sdhci - Implement ADMA2 transfer support. Keep SDMA support for now.

[dragonfly.git] / contrib / bmake / cond.c

/*      $NetBSD: cond.c,v 1.74 2016/02/18 18:29:14 christos Exp $       */

/*
 * Copyright (c) 1988, 1989, 1990 The Regents of the University of California.
 * 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. 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.
 */

/*
 * Copyright (c) 1988, 1989 by Adam de Boor
 * 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.
 */

#ifndef MAKE_NATIVE
static char rcsid[] = "$NetBSD: cond.c,v 1.74 2016/02/18 18:29:14 christos Exp $";
#else
#include <sys/cdefs.h>
#ifndef lint
#if 0
static char sccsid[] = "@(#)cond.c      8.2 (Berkeley) 1/2/94";
#else
__RCSID("$NetBSD: cond.c,v 1.74 2016/02/18 18:29:14 christos Exp $");
#endif
#endif /* not lint */
#endif

/*-
 * cond.c --
 *      Functions to handle conditionals in a makefile.
 *
 * Interface:
 *      Cond_Eval       Evaluate the conditional in the passed line.
 *
 */

#include    <ctype.h>
#include    <errno.h>    /* For strtoul() error checking */

#include    "make.h"
#include    "hash.h"
#include    "dir.h"
#include    "buf.h"

/*
 * The parsing of conditional expressions is based on this grammar:
 *      E -> F || E
 *      E -> F
 *      F -> T && F
 *      F -> T
 *      T -> defined(variable)
 *      T -> make(target)
 *      T -> exists(file)
 *      T -> empty(varspec)
 *      T -> target(name)
 *      T -> commands(name)
 *      T -> symbol
 *      T -> $(varspec) op value
 *      T -> $(varspec) == "string"
 *      T -> $(varspec) != "string"
 *      T -> "string"
 *      T -> ( E )
 *      T -> ! T
 *      op -> == | != | > | < | >= | <=
 *
 * 'symbol' is some other symbol to which the default function (condDefProc)
 * is applied.
 *
 * Tokens are scanned from the 'condExpr' string. The scanner (CondToken)
 * will return TOK_AND for '&' and '&&', TOK_OR for '|' and '||',
 * TOK_NOT for '!', TOK_LPAREN for '(', TOK_RPAREN for ')' and will evaluate
 * the other terminal symbols, using either the default function or the
 * function given in the terminal, and return the result as either TOK_TRUE
 * or TOK_FALSE.
 *
 * TOK_FALSE is 0 and TOK_TRUE 1 so we can directly assign C comparisons.
 *
 * All Non-Terminal functions (CondE, CondF and CondT) return TOK_ERROR on
 * error.
 */
typedef enum {
    TOK_FALSE = 0, TOK_TRUE = 1, TOK_AND, TOK_OR, TOK_NOT,
    TOK_LPAREN, TOK_RPAREN, TOK_EOF, TOK_NONE, TOK_ERROR
} Token;

/*-
 * Structures to handle elegantly the different forms of #if's. The
 * last two fields are stored in condInvert and condDefProc, respectively.
 */
static void CondPushBack(Token);
static int CondGetArg(char **, char **, const char *);
static Boolean CondDoDefined(int, const char *);
static int CondStrMatch(const void *, const void *);
static Boolean CondDoMake(int, const char *);
static Boolean CondDoExists(int, const char *);
static Boolean CondDoTarget(int, const char *);
static Boolean CondDoCommands(int, const char *);
static Boolean CondCvtArg(char *, double *);
static Token CondToken(Boolean);
static Token CondT(Boolean);
static Token CondF(Boolean);
static Token CondE(Boolean);
static int do_Cond_EvalExpression(Boolean *);

static const struct If {
    const char  *form;        /* Form of if */
    int         formlen;      /* Length of form */
    Boolean     doNot;        /* TRUE if default function should be negated */
    Boolean     (*defProc)(int, const char *); /* Default function to apply */
} ifs[] = {
    { "def",      3,      FALSE,  CondDoDefined },
    { "ndef",     4,      TRUE,   CondDoDefined },
    { "make",     4,      FALSE,  CondDoMake },
    { "nmake",    5,      TRUE,   CondDoMake },
    { "",         0,      FALSE,  CondDoDefined },
    { NULL,       0,      FALSE,  NULL }
};

static const struct If *if_info;        /* Info for current statement */
static char       *condExpr;            /* The expression to parse */
static Token      condPushBack=TOK_NONE;        /* Single push-back token used in
                                         * parsing */

static unsigned int     cond_depth = 0;         /* current .if nesting level */
static unsigned int     cond_min_depth = 0;     /* depth at makefile open */

