don't bother resolving onbld python module deps

[unleashed.git] / bin / ksh / misc.c

/*      $OpenBSD: misc.c,v 1.70 2018/04/09 17:53:36 tobias Exp $        */

/*
 * Miscellaneous functions
 */

#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "sh.h"
#include "charclass.h"

short ctypes [UCHAR_MAX+1];     /* type bits for unsigned char */

static int      do_gmatch(const unsigned char *, const unsigned char *,
                    const unsigned char *, const unsigned char *);
static const unsigned char *cclass(const unsigned char *, int);

/*
 * Fast character classes
 */
void
setctypes(const char *s, int t)
{
        int i;

        if (t & C_IFS) {
                for (i = 0; i < UCHAR_MAX+1; i++)
                        ctypes[i] &= ~C_IFS;
                ctypes[0] |= C_IFS; /* include \0 in C_IFS */
        }
        while (*s != 0)
                ctypes[(unsigned char) *s++] |= t;
}

void
initctypes(void)
{
        int c;

        for (c = 'a'; c <= 'z'; c++)
                ctypes[c] |= C_ALPHA;
        for (c = 'A'; c <= 'Z'; c++)
                ctypes[c] |= C_ALPHA;
        ctypes['_'] |= C_ALPHA;
        setctypes(" \t\n|&;<>()", C_LEX1); /* \0 added automatically */
        setctypes("*@#!$-?", C_VAR1);
        setctypes(" \t\n", C_IFSWS);
        setctypes("=-+?", C_SUBOP1);
        setctypes("#%", C_SUBOP2);
        setctypes(" \n\t\"#$&'()*;<>?[\\`|", C_QUOTE);
}

/* convert uint64_t to base N string */

char *
u64ton(uint64_t n, int base)
{
        char *p;
        static char buf [20];

        p = &buf[sizeof(buf)];
        *--p = '\0';
        do {
                *--p = "0123456789ABCDEF"[n%base];
                n /= base;
        } while (n != 0);
        return p;
}

char *
str_save(const char *s, Area *ap)
{
        size_t len;
        char *p;

        if (!s)
                return NULL;
        len = strlen(s)+1;
        p = alloc(len, ap);
        strlcpy(p, s, len);
        return (p);
}

/* Allocate a string of size n+1 and copy upto n characters from the possibly
 * null terminated string s into it.  Always returns a null terminated string
 * (unless n < 0).
 */
char *
str_nsave(const char *s, int n, Area *ap)
{
        char *ns;

        if (n < 0)
                return 0;
        ns = alloc(n + 1, ap);
        ns[0] = '\0';
        return strncat(ns, s, n);
}

/* called from expand.h:XcheckN() to grow buffer */
char *
Xcheck_grow_(XString *xsp, char *xp, size_t more)
{
        char *old_beg = xsp->beg;

        xsp->len += more > xsp->len ? more : xsp->len;
        xsp->beg = aresize(xsp->beg, xsp->len + 8, xsp->areap);
        xsp->end = xsp->beg + xsp->len;
        return xsp->beg + (xp - old_beg);
}

const struct option sh_options[] = {
        /* Special cases (see parse_args()): -A, -o, -s.
         * Options are sorted by their longnames - the order of these
         * entries MUST match the order of sh_flag F* enumerations in sh.h.
         */
        { "allexport",  'a',            OF_ANY },
        { "braceexpand",  0,            OF_ANY }, /* non-standard */
        { "bgnice",       0,            OF_ANY },
        { NULL, 'c',        OF_CMDLINE },
        { "csh-history",  0,            OF_ANY }, /* non-standard */
#ifdef EMACS
        { "emacs",        0,            OF_ANY },
#endif
        { "errexit",    'e',            OF_ANY },
#ifdef EMACS
        { "gmacs",        0,            OF_ANY },
#endif
        { "ignoreeof",    0,            OF_ANY },
        { "interactive",'i',        OF_CMDLINE },
        { "keyword",    'k',            OF_ANY },
        { "login",      'l',        OF_CMDLINE },
        { "markdirs",   'X',            OF_ANY },
        { "monitor",    'm',            OF_ANY },
        { "noclobber",  'C',            OF_ANY },
        { "noexec",     'n',            OF_ANY },
        { "noglob",     'f',            OF_ANY },
        { "nohup",        0,            OF_ANY },
        { "nolog",        0,            OF_ANY }, /* no effect */
        { "notify",     'b',            OF_ANY },
        { "nounset",    'u',            OF_ANY },
        { "physical",     0,            OF_ANY }, /* non-standard */
        { "posix",        0,            OF_ANY }, /* non-standard */
        { "privileged", 'p',            OF_ANY },
        { "restricted", 'r',        OF_CMDLINE },
        { "sh",           0,            OF_ANY }, /* non-standard */
        { "stdin",      's',        OF_CMDLINE }, /* pseudo non-standard */
        { "trackall",   'h',            OF_ANY },
        { "verbose",    'v',            OF_ANY },
#ifdef VI
        { "vi",           0,            OF_ANY },
        { "viraw",        0,            OF_ANY }, /* no effect */
        { "vi-show8",     0,            OF_ANY }, /* non-standard */
        { "vi-tabcomplete",  0,         OF_ANY }, /* non-standard */
        { "vi-esccomplete",  0,         OF_ANY }, /* non-standard */
#endif
        { "xtrace",     'x',            OF_ANY },
        /* Anonymous flags: used internally by shell only
         * (not visible to user)
         */
        { NULL, 0,              OF_INTERNAL }, /* FTALKING_I */
};

