/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1991, 1993
 *	The Regents of the University of California.  All rights reserved.
 * Copyright (c) 2026 Project Tick. 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 *getpwd_linux_procfs(void);

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

int
cdcmd(int argc, char **argv)
{
	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;

	INTOFF;
	if (chdir(dest) < 0) {
		INTON;
		return (-1);
	}
	p = findcwd(dest);
	if (p == NULL) {
		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, char **argv)
{
	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

static char *
getpwd_linux_procfs(void)
{
#ifdef __linux__
	char *pwd;
	int i;
	ssize_t length;

	for (i = MAXPWD;; i *= 2) {
		pwd = stalloc(i);
		length = readlink("/proc/self/cwd", pwd, i - 1);
		if (length >= 0) {
			if (length < i - 1) {
				pwd[length] = '\0';
				return pwd;
			}
		} else if (errno != ENAMETOOLONG) {
			stunalloc(pwd);
			return NULL;
		}
		stunalloc(pwd);
		if (i > INT_MAX / 2) {
			errno = ENAMETOOLONG;
			return NULL;
		}
	}
#else
	errno = ENOSYS;
	return NULL;
#endif
}

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

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

	saved_errno = errno;
	pwd = getpwd_linux_procfs();
	if (pwd != NULL)
		return pwd;
	errno = saved_errno;
	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);
}
