freebsd/bin/sh/cd.c
Jilles Tjoelker d3eae2a68e sh: Fix rare memory leak with SIGINT
If getcwd() failed earlier on but later succeeded in the pwd builtin,
there was no INTOFF protection between calling savestr() and storing its
result.

It is quite rare for getcwd() to fail, and rarer for it to succeed later in
the same directory.

Found via code inspection for changing ckmalloc() and similar to assert
INTOFF protection instead of applying it directly (which protects against
corrupting malloc's internal state but allows memory leaks or double frees).

MFC after:	1 week
2020-01-01 12:06:37 +00:00

434 lines
8.9 KiB
C

/*-
* 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.
*/
#ifndef lint
#if 0
static char sccsid[] = "@(#)cd.c 8.2 (Berkeley) 5/4/95";
#endif
#endif /* not lint */
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#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 = ".";
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);
}