/*
 * translate -o option into F* constant (also used for test -o option)
 */
int
option(const char *n)
{
        unsigned int ele;

        for (ele = 0; ele < NELEM(sh_options); ele++)
                if (sh_options[ele].name && strcmp(sh_options[ele].name, n) == 0)
                        return ele;

        return -1;
}

struct options_info {
        int opt_width;
        struct {
                const char *name;
                int     flag;
        } opts[NELEM(sh_options)];
};

static char *options_fmt_entry(void *arg, int i, char *buf, int buflen);
static void printoptions(int verbose);

/* format a single select menu item */
static char *
options_fmt_entry(void *arg, int i, char *buf, int buflen)
{
        struct options_info *oi = (struct options_info *) arg;

        shf_snprintf(buf, buflen, "%-*s %s",
            oi->opt_width, oi->opts[i].name,
            Flag(oi->opts[i].flag) ? "on" : "off");
        return buf;
}

static void
printoptions(int verbose)
{
        unsigned int ele;

        if (verbose) {
                struct options_info oi;
                unsigned int n;
                int len;

                /* verbose version */
                shprintf("Current option settings\n");

                for (ele = n = oi.opt_width = 0; ele < NELEM(sh_options); ele++) {
                        if (sh_options[ele].name) {
                                len = strlen(sh_options[ele].name);
                                oi.opts[n].name = sh_options[ele].name;
                                oi.opts[n++].flag = ele;
                                if (len > oi.opt_width)
                                        oi.opt_width = len;
                        }
                }
                print_columns(shl_stdout, n, options_fmt_entry, &oi,
                    oi.opt_width + 5, 1);
        } else {
                /* short version ala ksh93 */
                shprintf("set");
                for (ele = 0; ele < NELEM(sh_options); ele++) {
                        if (sh_options[ele].name)
                                shprintf(" %co %s",
                                         Flag(ele) ? '-' : '+',
                                         sh_options[ele].name);
                }
                shprintf("\n");
        }
}

char *
getoptions(void)
{
        unsigned int ele;
        char m[(int) FNFLAGS + 1];
        char *cp = m;

        for (ele = 0; ele < NELEM(sh_options); ele++)
                if (sh_options[ele].c && Flag(ele))
                        *cp++ = sh_options[ele].c;
        *cp = 0;
        return str_save(m, ATEMP);
}

/* change a Flag(*) value; takes care of special actions */
void
change_flag(enum sh_flag f,
    int what,           /* flag to change */
    int newval)         /* what is changing the flag (command line vs set) */
{
        int oldval;

        oldval = Flag(f);
        Flag(f) = newval;
        if (f == FMONITOR) {
                if (what != OF_CMDLINE && newval != oldval)
                        j_change();
        } else
        if (0
#ifdef VI
            || f == FVI
#endif /* VI */
#ifdef EMACS
            || f == FEMACS || f == FGMACS
#endif /* EMACS */
           )
        {
                if (newval) {
#ifdef VI
                        Flag(FVI) = 0;
#endif /* VI */
#ifdef EMACS
                        Flag(FEMACS) = Flag(FGMACS) = 0;
#endif /* EMACS */
                        Flag(f) = newval;
                }
        } else
        /* Turning off -p? */
        if (f == FPRIVILEGED && oldval && !newval) {
                gid_t gid = getgid();

                setresgid(gid, gid, gid);
                setgroups(1, &gid);
                setresuid(ksheuid, ksheuid, ksheuid);
        } else if (f == FPOSIX && newval) {
                Flag(FBRACEEXPAND) = 0;
        }
        /* Changing interactive flag? */
        if (f == FTALKING) {
                if ((what == OF_CMDLINE || what == OF_SET) && procpid == kshpid)
                        Flag(FTALKING_I) = newval;
        }
}

