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authorUlrich Drepper <drepper@gmail.com>2011-05-08 08:37:19 -0400
committerUlrich Drepper <drepper@gmail.com>2011-05-08 08:37:19 -0400
commit7fb90fb89bbdf273ab7ab96517fe1b156cd7aee1 (patch)
treec9fb5b27f0c75b57cd3090e2f3c857feba542f41 /sysdeps
parent28377d1bf58625172a1734b92e835591d4d23a18 (diff)
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Fix Linux getcwd for long paths
The getcwd syscall (so far?) can only handle path up to one page in size. There is no limit about directory hierarchy depth, though, and the POSIX getcwd is supposed to handle this. In that case fall back to the generic getcwd. Additionally, optimize the generic getcwd to use openat when possible to change the asymptotic performance from O(N^2) to O(n).
Diffstat (limited to 'sysdeps')
-rw-r--r--sysdeps/mach/hurd/rewinddir.c4
-rw-r--r--sysdeps/posix/getcwd.c356
-rw-r--r--sysdeps/unix/rewinddir.c3
-rw-r--r--sysdeps/unix/sysv/linux/Makefile2
-rw-r--r--sysdeps/unix/sysv/linux/dl-getcwd.c1
-rw-r--r--sysdeps/unix/sysv/linux/getcwd.c61
6 files changed, 285 insertions, 142 deletions
diff --git a/sysdeps/mach/hurd/rewinddir.c b/sysdeps/mach/hurd/rewinddir.c
index 6956453..322844e 100644
--- a/sysdeps/mach/hurd/rewinddir.c
+++ b/sysdeps/mach/hurd/rewinddir.c
@@ -1,4 +1,4 @@
-/* Copyright (C) 1994, 1997 Free Software Foundation, Inc.
+/* Copyright (C) 1994, 1997, 2011 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
@@ -22,10 +22,10 @@
#include <unistd.h>
/* Rewind DIRP to the beginning of the directory. */
-/* XXX should be __rewinddir ? */
void
rewinddir (dirp)
DIR *dirp;
{
seekdir (dirp, (off_t) 0L);
}
+libc_hidden_def (rewinddir)
diff --git a/sysdeps/posix/getcwd.c b/sysdeps/posix/getcwd.c
index f793521..f683158 100644
--- a/sysdeps/posix/getcwd.c
+++ b/sysdeps/posix/getcwd.c
@@ -1,4 +1,4 @@
-/* Copyright (C) 1991,92,93,94,95,96,97,98,99 Free Software Foundation, Inc.
+/* Copyright (C) 1991,92,93,94,95,96,97,98,99,11 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
@@ -35,6 +35,7 @@
#endif
#include <errno.h>
+#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
@@ -171,6 +172,13 @@ extern char *alloca ();
# include <sys/param.h>
#endif
+#if defined _LIBC && !defined NOT_IN_libc
+# include <not-cancel.h>
+#else
+# define openat_not_cancel_3(dfd, name, mode) openat (dfd, name, mode)
+# define close_not_cancel_no_status(fd) close (fd)
+#endif
+
#ifndef PATH_MAX
# ifdef MAXPATHLEN
# define PATH_MAX MAXPATHLEN
@@ -200,6 +208,12 @@ extern char *alloca ();
# define GETCWD_RETURN_TYPE char *
#endif
+#ifdef __ASSUME_ATFCTS
+# define have_openat 1
+#else
+static int have_openat = 0;
+#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
@@ -211,6 +225,7 @@ __getcwd (buf, size)
char *buf;
size_t size;
{
+#ifndef __ASSUME_ATFCTS
static const char dots[]
= "../../../../../../../../../../../../../../../../../../../../../../../\
../../../../../../../../../../../../../../../../../../../../../../../../../../\
@@ -218,14 +233,15 @@ __getcwd (buf, size)
const char *dotp = &dots[sizeof (dots)];
const char *dotlist = dots;
size_t dotsize = sizeof (dots) - 1;
- dev_t rootdev, thisdev;
- ino_t rootino, thisino;
- char *path;
- register char *pathp;
- struct stat st;
+#endif
int prev_errno = errno;
- size_t allocated = size;
+ DIR *dirstream = NULL;