/*
 * Indicate when we should be strict about lhs of comparisons.
 * TRUE when Cond_EvalExpression is called from Cond_Eval (.if etc)
 * FALSE when Cond_EvalExpression is called from var.c:ApplyModifiers
 * since lhs is already expanded and we cannot tell if 
 * it was a variable reference or not.
 */
static Boolean lhsStrict;

static int
istoken(const char *str, const char *tok, size_t len)
{
        return strncmp(str, tok, len) == 0 && !isalpha((unsigned char)str[len]);
}

/*-
 *-----------------------------------------------------------------------
 * CondPushBack --
 *      Push back the most recent token read. We only need one level of
 *      this, so the thing is just stored in 'condPushback'.
 *
 * Input:
 *      t               Token to push back into the "stream"
 *
 * Results:
 *      None.
 *
 * Side Effects:
 *      condPushback is overwritten.
 *
 *-----------------------------------------------------------------------
 */
static void
CondPushBack(Token t)
{
    condPushBack = t;
}
\f
/*-
 *-----------------------------------------------------------------------
 * CondGetArg --
 *      Find the argument of a built-in function.
 *
 * Input:
 *      parens          TRUE if arg should be bounded by parens
 *
 * Results:
 *      The length of the argument and the address of the argument.
 *
 * Side Effects:
 *      The pointer is set to point to the closing parenthesis of the
 *      function call.
 *
 *-----------------------------------------------------------------------
 */
static int
CondGetArg(char **linePtr, char **argPtr, const char *func)
{
    char          *cp;
    int           argLen;
    Buffer        buf;
    int           paren_depth;
    char          ch;

    cp = *linePtr;
    if (func != NULL)
        /* Skip opening '(' - verfied by caller */
        cp++;

    if (*cp == '\0') {
        /*
         * No arguments whatsoever. Because 'make' and 'defined' aren't really
         * "reserved words", we don't print a message. I think this is better
         * than hitting the user with a warning message every time s/he uses
         * the word 'make' or 'defined' at the beginning of a symbol...
         */
        *argPtr = NULL;
        return (0);
    }

    while (*cp == ' ' || *cp == '\t') {
        cp++;
    }

    /*
     * Create a buffer for the argument and start it out at 16 characters
     * long. Why 16? Why not?
     */
    Buf_Init(&buf, 16);

    paren_depth = 0;
    for (;;) {
        ch = *cp;
        if (ch == 0 || ch == ' ' || ch == '\t')
            break;
        if ((ch == '&' || ch == '|') && paren_depth == 0)
            break;
        if (*cp == '$') {
            /*
             * Parse the variable spec and install it as part of the argument
             * if it's valid. We tell Var_Parse to complain on an undefined
             * variable, so we don't do it too. Nor do we return an error,
             * though perhaps we should...
             */
            char        *cp2;
            int         len;
            void        *freeIt;

            cp2 = Var_Parse(cp, VAR_CMD, VARF_UNDEFERR|VARF_WANTRES,
                            &len, &freeIt);
            Buf_AddBytes(&buf, strlen(cp2), cp2);
            free(freeIt);
            cp += len;
            continue;
        }
        if (ch == '(')
            paren_depth++;
        else
            if (ch == ')' && --paren_depth < 0)
                break;
        Buf_AddByte(&buf, *cp);
        cp++;
    }

    *argPtr = Buf_GetAll(&buf, &argLen);
    Buf_Destroy(&buf, FALSE);

    while (*cp == ' ' || *cp == '\t') {
        cp++;
    }

    if (func != NULL && *cp++ != ')') {
        Parse_Error(PARSE_WARNING, "Missing closing parenthesis for %s()",
                     func);
        return (0);
    }

    *linePtr = cp;
    return (argLen);
}
\f
/*-
 *-----------------------------------------------------------------------
 * CondDoDefined --
 *      Handle the 'defined' function for conditionals.
 *
 * Results:
 *      TRUE if the given variable is defined.
 *
 * Side Effects:
 *      None.
 *
 *-----------------------------------------------------------------------
 */
static Boolean
CondDoDefined(int argLen MAKE_ATTR_UNUSED, const char *arg)
{
    char    *p1;
    Boolean result;

    if (Var_Value(arg, VAR_CMD, &p1) != NULL) {
        result = TRUE;
    } else {
        result = FALSE;
    }