/* parse command line & set command arguments.  returns the index of
 * non-option arguments, -1 if there is an error.
 */
int
parse_args(char **argv,
    int what,                   /* OF_CMDLINE or OF_SET */
    int *setargsp)
{
        static char cmd_opts[NELEM(sh_options) + 3]; /* o:\0 */
        static char set_opts[NELEM(sh_options) + 5]; /* Ao;s\0 */
        char *opts;
        char *array = NULL;
        Getopt go;
        int i, optc, sortargs = 0, arrayset = 0;
        unsigned int ele;

        /* First call?  Build option strings... */
        if (cmd_opts[0] == '\0') {
                char *p, *q;

                /* see cmd_opts[] declaration */
                strlcpy(cmd_opts, "o:", sizeof cmd_opts);
                p = cmd_opts + strlen(cmd_opts);
                /* see set_opts[] declaration */
                strlcpy(set_opts, "A:o;s", sizeof set_opts);
                q = set_opts + strlen(set_opts);
                for (ele = 0; ele < NELEM(sh_options); ele++) {
                        if (sh_options[ele].c) {
                                if (sh_options[ele].flags & OF_CMDLINE)
                                        *p++ = sh_options[ele].c;
                                if (sh_options[ele].flags & OF_SET)
                                        *q++ = sh_options[ele].c;
                        }
                }
                *p = '\0';
                *q = '\0';
        }

        if (what == OF_CMDLINE) {
                char *p;
                /* Set FLOGIN before parsing options so user can clear
                 * flag using +l.
                 */
                Flag(FLOGIN) = (argv[0][0] == '-' ||
                    ((p = strrchr(argv[0], '/')) && *++p == '-'));
                opts = cmd_opts;
        } else
                opts = set_opts;
        ksh_getopt_reset(&go, GF_ERROR|GF_PLUSOPT);
        while ((optc = ksh_getopt(argv, &go, opts)) != -1) {
                int set = (go.info & GI_PLUS) ? 0 : 1;
                switch (optc) {
                case 'A':
                        arrayset = set ? 1 : -1;
                        array = go.optarg;
                        break;

                case 'o':
                        if (go.optarg == NULL) {
                                /* lone -o: print options
                                 *
                                 * Note that on the command line, -o requires
                                 * an option (ie, can't get here if what is
                                 * OF_CMDLINE).
                                 */
                                printoptions(set);
                                break;
                        }
                        i = option(go.optarg);
                        if (i != -1 && set == Flag(i))
                                /* Don't check the context if the flag
                                 * isn't changing - makes "set -o interactive"
                                 * work if you're already interactive.  Needed
                                 * if the output of "set +o" is to be used.
                                 */
                                ;
                        else if (i != -1 && (sh_options[i].flags & what))
                                change_flag((enum sh_flag) i, what, set);
                        else {
                                bi_errorf("%s: bad option", go.optarg);
                                return -1;
                        }
                        break;

                case '?':
                        return -1;

                default:
                        /* -s: sort positional params (at&t ksh stupidity) */
                        if (what == OF_SET && optc == 's') {
                                sortargs = 1;
                                break;
                        }
                        for (ele = 0; ele < NELEM(sh_options); ele++)
                                if (optc == sh_options[ele].c &&
                                    (what & sh_options[ele].flags)) {
                                        change_flag((enum sh_flag) ele, what,
                                            set);
                                        break;
                                }
                        if (ele == NELEM(sh_options)) {
                                internal_errorf("%s: `%c'", __func__, optc);
                                return -1; /* not reached */
                        }
                }
        }
        if (!(go.info & GI_MINUSMINUS) && argv[go.optind] &&
            (argv[go.optind][0] == '-' || argv[go.optind][0] == '+') &&
            argv[go.optind][1] == '\0') {
                /* lone - clears -v and -x flags */
                if (argv[go.optind][0] == '-' && !Flag(FPOSIX))
                        Flag(FVERBOSE) = Flag(FXTRACE) = 0;
                /* set skips lone - or + option */
                go.optind++;
        }
        if (setargsp)
                /* -- means set $#/$* even if there are no arguments */
                *setargsp = !arrayset && ((go.info & GI_MINUSMINUS) ||
                    argv[go.optind]);

