521 lines
12 KiB
C
521 lines
12 KiB
C
/* $NetBSD: cd.c,v 1.53 2022/01/31 16:54:28 kre Exp $ */
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/*-
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* Copyright (c) 1991, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Kenneth Almquist.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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#ifndef lint
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#if 0
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static char sccsid[] = "@(#)cd.c 8.2 (Berkeley) 5/4/95";
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#else
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__RCSID("$NetBSD: cd.c,v 1.53 2022/01/31 16:54:28 kre Exp $");
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#endif
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#endif /* not lint */
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <stdbool.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <errno.h>
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/*
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* The cd and pwd commands.
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*/
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#include "shell.h"
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#include "var.h"
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#include "nodes.h" /* for jobs.h */
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#include "jobs.h"
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#include "options.h"
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#include "builtins.h"
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#include "output.h"
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#include "memalloc.h"
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#include "error.h"
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#include "exec.h"
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#include "redir.h"
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#include "mystring.h"
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#include "show.h"
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#include "cd.h"
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STATIC int docd(const char *, bool, bool);
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STATIC char *getcomponent(void);
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STATIC bool updatepwd(const char *);
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STATIC void find_curdir(int noerror);
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STATIC bool is_curdir(const char *);
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char *curdir = NULL; /* current working directory */
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char *prevdir; /* previous working directory */
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STATIC char *cdcomppath;
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int
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cdcmd(int argc, char **argv)
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{
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const char *dest;
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const char *path, *cp;
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char *p;
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char *d;
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struct stat statb;
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char opt;
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bool eopt = false;
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int print = cdprint; /* set -o cdprint to enable */
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while ((opt = nextopt("Pe")) != '\0')
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if (opt == 'e')
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eopt = true;
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/*
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* Try (quite hard) to have 'curdir' defined, nothing has set
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* it on entry to the shell, but we want 'cd fred; cd -' to work.
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*/
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getpwd(1);
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dest = *argptr;
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if (dest == NULL) {
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dest = bltinlookup("HOME", 1);
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if (dest == NULL)
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error("HOME not set");
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} else if (argptr[1]) {
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/* Do 'ksh' style substitution */
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if (!curdir)
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error("PWD not set");
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p = strstr(curdir, dest);
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if (!p)
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error("bad substitution");
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d = stalloc(strlen(curdir) + strlen(argptr[1]) + 1);
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memcpy(d, curdir, p - curdir);
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strcpy(d + (p - curdir), argptr[1]);
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strcat(d, p + strlen(dest));
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dest = d;
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print = 1;
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} else if (dest[0] == '-' && dest[1] == '\0') {
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dest = prevdir ? prevdir : curdir;
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print = 1;
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}
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if (*dest == '\0')
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dest = ".";
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cp = dest;
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if (*cp == '.' && *++cp == '.')
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cp++;
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if (*cp == 0 || *cp == '/' || (path = bltinlookup("CDPATH", 1)) == NULL)
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path = nullstr;
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while ((p = padvance(&path, dest, 0)) != NULL) {
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stunalloc(p);
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if (stat(p, &statb) >= 0 && S_ISDIR(statb.st_mode)) {
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int dopr = print;
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int x;
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if (!print)
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dopr = strcmp(p, dest);
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if ((x = docd(p, dopr != 0, eopt)) >= 0)
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return x;
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}
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}
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error("can't cd to %s", dest);
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/* NOTREACHED */
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}
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/*
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* Actually do the chdir. In an interactive shell, print the
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* directory name if "print" is nonzero.
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*/
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STATIC int
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docd(const char *dest, bool print, bool eopt)
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{
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bool gotpwd;
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#if 0 /* no "cd -L" (ever) so all this is just a waste of time ... */
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char *p;
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char *q;
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char *component;
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struct stat statb;
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int first;
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int badstat;
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/*
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* Check each component of the path. If we find a symlink or
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* something we can't stat, clear curdir to force a getcwd()
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* next time we get the value of the current directory.
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*/
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badstat = 0;
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cdcomppath = stalloc(strlen(dest) + 1);
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scopy(dest, cdcomppath);
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STARTSTACKSTR(p);
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if (*dest == '/') {
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STPUTC('/', p);
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cdcomppath++;
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}
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first = 1;
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while ((q = getcomponent()) != NULL) {
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if (q[0] == '\0' || (q[0] == '.' && q[1] == '\0'))
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continue;
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if (! first)
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STPUTC('/', p);
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first = 0;
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component = q;
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while (*q)
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STPUTC(*q++, p);
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if (equal(component, ".."))
