diff options
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/getcwd.c | 388 |
1 files changed, 351 insertions, 37 deletions
diff --git a/lib/getcwd.c b/lib/getcwd.c index 3d63f0480..7a583070f 100644 --- a/lib/getcwd.c +++ b/lib/getcwd.c @@ -1,5 +1,6 @@ -/* Provide a replacement for the POSIX getcwd function. - Copyright (C) 2003, 2004 Free Software Foundation, Inc. +/* Copyright (C) 1991,92,93,94,95,96,97,98,99,2004 Free Software Foundation, + Inc. + This file is part of the GNU C Library. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -11,59 +12,372 @@ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. - You should have received a copy of the GNU General Public License - along with this program; if not, write to the Free Software Foundation, + You should have received a copy of the GNU General Public License along + with this program; if not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ -/* written by Jim Meyering */ +#ifdef HAVE_CONFIG_H +# include "config.h" +#endif -#include <config.h> +#if !_LIBC +# include "getcwd.h" +#endif -#include <stdlib.h> -#include <string.h> #include <errno.h> #include <sys/types.h> +#include <sys/stat.h> +#include <stdbool.h> +#include <stddef.h> + +#if HAVE_FCNTL_H +# include <fcntl.h> /* For AT_FDCWD on Solaris 9. */ +#endif -#include "pathmax.h" -#include "same.h" +#ifndef __set_errno +# define __set_errno(val) (errno = (val)) +#endif -/* Guess high, because that makes the test below more conservative. - But this is a kludge, because we should really use - pathconf (".", _PC_NAME_MAX). But it's probably not worth the cost. */ -#define KLUDGE_POSIX_NAME_MAX 255 +#if HAVE_DIRENT_H || _LIBC +# include <dirent.h> +# ifndef _D_EXACT_NAMLEN +# define _D_EXACT_NAMLEN(d) strlen ((d)->d_name) +# endif +#else +# define dirent direct +# if HAVE_SYS_NDIR_H +# include <sys/ndir.h> +# endif +# if HAVE_SYS_DIR_H +# include <sys/dir.h> +# endif +# if HAVE_NDIR_H +# include <ndir.h> +# endif +#endif +#ifndef _D_EXACT_NAMLEN +# define _D_EXACT_NAMLEN(d) ((d)->d_namlen) +#endif +#ifndef _D_ALLOC_NAMLEN +# define _D_ALLOC_NAMLEN(d) (_D_EXACT_NAMLEN (d) + 1) +#endif -#define MAX_SAFE_LEN (PATH_MAX - 1 - KLUDGE_POSIX_NAME_MAX - 1) +#if HAVE_UNISTD_H || _LIBC +# include <unistd.h> +#endif -/* Undefine getcwd here, as near the use as possible, in case any - of the files included above define it to rpl_getcwd. */ -#undef getcwd +#include <stdlib.h> +#include <string.h> -/* Any declaration of getcwd from headers included above has - been changed to a declaration of rpl_getcwd. Declare it here. */ -extern char *getcwd (char *buf, size_t size); +#if _LIBC +# ifndef mempcpy +# define mempcpy __mempcpy +# endif +#else +# include "mempcpy.h" +#endif -/* This is a wrapper for getcwd. - Some implementations (at least GNU libc 2.3.1 + linux-2.4.20) return - non-NULL for a working directory name longer than PATH_MAX, yet the - returned string is a strict prefix of the desired directory name. - Upon such a failure, free the offending string, set errno to - ENAMETOOLONG, and return NULL. +#include <limits.h> - I've heard that this is a Linux kernel bug, and that it has - been fixed between 2.4.21-pre3 and 2.4.21-pre4. */ +#ifndef MAX +# define MAX(a, b) ((a) < (b) ? (b) : (a)) +#endif +#ifndef MIN +# define MIN(a, b) ((a) < (b) ? (a) : (b)) +#endif + +#ifndef PATH_MAX +# ifdef MAXPATHLEN +# define PATH_MAX MAXPATHLEN +# else +# define PATH_MAX 1024 +# endif +#endif + +#if D_INO_IN_DIRENT +# define MATCHING_INO(dp, ino) ((dp)->d_ino == (ino)) +#else +# define MATCHING_INO(dp, ino) true +#endif + +#if !