        if (arrayset && (!*array || *skip_varname(array, false))) {
                bi_errorf("%s: is not an identifier", array);
                return -1;
        }
        if (sortargs) {
                for (i = go.optind; argv[i]; i++)
                        ;
                qsortp((void **) &argv[go.optind], (size_t) (i - go.optind),
                    xstrcmp);
        }
        if (arrayset) {
                set_array(array, arrayset, argv + go.optind);
                for (; argv[go.optind]; go.optind++)
                        ;
        }

        return go.optind;
}

/* parse a decimal number: returns 0 if string isn't a number, 1 otherwise */
int
getn(const char *as, int *ai)
{
        char *p;
        long n;

        n = strtol(as, &p, 10);

        if (!*as || *p || INT_MIN >= n || n >= INT_MAX)
                return 0;

        *ai = (int)n;
        return 1;
}

/* getn() that prints error */
int
bi_getn(const char *as, int *ai)
{
        int rv = getn(as, ai);

        if (!rv)
                bi_errorf("%s: bad number", as);
        return rv;
}

/* -------- gmatch.c -------- */

/*
 * int gmatch(string, pattern)
 * char *string, *pattern;
 *
 * Match a pattern as in sh(1).
 * pattern character are prefixed with MAGIC by expand.
 */

int
gmatch(const char *s, const char *p, int isfile)
{
        const char *se, *pe;

        if (s == NULL || p == NULL)
                return 0;
        se = s + strlen(s);
        pe = p + strlen(p);
        /* isfile is false iff no syntax check has been done on
         * the pattern.  If check fails, just to a strcmp().
         */
        if (!isfile && !has_globbing(p, pe)) {
                size_t len = pe - p + 1;
                char tbuf[64];
                char *t = len <= sizeof(tbuf) ? tbuf :
                    alloc(len, ATEMP);
                debunk(t, p, len);
                return !strcmp(t, s);
        }
        return do_gmatch((const unsigned char *) s, (const unsigned char *) se,
            (const unsigned char *) p, (const unsigned char *) pe);
}

/* Returns if p is a syntacticly correct globbing pattern, false
 * if it contains no pattern characters or if there is a syntax error.
 * Syntax errors are:
 *      - [ with no closing ]
 *      - imbalanced $(...) expression
 *      - [...] and *(...) not nested (eg, [a$(b|]c), *(a[b|c]d))
 */
/*XXX
- if no magic,
        if dest given, copy to dst
        return ?
- if magic && (no globbing || syntax error)
        debunk to dst
        return ?
- return ?
*/
int
has_globbing(const char *xp, const char *xpe)
{
        const unsigned char *p = (const unsigned char *) xp;
        const unsigned char *pe = (const unsigned char *) xpe;
        int c;
        int nest = 0, bnest = 0;
        int saw_glob = 0;
        int in_bracket = 0; /* inside [...] */

        for (; p < pe; p++) {
                if (!ISMAGIC(*p))
                        continue;
                if ((c = *++p) == '*' || c == '?')
                        saw_glob = 1;
                else if (c == '[') {
                        if (!in_bracket) {
                                saw_glob = 1;
                                in_bracket = 1;
                                if (ISMAGIC(p[1]) && p[2] == '!')
                                        p += 2;
                                if (ISMAGIC(p[1]) && p[2] == ']')
                                        p += 2;
                        }
                        /* XXX Do we need to check ranges here? POSIX Q */
                } else if (c == ']') {
                        if (in_bracket) {
                                if (bnest)              /* [a*(b]) */
                                        return 0;
                                in_bracket = 0;
                        }
                } else if ((c & 0x80) && strchr("*+?@! ", c & 0x7f)) {
                        saw_glob = 1;
                        if (in_bracket)
                                bnest++;
                        else
                                nest++;
                } else if (c == '|') {
                        if (in_bracket && !bnest)       /* *(a[foo|bar]) */
                                return 0;
                } else if (c == /*(*/ ')') {
                        if (in_bracket) {
                                if (!bnest--)           /* *(a[b)c] */
                                        return 0;
                        } else if (nest)
                                nest--;
                }
                /* else must be a MAGIC-MAGIC, or MAGIC-!, MAGIC--, MAGIC-]
                         MAGIC-{, MAGIC-,, MAGIC-} */
        }
        return saw_glob && !in_bracket && !nest;
}

