source: vendor/NetBSD-ash/current/var.c

/*      $NetBSD: var.c,v 1.36 2004/10/06 10:23:43 enami Exp $   */

/*-
 * Copyright (c) 1991, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Kenneth Almquist.
 *
 * 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.
 */

#include <sys/cdefs.h>
#ifndef lint
#if 0
static char sccsid[] = "@(#)var.c       8.3 (Berkeley) 5/4/95";
#else
__RCSID("$NetBSD: var.c,v 1.36 2004/10/06 10:23:43 enami Exp $");
#endif
#endif /* not lint */

#include <unistd.h>
#include <stdlib.h>
#include <strings.h>
#include <paths.h>

/*
 * Shell variables.
 */

#include "shell.h"
#include "output.h"
#include "expand.h"
#include "nodes.h"      /* for other headers */
#include "eval.h"       /* defines cmdenviron */
#include "exec.h"
#include "syntax.h"
#include "options.h"
#include "mail.h"
#include "var.h"
#include "memalloc.h"
#include "error.h"
#include "mystring.h"
#include "parser.h"
#include "show.h"
#ifndef SMALL
#include "myhistedit.h"
#endif

#ifdef SMALL
#define VTABSIZE 39
#else
#define VTABSIZE 517
#endif


struct varinit {
        struct var *var;
        int flags;
        const char *text;
        void (*func)(const char *);
};


#if ATTY
struct var vatty;
#endif
#ifndef SMALL
struct var vhistsize;
struct var vterm;
#endif
struct var vifs;
struct var vmail;
struct var vmpath;
struct var vpath;
struct var vps1;
struct var vps2;
struct var vps4;
struct var vvers;
struct var voptind;

const struct varinit varinit[] = {
#if ATTY
        { &vatty,       VSTRFIXED|VTEXTFIXED|VUNSET,    "ATTY=",
          NULL },
#endif
#ifndef SMALL
        { &vhistsize,   VSTRFIXED|VTEXTFIXED|VUNSET,    "HISTSIZE=",
          sethistsize },
#endif
        { &vifs,        VSTRFIXED|VTEXTFIXED,           "IFS= \t\n",
          NULL },
        { &vmail,       VSTRFIXED|VTEXTFIXED|VUNSET,    "MAIL=",
          NULL },
        { &vmpath,      VSTRFIXED|VTEXTFIXED|VUNSET,    "MAILPATH=",
          NULL },
        { &vpath,       VSTRFIXED|VTEXTFIXED,           "PATH=" _PATH_DEFPATH,
          changepath },
        /*
         * vps1 depends on uid
         */
        { &vps2,        VSTRFIXED|VTEXTFIXED,           "PS2=> ",
          NULL },
        { &vps4,        VSTRFIXED|VTEXTFIXED,           "PS4=+ ",
          NULL },
#ifndef SMALL
        { &vterm,       VSTRFIXED|VTEXTFIXED|VUNSET,    "TERM=",
          setterm },
#endif
        { &voptind,     VSTRFIXED|VTEXTFIXED|VNOFUNC,   "OPTIND=1",
          getoptsreset },
        { NULL, 0,                              NULL,
          NULL }
};

struct var *vartab[VTABSIZE];

STATIC int strequal(const char *, const char *);
STATIC struct var *find_var(const char *, struct var ***, int *);

/*
 * Initialize the varable symbol tables and import the environment
 */

#ifdef mkinit
INCLUDE "var.h"
MKINIT char **environ;
INIT {
        char **envp;

        initvar();
        for (envp = environ ; *envp ; envp++) {
                if (strchr(*envp, '=')) {
                        setvareq(*envp, VEXPORT|VTEXTFIXED);
                }
        }
}
#endif


