X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=lib%2Fopenat.c;h=cd496540e7129d52e27c441aa96c95f6512ab1e1;hb=10a617319435e5050434a864c2934967ebe4ac2f;hp=fa617b807f39ddc5e5a91fe7158af6a4b651a970;hpb=d9203c96c70e64ae24a2f2d36e1ba80d79628dc5;p=gnulib.git diff --git a/lib/openat.c b/lib/openat.c index fa617b807..cd496540e 100644 --- a/lib/openat.c +++ b/lib/openat.c @@ -1,5 +1,5 @@ /* provide a replacement openat function - Copyright (C) 2004 Free Software Foundation, Inc. + Copyright (C) 2004, 2005, 2006 Free Software Foundation, Inc. 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 @@ -13,7 +13,7 @@ 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. */ + Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */ /* written by Jim Meyering */ @@ -21,33 +21,27 @@ #include "openat.h" -#include #include -#include -#include -#include +#include -#include "error.h" -#include "exitfail.h" +#include "dirname.h" /* solely for definition of IS_ABSOLUTE_FILE_NAME */ +#include "fcntl--.h" +#include "lchown.h" +#include "lstat.h" +#include "openat-priv.h" #include "save-cwd.h" -#include "gettext.h" -#define _(msgid) gettext (msgid) - /* Replacement for Solaris' openat function. - Simulate it by doing save_cwd/fchdir/open/restore_cwd. - If either the save_cwd or the restore_cwd fails (relatively unlikely, - and usually indicative of a problem that deserves close attention), + First, try to simulate it via open ("/proc/self/fd/FD/FILE"). + Failing that, simulate it by doing save_cwd/fchdir/open/restore_cwd. + If either the save_cwd or the restore_cwd fails (relatively unlikely), then give a diagnostic and exit nonzero. Otherwise, upon failure, set errno and return -1, as openat does. Upon successful completion, return a file descriptor. */ int -rpl_openat (int fd, char const *filename, int flags, ...) +openat (int fd, char const *file, int flags, ...) { - struct saved_cwd saved_cwd; - int saved_errno; - int new_fd; mode_t mode = 0; if (flags & O_CREAT) @@ -55,37 +49,222 @@ rpl_openat (int fd, char const *filename, int flags, ...) va_list arg; va_start (arg, flags); - /* Assume that mode_t is passed compatibly with mode_t's type - after argument promotion. */ - mode = va_arg (arg, mode_t); + /* If mode_t is narrower than int, use the promoted type (int), + not mode_t. Use sizeof to guess whether mode_t is narrower; + we don't know of any practical counterexamples. */ + mode = (sizeof (mode_t) < sizeof (int) + ? va_arg (arg, int) + : va_arg (arg, mode_t)); va_end (arg); } - if (fd == AT_FDCWD || *filename == '/') - return open (filename, flags, mode); + return openat_permissive (fd, file, flags, mode, NULL); +} + +/* Like openat (FD, FILE, FLAGS, MODE), but if CWD_ERRNO is + nonnull, set *CWD_ERRNO to an errno value if unable to save + or restore the initial working directory. This is needed only + the first time remove.c's remove_dir opens a command-line + directory argument. + + If a previous attempt to restore the current working directory + failed, then we must not even try to access a `.'-relative name. + It is the caller's responsibility not to call this function + in that case. */ + +int +openat_permissive (int fd, char const *file, int flags, mode_t mode, + int *cwd_errno) +{ + struct saved_cwd saved_cwd; + int saved_errno; + int err; + bool save_ok; - if (save_cwd (&saved_cwd) != 0) - error (exit_failure, errno, - _("openat: unable to record current working directory")); + if (fd == AT_FDCWD || IS_ABSOLUTE_FILE_NAME (file)) + return open (file, flags, mode); - if (fchdir (fd) != 0) + { + char buf[OPENAT_BUFFER_SIZE]; + char *proc_file = openat_proc_name (buf, fd, file); + if (proc_file) + { + int open_result = open (proc_file, flags, mode); + int open_errno = errno; + if (proc_file != buf) + free (proc_file); + /* If the syscall succeeds, or if it fails with an unexpected + errno value, then return right away. Otherwise, fall through + and resort to using save_cwd/restore_cwd. */ + if (0 <= open_result || ! EXPECTED_ERRNO (open_errno)) + { + errno = open_errno; + return open_result; + } + } + } + + save_ok = (save_cwd (&saved_cwd) == 0); + if (! save_ok) { - saved_errno = errno; - free_cwd (&saved_cwd); - errno = saved_errno; - return -1; + if (! cwd_errno) + openat_save_fail (errno); + *cwd_errno = errno; } - new_fd = open (filename, flags, mode); + err = fchdir (fd); saved_errno = errno; - if (restore_cwd (&saved_cwd) != 0) - error (exit_failure, errno, - _("openat: unable to restore working directory")); + if (! err) + { + err = open (file, flags, mode); + saved_errno = errno; + if (save_ok && restore_cwd (&saved_cwd) != 0) + { + if (! cwd_errno) + openat_restore_fail (errno); + *cwd_errno = errno; + } + } free_cwd (&saved_cwd); + errno = saved_errno; + return err; +} + +/* Return true if our openat implementation must resort to + using save_cwd and restore_cwd. */ +bool +openat_needs_fchdir (void) +{ + bool needs_fchdir = true; + int fd = open ("/", O_RDONLY); + + if (0 <= fd) + { + char buf[OPENAT_BUFFER_SIZE]; + char *proc_file = openat_proc_name (buf, fd, "."); + if (proc_file) + { + needs_fchdir = false; + if (proc_file != buf) + free (proc_file); + } + close (fd); + } + + return needs_fchdir; +} + +#if !HAVE_FDOPENDIR +/* Replacement for Solaris' function by the same name. + + First, try to simulate it via opendir ("/proc/self/fd/FD"). Failing + that, simulate it by doing save_cwd/fchdir/opendir(".")/restore_cwd. + If either the save_cwd or the restore_cwd fails (relatively unlikely), + then give a diagnostic and exit nonzero. + Otherwise, this function works just like Solaris' fdopendir. + + W A R N I N G: + Unlike the other fd-related functions here, this one + effectively consumes its FD parameter. The caller should not + close or otherwise manipulate FD if this function returns successfully. */ +DIR * +fdopendir (int fd) +{ + struct saved_cwd saved_cwd; + int saved_errno; + DIR *dir; + + char buf[OPENAT_BUFFER_SIZE]; + char *proc_file = openat_proc_name (buf, fd, "."); + if (proc_file) + { + dir = opendir (proc_file); + saved_errno = errno; + } + else + { + dir = NULL; + saved_errno = EOPNOTSUPP; + } + + /* If the syscall fails with an expected errno value, resort to + save_cwd/restore_cwd. */ + if (! dir && EXPECTED_ERRNO (saved_errno)) + { + if (save_cwd (&saved_cwd) != 0) + openat_save_fail (errno); + + if (fchdir (fd) != 0) + { + dir = NULL; + saved_errno = errno; + } + else + { + dir = opendir ("."); + saved_errno = errno; + + if (restore_cwd (&saved_cwd) != 0) + openat_restore_fail (errno); + } + + free_cwd (&saved_cwd); + } + + if (dir) + close (fd); + if (proc_file != buf) + free (proc_file); errno = saved_errno; - return new_fd; + return dir; } + +#endif + +/* Replacement for Solaris' function by the same name. + + First, try to simulate it via l?stat ("/proc/self/fd/FD/FILE"). + Failing that, simulate it via save_cwd/fchdir/(stat|lstat)/restore_cwd. + If either the save_cwd or the restore_cwd fails (relatively unlikely), + then give a diagnostic and exit nonzero. + Otherwise, this function works just like Solaris' fstatat. */ + +#define AT_FUNC_NAME fstatat +#define AT_FUNC_F1 lstat +#define AT_FUNC_F2 stat +#define AT_FUNC_USE_F1_COND flag == AT_SYMLINK_NOFOLLOW +#define AT_FUNC_POST_FILE_PARAM_DECLS , struct stat *st, int flag +#define AT_FUNC_POST_FILE_ARGS , st +#include "at-func.c" +#undef AT_FUNC_NAME +#undef AT_FUNC_F1 +#undef AT_FUNC_F2 +#undef AT_FUNC_USE_F1_COND +#undef AT_FUNC_POST_FILE_PARAM_DECLS +#undef AT_FUNC_POST_FILE_ARGS + +/* Replacement for Solaris' function by the same name. + + First, try to simulate it via (unlink|rmdir) ("/proc/self/fd/FD/FILE"). + Failing that, simulate it via save_cwd/fchdir/(unlink|rmdir)/restore_cwd. + If either the save_cwd or the restore_cwd fails (relatively unlikely), + then give a diagnostic and exit nonzero. + Otherwise, this function works just like Solaris' unlinkat. */ + +#define AT_FUNC_NAME unlinkat +#define AT_FUNC_F1 rmdir +#define AT_FUNC_F2 unlink +#define AT_FUNC_USE_F1_COND flag == AT_REMOVEDIR +#define AT_FUNC_POST_FILE_PARAM_DECLS , int flag +#define AT_FUNC_POST_FILE_ARGS /* empty */ +#include "at-func.c" +#undef AT_FUNC_NAME +#undef AT_FUNC_F1 +#undef AT_FUNC_F2 +#undef AT_FUNC_USE_F1_COND +#undef AT_FUNC_POST_FILE_PARAM_DECLS +#undef AT_FUNC_POST_FILE_ARGS