+ bool fd_needs_closing = false;
+ int fd = AT_FDCWD;
+ char *path;
+#ifndef NO_ALLOCATION
+ size_t allocated = size;
if (size == 0)
{
if (buf != NULL)
@@ -237,189 +253,285 @@ __getcwd (buf, size)
allocated = PATH_MAX + 1;
}
- if (buf != NULL)
- path = buf;
- else
+ if (buf == NULL)
{
path = malloc (allocated);
if (path == NULL)
return NULL;
}
+ else
+#else
+# define allocated size
+#endif
+ path = buf;
- pathp = path + allocated;
+ char *pathp = path + allocated;
*--pathp = '\0';
+ struct stat st;
if (__lstat (".", &st) < 0)
- goto lose2;
- thisdev = st.st_dev;
- thisino = st.st_ino;
+ goto lose;
+ dev_t thisdev = st.st_dev;
+ ino_t thisino = st.st_ino;
if (__lstat ("/", &st) < 0)
- goto lose2;
- rootdev = st.st_dev;
- rootino = st.st_ino;
+ goto lose;
+ dev_t rootdev = st.st_dev;
+ ino_t rootino = st.st_ino;
while (!(thisdev == rootdev && thisino == rootino))
{
- register DIR *dirstream;
- struct dirent *d;
- dev_t dotdev;
- ino_t dotino;
- char mount_point;
-
- /* Look at the parent directory. */
- if (dotp == dotlist)
+ if (have_openat >= 0)
{
- /* My, what a deep directory tree you have, Grandma. */
- char *new;
- if (dotlist == dots)
- {
- new = malloc (dotsize * 2 + 1);
- if (new == NULL)
- goto lose;
-#ifdef HAVE_MEMPCPY
- dotp = mempcpy (new, dots, dotsize);
-#else
- memcpy (new, dots, dotsize);
- dotp = &new[dotsize];
+ int mode = O_RDONLY;
+#ifdef O_CLOEXEC
+ mode |= O_CLOEXEC;
#endif
- }
- else
+ fd = openat_not_cancel_3 (fd, "..", mode);
+ }
+ else
+ fd = -1;
+ if (fd >= 0)
+ {
+ fd_needs_closing = true;
+ if (__fstat (fd, &st) < 0)
+ goto lose;
+ }
+#ifndef __ASSUME_ATFCTS
+ else if (errno == ENOSYS)
+ {
+ have_openat = -1;
+
+ /* Look at the parent directory. */
+ if (dotp == dotlist)
{
- new = realloc ((__ptr_t) dotlist, dotsize * 2 + 1);
- if (new == NULL)
- goto lose;
- dotp = &new[dotsize];
+# ifdef NO_ALLOCATION
+ __set_errno (ENOMEM);
+ goto lose;
+# else
+ /* My, what a deep directory tree you have, Grandma. */
+ char *new;
+ if (dotlist == dots)
+ {
+ new = malloc (dotsize * 2 + 1);
+ if (new == NULL)
+ goto lose;
+# ifdef HAVE_MEMPCPY
+ dotp = mempcpy (new, dots, dotsize);
+# else
+ memcpy (new, dots, dotsize);
+ dotp = &new[dotsize];
+# endif
+ }
+ else
+ {
+ new = realloc ((__ptr_t) dotlist, dotsize * 2 + 1);
+ if (new == NULL)
+ goto lose;
+ dotp = &new[dotsize];
+ }
+# ifdef HAVE_MEMPCPY
+ *((char *) mempcpy ((char *) dotp, new, dotsize)) = '\0';
+ dotsize *= 2;
+# else
+ memcpy ((char *) dotp, new, dotsize);
+ dotsize *= 2;
+ new[dotsize] = '\0';
+# endif
+ dotlist = new;
+# endif
}
-#ifdef HAVE_MEMPCPY
- *((char *) mempcpy ((char *) dotp, new, dotsize)) = '\0';
- dotsize *= 2;
-#else
- memcpy ((char *) dotp, new, dotsize);
- dotsize *= 2;
- new[dotsize] = '\0';
-#endif
- dotlist = new;
- }
- dotp -= 3;
+ dotp -= 3;
- /* Figure out if this directory is a mount point. */
- if (__lstat (dotp, &st) < 0)
+ /* Figure out if this directory is a mount point. */
+ if (__lstat (dotp, &st) < 0)
+ goto lose;
+ }
+#endif
+ else
goto lose;
- dotdev = st.st_dev;
- dotino = st.st_ino;
- mount_point = dotdev != thisdev;
+
+ if (dirstream && __closedir (dirstream) != 0)
+ {
+ dirstream = NULL;
+ goto lose;
+ }
+
+ dev_t dotdev = st.st_dev;
+ ino_t dotino = st.st_ino;
+ bool mount_point = dotdev != thisdev;
/* Search for the last directory. */