/*
 * This routine initializes the builtin variables.  It is called when the
 * shell is initialized and again when a shell procedure is spawned.
 */

void
initvar(void)
{
        const struct varinit *ip;
        struct var *vp;
        struct var **vpp;

        for (ip = varinit ; (vp = ip->var) != NULL ; ip++) {
                if (find_var(ip->text, &vpp, &vp->name_len) != NULL)
                        continue;
                vp->next = *vpp;
                *vpp = vp;
                vp->text = strdup(ip->text);
                vp->flags = ip->flags;
                vp->func = ip->func;
        }
        /*
         * PS1 depends on uid
         */
        if (find_var("PS1", &vpp, &vps1.name_len) == NULL) {
                vps1.next = *vpp;
                *vpp = &vps1;
                vps1.text = strdup(geteuid() ? "PS1=$ " : "PS1=# ");
                vps1.flags = VSTRFIXED|VTEXTFIXED;
        }
}

/*
 * Safe version of setvar, returns 1 on success 0 on failure.
 */

int
setvarsafe(const char *name, const char *val, int flags)
{
        struct jmploc jmploc;
        struct jmploc *volatile savehandler = handler;
        int err = 0;
#ifdef __GNUC__
        (void) &err;
#endif

        if (setjmp(jmploc.loc))
                err = 1;
        else {
                handler = &jmploc;
                setvar(name, val, flags);
        }
        handler = savehandler;
        return err;
}

/*
 * Set the value of a variable.  The flags argument is ored with the
 * flags of the variable.  If val is NULL, the variable is unset.
 */

void
setvar(const char *name, const char *val, int flags)
{
        const char *p;
        const char *q;
        char *d;
        int len;
        int namelen;
        char *nameeq;
        int isbad;

        isbad = 0;
        p = name;
        if (! is_name(*p))
                isbad = 1;
        p++;
        for (;;) {
                if (! is_in_name(*p)) {
                        if (*p == '\0' || *p == '=')
                                break;
                        isbad = 1;
                }
                p++;
        }
        namelen = p - name;
        if (isbad)
                error("%.*s: bad variable name", namelen, name);
        len = namelen + 2;              /* 2 is space for '=' and '\0' */
        if (val == NULL) {
                flags |= VUNSET;
        } else {
                len += strlen(val);
        }
        d = nameeq = ckmalloc(len);
        q = name;
        while (--namelen >= 0)
                *d++ = *q++;
        *d++ = '=';
        *d = '\0';
        if (val)
                scopy(val, d);
        setvareq(nameeq, flags);
}



/*
 * Same as setvar except that the variable and value are passed in
 * the first argument as name=value.  Since the first argument will
 * be actually stored in the table, it should not be a string that
 * will go away.
 */

void
setvareq(char *s, int flags)
{
        struct var *vp, **vpp;
        int nlen;

        if (aflag)
                flags |= VEXPORT;
        vp = find_var(s, &vpp, &nlen);
        if (vp != NULL) {
                if (vp->flags & VREADONLY)
                        error("%.*s: is read only", vp->name_len, s);
                if (flags & VNOSET)
                        return;
                INTOFF;

                if (vp->func && (flags & VNOFUNC) == 0)
                        (*vp->func)(s + vp->name_len + 1);

                if ((vp->flags & (VTEXTFIXED|VSTACK)) == 0)
                        ckfree(vp->text);

                vp->flags &= ~(VTEXTFIXED|VSTACK|VUNSET);
                vp->flags |= flags & ~VNOFUNC;
                vp->text = s;

                /*
                 * We could roll this to a function, to handle it as
                 * a regular variable function callback, but why bother?
                 */
                if (vp == &vmpath || (vp == &vmail && ! mpathset()))
                        chkmail(1);
                INTON;
                return;
        }
        /* not found */
        if (flags & VNOSET)
                return;
        vp = ckmalloc(sizeof (*vp));
        vp->flags = flags & ~VNOFUNC;
        vp->text = s;
        vp->name_len = nlen;
        vp->next = *vpp;
        vp->func = NULL;
        *vpp = vp;
}



/*
 * Process a linked list of variable assignments.
 */

void
listsetvar(struct strlist *list, int flags)
{
        struct strlist *lp;

