var.c

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/*	$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 <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 "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
#ifdef WITH_HISTORY
struct var vhistsize;
struct var vterm;
#endif
struct var vifs;
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
#ifdef WITH_HISTORY
	{ &vhistsize,	VSTRFIXED|VTEXTFIXED|VUNSET,	"HISTSIZE=",
	  sethistsize },
#endif
	{ &vifs,	VSTRFIXED|VTEXTFIXED,		"IFS= \t\n",
	  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 },
#ifdef WITH_HISTORY
	{ &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;

		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;
}