    free(p1);
    return (result);
}
\f
/*-
 *-----------------------------------------------------------------------
 * CondStrMatch --
 *      Front-end for Str_Match so it returns 0 on match and non-zero
 *      on mismatch. Callback function for CondDoMake via Lst_Find
 *
 * Results:
 *      0 if string matches pattern
 *
 * Side Effects:
 *      None
 *
 *-----------------------------------------------------------------------
 */
static int
CondStrMatch(const void *string, const void *pattern)
{
    return(!Str_Match(string, pattern));
}
\f
/*-
 *-----------------------------------------------------------------------
 * CondDoMake --
 *      Handle the 'make' function for conditionals.
 *
 * Results:
 *      TRUE if the given target is being made.
 *
 * Side Effects:
 *      None.
 *
 *-----------------------------------------------------------------------
 */
static Boolean
CondDoMake(int argLen MAKE_ATTR_UNUSED, const char *arg)
{
    return Lst_Find(create, arg, CondStrMatch) != NULL;
}
\f
/*-
 *-----------------------------------------------------------------------
 * CondDoExists --
 *      See if the given file exists.
 *
 * Results:
 *      TRUE if the file exists and FALSE if it does not.
 *
 * Side Effects:
 *      None.
 *
 *-----------------------------------------------------------------------
 */
static Boolean
CondDoExists(int argLen MAKE_ATTR_UNUSED, const char *arg)
{
    Boolean result;
    char    *path;

    path = Dir_FindFile(arg, dirSearchPath);
    if (DEBUG(COND)) {
        fprintf(debug_file, "exists(%s) result is \"%s\"\n",
               arg, path ? path : "");
    }    
    if (path != NULL) {
        result = TRUE;
        free(path);
    } else {
        result = FALSE;
    }
    return (result);
}
\f
/*-
 *-----------------------------------------------------------------------
 * CondDoTarget --
 *      See if the given node exists and is an actual target.
 *
 * Results:
 *      TRUE if the node exists as a target and FALSE if it does not.
 *
 * Side Effects:
 *      None.
 *
 *-----------------------------------------------------------------------
 */
static Boolean
CondDoTarget(int argLen MAKE_ATTR_UNUSED, const char *arg)
{
    GNode   *gn;

    gn = Targ_FindNode(arg, TARG_NOCREATE);
    return (gn != NULL) && !OP_NOP(gn->type);
}

/*-
 *-----------------------------------------------------------------------
 * CondDoCommands --
 *      See if the given node exists and is an actual target with commands
 *      associated with it.
 *
 * Results:
 *      TRUE if the node exists as a target and has commands associated with
 *      it and FALSE if it does not.
 *
 * Side Effects:
 *      None.
 *
 *-----------------------------------------------------------------------
 */
static Boolean
CondDoCommands(int argLen MAKE_ATTR_UNUSED, const char *arg)
{
    GNode   *gn;

    gn = Targ_FindNode(arg, TARG_NOCREATE);
    return (gn != NULL) && !OP_NOP(gn->type) && !Lst_IsEmpty(gn->commands);
}
\f
/*-
 *-----------------------------------------------------------------------
 * CondCvtArg --
 *      Convert the given number into a double.
 *      We try a base 10 or 16 integer conversion first, if that fails
 *      then we try a floating point conversion instead.
 *
 * Results:
 *      Sets 'value' to double value of string.
 *      Returns 'true' if the convertion suceeded
 *
 *-----------------------------------------------------------------------
 */
static Boolean
CondCvtArg(char *str, double *value)
{
    char *eptr, ech;
    unsigned long l_val;
    double d_val;

    errno = 0;
    if (!*str) {
        *value = (double)0;
        return TRUE;
    }
    l_val = strtoul(str, &eptr, str[1] == 'x' ? 16 : 10);
    ech = *eptr;
    if (ech == 0 && errno != ERANGE) {
        d_val = str[0] == '-' ? -(double)-l_val : (double)l_val;
    } else {
        if (ech != 0 && ech != '.' && ech != 'e' && ech != 'E')
            return FALSE;
        d_val = strtod(str, &eptr);
        if (*eptr)
            return FALSE;
    }

    *value = d_val;
    return TRUE;
}

/*-
 *-----------------------------------------------------------------------
 * CondGetString --
 *      Get a string from a variable reference or an optionally quoted
 *      string.  This is called for the lhs and rhs of string compares.
 *
 * Results:
 *      Sets freeIt if needed,
 *      Sets quoted if string was quoted,
 *      Returns NULL on error,
 *      else returns string - absent any quotes.
 *
 * Side Effects:
 *      Moves condExpr to end of this token.
 *
 *
 *-----------------------------------------------------------------------
 */
/* coverity:[+alloc : arg-*2] */
static char *
CondGetString(Boolean doEval, Boolean *quoted, void **freeIt, Boolean strictLHS)
{
    Buffer buf;
    char *cp;
    char *str;
    int len;
    int qt;
    char *start;