        INTOFF;
        for (lp = list ; lp ; lp = lp->next) {
                setvareq(savestr(lp->text), flags);
        }
        INTON;
}

void
listmklocal(struct strlist *list, int flags)
{
        struct strlist *lp;

        for (lp = list ; lp ; lp = lp->next)
                mklocal(lp->text, flags);
}


/*
 * Find the value of a variable.  Returns NULL if not set.
 */

char *
lookupvar(const char *name)
{
        struct var *v;

        v = find_var(name, NULL, NULL);
        if (v == NULL || v->flags & VUNSET)
                return NULL;
        return v->text + v->name_len + 1;
}



/*
 * Search the environment of a builtin command.  If the second argument
 * is nonzero, return the value of a variable even if it hasn't been
 * exported.
 */

char *
bltinlookup(const char *name, int doall)
{
        struct strlist *sp;
        struct var *v;

        for (sp = cmdenviron ; sp ; sp = sp->next) {
                if (strequal(sp->text, name))
                        return strchr(sp->text, '=') + 1;
        }

        v = find_var(name, NULL, NULL);

        if (v == NULL || v->flags & VUNSET || (!doall && !(v->flags & VEXPORT)))
                return NULL;
        return v->text + v->name_len + 1;
}



/*
 * Generate a list of exported variables.  This routine is used to construct
 * the third argument to execve when executing a program.
 */

char **
environment(void)
{
        int nenv;
        struct var **vpp;
        struct var *vp;
        char **env;
        char **ep;

        nenv = 0;
        for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
                for (vp = *vpp ; vp ; vp = vp->next)
                        if (vp->flags & VEXPORT)
                                nenv++;
        }
        ep = env = stalloc((nenv + 1) * sizeof *env);
        for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
                for (vp = *vpp ; vp ; vp = vp->next)
                        if (vp->flags & VEXPORT)
                                *ep++ = vp->text;
        }
        *ep = NULL;
        return env;
}


/*
 * Called when a shell procedure is invoked to clear out nonexported
 * variables.  It is also necessary to reallocate variables of with
 * VSTACK set since these are currently allocated on the stack.
 */

#ifdef mkinit
void shprocvar(void);

SHELLPROC {
        shprocvar();
}
#endif

void
shprocvar(void)
{
        struct var **vpp;
        struct var *vp, **prev;

        for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
                for (prev = vpp ; (vp = *prev) != NULL ; ) {
                        if ((vp->flags & VEXPORT) == 0) {
                                *prev = vp->next;
                                if ((vp->flags & VTEXTFIXED) == 0)
                                        ckfree(vp->text);
                                if ((vp->flags & VSTRFIXED) == 0)
                                        ckfree(vp);
                        } else {
                                if (vp->flags & VSTACK) {
                                        vp->text = savestr(vp->text);
                                        vp->flags &=~ VSTACK;
                                }
                                prev = &vp->next;
                        }
                }
        }
        initvar();
}



/*
 * Command to list all variables which are set.  Currently this command
 * is invoked from the set command when the set command is called without
 * any variables.
 */

void
print_quoted(const char *p)
{
        const char *q;

        if (strcspn(p, "|&;<>()$`\\\"' \t\n*?[]#~=%") == strlen(p)) {
                out1fmt("%s", p);
                return;
        }
        while (*p) {
                if (*p == '\'') {
                        out1fmt("\\'");
                        p++;
                        continue;
                }
                q = index(p, '\'');
                if (!q) {
                        out1fmt("'%s'", p );
                        return;
                }
                out1fmt("'%.*s'", (int)(q - p), p );
                p = q;
        }
}

static int
sort_var(const void *v_v1, const void *v_v2)
{
        const struct var * const *v1 = v_v1;
        const struct var * const *v2 = v_v2;

        /* XXX Will anyone notice we include the '=' of the shorter name? */
        return strcoll((*v1)->text, (*v2)->text);
}

