xref: /freebsd-9.3-release/bin/sh/cd.c

/*-
 * 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.
 * 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 lint
#if 0
static char sccsid[] = "@(#)cd.c	8.2 (Berkeley) 5/4/95";
#endif
#endif /* not lint */
#include <sys/cdefs.h>
__FBSDID("$FreeBSD: head/bin/sh/cd.c 216622 2010-12-21 20:47:06Z jilles $");

#include <sys/types.h>
#include <sys/stat.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <limits.h>

/*
 * The cd and pwd commands.
 */

#include "shell.h"
#include "var.h"
#include "nodes.h"	/* for jobs.h */
#include "jobs.h"
#include "options.h"
#include "output.h"
#include "memalloc.h"
#include "error.h"
#include "exec.h"
#include "redir.h"
#include "mystring.h"
#include "show.h"
#include "cd.h"

static int cdlogical(char *);
static int cdphysical(char *);
static int docd(char *, int, int);
static char *getcomponent(void);
static char *findcwd(char *);
static void updatepwd(char *);
static char *getpwd(void);
static char *getpwd2(void);

static char *curdir = NULL;	/* current working directory */
static char *prevdir;		/* previous working directory */
static char *cdcomppath;

int
cdcmd(int argc, char **argv)
{
	const char *dest;
	const char *path;
	char *p;
	struct stat statb;
	int ch, phys, print = 0;

	optreset = 1; optind = 1; opterr = 0; /* initialize getopt */
	phys = Pflag;
	while ((ch = getopt(argc, argv, "LP")) != -1) {
		switch (ch) {
		case 'L':
			phys = 0;
			break;
		case 'P':
			phys = 1;
			break;
		default:
			error("unknown option: -%c", optopt);
			break;
		}
	}
	argc -= optind;
	argv += optind;

	if (argc > 1)
		error("too many arguments");

	if ((dest = *argv) == NULL && (dest = bltinlookup("HOME", 1)) == NULL)
		error("HOME not set");
	if (*dest == '\0')
		dest = ".";
	if (dest[0] == '-' && dest[1] == '\0') {
		dest = prevdir ? prevdir : curdir;
		if (dest)
			print = 1;
		else
			dest = ".";
	}
	if (*dest == '/' || (path = bltinlookup("CDPATH", 1)) == NULL)
		path = nullstr;
	while ((p = padvance(&path, dest)) != NULL) {
		if (stat(p, &statb) >= 0 && S_ISDIR(statb.st_mode)) {
			if (!print) {
				/*
				 * XXX - rethink
				 */
				if (p[0] == '.' && p[1] == '/' && p[2] != '\0')
					print = strcmp(p + 2, dest);
				else
					print = strcmp(p, dest);
			}
			if (docd(p, print, phys) >= 0)
				return 0;
		}
	}
	error("can't cd to %s", dest);
	/*NOTREACHED*/
	return 0;
}


/*
 * Actually change the directory.  In an interactive shell, print the
 * directory name if "print" is nonzero.
 */
static int
docd(char *dest, int print, int phys)
{

	TRACE(("docd(\"%s\", %d, %d) called\n", dest, print, phys));

	/* If logical cd fails, fall back to physical. */
	if ((phys || cdlogical(dest) < 0) && cdphysical(dest) < 0)
		return (-1);

	if (print && iflag && curdir)
		out1fmt("%s\n", curdir);

	return 0;
}

static int
cdlogical(char *dest)
{
	char *p;
	char *q;
	char *component;
	struct stat statb;
	int first;
	int badstat;

	/*
	 *  Check each component of the path. If we find a symlink or
	 *  something we can't stat, clear curdir to force a getcwd()
	 *  next time we get the value of the current directory.
	 */
	badstat = 0;
	cdcomppath = stalloc(strlen(dest) + 1);
	scopy(dest, cdcomppath);
	STARTSTACKSTR(p);
	if (*dest == '/') {
		STPUTC('/', p);
		cdcomppath++;
	}
	first = 1;
	while ((q = getcomponent()) != NULL) {
		if (q[0] == '\0' || (q[0] == '.' && q[1] == '\0'))
			continue;
		if (! first)
			STPUTC('/', p);
		first = 0;
		component = q;
		STPUTS(q, p);
		if (equal(component, ".."))
			continue;
		STACKSTRNUL(p);
		if (lstat(stackblock(), &statb) < 0) {
			badstat = 1;
			break;
		}
	}

	INTOFF;
	if ((p = findcwd(badstat ? NULL : dest)) == NULL || chdir(p) < 0) {
		INTON;
		return (-1);
	}
	updatepwd(p);
	INTON;
	return (0);
}

static int
cdphysical(char *dest)
{
	char *p;