- dirstream = __opendir (dotp);
+ if (have_openat >= 0)
+ dirstream = __fdopendir (fd);
+#ifndef __ASSUME_ATFCTS
+ else
+ dirstream = __opendir (dotp);
+#endif
if (dirstream == NULL)
goto lose;
- /* Clear errno to distinguish EOF from error if readdir returns
- NULL. */
- __set_errno (0);
- while ((d = __readdir (dirstream)) != NULL)
+ fd_needs_closing = false;
+
+ struct dirent *d;
+ bool use_d_ino = true;
+ while (1)
{
- if (d->d_name[0] == '.' &&
- (d->d_name[1] == '\0' ||
- (d->d_name[1] == '.' && d->d_name[2] == '\0')))
+ /* Clear errno to distinguish EOF from error if readdir returns
+ NULL. */
+ __set_errno (0);
+ d = __readdir (dirstream);
+ if (d == NULL)
+ {
+ if (errno == 0)
+ {
+ /* When we've iterated through all directory entries
+ without finding one with a matching d_ino, rewind the
+ stream and consider each name again, but this time, using
+ lstat. This is necessary in a chroot on at least one
+ system. */
+ if (use_d_ino)
+ {
+ use_d_ino = false;
+ rewinddir (dirstream);
+ continue;
+ }
+
+ /* EOF on dirstream, which means that the current directory
+ has been removed. */
+ __set_errno (ENOENT);
+ }
+ goto lose;
+ }
+
+ if (d->d_type != DT_DIR && d->d_type != DT_UNKNOWN)
+ continue;
+ if (d->d_name[0] == '.'
+ && (d->d_name[1] == '\0'
+ || (d->d_name[1] == '.' && d->d_name[2] == '\0')))
continue;
- if (mount_point || (ino_t) d->d_ino == thisino)
+ if (use_d_ino && !mount_point && (ino_t) d->d_ino != thisino)
+ continue;
+
+ if (have_openat >= 0)
+ {
+ /* 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 (__fstatat (fd, d->d_name, &st, AT_SYMLINK_NOFOLLOW) < 0)
+ continue;
+ }
+#ifndef __ASSUME_ATFCTS
+ else
{
char name[dotlist + dotsize - dotp + 1 + _D_ALLOC_NAMLEN (d)];
-#ifdef HAVE_MEMPCPY
+# ifdef HAVE_MEMPCPY
char *tmp = mempcpy (name, dotp, dotlist + dotsize - dotp);
*tmp++ = '/';
strcpy (tmp, d->d_name);
-#else
+# else
memcpy (name, dotp, dotlist + dotsize - dotp);
name[dotlist + dotsize - dotp] = '/';
strcpy (&name[dotlist + dotsize - dotp + 1], d->d_name);
-#endif
+# 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 (__lstat (name, &st) >= 0
- && st.st_dev == thisdev && st.st_ino == thisino)
- break;
+ if (__lstat (name, &st) < 0)
+ continue;
}
+#endif
+ if (S_ISDIR (st.st_mode)
+ && st.st_dev == thisdev && st.st_ino == thisino)
+ break;
}
- if (d == NULL)
- {
- int save = errno;
- (void) __closedir (dirstream);
- if (save == 0)
- /* EOF on dirstream, which means that the current directory
- has been removed. */
- save = ENOENT;
- __set_errno (save);
- goto lose;
- }
- else
- {
- size_t namlen = _D_EXACT_NAMLEN (d);
- if ((size_t) (pathp - path) <= namlen)
+ size_t namlen = _D_EXACT_NAMLEN (d);
+
+ if ((size_t) (pathp - path) <= namlen)
+ {
+#ifndef NO_ALLOCATION
+ if (size == 0)
{
- if (size != 0)
- {
- (void) __closedir (dirstream);
- __set_errno (ERANGE);
- goto lose;
- }
- else
- {
- char *tmp;
- size_t oldsize = allocated;
+ size_t oldsize = allocated;
- allocated = 2 * MAX (allocated, namlen);
- tmp = realloc (path, allocated);
- if (tmp == NULL)
- {
- (void) __closedir (dirstream);
- __set_errno (ENOMEM);/* closedir might have changed it.*/
- goto lose;
- }
+ allocated = 2 * MAX (allocated, namlen);
+ char *tmp = realloc (path, allocated);
+ if (tmp == NULL)
+ goto lose;
- /* Move current contents up to the end of the buffer.
