X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=lib%2Fopenat.c;h=7f92c7cc78dda84fba24c302d42500f3e9efe7c9;hb=8e99d1a0adfc4eb035e73219ef7001494ecb0c50;hp=572e6d55328a3a5e20bcfc4ef050005468f23999;hpb=77f269d576ef80619fe96e4920df7515447abf89;p=gnulib.git diff --git a/lib/openat.c b/lib/openat.c index 572e6d553..7f92c7cc7 100644 --- a/lib/openat.c +++ b/lib/openat.c @@ -1,5 +1,5 @@ /* provide a replacement openat function - Copyright (C) 2004, 2005 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 @@ -17,27 +17,25 @@ /* written by Jim Meyering */ -#ifdef HAVE_CONFIG_H -# include -#endif +#include #include "openat.h" +#include +#include + #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 "unistd--.h" - -#include -#include -#include /* 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. */ @@ -52,7 +50,7 @@ openat (int fd, char const *file, int flags, ...) va_start (arg, flags); /* If mode_t is narrower than int, use the promoted type (int), - not mode_t. Use sizeof to guess whether mode_t is nerrower; + 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) @@ -88,14 +86,23 @@ openat_permissive (int fd, char const *file, int flags, mode_t mode, return open (file, flags, mode); { - char *proc_file; - BUILD_PROC_NAME (proc_file, fd, file); - err = open (proc_file, flags, mode); - /* 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 <= err || ! EXPECTED_ERRNO (errno)) - return err; + 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); @@ -126,13 +133,37 @@ openat_permissive (int fd, char const *file, int flags, mode_t mode, 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. - Simulate it by doing save_cwd/fchdir/opendir(".")/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 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. @@ -147,10 +178,18 @@ fdopendir (int fd) int saved_errno; DIR *dir; - char *proc_file; - BUILD_PROC_NAME (proc_file, fd, "."); - dir = opendir (proc_file); - saved_errno = errno; + 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. */ @@ -178,6 +217,8 @@ fdopendir (int fd) if (dir) close (fd); + if (proc_file != buf) + free (proc_file); errno = saved_errno; return dir; } @@ -186,102 +227,60 @@ fdopendir (int fd) /* Replacement for Solaris' function by the same name. - Simulate it by doing save_cwd/fchdir/(stat|lstat)/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 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. */ -int -fstatat (int fd, char const *file, struct stat *st, int flag) -{ - struct saved_cwd saved_cwd; - int saved_errno; - int err; - - if (fd == AT_FDCWD || IS_ABSOLUTE_FILE_NAME (file)) - return (flag == AT_SYMLINK_NOFOLLOW - ? lstat (file, st) - : stat (file, st)); - - { - char *proc_file; - BUILD_PROC_NAME (proc_file, fd, file); - err = (flag == AT_SYMLINK_NOFOLLOW - ? lstat (proc_file, st) - : stat (proc_file, st)); - /* 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 <= err || ! EXPECTED_ERRNO (errno)) - return err; - } - - if (save_cwd (&saved_cwd) != 0) - openat_save_fail (errno); - - err = fchdir (fd); - saved_errno = errno; - - if (! err) - { - err = (flag == AT_SYMLINK_NOFOLLOW - ? lstat (file, st) - : stat (file, st)); - saved_errno = errno; - if (restore_cwd (&saved_cwd) != 0) - openat_restore_fail (errno); - } - - free_cwd (&saved_cwd); - errno = saved_errno; - return err; -} +#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. - Simulate it by doing save_cwd/fchdir/(unlink|rmdir)/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 (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. */ -int -unlinkat (int fd, char const *file, int flag) -{ - struct saved_cwd saved_cwd; - int saved_errno; - int err; - if (fd == AT_FDCWD || IS_ABSOLUTE_FILE_NAME (file)) - return (flag == AT_REMOVEDIR ? rmdir (file) : unlink (file)); +#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 - { - char *proc_file; - BUILD_PROC_NAME (proc_file, fd, file); - err = (flag == AT_REMOVEDIR ? rmdir (proc_file) : unlink (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 <= err || ! EXPECTED_ERRNO (errno)) - return err; - } - - if (save_cwd (&saved_cwd) != 0) - openat_save_fail (errno); - - err = fchdir (fd); - saved_errno = errno; - - if (! err) - { - err = (flag == AT_REMOVEDIR ? rmdir (file) : unlink (file)); - saved_errno = errno; - - if (restore_cwd (&saved_cwd) != 0) - openat_restore_fail (errno); - } - - free_cwd (&saved_cwd); - errno = saved_errno; - return err; -} +/* Replacement for Solaris' function by the same name. + Invoke chown or lchown on file, FILE, using OWNER and GROUP, in the + directory open on descriptor FD. If FLAG is AT_SYMLINK_NOFOLLOW, then + use lchown, otherwise, use chown. If possible, do it without changing + the working directory. Otherwise, resort to using save_cwd/fchdir, + then mkdir/restore_cwd. If either the save_cwd or the restore_cwd + fails, then give a diagnostic and exit nonzero. */ + +#define AT_FUNC_NAME fchownat +#define AT_FUNC_F1 lchown +#define AT_FUNC_F2 chown +#define AT_FUNC_USE_F1_COND flag == AT_SYMLINK_NOFOLLOW +#define AT_FUNC_POST_FILE_PARAM_DECLS , uid_t owner, gid_t group, int flag +#define AT_FUNC_POST_FILE_ARGS , owner, group +#include "at-func.c"