source: trunk/ash/cd.c@ 3866

/*      $NetBSD: cd.c,v 1.34 2003/11/14 20:00:28 dsl 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[] = "@(#)cd.c        8.2 (Berkeley) 5/4/95";
#else
__RCSID("$NetBSD: cd.c,v 1.34 2003/11/14 20:00:28 dsl Exp $");
#endif
#endif /* not lint */

#include <sys/types.h>
#include <sys/stat.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.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 docd(char *, int);
STATIC char *getcomponent(void);
STATIC void updatepwd(char *);
STATIC void find_curdir(int noerror);

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

int
cdcmd(int argc, char **argv)
{
        const char *dest;
        const char *path;
        char *p, *d;
        struct stat statb;
        int print = cdprint;    /* set -cdprint to enable */

        nextopt(nullstr);

        /*
         * Try (quite hard) to have 'curdir' defined, nothing has set
         * it on entry to the shell, but we want 'cd fred; cd -' to work.
         */
        getpwd(1);
        dest = *argptr;
        if (dest == NULL) {
                dest = bltinlookup("HOME", 1);
                if (dest == NULL)
                        error("HOME not set");
        } else {
                if (argptr[1]) {
                        /* Do 'ksh' style substitution */
                        if (!curdir)
                                error("PWD not set");
                        p = strstr(curdir, dest);
                        if (!p)
                                error("bad substitution");
                        d = stalloc(strlen(curdir) + strlen(argptr[1]) + 1);
                        memcpy(d, curdir, p - curdir);
                        strcpy(d + (p - curdir), argptr[1]);
                        strcat(d, p + strlen(dest));
                        dest = d;
                        print = 1;
                }
        }

        if (dest[0] == '-' && dest[1] == '\0') {
                dest = prevdir ? prevdir : curdir;
                print = 1;
        }
        if (*dest == '\0')
                dest = ".";
        if (IS_ROOT(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')
                                        p += 2;
                                print = strcmp(p, dest);
                        }
                        if (docd(p, print) >= 0)
                                return 0;

                }
        }
        error("can't cd to %s", dest);
        /* NOTREACHED */
}


/*
 * Actually do the chdir.  In an interactive shell, print the
 * directory name if "print" is nonzero.
 */

STATIC int
docd(char *dest, int print)
{
        char *p;
        char *q;
        char *component;
        struct stat statb;
        int first;
        int badstat;

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

        /*
         *  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 (IS_ROOT(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;
                while (*q)
                        STPUTC(*q++, p);
                if (equal(component, ".."))
                        continue;
                STACKSTRNUL(p);
                if ((lstat(stackblock(), &statb) < 0)
                    || (S_ISLNK(statb.st_mode)))  {
                        /* print = 1; */
                        badstat = 1;
                        break;
                }
        }

        INTOFF;
        if (chdir(dest) < 0) {
                INTON;
                return -1;
        }
        updatepwd(badstat ? NULL : dest);
        INTON;
        if (print && iflag && curdir)
                out1fmt("%s\n", curdir);
        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()
{
        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;
}



/*
 * 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)
{
        char *new;
        char *p;

        hashcd();                               /* update command hash table */

        /*
         * 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)  {
                if (prevdir)
                        ckfree(prevdir);
                INTOFF;
                prevdir = curdir;
                curdir = NULL;
                getpwd(1);
                INTON;
                if (curdir)
                        setvar("PWD", curdir, VEXPORT);
                else
                        unsetvar("PWD", 0);
                return;
        }
        cdcomppath = stalloc(strlen(dir) + 1);
        scopy(dir, cdcomppath);
        STARTSTACKSTR(new);
        if (!IS_ROOT(dir)) {
                p = curdir;
                while (*p)
                        STPUTC(*p++, new);
                if (p[-1] == '/')
                        STUNPUTC(new);
        }
        while ((p = getcomponent()) != NULL) {
                if (equal(p, "..")) {
                        while (new > stackblock() && (STUNPUTC(new), *new) != '/');
                } else if (*p != '\0' && ! equal(p, ".")) {
                        STPUTC('/', new);
                        while (*p)
                                STPUTC(*p++, new);
                }
        }
        if (new == stackblock())
                STPUTC('/', new);
        STACKSTRNUL(new);
        INTOFF;
        if (prevdir)
                ckfree(prevdir);
        prevdir = curdir;
        curdir = savestr(stackblock());
        setvar("PWD", curdir, VEXPORT);
        INTON;
}

