1/* provide a replacement fdopendir function 2 Copyright (C) 2004-2010 Free Software Foundation, Inc. 3 4 This program is free software: you can redistribute it and/or modify 5 it under the terms of the GNU General Public License as published by 6 the Free Software Foundation; either version 3 of the License, or 7 (at your option) any later version. 8 9 This program is distributed in the hope that it will be useful, 10 but WITHOUT ANY WARRANTY; without even the implied warranty of 11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 GNU General Public License for more details. 13 14 You should have received a copy of the GNU General Public License 15 along with this program. If not, see <http://www.gnu.org/licenses/>. */ 16 17/* written by Jim Meyering */ 18 19#include <config.h> 20 21#include <dirent.h> 22 23#include <stdlib.h> 24#include <unistd.h> 25 26#if !HAVE_FDOPENDIR 27 28# include "openat.h" 29# include "openat-priv.h" 30# include "save-cwd.h" 31 32# if GNULIB_DIRENT_SAFER 33# include "dirent--.h" 34# endif 35 36/* Replacement for Solaris' function by the same name. 37 <http://www.google.com/search?q=fdopendir+site:docs.sun.com> 38 First, try to simulate it via opendir ("/proc/self/fd/FD"). Failing 39 that, simulate it by using fchdir metadata, or by doing 40 save_cwd/fchdir/opendir(".")/restore_cwd. 41 If either the save_cwd or the restore_cwd fails (relatively unlikely), 42 then give a diagnostic and exit nonzero. 43 Otherwise, this function works just like Solaris' fdopendir. 44 45 W A R N I N G: 46 Unlike other fd-related functions, this one effectively consumes 47 its FD parameter. The caller should not close or otherwise 48 manipulate FD if this function returns successfully. Also, this 49 implementation does not guarantee that dirfd(fdopendir(n))==n; 50 the open directory stream may use a clone of FD, or have no 51 associated fd at all. */ 52DIR * 53fdopendir (int fd) 54{ 55 int saved_errno; 56 DIR *dir; 57 58 char buf[OPENAT_BUFFER_SIZE]; 59 char *proc_file = openat_proc_name (buf, fd, "."); 60 if (proc_file) 61 { 62 dir = opendir (proc_file); 63 saved_errno = errno; 64 } 65 else 66 { 67 dir = NULL; 68 saved_errno = EOPNOTSUPP; 69 } 70 71 /* If the syscall fails with an expected errno value, resort to 72 save_cwd/restore_cwd. */ 73 if (! dir && EXPECTED_ERRNO (saved_errno)) 74 { 75# if REPLACE_FCHDIR 76 const char *name = _gl_directory_name (fd); 77 if (name) 78 dir = opendir (name); 79 saved_errno = errno; 80# else /* !REPLACE_FCHDIR */ 81 struct saved_cwd saved_cwd; 82 if (save_cwd (&saved_cwd) != 0) 83 openat_save_fail (errno); 84 85 if (fchdir (fd) != 0) 86 { 87 dir = NULL; 88 saved_errno = errno; 89 } 90 else 91 { 92 dir = opendir ("."); 93 saved_errno = errno; 94 95 if (restore_cwd (&saved_cwd) != 0) 96 openat_restore_fail (errno); 97 } 98 99 free_cwd (&saved_cwd); 100# endif /* !REPLACE_FCHDIR */ 101 } 102 103 if (dir) 104 close (fd); 105 if (proc_file != buf) 106 free (proc_file); 107 errno = saved_errno; 108 return dir; 109} 110 111#else /* HAVE_FDOPENDIR */ 112 113# include <errno.h> 114# include <sys/stat.h> 115 116# undef fdopendir 117 118/* Like fdopendir, but work around GNU/Hurd bug by validating FD. */ 119 120DIR * 121rpl_fdopendir (int fd) 122{ 123 struct stat st; 124 if (fstat (fd, &st)) 125 return NULL; 126 if (!S_ISDIR (st.st_mode)) 127 { 128 errno = ENOTDIR; 129 return NULL; 130 } 131 return fdopendir (fd); 132} 133 134#endif /* HAVE_FDOPENDIR */ 135