	INTOFF;
	if (chdir(dest) < 0) {
		INTON;
		return (-1);
	}
	p = findcwd(NULL);
	if (p == NULL)
		warning("warning: failed to get name of current directory");
	updatepwd(p);
	INTON;
	return (0);
}

/*
 * Get the next component of the path name pointed to by cdcomppath.
 * This routine overwrites the string pointed to by cdcomppath.
 */
static char *
getcomponent(void)
{
	char *p;
	char *start;

	if ((p = cdcomppath) == NULL)
		return NULL;
	start = cdcomppath;
	while (*p != '/' && *p != '\0')
		p++;
	if (*p == '\0') {
		cdcomppath = NULL;
	} else {
		*p++ = '\0';
		cdcomppath = p;
	}
	return start;
}


static char *
findcwd(char *dir)
{
	char *new;
	char *p;

	/*
	 * If our argument is NULL, we don't know the current directory
	 * any more because we traversed a symbolic link or something
	 * we couldn't stat().
	 */
	if (dir == NULL || curdir == NULL)
		return getpwd2();
	cdcomppath = stalloc(strlen(dir) + 1);
	scopy(dir, cdcomppath);
	STARTSTACKSTR(new);
	if (*dir != '/') {
		STPUTS(curdir, new);
		if (STTOPC(new) == '/')
			STUNPUTC(new);
	}
	while ((p = getcomponent()) != NULL) {
		if (equal(p, "..")) {
			while (new > stackblock() && (STUNPUTC(new), *new) != '/');
		} else if (*p != '\0' && ! equal(p, ".")) {
			STPUTC('/', new);
			STPUTS(p, new);
		}
	}
	if (new == stackblock())
		STPUTC('/', new);
	STACKSTRNUL(new);
	return stackblock();
}

/*
 * Update curdir (the name of the current directory) in response to a
 * cd command.  We also call hashcd to let the routines in exec.c know
 * that the current directory has changed.
 */
static void
updatepwd(char *dir)
{
	hashcd();				/* update command hash table */

	if (prevdir)
		ckfree(prevdir);
	prevdir = curdir;
	curdir = dir ? savestr(dir) : NULL;
	setvar("PWD", curdir, VEXPORT);
	setvar("OLDPWD", prevdir, VEXPORT);
}

int
pwdcmd(int argc, char **argv)
{
	char *p;
	int ch, phys;

	optreset = 1; optind = 1; opterr = 0; /* initialize getopt */
	phys = Pflag;
	while ((ch = getopt(argc, argv, "LP")) != -1) {
		switch (ch) {
		case 'L':
			phys = 0;
			break;
		case 'P':
			phys = 1;
			break;
		default:
			error("unknown option: -%c", optopt);
			break;
		}
	}
	argc -= optind;
	argv += optind;

	if (argc != 0)
		error("too many arguments");

	if (!phys && getpwd()) {
		out1str(curdir);
		out1c('\n');
	} else {
		if ((p = getpwd2()) == NULL)
			error(".: %s", strerror(errno));
		out1str(p);
		out1c('\n');
	}

	return 0;
}

/*
 * Get the current directory and cache the result in curdir.
 */
static char *
getpwd(void)
{
	char *p;

	if (curdir)
		return curdir;

	p = getpwd2();
	if (p != NULL)
		curdir = savestr(p);

	return curdir;
}

#define MAXPWD 256

/*
 * Return the current directory.
 */
static char *
getpwd2(void)
{
	char *pwd;
	int i;

	for (i = MAXPWD;; i *= 2) {
		pwd = stalloc(i);
		if (getcwd(pwd, i) != NULL)
			return pwd;
		stunalloc(pwd);
		if (errno != ERANGE)
			break;
	}

	return NULL;
}

/*
 * Initialize PWD in a new shell.
 * If the shell is interactive, we need to warn if this fails.
 */
void
pwd_init(int warn)
{
	char *pwd;
	struct stat stdot, stpwd;

	pwd = lookupvar("PWD");
	if (pwd && *pwd == '/' && stat(".", &stdot) != -1 &&
	    stat(pwd, &stpwd) != -1 &&
	    stdot.st_dev == stpwd.st_dev &&
	    stdot.st_ino == stpwd.st_ino) {
		if (curdir)
			ckfree(curdir);
		curdir = savestr(pwd);
	}
	if (getpwd() == NULL && warn)
		out2fmt_flush("sh: cannot determine working directory\n");
	setvar("PWD", curdir, VEXPORT);
}