/*
 * Posix says the default should be 'pwd -L' (as below), however
 * the 'cd' command (above) does something much nearer to the
 * posix 'cd -P' (not the posix default of 'cd -L').
 * If 'cd' is changed to support -P/L then the default here
 * needs to be revisited if the historic behaviour is to be kept.
 */

int
pwdcmd(int argc, char **argv)
{
        int i;
        char opt = 'L';

        while ((i = nextopt("LP")) != '\0')
                opt = i;
        if (*argptr)
                error("unexpected argument");

        if (opt == 'L')
                getpwd(0);
        else
                find_curdir(0);

        setvar("PWD", curdir, VEXPORT);
        out1str(curdir);
        out1c('\n');
        return 0;
}




#define MAXPWD 256

/*
 * Find out what the current directory is. If we already know the current
 * directory, this routine returns immediately.
 */
void
getpwd(int noerror)
{
        char *pwd;
        struct stat stdot, stpwd;
        static int first = 1;

        if (curdir)
                return;

        if (first) {
                first = 0;
                pwd = getenv("PWD");
                if (pwd && IS_ROOT(pwd) && stat(".", &stdot) != -1 &&
                    stat(pwd, &stpwd) != -1 &&
                    stdot.st_dev == stpwd.st_dev &&
                    stdot.st_ino == stpwd.st_ino) {
                        curdir = savestr(pwd);
                        return;
                }
        }

        find_curdir(noerror);

        return;
}

STATIC void
find_curdir(int noerror)
{
        int i;
        char *pwd;

        /*
         * Things are a bit complicated here; we could have just used
         * getcwd, but traditionally getcwd is implemented using popen
         * to /bin/pwd. This creates a problem for us, since we cannot
         * keep track of the job if it is being ran behind our backs.
         * So we re-implement getcwd(), and we suppress interrupts
         * throughout the process. This is not completely safe, since
         * the user can still break out of it by killing the pwd program.
         * We still try to use getcwd for systems that we know have a
         * c implementation of getcwd, that does not open a pipe to
         * /bin/pwd.
         */
#if defined(__NetBSD__) || defined(__SVR4) || defined(__INNOTEK_LIBC__)

        for (i = MAXPWD;; i *= 2) {
                pwd = stalloc(i);
                if (getcwd(pwd, i) != NULL) {
                        curdir = savestr(pwd);
                        return;
                }
                stunalloc(pwd);
                if (errno == ERANGE)
                        continue;
                if (!noerror)
                        error("getcwd() failed: %s", strerror(errno));
                return;
        }
#else
        {
                char *p;
                int status;
                struct job *jp;
                int pip[2];

                pwd = stalloc(MAXPWD);
                INTOFF;
                if (pipe(pip) < 0)
                        error("Pipe call failed");
                jp = makejob((union node *)NULL, 1);
                if (forkshell(jp, (union node *)NULL, FORK_NOJOB) == 0) {
                        (void) close(pip[0]);
                        if (pip[1] != 1) {
                                close(1);
                                copyfd(pip[1], 1);
                                close(pip[1]);
                        }
                        (void) execl("/bin/pwd", "pwd", (char *)0);
                        error("Cannot exec /bin/pwd");
                }
                (void) close(pip[1]);
                pip[1] = -1;
                p = pwd;
                while ((i = read(pip[0], p, pwd + MAXPWD - p)) > 0
                     || (i == -1 && errno == EINTR)) {
                        if (i > 0)
                                p += i;
                }
                (void) close(pip[0]);
                pip[0] = -1;
                status = waitforjob(jp);
                if (status != 0)
                        error((char *)0);
                if (i < 0 || p == pwd || p[-1] != '\n') {
                        if (noerror) {
                                INTON;
                                return;
                        }
                        error("pwd command failed");
                }
                p[-1] = '\0';
                INTON;
                curdir = savestr(pwd);
                return;
        }
#endif
}