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continue;
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STACKSTRNUL(p);
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if (lstat(stackblock(), &statb) < 0) {
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badstat = 1;
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break;
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}
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}
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#endif
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CTRACE(DBG_CMDS, ("docd(\"%s\", %s, %s) called\n", dest,
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print ? "true" : "false", eopt ? "true" : "false"));
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INTOFF;
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if (chdir(dest) < 0) {
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INTON;
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return -1;
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}
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gotpwd = updatepwd(NULL); /* only do cd -P, no "pretend" -L mode */
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INTON;
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if (print && (iflag || posix))
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out1fmt("%s\n", gotpwd ? curdir : dest);
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return gotpwd || !eopt ? 0 : 1;
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}
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/*
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* Get the next component of the path name pointed to by cdcomppath.
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* This routine overwrites the string pointed to by cdcomppath.
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*/
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STATIC char *
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getcomponent(void)
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{
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char *p;
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char *start;
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if ((p = cdcomppath) == NULL)
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return NULL;
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start = cdcomppath;
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while (*p != '/' && *p != '\0')
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p++;
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if (*p == '\0') {
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cdcomppath = NULL;
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} else {
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*p++ = '\0';
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cdcomppath = p;
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}
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return start;
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}
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/*
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* Update curdir (the name of the current directory) in response to a
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* cd command. We also call hashcd to let the routines in exec.c know
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* that the current directory has changed.
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*/
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STATIC bool
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updatepwd(const char *dir)
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{
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char *new;
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char *p;
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hashcd(); /* update command hash table */
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/*
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* If our argument is NULL, we don't know the current directory
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* any more because we traversed a symbolic link or something
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* we couldn't stat(). Or we simply don't trust what we had.
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*/
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if (dir == NULL || curdir == NULL) {
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if (prevdir)
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ckfree(prevdir);
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INTOFF;
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prevdir = curdir;
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curdir = NULL;
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getpwd(1);
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INTON;
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if (curdir) {
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setvar("OLDPWD", prevdir, VEXPORT);
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setvar("PWD", curdir, VEXPORT);
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return true;
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} else
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unsetvar("PWD", 0);
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return false;
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}
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/* XXX none of the following code is ever executed any more */
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cdcomppath = stalloc(strlen(dir) + 1);
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scopy(dir, cdcomppath);
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STARTSTACKSTR(new);
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if (*dir != '/') {
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p = curdir;
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while (*p)
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STPUTC(*p++, new);
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if (p[-1] == '/')
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STUNPUTC(new);
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}
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while ((p = getcomponent()) != NULL) {
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if (equal(p, "..")) {
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while (new > stackblock() && (STUNPUTC(new), *new) != '/');
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} else if (*p != '\0' && ! equal(p, ".")) {
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STPUTC('/', new);
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while (*p)
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STPUTC(*p++, new);
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}
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}
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if (new == stackblock())
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STPUTC('/', new);
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STACKSTRNUL(new);
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INTOFF;
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if (prevdir)
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ckfree(prevdir);
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prevdir = curdir;
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curdir = savestr(stackblock());
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setvar("OLDPWD", prevdir, VEXPORT);
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setvar("PWD", curdir, VEXPORT);
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INTON;
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return true;
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}
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/*
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* Test whether we are currently in the direcory given
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* (provided it is given, and is absolute)
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* ie: determine if path is fully qualified pathname of "."
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*/
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STATIC bool
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is_curdir(const char *path)
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{
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struct stat stdot, stpath;
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return path != NULL &&
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*path == '/' &&
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stat(".", &stdot) != -1 &&
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stat(path, &stpath) != -1 &&
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stdot.st_dev == stpath.st_dev &&
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stdot.st_ino == stpath.st_ino;
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}
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/*
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* Posix says the default should be 'pwd -L' (as below), however
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* the 'cd' command (above) does something much nearer to the
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* posix 'cd -P' (not the posix default of 'cd -L').
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* If 'cd' is changed to support -P/L then the default here
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* needs to be revisited if the historic behaviour is to be kept.