    Buf_Init(&buf, 0);
    str = NULL;
    *freeIt = NULL;
    *quoted = qt = *condExpr == '"' ? 1 : 0;
    if (qt)
        condExpr++;
    for (start = condExpr; *condExpr && str == NULL; condExpr++) {
        switch (*condExpr) {
        case '\\':
            if (condExpr[1] != '\0') {
                condExpr++;
                Buf_AddByte(&buf, *condExpr);
            }
            break;
        case '"':
            if (qt) {
                condExpr++;             /* we don't want the quotes */
                goto got_str;
            } else
                Buf_AddByte(&buf, *condExpr); /* likely? */
            break;
        case ')':
        case '!':
        case '=':
        case '>':
        case '<':
        case ' ':
        case '\t':
            if (!qt)
                goto got_str;
            else
                Buf_AddByte(&buf, *condExpr);
            break;
        case '$':
            /* if we are in quotes, then an undefined variable is ok */
            str = Var_Parse(condExpr, VAR_CMD,
                            ((!qt && doEval) ? VARF_UNDEFERR : 0) |
                            VARF_WANTRES, &len, freeIt);
            if (str == var_Error) {
                if (*freeIt) {
                    free(*freeIt);
                    *freeIt = NULL;
                }
                /*
                 * Even if !doEval, we still report syntax errors, which
                 * is what getting var_Error back with !doEval means.
                 */
                str = NULL;
                goto cleanup;
            }
            condExpr += len;
            /*
             * If the '$' was first char (no quotes), and we are
             * followed by space, the operator or end of expression,
             * we are done.
             */
            if ((condExpr == start + len) &&
                (*condExpr == '\0' ||
                 isspace((unsigned char) *condExpr) ||
                 strchr("!=><)", *condExpr))) {
                goto cleanup;
            }
            /*
             * Nope, we better copy str to buf
             */
            for (cp = str; *cp; cp++) {
                Buf_AddByte(&buf, *cp);
            }
            if (*freeIt) {
                free(*freeIt);
                *freeIt = NULL;
            }
            str = NULL;                 /* not finished yet */
            condExpr--;                 /* don't skip over next char */
            break;
        default:
            if (strictLHS && !qt && *start != '$' &&
                !isdigit((unsigned char) *start)) {
                /* lhs must be quoted, a variable reference or number */
                if (*freeIt) {
                    free(*freeIt);
                    *freeIt = NULL;
                }
                str = NULL;
                goto cleanup;
            }
            Buf_AddByte(&buf, *condExpr);
            break;
        }
    }
 got_str:
    str = Buf_GetAll(&buf, NULL);
    *freeIt = str;
 cleanup:
    Buf_Destroy(&buf, FALSE);
    return str;
}
\f
/*-
 *-----------------------------------------------------------------------
 * CondToken --
 *      Return the next token from the input.
 *
 * Results:
 *      A Token for the next lexical token in the stream.
 *
 * Side Effects:
 *      condPushback will be set back to TOK_NONE if it is used.
 *
 *-----------------------------------------------------------------------
 */
static Token
compare_expression(Boolean doEval)
{
    Token       t;
    char        *lhs;
    char        *rhs;
    char        *op;
    void        *lhsFree;
    void        *rhsFree;
    Boolean lhsQuoted;
    Boolean rhsQuoted;
    double      left, right;

    t = TOK_ERROR;
    rhs = NULL;
    lhsFree = rhsFree = FALSE;
    lhsQuoted = rhsQuoted = FALSE;
    
    /*
     * Parse the variable spec and skip over it, saving its
     * value in lhs.
     */
    lhs = CondGetString(doEval, &lhsQuoted, &lhsFree, lhsStrict);
    if (!lhs)
        goto done;

    /*
     * Skip whitespace to get to the operator
     */
    while (isspace((unsigned char) *condExpr))
        condExpr++;

    /*
     * Make sure the operator is a valid one. If it isn't a
     * known relational operator, pretend we got a
     * != 0 comparison.
     */
    op = condExpr;
    switch (*condExpr) {
        case '!':
        case '=':
        case '<':
        case '>':
            if (condExpr[1] == '=') {
                condExpr += 2;
            } else {
                condExpr += 1;
            }
            break;
        default:
            if (!doEval) {
                t = TOK_FALSE;
                goto done;
            }
            /* For .ifxxx "..." check for non-empty string. */
            if (lhsQuoted) {
                t = lhs[0] != 0;
                goto done;
            }
            /* For .ifxxx <number> compare against zero */
            if (CondCvtArg(lhs, &left)) { 
                t = left != 0.0;
                goto done;
            }
            /* For .if ${...} check for non-empty string (defProc is ifdef). */
            if (if_info->form[0] == 0) {
                t = lhs[0] != 0;
                goto done;
            }
            /* Otherwise action default test ... */
            t = if_info->defProc(strlen(lhs), lhs) != if_info->doNot;
            goto done;
    }

    while (isspace((unsigned char)*condExpr))
        condExpr++;

    if (*condExpr == '\0') {
        Parse_Error(PARSE_WARNING,
                    "Missing right-hand-side of operator");
        goto done;
    }

    rhs = CondGetString(doEval, &rhsQuoted, &rhsFree, FALSE);
    if (!rhs)
        goto done;

    if (rhsQuoted || lhsQuoted) {
do_string_compare:
        if (((*op != '!') && (*op != '=')) || (op[1] != '=')) {
            Parse_Error(PARSE_WARNING,
    "String comparison operator should be either == or !=");
            goto done;
        }