/* Function must return either 0 or 1 (assumed by code for 0x80|'!') */
static int
do_gmatch(const unsigned char *s, const unsigned char *se,
    const unsigned char *p, const unsigned char *pe)
{
        int sc, pc;
        const unsigned char *prest, *psub, *pnext;
        const unsigned char *srest;

        if (s == NULL || p == NULL)
                return 0;
        while (p < pe) {
                pc = *p++;
                sc = s < se ? *s : '\0';
                s++;
                if (!ISMAGIC(pc)) {
                        if (sc != pc)
                                return 0;
                        continue;
                }
                switch (*p++) {
                case '[':
                        if (sc == 0 || (p = cclass(p, sc)) == NULL)
                                return 0;
                        break;

                case '?':
                        if (sc == 0)
                                return 0;
                        break;

                case '*':
                        if (p == pe)
                                return 1;
                        s--;
                        do {
                                if (do_gmatch(s, se, p, pe))
                                        return 1;
                        } while (s++ < se);
                        return 0;

                  /*
                   * [*+?@!](pattern|pattern|..)
                   *
                   * Not ifdef'd KSH as this is needed for ${..%..}, etc.
                   */
                case 0x80|'+': /* matches one or more times */
                case 0x80|'*': /* matches zero or more times */
                        if (!(prest = pat_scan(p, pe, 0)))
                                return 0;
                        s--;
                        /* take care of zero matches */
                        if (p[-1] == (0x80 | '*') &&
                            do_gmatch(s, se, prest, pe))
                                return 1;
                        for (psub = p; ; psub = pnext) {
                                pnext = pat_scan(psub, pe, 1);
                                for (srest = s; srest <= se; srest++) {
                                        if (do_gmatch(s, srest, psub, pnext - 2) &&
                                            (do_gmatch(srest, se, prest, pe) ||
                                            (s != srest && do_gmatch(srest,
                                            se, p - 2, pe))))
                                                return 1;
                                }
                                if (pnext == prest)
                                        break;
                        }
                        return 0;

                case 0x80|'?': /* matches zero or once */
                case 0x80|'@': /* matches one of the patterns */
                case 0x80|' ': /* simile for @ */
                        if (!(prest = pat_scan(p, pe, 0)))
                                return 0;
                        s--;
                        /* Take care of zero matches */
                        if (p[-1] == (0x80 | '?') &&
                            do_gmatch(s, se, prest, pe))
                                return 1;
                        for (psub = p; ; psub = pnext) {
                                pnext = pat_scan(psub, pe, 1);
                                srest = prest == pe ? se : s;
                                for (; srest <= se; srest++) {
                                        if (do_gmatch(s, srest, psub, pnext - 2) &&
                                            do_gmatch(srest, se, prest, pe))
                                                return 1;
                                }
                                if (pnext == prest)
                                        break;
                        }
                        return 0;

                case 0x80|'!': /* matches none of the patterns */
                        if (!(prest = pat_scan(p, pe, 0)))
                                return 0;
                        s--;
                        for (srest = s; srest <= se; srest++) {
                                int matched = 0;

                                for (psub = p; ; psub = pnext) {
                                        pnext = pat_scan(psub, pe, 1);
                                        if (do_gmatch(s, srest, psub,
                                            pnext - 2)) {
                                                matched = 1;
                                                break;
                                        }
                                        if (pnext == prest)
                                                break;
                                }
                                if (!matched &&
                                    do_gmatch(srest, se, prest, pe))
                                        return 1;
                        }
                        return 0;

                default:
                        if (sc != p[-1])
                                return 0;
                        break;
                }
        }
        return s == se;
}

static int
posix_cclass(const unsigned char *pattern, int test, const unsigned char **ep)
{
        struct cclass *cc;
        const unsigned char *colon;
        size_t len;
        int rval = 0;

        if ((colon = strchr(pattern, ':')) == NULL || colon[1] != MAGIC) {
                *ep = pattern - 2;
                return -1;
        }
        *ep = colon + 3; /* skip MAGIC */
        len = (size_t)(colon - pattern);

