/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * 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/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"
#include "builtins.h"

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

static char *curdir = NULL;     /* current working directory */

int
cdcmd(int argc __unused, char **argv __unused)
{
        const char *dest;
        const char *path;
        char *p;
        struct stat statb;
        int ch, phys, print = 0, getcwderr = 0;
        int rc;
        int errno1 = ENOENT;

        phys = Pflag;
        while ((ch = nextopt("eLP")) != '\0') {
                switch (ch) {
                case 'e':
                        getcwderr = 1;
                        break;
                case 'L':
                        phys = 0;
                        break;
                case 'P':
                        phys = 1;
                        break;
                }
        }

        if (*argptr != NULL && argptr[1] != NULL)
                error("too many arguments");

        if ((dest = *argptr) == NULL && (dest = bltinlookup("HOME", 1)) == NULL)
                error("HOME not set");
        if (dest[0] == '-' && dest[1] == '\0') {
                dest = bltinlookup("OLDPWD", 1);
                if (dest == NULL)
                        error("OLDPWD not set");
                print = 1;
        }
        if (dest[0] == '/' ||
            (dest[0] == '.' && (dest[1] == '/' || dest[1] == '\0')) ||
            (dest[0] == '.' && dest[1] == '.' && (dest[2] == '/' || dest[2] == '\0')) ||
            (path = bltinlookup("CDPATH", 1)) == NULL)
                path = "";
        while ((p = padvance(&path, NULL, dest)) != NULL) {
                if (stat(p, &statb) < 0) {
                        if (errno != ENOENT)
                                errno1 = errno;
                } else if (!S_ISDIR(statb.st_mode))
                        errno1 = ENOTDIR;
                else {
                        if (!print) {
                                /*
                                 * XXX - rethink
                                 */
                                if (p[0] == '.' && p[1] == '/' && p[2] != '\0')
                                        print = strcmp(p + 2, dest);
                                else
                                        print = strcmp(p, dest);
                        }
                        rc = docd(p, print, phys);
                        if (rc >= 0)
                                return getcwderr ? rc : 0;
                        if (errno != ENOENT)
                                errno1 = errno;
                }
        }
        error("%s: %s", dest, strerror(errno1));
        /*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)
{
        int rc;

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

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

        if (print && iflag && curdir) {
                out1fmt("%s\n", curdir);
                /*
                 * Ignore write errors to preserve the invariant that the
                 * current directory is changed iff the exit status is 0
                 * (or 1 if -e was given and the full pathname could not be
                 * determined).
                 */
                flushout(out1);
                outclearerror(out1);
        }

        return (rc);
}

static int
cdlogical(char *dest)
{
        char *p;
        char *q;
        char *component;
        char *path;
        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;
        path = stsavestr(dest);
        STARTSTACKSTR(p);
        if (*dest == '/') {
                STPUTC('/', p);
                path++;
        }
        first = 1;
        while ((q = getcomponent(&path)) != 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;
        int rc = 0;

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

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

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


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

        /*
         * 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();
        path = stsavestr(dir);
        STARTSTACKSTR(new);
        if (*dir != '/') {
                STPUTS(curdir, new);
                if (STTOPC(new) == '/')
                        STUNPUTC(new);
        }
        while ((p = getcomponent(&path)) != 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)
{
        char *prevdir;

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

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

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

        phys = Pflag;
        while ((ch = nextopt("LP")) != '\0') {
                switch (ch) {
                case 'L':
                        phys = 0;
                        break;
                case 'P':
                        phys = 1;
                        break;
                }
        }

        if (*argptr != NULL)
                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) {
                INTOFF;
                curdir = savestr(p);
                INTON;
        }

        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);
}