/*
 * POSIX requires that 'set' (but not export or readonly) output the
 * variables in lexicographic order - by the locale's collating order (sigh).
 * Maybe we could keep them in an ordered balanced binary tree
 * instead of hashed lists.
 * For now just roll 'em through qsort for printing...
 */

int
showvars(const char *name, int flag, int show_value)
{
        struct var **vpp;
        struct var *vp;
        const char *p;

        static struct var **list;       /* static in case we are interrupted */
        static int list_len;
        int count = 0;

        if (!list) {
                list_len = 32;
                list = ckmalloc(list_len * sizeof *list);
        }

        for (vpp = vartab ; vpp < vartab + VTABSIZE ; vpp++) {
                for (vp = *vpp ; vp ; vp = vp->next) {
                        if (flag && !(vp->flags & flag))
                                continue;
                        if (vp->flags & VUNSET && !(show_value & 2))
                                continue;
                        if (count >= list_len) {
                                list = ckrealloc(list,
                                        (list_len << 1) * sizeof *list);
                                list_len <<= 1;
                        }
                        list[count++] = vp;
                }
        }

        qsort(list, count, sizeof *list, sort_var);

        for (vpp = list; count--; vpp++) {
                vp = *vpp;
                if (name)
                        out1fmt("%s ", name);
                for (p = vp->text ; *p != '=' ; p++)
                        out1c(*p);
                if (!(vp->flags & VUNSET) && show_value) {
                        out1fmt("=");
                        print_quoted(++p);
                }
                out1c('\n');
        }
        return 0;
}



/*
 * The export and readonly commands.
 */

int
exportcmd(int argc, char **argv)
{
        struct var *vp;
        char *name;
        const char *p;
        int flag = argv[0][0] == 'r'? VREADONLY : VEXPORT;
        int pflag;

        pflag = nextopt("p") == 'p' ? 3 : 0;
        if (argc <= 1 || pflag) {
                showvars( pflag ? argv[0] : 0, flag, pflag );
                return 0;
        }

        while ((name = *argptr++) != NULL) {
                if ((p = strchr(name, '=')) != NULL) {
                        p++;
                } else {
                        vp = find_var(name, NULL, NULL);
                        if (vp != NULL) {
                                vp->flags |= flag;
                                continue;
                        }
                }
                setvar(name, p, flag);
        }
        return 0;
}


/*
 * The "local" command.
 */

int
localcmd(int argc, char **argv)
{
        char *name;

        if (! in_function())
                error("Not in a function");
        while ((name = *argptr++) != NULL) {
                mklocal(name, 0);
        }
        return 0;
}


/*
 * Make a variable a local variable.  When a variable is made local, it's
 * value and flags are saved in a localvar structure.  The saved values
 * will be restored when the shell function returns.  We handle the name
 * "-" as a special case.
 */

void
mklocal(const char *name, int flags)
{
        struct localvar *lvp;
        struct var **vpp;
        struct var *vp;

        INTOFF;
        lvp = ckmalloc(sizeof (struct localvar));
        if (name[0] == '-' && name[1] == '\0') {
                char *p;
                p = ckmalloc(sizeof_optlist);
                lvp->text = memcpy(p, optlist, sizeof_optlist);
                vp = NULL;
        } else {
                vp = find_var(name, &vpp, NULL);
                if (vp == NULL) {
                        if (strchr(name, '='))
                                setvareq(savestr(name), VSTRFIXED|flags);
                        else
                                setvar(name, NULL, VSTRFIXED|flags);
                        vp = *vpp;      /* the new variable */
                        lvp->text = NULL;
                        lvp->flags = VUNSET;
                } else {
                        lvp->text = vp->text;
                        lvp->flags = vp->flags;
                        vp->flags |= VSTRFIXED|VTEXTFIXED;
                        if (name[vp->name_len] == '=')
                                setvareq(savestr(name), flags);
                }
        }
        lvp->vp = vp;
        lvp->next = localvars;
        localvars = lvp;
        INTON;
}