        for (cc = cclasses; cc->name != NULL; cc++) {
                if (!strncmp(pattern, cc->name, len) && cc->name[len] == '\0') {
                        if (cc->isctype(test))
                                rval = 1;
                        break;
                }
        }
        if (cc->name == NULL) {
                rval = -2;      /* invalid character class */
        }
        return rval;
}

static const unsigned char *
cclass(const unsigned char *p, int sub)
{
        int c, d, rv, not, found = 0;
        const unsigned char *orig_p = p;

        if ((not = (ISMAGIC(*p) && *++p == '!')))
                p++;
        do {
                /* check for POSIX character class (e.g. [[:alpha:]]) */
                if ((p[0] == MAGIC && p[1] == '[' && p[2] == ':') ||
                    (p[0] == '[' && p[1] == ':')) {
                        do {
                                const char *pp = p + (*p == MAGIC) + 2;
                                rv = posix_cclass(pp, sub, &p);
                                switch (rv) {
                                case 1:
                                        found = 1;
                                        break;
                                case -2:
                                        return NULL;
                                }
                        } while (rv != -1 && p[0] == MAGIC && p[1] == '[' && p[2] == ':');
                        if (p[0] == MAGIC && p[1] == ']')
                                break;
                }

                c = *p++;
                if (ISMAGIC(c)) {
                        c = *p++;
                        if ((c & 0x80) && !ISMAGIC(c)) {
                                c &= 0x7f;/* extended pattern matching: *+?@! */
                                /* XXX the ( char isn't handled as part of [] */
                                if (c == ' ') /* simile for @: plain (..) */
                                        c = '(' /*)*/;
                        }
                }
                if (c == '\0')
                        /* No closing ] - act as if the opening [ was quoted */
                        return sub == '[' ? orig_p : NULL;
                if (ISMAGIC(p[0]) && p[1] == '-' &&
                    (!ISMAGIC(p[2]) || p[3] != ']')) {
                        p += 2; /* MAGIC- */
                        d = *p++;
                        if (ISMAGIC(d)) {
                                d = *p++;
                                if ((d & 0x80) && !ISMAGIC(d))
                                        d &= 0x7f;
                        }
                        /* POSIX says this is an invalid expression */
                        if (c > d)
                                return NULL;
                } else
                        d = c;
                if (c == sub || (c <= sub && sub <= d))
                        found = 1;
        } while (!(ISMAGIC(p[0]) && p[1] == ']'));

        return (found != not) ? p+2 : NULL;
}

/* Look for next ) or | (if match_sep) in *(foo|bar) pattern */
const unsigned char *
pat_scan(const unsigned char *p, const unsigned char *pe, int match_sep)
{
        int nest = 0;

        for (; p < pe; p++) {
                if (!ISMAGIC(*p))
                        continue;
                if ((*++p == /*(*/ ')' && nest-- == 0) ||
                    (*p == '|' && match_sep && nest == 0))
                        return ++p;
                if ((*p & 0x80) && strchr("*+?@! ", *p & 0x7f))
                        nest++;
        }
        return NULL;
}

/*
 * quick sort of array of generic pointers to objects.
 */
void
qsortp(void **base,                     /* base address */
    size_t n,                           /* elements */
    int (*f) (const void *, const void *)) /* compare function */
{
        qsort(base, n, sizeof(char *), f);
}

int
xstrcmp(const void *p1, const void *p2)
{
        return (strcmp(*(char **)p1, *(char **)p2));
}

/* Initialize a Getopt structure */
void
ksh_getopt_reset(Getopt *go, int flags)
{
        go->optind = 1;
        go->optarg = NULL;
        go->p = 0;
        go->flags = flags;
        go->info = 0;
        go->buf[1] = '\0';
}