- This is guaranteed to be non-overlapping. */
- pathp = memcpy (tmp + allocated - (path + oldsize - pathp),
- tmp + (pathp - path),
- path + oldsize - pathp);
- path = tmp;
- }
+ /* Move current contents up to the end of the buffer.
+ This is guaranteed to be non-overlapping. */
+ pathp = memcpy (tmp + allocated - (path + oldsize - pathp),
+ tmp + (pathp - path),
+ path + oldsize - pathp);
+ path = tmp;
+ }
+ else
+#endif
+ {
+ __set_errno (ERANGE);
+ goto lose;
}
- pathp -= namlen;
- (void) memcpy (pathp, d->d_name, namlen);
- *--pathp = '/';
- (void) __closedir (dirstream);
}
+ pathp -= namlen;
+ (void) memcpy (pathp, d->d_name, namlen);
+ *--pathp = '/';
thisdev = dotdev;
thisino = dotino;
}
+ if (dirstream != NULL && __closedir (dirstream) != 0)
+ {
+ dirstream = NULL;
+ goto lose;
+ }
+
if (pathp == &path[allocated - 1])
*--pathp = '/';
+#ifndef __ASSUME_ATFCTS
if (dotlist != dots)
free ((__ptr_t) dotlist);
+#endif
- memmove (path, pathp, path + allocated - pathp);
+ size_t used = path + allocated - pathp;
+ memmove (path, pathp, used);
+
+ if (size == 0)
+ /* Ensure that the buffer is only as large as necessary. */
+ buf = realloc (path, used);
+
+ if (buf == NULL)
+ /* Either buf was NULL all along, or `realloc' failed but
+ we still have the original string. */
+ buf = path;
/* Restore errno on successful return. */
__set_errno (prev_errno);
- return path;
+ return buf;
- lose:
+ lose:;
+ int save_errno = errno;
+#ifndef __ASSUME_ATFCTS
if (dotlist != dots)
free ((__ptr_t) dotlist);
- lose2:
+#endif
+ if (dirstream != NULL)
+ __closedir (dirstream);
+ if (fd_needs_closing)
+ close_not_cancel_no_status (fd);
+#ifndef NO_ALLOCATION
if (buf == NULL)
free (path);
+#endif
+ __set_errno (save_errno);
return NULL;
}
diff --git a/sysdeps/unix/rewinddir.c b/sysdeps/unix/rewinddir.c
index 051e935..89b0e6d 100644
--- a/sysdeps/unix/rewinddir.c
+++ b/sysdeps/unix/rewinddir.c
@@ -1,4 +1,4 @@
-/* Copyright (C) 1991, 1995-1998, 2005 Free Software Foundation, Inc.
+/* Copyright (C) 1991, 1995-1998, 2005, 2011 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
@@ -35,3 +35,4 @@ rewinddir (dirp)
dirp->size = 0;
__libc_lock_unlock (dirp->lock);
}
+libc_hidden_def (rewinddir)
diff --git a/sysdeps/unix/sysv/linux/Makefile b/sysdeps/unix/sysv/linux/Makefile
index 7066ffe..61fbfb4 100644
--- a/sysdeps/unix/sysv/linux/Makefile
+++ b/sysdeps/unix/sysv/linux/Makefile
@@ -147,7 +147,7 @@ sysdep_routines += xstatconv internal_statvfs internal_statvfs64 \
endif
ifeq ($(subdir),elf)
-sysdep-rtld-routines += dl-brk dl-sbrk
+sysdep-rtld-routines += dl-brk dl-sbrk dl-getcwd
CPPFLAGS-lddlibc4 += -DNOT_IN_libc
endif
diff --git a/sysdeps/unix/sysv/linux/dl-getcwd.c b/sysdeps/unix/sysv/linux/dl-getcwd.c
new file mode 100644
index 0000000..4bd5657
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/dl-getcwd.c
@@ -0,0 +1 @@
+#include "getcwd.c"
diff --git a/sysdeps/unix/sysv/linux/getcwd.c b/sysdeps/unix/sysv/linux/getcwd.c
index 911d85f..db3e292 100644
--- a/sysdeps/unix/sysv/linux/getcwd.c
+++ b/sysdeps/unix/sysv/linux/getcwd.c
@@ -1,5 +1,5 @@
/* Determine current working directory. Linux version.