/*
 * Called after a function returns.
 */

void
poplocalvars(void)
{
        struct localvar *lvp;
        struct var *vp;

        while ((lvp = localvars) != NULL) {
                localvars = lvp->next;
                vp = lvp->vp;
                TRACE(("poplocalvar %s", vp ? vp->text : "-"));
                if (vp == NULL) {       /* $- saved */
                        memcpy(optlist, lvp->text, sizeof_optlist);
                        ckfree(lvp->text);
                } else if ((lvp->flags & (VUNSET|VSTRFIXED)) == VUNSET) {
                        (void)unsetvar(vp->text, 0);
                } else {
                        if (vp->func && (vp->flags & VNOFUNC) == 0)
                                (*vp->func)(lvp->text + vp->name_len + 1);
                        if ((vp->flags & VTEXTFIXED) == 0)
                                ckfree(vp->text);
                        vp->flags = lvp->flags;
                        vp->text = lvp->text;
                }
                ckfree(lvp);
        }
}


int
setvarcmd(int argc, char **argv)
{
        if (argc <= 2)
                return unsetcmd(argc, argv);
        else if (argc == 3)
                setvar(argv[1], argv[2], 0);
        else
                error("List assignment not implemented");
        return 0;
}


/*
 * The unset builtin command.  We unset the function before we unset the
 * variable to allow a function to be unset when there is a readonly variable
 * with the same name.
 */

int
unsetcmd(int argc, char **argv)
{
        char **ap;
        int i;
        int flg_func = 0;
        int flg_var = 0;
        int ret = 0;

        while ((i = nextopt("evf")) != '\0') {
                if (i == 'f')
                        flg_func = 1;
                else
                        flg_var = i;
        }
        if (flg_func == 0 && flg_var == 0)
                flg_var = 1;

        for (ap = argptr; *ap ; ap++) {
                if (flg_func)
                        ret |= unsetfunc(*ap);
                if (flg_var)
                        ret |= unsetvar(*ap, flg_var == 'e');
        }
        return ret;
}


/*
 * Unset the specified variable.
 */

int
unsetvar(const char *s, int unexport)
{
        struct var **vpp;
        struct var *vp;

        vp = find_var(s, &vpp, NULL);
        if (vp == NULL)
                return 1;

        if (vp->flags & VREADONLY)
                return (1);

        INTOFF;
        if (unexport) {
                vp->flags &= ~VEXPORT;
        } else {
                if (vp->text[vp->name_len + 1] != '\0')
                        setvar(s, nullstr, 0);
                vp->flags &= ~VEXPORT;
                vp->flags |= VUNSET;
                if ((vp->flags & VSTRFIXED) == 0) {
                        if ((vp->flags & VTEXTFIXED) == 0)
                                ckfree(vp->text);
                        *vpp = vp->next;
                        ckfree(vp);
                }
        }
        INTON;
        return 0;
}


/*
 * Returns true if the two strings specify the same varable.  The first
 * variable name is terminated by '='; the second may be terminated by
 * either '=' or '\0'.
 */

STATIC int
strequal(const char *p, const char *q)
{
        while (*p == *q++) {
                if (*p++ == '=')
                        return 1;
        }
        if (*p == '=' && *(q - 1) == '\0')
                return 1;
        return 0;
}

/*
 * Search for a variable.
 * 'name' may be terminated by '=' or a NUL.
 * vppp is set to the pointer to vp, or the list head if vp isn't found
 * lenp is set to the number of charactets in 'name'
 */

STATIC struct var *
find_var(const char *name, struct var ***vppp, int *lenp)
{
        unsigned int hashval;
        int len;
        struct var *vp, **vpp;
        const char *p = name;

        hashval = 0;
        while (*p && *p != '=')
                hashval = 2 * hashval + (unsigned char)*p++;
        len = p - name;

        if (lenp)
                *lenp = len;
        vpp = &vartab[hashval % VTABSIZE];
        if (vppp)
                *vppp = vpp;

        for (vp = *vpp ; vp ; vpp = &vp->next, vp = *vpp) {
                if (vp->name_len != len)
                        continue;
                if (memcmp(vp->text, name, len) != 0)
                        continue;
                if (vppp)
                        *vppp = vpp;
                return vp;
        }
        return NULL;
}