        if (DEBUG(COND)) {
            fprintf(debug_file, "lhs = \"%s\", rhs = \"%s\", op = %.2s\n",
                   lhs, rhs, op);
        }
        /*
         * Null-terminate rhs and perform the comparison.
         * t is set to the result.
         */
        if (*op == '=') {
            t = strcmp(lhs, rhs) == 0;
        } else {
            t = strcmp(lhs, rhs) != 0;
        }
    } else {
        /*
         * rhs is either a float or an integer. Convert both the
         * lhs and the rhs to a double and compare the two.
         */
    
        if (!CondCvtArg(lhs, &left) || !CondCvtArg(rhs, &right))
            goto do_string_compare;

        if (DEBUG(COND)) {
            fprintf(debug_file, "left = %f, right = %f, op = %.2s\n", left,
                   right, op);
        }
        switch(op[0]) {
        case '!':
            if (op[1] != '=') {
                Parse_Error(PARSE_WARNING,
                            "Unknown operator");
                goto done;
            }
            t = (left != right);
            break;
        case '=':
            if (op[1] != '=') {
                Parse_Error(PARSE_WARNING,
                            "Unknown operator");
                goto done;
            }
            t = (left == right);
            break;
        case '<':
            if (op[1] == '=') {
                t = (left <= right);
            } else {
                t = (left < right);
            }
            break;
        case '>':
            if (op[1] == '=') {
                t = (left >= right);
            } else {
                t = (left > right);
            }
            break;
        }
    }

done:
    free(lhsFree);
    free(rhsFree);
    return t;
}

static int
get_mpt_arg(char **linePtr, char **argPtr, const char *func MAKE_ATTR_UNUSED)
{
    /*
     * Use Var_Parse to parse the spec in parens and return
     * TOK_TRUE if the resulting string is empty.
     */
    int     length;
    void    *freeIt;
    char    *val;
    char    *cp = *linePtr;

    /* We do all the work here and return the result as the length */
    *argPtr = NULL;

    val = Var_Parse(cp - 1, VAR_CMD, VARF_WANTRES, &length, &freeIt);
    /*
     * Advance *linePtr to beyond the closing ). Note that
     * we subtract one because 'length' is calculated from 'cp - 1'.
     */
    *linePtr = cp - 1 + length;

    if (val == var_Error) {
        free(freeIt);
        return -1;
    }

    /* A variable is empty when it just contains spaces... 4/15/92, christos */
    while (isspace(*(unsigned char *)val))
        val++;

    /*
     * For consistency with the other functions we can't generate the
     * true/false here.
     */
    length = *val ? 2 : 1;
    free(freeIt);
    return length;
}

static Boolean
CondDoEmpty(int arglen, const char *arg MAKE_ATTR_UNUSED)
{
    return arglen == 1;
}

static Token
compare_function(Boolean doEval)
{
    static const struct fn_def {
        const char  *fn_name;
        int         fn_name_len;
        int         (*fn_getarg)(char **, char **, const char *);
        Boolean     (*fn_proc)(int, const char *);
    } fn_defs[] = {
        { "defined",   7, CondGetArg, CondDoDefined },
        { "make",      4, CondGetArg, CondDoMake },
        { "exists",    6, CondGetArg, CondDoExists },
        { "empty",     5, get_mpt_arg, CondDoEmpty },
        { "target",    6, CondGetArg, CondDoTarget },
        { "commands",  8, CondGetArg, CondDoCommands },
        { NULL,        0, NULL, NULL },
    };
    const struct fn_def *fn_def;
    Token       t;
    char        *arg = NULL;
    int arglen;
    char *cp = condExpr;
    char *cp1;

    for (fn_def = fn_defs; fn_def->fn_name != NULL; fn_def++) {
        if (!istoken(cp, fn_def->fn_name, fn_def->fn_name_len))
            continue;
        cp += fn_def->fn_name_len;
        /* There can only be whitespace before the '(' */
        while (isspace(*(unsigned char *)cp))
            cp++;
        if (*cp != '(')
            break;

        arglen = fn_def->fn_getarg(&cp, &arg, fn_def->fn_name);
        if (arglen <= 0) {
            condExpr = cp;
            return arglen < 0 ? TOK_ERROR : TOK_FALSE;
        }
        /* Evaluate the argument using the required function. */
        t = !doEval || fn_def->fn_proc(arglen, arg);
        free(arg);
        condExpr = cp;
        return t;
    }

    /* Push anything numeric through the compare expression */
    cp = condExpr;
    if (isdigit((unsigned char)cp[0]) || strchr("+-", cp[0]))
        return compare_expression(doEval);