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*/
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int
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pwdcmd(int argc, char **argv)
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{
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int i;
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char opt = 'L';
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while ((i = nextopt("LP")) != '\0')
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opt = i;
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if (*argptr)
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error("unexpected argument");
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if (opt == 'L')
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getpwd(0);
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else
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find_curdir(0);
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#if 0 /* posix has been changed to forbid this */
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setvar("OLDPWD", prevdir, VEXPORT);
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setvar("PWD", curdir, VEXPORT);
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#endif
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if (!is_curdir(curdir)) {
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find_curdir(1);
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if (curdir == NULL)
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error("Unable to find current directory");
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}
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flushout(out1); /* make sure buffer is empty */
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clr_err(out1); /* and forget any earlier errors */
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out1str(curdir);
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out1c('\n');
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flushout(out1);
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if (io_err(out1))
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error("stdout: %s", strerror(errno));
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return 0;
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}
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void
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initpwd(void)
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{
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getpwd(1);
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if (curdir)
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setvar("PWD", curdir, VEXPORT);
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else
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sh_warnx("Cannot determine current working directory");
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}
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#define MAXPWD 256
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/*
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* Find out what the current directory is. If we already know the current
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* directory, this routine returns immediately.
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*/
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void
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getpwd(int noerror)
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{
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char *pwd;
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static int first = 1;
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if (curdir)
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return;
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if (first) {
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/*
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* Note that this happens via the call from initpwd()
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* just above, which is called early from main() during
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* sh startup, so fetching PWD from the entry environment
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* (which is what getenv() does) is acceptable. Here we
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* could use normal sh var lookup functions instead, as
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* the arriving environment has already been imported before
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* we get here, but it makes little difference.
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*
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* XXX What would be better perhaps would be to move all of
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* this into initpwd() instead of here, so we could get rid of
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* this "first" static - that function is only ever called once.
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* XXX Some other day.
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*/
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first = 0;
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pwd = getenv("PWD");
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if (is_curdir(pwd)) {
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curdir = savestr(pwd);
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return;
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}
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}
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find_curdir(noerror);
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return;
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}
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STATIC void
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find_curdir(int noerror)
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{
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int i;
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char *pwd;
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/*
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* Things are a bit complicated here; we could have just used
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* getcwd, but traditionally getcwd is implemented using popen
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* to /bin/pwd. This creates a problem for us, since we cannot
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* keep track of the job if it is being ran behind our backs.
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* XXX That's not actually the problem, a process created and
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* XXX destroyed that we know nothing about is harmless. The
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* XXX problem is that old popen() implementations would use
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* XXX wait(2) to await completion of the command, and that might
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* XXX collect (and ignore) our children. As long as we are
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* XXX confident that popen() uses waitpid() (or the equv) there
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* XXX would not be a problem. But how do we know that?
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* So we re-implement getcwd(), and we suppress interrupts
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* throughout the process. This is not completely safe, since
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* the user can still break out of it by killing the pwd program.
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* We still try to use getcwd for systems that we know have a
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* c implementation of getcwd, that does not open a pipe to
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* /bin/pwd.
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*/
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#if defined(__NetBSD__) || defined(__SVR4)
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for (i = MAXPWD;; i *= 2) {
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pwd = stalloc(i);
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if (getcwd(pwd, i) != NULL) {
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curdir = savestr(pwd);
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stunalloc(pwd);
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return;
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}
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stunalloc(pwd);
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if (errno == ERANGE)
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continue;
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if (!noerror)
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error("getcwd() failed: %s", strerror(errno));
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return;
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}
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#else
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{
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char *p;
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int status;
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struct job *jp;
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int pip[2];
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pwd = stalloc(MAXPWD);
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INTOFF;
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if (pipe(pip) < 0)
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error("Pipe call failed");
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jp = makejob(NULL, 1);
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if (forkshell(jp, NULL, FORK_NOJOB) == 0) {
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(void) close(pip[0]);
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movefd(pip[1], 1);
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(void) execl("/bin/pwd", "pwd", (char *)0);
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error("Cannot exec /bin/pwd");
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}
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(void) close(pip[1]);
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pip[1] = -1;
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p = pwd;
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while ((i = read(pip[0], p, pwd + MAXPWD - p)) > 0
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|| (i == -1 && errno == EINTR)) {
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if (i > 0)
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p += i;
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}
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(void) close(pip[0]);
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pip[0] = -1;
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status = waitforjob(jp);
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if (status != 0)
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error((char *)0);
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if (i < 0 || p == pwd || p[-1] != '\n') {
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if (noerror) {
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INTON;
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return;
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}
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error("pwd command failed");
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}
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p[-1] = '\0';
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INTON;
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curdir = savestr(pwd);
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stunalloc(pwd);
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return;
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}
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#endif
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}
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