/* getopt() used for shell built-in commands, the getopts command, and
 * command line options.
 * A leading ':' in options means don't print errors, instead return '?'
 * or ':' and set go->optarg to the offending option character.
 * If GF_ERROR is set (and option doesn't start with :), errors result in
 * a call to bi_errorf().
 *
 * Non-standard features:
 *      - ';' is like ':' in options, except the argument is optional
 *        (if it isn't present, optarg is set to 0).
 *        Used for 'set -o'.
 *      - ',' is like ':' in options, except the argument always immediately
 *        follows the option character (optarg is set to the null string if
 *        the option is missing).
 *        Used for 'read -u2', 'print -u2' and fc -40.
 *      - '#' is like ':' in options, expect that the argument is optional
 *        and must start with a digit or be the string "unlimited".  If the
 *        argument doesn't match, it is assumed to be missing and normal option
 *        processing continues (optarg is set to 0 if the option is missing).
 *        Used for 'typeset -LZ4' and 'ulimit -adunlimited'.
 *      - accepts +c as well as -c IF the GF_PLUSOPT flag is present.  If an
 *        option starting with + is accepted, the GI_PLUS flag will be set
 *        in go->info.
 */
int
ksh_getopt(char **argv, Getopt *go, const char *options)
{
        char c;
        char *o;

        if (go->p == 0 || (c = argv[go->optind - 1][go->p]) == '\0') {
                char *arg = argv[go->optind], flag = arg ? *arg : '\0';

                go->p = 1;
                if (flag == '-' && arg[1] == '-' && arg[2] == '\0') {
                        go->optind++;
                        go->p = 0;
                        go->info |= GI_MINUSMINUS;
                        return -1;
                }
                if (arg == NULL ||
                    ((flag != '-' ) && /* neither a - nor a + (if + allowed) */
                    (!(go->flags & GF_PLUSOPT) || flag != '+')) ||
                    (c = arg[1]) == '\0') {
                        go->p = 0;
                        return -1;
                }
                go->optind++;
                go->info &= ~(GI_MINUS|GI_PLUS);
                go->info |= flag == '-' ? GI_MINUS : GI_PLUS;
        }
        go->p++;
        if (c == '?' || c == ':' || c == ';' || c == ',' || c == '#' ||
            !(o = strchr(options, c))) {
                if (options[0] == ':') {
                        go->buf[0] = c;
                        go->optarg = go->buf;
                } else {
                        warningf(true, "%s%s-%c: unknown option",
                            (go->flags & GF_NONAME) ? "" : argv[0],
                            (go->flags & GF_NONAME) ? "" : ": ", c);
                        if (go->flags & GF_ERROR)
                                bi_errorf(NULL);
                }
                return '?';
        }
        /* : means argument must be present, may be part of option argument
         *   or the next argument
         * ; same as : but argument may be missing
         * , means argument is part of option argument, and may be null.
         */
        if (*++o == ':' || *o == ';') {
                if (argv[go->optind - 1][go->p])
                        go->optarg = argv[go->optind - 1] + go->p;
                else if (argv[go->optind])
                        go->optarg = argv[go->optind++];
                else if (*o == ';')
                        go->optarg = NULL;
                else {
                        if (options[0] == ':') {
                                go->buf[0] = c;
                                go->optarg = go->buf;
                                return ':';
                        }
                        warningf(true, "%s%s-`%c' requires argument",
                            (go->flags & GF_NONAME) ? "" : argv[0],
                            (go->flags & GF_NONAME) ? "" : ": ", c);
                        if (go->flags & GF_ERROR)
                                bi_errorf(NULL);
                        return '?';
                }
                go->p = 0;
        } else if (*o == ',') {
                /* argument is attached to option character, even if null */
                go->optarg = argv[go->optind - 1] + go->p;
                go->p = 0;
        } else if (*o == '#') {
                /* argument is optional and may be attached or unattached
                 * but must start with a digit.  optarg is set to 0 if the
                 * argument is missing.
                 */
                if (argv[go->optind - 1][go->p]) {
                        if (digit(argv[go->optind - 1][go->p]) ||
                            !strcmp(&argv[go->optind - 1][go->p], "unlimited")) {
                                go->optarg = argv[go->optind - 1] + go->p;
                                go->p = 0;
                        } else
                                go->optarg = NULL;
                } else {
                        if (argv[go->optind] && (digit(argv[go->optind][0]) ||
                            !strcmp(argv[go->optind], "unlimited"))) {
                                go->optarg = argv[go->optind++];
                                go->p = 0;
                        } else
                                go->optarg = NULL;
                }
        }
        return c;
}

/* print variable/alias value using necessary quotes
 * (POSIX says they should be suitable for re-entry...)
 * No trailing newline is printed.
 */
void
print_value_quoted(const char *s)
{
        const char *p;
        int inquote = 0;