    /*
     * Most likely we have a naked token to apply the default function to.
     * However ".if a == b" gets here when the "a" is unquoted and doesn't
     * start with a '$'. This surprises people.
     * If what follows the function argument is a '=' or '!' then the syntax
     * would be invalid if we did "defined(a)" - so instead treat as an
     * expression.
     */
    arglen = CondGetArg(&cp, &arg, NULL);
    for (cp1 = cp; isspace(*(unsigned char *)cp1); cp1++)
        continue;
    if (*cp1 == '=' || *cp1 == '!')
        return compare_expression(doEval);
    condExpr = cp;

    /*
     * Evaluate the argument using the default function.
     * This path always treats .if as .ifdef. To get here the character
     * after .if must have been taken literally, so the argument cannot
     * be empty - even if it contained a variable expansion.
     */
    t = !doEval || if_info->defProc(arglen, arg) != if_info->doNot;
    free(arg);
    return t;
}

static Token
CondToken(Boolean doEval)
{
    Token t;

    t = condPushBack;
    if (t != TOK_NONE) {
        condPushBack = TOK_NONE;
        return t;
    }

    while (*condExpr == ' ' || *condExpr == '\t') {
        condExpr++;
    }

    switch (*condExpr) {

    case '(':
        condExpr++;
        return TOK_LPAREN;

    case ')':
        condExpr++;
        return TOK_RPAREN;

    case '|':
        if (condExpr[1] == '|') {
            condExpr++;
        }
        condExpr++;
        return TOK_OR;

    case '&':
        if (condExpr[1] == '&') {
            condExpr++;
        }
        condExpr++;
        return TOK_AND;

    case '!':
        condExpr++;
        return TOK_NOT;

    case '#':
    case '\n':
    case '\0':
        return TOK_EOF;

    case '"':
    case '$':
        return compare_expression(doEval);

    default:
        return compare_function(doEval);
    }
}

/*-
 *-----------------------------------------------------------------------
 * CondT --
 *      Parse a single term in the expression. This consists of a terminal
 *      symbol or TOK_NOT and a terminal symbol (not including the binary
 *      operators):
 *          T -> defined(variable) | make(target) | exists(file) | symbol
 *          T -> ! T | ( E )
 *
 * Results:
 *      TOK_TRUE, TOK_FALSE or TOK_ERROR.
 *
 * Side Effects:
 *      Tokens are consumed.
 *
 *-----------------------------------------------------------------------
 */
static Token
CondT(Boolean doEval)
{
    Token   t;

    t = CondToken(doEval);

    if (t == TOK_EOF) {
        /*
         * If we reached the end of the expression, the expression
         * is malformed...
         */
        t = TOK_ERROR;
    } else if (t == TOK_LPAREN) {
        /*
         * T -> ( E )
         */
        t = CondE(doEval);
        if (t != TOK_ERROR) {
            if (CondToken(doEval) != TOK_RPAREN) {
                t = TOK_ERROR;
            }
        }
    } else if (t == TOK_NOT) {
        t = CondT(doEval);
        if (t == TOK_TRUE) {
            t = TOK_FALSE;
        } else if (t == TOK_FALSE) {
            t = TOK_TRUE;
        }
    }
    return (t);
}
\f
/*-
 *-----------------------------------------------------------------------
 * CondF --
 *      Parse a conjunctive factor (nice name, wot?)
 *          F -> T && F | T
 *
 * Results:
 *      TOK_TRUE, TOK_FALSE or TOK_ERROR
 *
 * Side Effects:
 *      Tokens are consumed.
 *
 *-----------------------------------------------------------------------
 */
static Token
CondF(Boolean doEval)
{
    Token   l, o;

    l = CondT(doEval);
    if (l != TOK_ERROR) {
        o = CondToken(doEval);

        if (o == TOK_AND) {
            /*
             * F -> T && F
             *
             * If T is TOK_FALSE, the whole thing will be TOK_FALSE, but we have to
             * parse the r.h.s. anyway (to throw it away).
             * If T is TOK_TRUE, the result is the r.h.s., be it an TOK_ERROR or no.
             */
            if (l == TOK_TRUE) {
                l = CondF(doEval);
            } else {
                (void)CondF(FALSE);
            }
        } else {
            /*
             * F -> T
             */
            CondPushBack(o);
        }
    }
    return (l);
}
\f
/*-
 *-----------------------------------------------------------------------
 * CondE --
 *      Main expression production.
 *          E -> F || E | F
 *
 * Results:
 *      TOK_TRUE, TOK_FALSE or TOK_ERROR.
 *
 * Side Effects:
 *      Tokens are, of course, consumed.
 *
 *-----------------------------------------------------------------------
 */
static Token
CondE(Boolean doEval)
{
    Token   l, o;

    l = CondF(doEval);
    if (l != TOK_ERROR) {
        o = CondToken(doEval);

        if (o == TOK_OR) {
            /*
             * E -> F || E
             *
             * A similar thing occurs for ||, except that here we make sure
             * the l.h.s. is TOK_FALSE before we bother to evaluate the r.h.s.
             * Once again, if l is TOK_FALSE, the result is the r.h.s. and once
             * again if l is TOK_TRUE, we parse the r.h.s. to throw it away.
             */
            if (l == TOK_FALSE) {
                l = CondE(doEval);
            } else {
                (void)CondE(FALSE);
            }
        } else {
            /*
             * E -> F
             */
            CondPushBack(o);
        }
    }
    return (l);
}