- Copyright (C) 1997,1998,1999,2000,2002,2003,2006
+ Copyright (C) 1997,1998,1999,2000,2002,2003,2006,2011
Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
@@ -45,20 +45,13 @@
compiling under 2.1.92+ the libc still runs under older kernels. */
# define no_syscall_getcwd 0
# define have_new_dcache 1
-/* This is a trick since we don't define generic_getcwd. */
-# define generic_getcwd getcwd
#else
-/* The "proc" filesystem provides an easy method to retrieve the value.
- For each process, the corresponding directory contains a symbolic link
- named `cwd'. Reading the content of this link immediate gives us the
- information. But we have to take care for systems which do not have
- the proc filesystem mounted. Use the POSIX implementation in this case. */
-static char *generic_getcwd (char *buf, size_t size) internal_function;
-
# if __NR_getcwd
/* Kernel 2.1.92 introduced a third way to get the current working
directory: a syscall. We've got to be careful that even when
- compiling under 2.1.92+ the libc still runs under older kernels. */
+ compiling under 2.1.92+ the libc still runs under older kernels.
+ An additional problem is that the system call does not return
+ the path of directories longer than one page. */
static int no_syscall_getcwd;
static int have_new_dcache;
# else
@@ -67,6 +60,13 @@ static int have_new_dcache = 1;
# endif
#endif
+/* The "proc" filesystem provides an easy method to retrieve the value.
+ For each process, the corresponding directory contains a symbolic link
+ named `cwd'. Reading the content of this link immediate gives us the
+ information. But we have to take care for systems which do not have
+ the proc filesystem mounted. Use the POSIX implementation in this case. */
+static char *generic_getcwd (char *buf, size_t size) internal_function;
+
char *
__getcwd (char *buf, size_t size)
{
@@ -124,6 +124,33 @@ __getcwd (char *buf, size_t size)
return buf;
}
+ // XXX This should not be necessary but the full getcwd implementation
+ // drags in too much for the current build proces of ld.so to handle
+#ifndef NOT_IN_libc
+ /* The system call cannot handle paths longer than a page.
+ Neither can the magic symlink in /proc/self. Just use the
+ generic implementation right away. */
+ if (errno == ENAMETOOLONG)
+ {
+# ifndef NO_ALLOCATION
+ if (buf == NULL && size == 0)
+ {
+ free (path);
+ path = NULL;
+ }
+# endif
+
+ result = generic_getcwd (path, size);
+
+# ifndef NO_ALLOCATION
+ if (result == NULL && buf == NULL && size != 0)
+ free (path);
+# endif
+
+ return result;
+ }
+#endif
+
# if __ASSUME_GETCWD_SYSCALL
/* It should never happen that the `getcwd' syscall failed because
the buffer is too small if we allocated the buffer ourselves
@@ -196,7 +223,7 @@ __getcwd (char *buf, size_t size)
#ifndef NO_ALLOCATION
/* Don't put restrictions on the length of the path unless the user does. */
- if (size == 0)
+ if (buf == NULL && size == 0)
{
free (path);
path = NULL;
@@ -214,9 +241,11 @@ __getcwd (char *buf, size_t size)
}
weak_alias (__getcwd, getcwd)
-#if __ASSUME_GETCWD_SYSCALL == 0
+ // XXX This should not be necessary but the full getcwd implementation
+ // drags in too much for the current build proces of ld.so to handle
+#ifndef NOT_IN_libc
/* Get the code for the generic version. */
-# define GETCWD_RETURN_TYPE static char * internal_function
-# define __getcwd generic_getcwd
-# include <sysdeps/posix/getcwd.c>
+#define GETCWD_RETURN_TYPE static char * internal_function
+#define __getcwd generic_getcwd
+#include <sysdeps/posix/getcwd.c>
#endif