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+/* $NetBSD: cd.c,v 1.50 2017/07/05 20:00:27 kre 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 1.50 2017/07/05 20:00:27 kre 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 "builtins.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(const char *, int);
+STATIC char *getcomponent(void);
+STATIC void updatepwd(const 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, *cp;
+ char *p;
+ char *d;
+ struct stat statb;
+ int print = cdprint; /* set -o cdprint to enable */
+
+ while (nextopt("P") != '\0')
+ ;
+
+ /*
+ * 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;
+ } else if (dest[0] == '-' && dest[1] == '\0') {
+ dest = prevdir ? prevdir : curdir;
+ print = 1;
+ }
+ if (*dest == '\0')
+ dest = ".";
+
+ cp = dest;
+ if (*cp == '.' && *++cp == '.')
+ cp++;
+ if (*cp == 0 || *cp == '/' || (path = bltinlookup("CDPATH", 1)) == NULL)
+ path = nullstr;
+ while ((p = padvance(&path, dest, 0)) != NULL) {
+ stunalloc(p);
+ if (stat(p, &statb) >= 0 && S_ISDIR(statb.st_mode)) {
+ int dopr = print;
+
+ if (!print) {
+ /*
+ * XXX - rethink
+ */
+ if (p[0] == '.' && p[1] == '/' && p[2] != '\0')
+ dopr = strcmp(p + 2, dest);
+ else
+ dopr = strcmp(p, dest);
+ }
+ if (docd(p, dopr) >= 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(const char *dest, int print)
+{
+#if 0 /* no "cd -L" (ever) so all this is just a waste of time ... */
+ char *p;
+ char *q;
+ char *component;
+ struct stat statb;
+ int first;
+ int badstat;
+
+ CTRACE(DBG_CMDS, ("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 (*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) {
+ badstat = 1;
+ break;
+ }
+ }
+#endif
+
+ INTOFF;
+ if (chdir(dest) < 0) {
+ INTON;
+ return -1;
+ }
+ updatepwd(NULL); /* only do cd -P, no "pretend" -L mode */
+ INTON;
+ if (print && iflag == 1 && 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(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;
+}
+
+
+
+/*
+ * 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(const 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("OLDPWD", prevdir, VEXPORT);
+ setvar("PWD", curdir, VEXPORT);
+ } else
+ unsetvar("PWD", 0);
+ return;
+ }
+ cdcomppath = stalloc(strlen(dir) + 1);
+ scopy(dir, cdcomppath);
+ STARTSTACKSTR(new);
+ if (*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("OLDPWD", prevdir, VEXPORT);
+ 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("OLDPWD", prevdir, VEXPORT);
+ setvar("PWD", curdir, VEXPORT);
+ out1str(curdir);
+ out1c('\n');
+ return 0;
+}
+
+
+
+void
+initpwd(void)
+{
+ getpwd(1);
+ if (curdir)
+ setvar("PWD", curdir, VEXPORT);
+ else
+ sh_warnx("Cannot determine current working directory");
+}
+
+#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 && *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)
+
+ for (i = MAXPWD;; i *= 2) {
+ pwd = stalloc(i);
+ if (getcwd(pwd, i) != NULL) {
+ curdir = savestr(pwd);
+ stunalloc(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(NULL, 1);
+ if (forkshell(jp, NULL, FORK_NOJOB) == 0) {
+ (void) close(pip[0]);
+ movefd(pip[1], 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);
+ stunalloc(pwd);
+ return;
+ }
+#endif
+}
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