/*-
 *-----------------------------------------------------------------------
 * Cond_EvalExpression --
 *      Evaluate an expression in the passed line. The expression
 *      consists of &&, ||, !, make(target), defined(variable)
 *      and parenthetical groupings thereof.
 *
 * Results:
 *      COND_PARSE      if the condition was valid grammatically
 *      COND_INVALID    if not a valid conditional.
 *
 *      (*value) is set to the boolean value of the condition
 *
 * Side Effects:
 *      None.
 *
 *-----------------------------------------------------------------------
 */
int
Cond_EvalExpression(const struct If *info, char *line, Boolean *value, int eprint, Boolean strictLHS)
{
    static const struct If *dflt_info;
    const struct If *sv_if_info = if_info;
    char *sv_condExpr = condExpr;
    Token sv_condPushBack = condPushBack;
    int rval;

    lhsStrict = strictLHS;

    while (*line == ' ' || *line == '\t')
        line++;

    if (info == NULL && (info = dflt_info) == NULL) {
        /* Scan for the entry for .if - it can't be first */
        for (info = ifs; ; info++)
            if (info->form[0] == 0)
                break;
        dflt_info = info;
    }

    if_info = info != NULL ? info : ifs + 4;
    condExpr = line;
    condPushBack = TOK_NONE;

    rval = do_Cond_EvalExpression(value);

    if (rval == COND_INVALID && eprint)
        Parse_Error(PARSE_FATAL, "Malformed conditional (%s)", line);

    if_info = sv_if_info;
    condExpr = sv_condExpr;
    condPushBack = sv_condPushBack;

    return rval;
}

static int
do_Cond_EvalExpression(Boolean *value)
{

    switch (CondE(TRUE)) {
    case TOK_TRUE:
        if (CondToken(TRUE) == TOK_EOF) {
            *value = TRUE;
            return COND_PARSE;
        }
        break;
    case TOK_FALSE:
        if (CondToken(TRUE) == TOK_EOF) {
            *value = FALSE;
            return COND_PARSE;
        }
        break;
    default:
    case TOK_ERROR:
        break;
    }

    return COND_INVALID;
}

\f
/*-
 *-----------------------------------------------------------------------
 * Cond_Eval --
 *      Evaluate the conditional in the passed line. The line
 *      looks like this:
 *          .<cond-type> <expr>
 *      where <cond-type> is any of if, ifmake, ifnmake, ifdef,
 *      ifndef, elif, elifmake, elifnmake, elifdef, elifndef
 *      and <expr> consists of &&, ||, !, make(target), defined(variable)
 *      and parenthetical groupings thereof.
 *
 * Input:
 *      line            Line to parse
 *
 * Results:
 *      COND_PARSE      if should parse lines after the conditional
 *      COND_SKIP       if should skip lines after the conditional
 *      COND_INVALID    if not a valid conditional.
 *
 * Side Effects:
 *      None.
 *
 * Note that the states IF_ACTIVE and ELSE_ACTIVE are only different in order
 * to detect splurious .else lines (as are SKIP_TO_ELSE and SKIP_TO_ENDIF)
 * otherwise .else could be treated as '.elif 1'.
 *
 *-----------------------------------------------------------------------
 */
int
Cond_Eval(char *line)
{
#define     MAXIF      128      /* maximum depth of .if'ing */
#define     MAXIF_BUMP  32      /* how much to grow by */
    enum if_states {
        IF_ACTIVE,              /* .if or .elif part active */
        ELSE_ACTIVE,            /* .else part active */
        SEARCH_FOR_ELIF,        /* searching for .elif/else to execute */
        SKIP_TO_ELSE,           /* has been true, but not seen '.else' */
        SKIP_TO_ENDIF           /* nothing else to execute */
    };
    static enum if_states *cond_state = NULL;
    static unsigned int max_if_depth = MAXIF;

    const struct If *ifp;
    Boolean         isElif;
    Boolean         value;
    int             level;      /* Level at which to report errors. */
    enum if_states  state;

    level = PARSE_FATAL;
    if (!cond_state) {
        cond_state = bmake_malloc(max_if_depth * sizeof(*cond_state));
        cond_state[0] = IF_ACTIVE;
    }
    /* skip leading character (the '.') and any whitespace */
    for (line++; *line == ' ' || *line == '\t'; line++)
        continue;

