, bool expandVars)
{
        LstNode         *n;

        LST_FOREACH(n, vlist) {
                const char *name = Lst_Datum(n);

                if (expandVars) {
                        char            *v;
                        char            *value;

                        v = emalloc(strlen(name) + 1 + 3);
                        sprintf(v, "${%s}", name);

                        value = Buf_Peel(Var_Subst(v, VAR_GLOBAL, false));
                        printf("%s\n", value);

                        free(v);
                        free(value);
                } else {
                        const char *value = Var_Value(name, VAR_GLOBAL);
                        printf("%s\n", value != NULL ? value : "");
                }
        }
}