        /* Test if any quotes are needed */
        for (p = s; *p; p++)
                if (ctype(*p, C_QUOTE))
                        break;
        if (!*p) {
                shprintf("%s", s);
                return;
        }
        for (p = s; *p; p++) {
                if (*p == '\'') {
                        shprintf(inquote ? "'\\'" : "\\'");
                        inquote = 0;
                } else {
                        if (!inquote) {
                                shprintf("'");
                                inquote = 1;
                        }
                        shf_putc(*p, shl_stdout);
                }
        }
        if (inquote)
                shprintf("'");
}

/* Print things in columns and rows - func() is called to format the ith
 * element
 */
void
print_columns(struct shf *shf, int n, char *(*func) (void *, int, char *, int),
    void *arg, int max_width, int prefcol)
{
        char *str = alloc(max_width + 1, ATEMP);
        int i;
        int r, c;
        int rows, cols;
        int nspace;
        int col_width;

        /* max_width + 1 for the space.  Note that no space
         * is printed after the last column to avoid problems
         * with terminals that have auto-wrap.
         */
        cols = x_cols / (max_width + 1);
        if (!cols)
                cols = 1;
        rows = (n + cols - 1) / cols;
        if (prefcol && n && cols > rows) {
                int tmp = rows;

                rows = cols;
                cols = tmp;
                if (rows > n)
                        rows = n;
        }

        col_width = max_width;
        if (cols == 1)
                col_width = 0; /* Don't pad entries in single column output. */
        nspace = (x_cols - max_width * cols) / cols;
        if (nspace <= 0)
                nspace = 1;
        for (r = 0; r < rows; r++) {
                for (c = 0; c < cols; c++) {
                        i = c * rows + r;
                        if (i < n) {
                                shf_fprintf(shf, "%-*s",
                                    col_width,
                                    (*func)(arg, i, str, max_width + 1));
                                if (c + 1 < cols)
                                        shf_fprintf(shf, "%*s", nspace, "");
                        }
                }
                shf_putchar('\n', shf);
        }
        afree(str, ATEMP);
}

/* Strip any nul bytes from buf - returns new length (nbytes - # of nuls) */
int
strip_nuls(char *buf, int nbytes)
{
        char *dst;

        if ((dst = memchr(buf, '\0', nbytes))) {
                char *end = buf + nbytes;
                char *p, *q;

                for (p = dst; p < end; p = q) {
                        /* skip a block of nulls */
                        while (++p < end && *p == '\0')
                                ;
                        /* find end of non-null block */
                        if (!(q = memchr(p, '\0', end - p)))
                                q = end;
                        memmove(dst, p, q - p);
                        dst += q - p;
                }
                *dst = '\0';
                return dst - buf;
        }
        return nbytes;
}

/* Like read(2), but if read fails due to non-blocking flag, resets flag
 * and restarts read.
 */
int
blocking_read(int fd, char *buf, int nbytes)
{
        int ret;
        int tried_reset = 0;

        while ((ret = read(fd, buf, nbytes)) < 0) {
                if (!tried_reset && errno == EAGAIN) {
                        int oerrno = errno;
                        if (reset_nonblock(fd) > 0) {
                                tried_reset = 1;
                                continue;
                        }
                        errno = oerrno;
                }
                break;
        }
        return ret;
}

/* Reset the non-blocking flag on the specified file descriptor.
 * Returns -1 if there was an error, 0 if non-blocking wasn't set,
 * 1 if it was.
 */
int
reset_nonblock(int fd)
{
        int flags;

        if ((flags = fcntl(fd, F_GETFL)) < 0)
                return -1;
        if (!(flags & O_NONBLOCK))
                return 0;
        flags &= ~O_NONBLOCK;
        if (fcntl(fd, F_SETFL, flags) < 0)
                return -1;
        return 1;
}


/* Like getcwd(), except bsize is ignored if buf is 0 (PATH_MAX is used) */
char *
ksh_get_wd(char *buf, int bsize)
{
        char *b;
        char *ret;

        /* Note: we could just use plain getcwd(), but then we'd had to
         * inject possibly allocated space into the ATEMP area. */
        /* Assume getcwd() available */
        if (!buf) {
                bsize = PATH_MAX;
                b = alloc(PATH_MAX + 1, ATEMP);
        } else
                b = buf;

        ret = getcwd(b, bsize);

        if (!buf) {
                if (ret)
                        ret = aresize(b, strlen(b) + 1, ATEMP);
                else
                        afree(b, ATEMP);
        }

        return ret;
}