    /* Find what type of if we're dealing with.  */
    if (line[0] == 'e') {
        if (line[1] != 'l') {
            if (!istoken(line + 1, "ndif", 4))
                return COND_INVALID;
            /* End of conditional section */
            if (cond_depth == cond_min_depth) {
                Parse_Error(level, "if-less endif");
                return COND_PARSE;
            }
            /* Return state for previous conditional */
            cond_depth--;
            return cond_state[cond_depth] <= ELSE_ACTIVE ? COND_PARSE : COND_SKIP;
        }

        /* Quite likely this is 'else' or 'elif' */
        line += 2;
        if (istoken(line, "se", 2)) {
            /* It is else... */
            if (cond_depth == cond_min_depth) {
                Parse_Error(level, "if-less else");
                return COND_PARSE;
            }

            state = cond_state[cond_depth];
            switch (state) {
            case SEARCH_FOR_ELIF:
                state = ELSE_ACTIVE;
                break;
            case ELSE_ACTIVE:
            case SKIP_TO_ENDIF:
                Parse_Error(PARSE_WARNING, "extra else");
                /* FALLTHROUGH */
            default:
            case IF_ACTIVE:
            case SKIP_TO_ELSE:
                state = SKIP_TO_ENDIF;
                break;
            }
            cond_state[cond_depth] = state;
            return state <= ELSE_ACTIVE ? COND_PARSE : COND_SKIP;
        }
        /* Assume for now it is an elif */
        isElif = TRUE;
    } else
        isElif = FALSE;

    if (line[0] != 'i' || line[1] != 'f')
        /* Not an ifxxx or elifxxx line */
        return COND_INVALID;

    /*
     * Figure out what sort of conditional it is -- what its default
     * function is, etc. -- by looking in the table of valid "ifs"
     */
    line += 2;
    for (ifp = ifs; ; ifp++) {
        if (ifp->form == NULL)
            return COND_INVALID;
        if (istoken(ifp->form, line, ifp->formlen)) {
            line += ifp->formlen;
            break;
        }
    }

    /* Now we know what sort of 'if' it is... */

    if (isElif) {
        if (cond_depth == cond_min_depth) {
            Parse_Error(level, "if-less elif");
            return COND_PARSE;
        }
        state = cond_state[cond_depth];
        if (state == SKIP_TO_ENDIF || state == ELSE_ACTIVE) {
            Parse_Error(PARSE_WARNING, "extra elif");
            cond_state[cond_depth] = SKIP_TO_ENDIF;
            return COND_SKIP;
        }
        if (state != SEARCH_FOR_ELIF) {
            /* Either just finished the 'true' block, or already SKIP_TO_ELSE */
            cond_state[cond_depth] = SKIP_TO_ELSE;
            return COND_SKIP;
        }
    } else {
        /* Normal .if */
        if (cond_depth + 1 >= max_if_depth) {
            /*
             * This is rare, but not impossible.
             * In meta mode, dirdeps.mk (only runs at level 0)
             * can need more than the default.
             */
            max_if_depth += MAXIF_BUMP;
            cond_state = bmake_realloc(cond_state, max_if_depth *
                sizeof(*cond_state));
        }
        state = cond_state[cond_depth];
        cond_depth++;
        if (state > ELSE_ACTIVE) {
            /* If we aren't parsing the data, treat as always false */
            cond_state[cond_depth] = SKIP_TO_ELSE;
            return COND_SKIP;
        }
    }

    /* And evaluate the conditional expresssion */
    if (Cond_EvalExpression(ifp, line, &value, 1, TRUE) == COND_INVALID) {
        /* Syntax error in conditional, error message already output. */
        /* Skip everything to matching .endif */
        cond_state[cond_depth] = SKIP_TO_ELSE;
        return COND_SKIP;
    }

    if (!value) {
        cond_state[cond_depth] = SEARCH_FOR_ELIF;
        return COND_SKIP;
    }
    cond_state[cond_depth] = IF_ACTIVE;
    return COND_PARSE;
}


\f
/*-
 *-----------------------------------------------------------------------
 * Cond_End --
 *      Make sure everything's clean at the end of a makefile.
 *
 * Results:
 *      None.
 *
 * Side Effects:
 *      Parse_Error will be called if open conditionals are around.
 *
 *-----------------------------------------------------------------------
 */
void
Cond_restore_depth(unsigned int saved_depth)
{
    int open_conds = cond_depth - cond_min_depth;

    if (open_conds != 0 || saved_depth > cond_depth) {
        Parse_Error(PARSE_FATAL, "%d open conditional%s", open_conds,
                    open_conds == 1 ? "" : "s");
        cond_depth = cond_min_depth;
    }

    cond_min_depth = saved_depth;
}

unsigned int
Cond_save_depth(void)
{
    int depth = cond_min_depth;

    cond_min_depth = cond_depth;
    return depth;
}