_LIBC +# define __getcwd getcwd +# define __lstat lstat +# define __closedir closedir +# define __opendir opendir +# define __readdir readdir +#endif + +/* Get the pathname of the current working directory, and put it in SIZE + bytes of BUF. Returns NULL if the directory couldn't be determined or + SIZE was too small. If successful, returns BUF. In GNU, if BUF is + NULL, an array is allocated with `malloc'; the array is SIZE bytes long, + unless SIZE == 0, in which case it is as big as necessary. */ char * -rpl_getcwd (char *buf, size_t size) +__getcwd (char *buf, size_t size) { - char *cwd = getcwd (buf, size); + /* Lengths of big file name components and entire file names, and a + deep level of file name nesting. These numbers are not upper + bounds; they are merely large values suitable for initial + allocations, designed to be large enough for most real-world + uses. */ + enum + { + BIG_FILE_NAME_COMPONENT_LENGTH = 255, + BIG_FILE_NAME_LENGTH = MIN (4095, PATH_MAX - 1), + DEEP_NESTING = 100 + }; + +#ifdef AT_FDCWD + int fd = AT_FDCWD; + bool fd_needs_closing = false; +#else + char dots[DEEP_NESTING * sizeof ".." + BIG_FILE_NAME_COMPONENT_LENGTH + 1]; + char *dotlist = dots; + size_t dotsize = sizeof dots; + size_t dotlen = 0; +#endif + DIR *dirstream = NULL; + dev_t rootdev, thisdev; + ino_t rootino, thisino; + char *path; + register char *pathp; + struct stat st; + int prev_errno = errno; + size_t allocated = size; + + if (size == 0) + { + if (buf != NULL) + { + __set_errno (EINVAL); + return NULL; + } + + allocated = BIG_FILE_NAME_LENGTH + 1; + } + + if (buf != NULL) + path = buf; + else + { + path = malloc (allocated); + if (path == NULL) + return NULL; + } + + pathp = path + allocated; + *--pathp = '\0'; + + if (__lstat (".", &st) < 0) + goto lose; + thisdev = st.st_dev; + thisino = st.st_ino; + + if (__lstat ("/", &st) < 0) + goto lose; + rootdev = st.st_dev; + rootino = st.st_ino; + + while (!(thisdev == rootdev && thisino == rootino)) + { + struct dirent *d; + dev_t dotdev; + ino_t dotino; + bool mount_point; + int parent_status; + + /* Look at the parent directory. */ +#ifdef AT_FDCWD + fd = openat (fd, "..", O_RDONLY); + if (fd < 0) + goto lose; + fd_needs_closing = true; + parent_status = fstat (fd, &st); +#else + dotlist[dotlen++] = '.'; + dotlist[dotlen++] = '.'; + dotlist[dotlen] = '\0'; + parent_status = __lstat (dotlist, &st); +#endif + if (parent_status != 0) + goto lose; - if (cwd == NULL) - return NULL; + if (dirstream && __closedir (dirstream) != 0) + { + dirstream = NULL; + goto lose; + } - if (strlen (cwd) <= MAX_SAFE_LEN || same_name (cwd, ".")) - return cwd; + /* Figure out if this directory is a mount point. */ + dotdev = st.st_dev; + dotino = st.st_ino; + mount_point = dotdev != thisdev; - free (cwd); - errno = ENAMETOOLONG; + /* Search for the last directory. */ +#ifdef AT_FDCWD + dirstream = fdopendir (fd); + if (dirstream == NULL) + goto lose; + fd_needs_closing = false; +#else + dirstream = __opendir (dotlist); + if (dirstream == NULL) + goto lose; + dotlist[dotlen++] = '/'; +#endif + /* Clear errno to distinguish EOF from error if readdir returns + NULL. */ + __set_errno (0); + while ((d = __readdir (dirstream)) != NULL) + { + if (d->d_name[0] == '.' && + (d->d_name[1] == '\0' || + (d->d_name[1] == '.' && d->d_name[2] == '\0'))) + continue; + if (MATCHING_INO (d, thisino) || mount_point) + { + int entry_status; +#ifdef AT_FDCWD + entry_status = fstatat (fd, d->d_name, &st, AT_SYMLINK_NOFOLLOW); +#else + /* Compute size needed for this file name, or for the file + name ".." in the same directory, whichever is larger. + Room for ".." might be needed the next time through + the outer loop. */ + size_t name_alloc = _D_ALLOC_NAMLEN (d); + size_t filesize = dotlen + MAX (sizeof "..", name_alloc); + + if (filesize < dotlen) + goto memory_exhausted; + + if (dotsize < filesize) + { + /* My, what a deep directory tree you have, Grandma. */ + size_t newsize = MAX (filesize, dotsize * 2); + size_t i; + if (newsize < dotsize) + goto memory_exhausted; + if (dotlist != dots) + free (dotlist); + dotlist = malloc (newsize); + if (dotlist == NULL) + goto lose; + dotsize = newsize; + + i = 0; + do + { + dotlist[i++] = '.'; + dotlist[i++] = '.'; + dotlist[i++] = '/'; + } + while (i < dotlen); + } + + strcpy (dotlist + dotlen, d->d_name); + entry_status = __lstat (dotlist, &st); +#endif + /* We don't fail here if we cannot stat() a directory entry. + This can happen when (network) filesystems fail. If this + entry is in fact the one we are looking for we will find + out soon as we reach the end of the directory without + having found anything. */ + if (entry_status == 0 && S_ISDIR (st.st_mode) + && st.st_dev == thisdev && st.st_ino == thisino) + break; + } + } + if (d == NULL) + { + if (errno == 0) + /* EOF on dirstream, which means that the current directory + has been removed. */ + __set_errno (ENOENT); + goto lose; + } + else + { + size_t pathroom = pathp - path; + size_t namlen = _D_EXACT_NAMLEN (d); + + if (pathroom <= namlen) + { + if (size != 0) + { + __set_errno (ERANGE); + goto lose; + } + else + { + char *tmp; + size_t oldsize = allocated; + + allocated += MAX (allocated, namlen); + if (allocated < oldsize + || ! (tmp = realloc (path, allocated))) + goto memory_exhausted; + + /* Move current contents up to the end of the buffer. + This is guaranteed to be non-overlapping. */ + pathp = memcpy (tmp + allocated - (oldsize - pathroom), + tmp + pathroom, + oldsize - pathroom); + path = tmp; + } + } + pathp -= namlen; + memcpy (pathp, d->d_name, namlen); + *--pathp = '/'; + } + + thisdev = dotdev; + thisino = dotino; + } + + if (dirstream && __closedir (dirstream) != 0) + { + dirstream = NULL; + goto lose; + } + + if (pathp == &path[allocated - 1]) + *--pathp = '/'; + +#ifndef AT_FDCWD + if (dotlist != dots) + free (dotlist); +#endif + + memmove (path, pathp, path + allocated - pathp); + + /* Restore errno on successful return. */ + __set_errno (prev_errno); + + return path; + + memory_exhausted: + __set_errno (ENOMEM); + lose: + { + int save = errno; + if (dirstream) + __closedir (dirstream); +#ifdef AT_FDCWD + if (fd_needs_closing) + close (fd); +#else + if (dotlist != dots) + free (dotlist); +#endif + if (buf == NULL) + free (path); + __set_errno (save); + } return NULL; } + +#ifdef weak_alias +weak_alias (__getcwd, getcwd) +#endif |