From 28ef1abc10cfbc2c3d2747c008eb2300858d0426 Mon Sep 17 00:00:00 2001 From: Lorry Tar Creator Date: Fri, 22 Apr 2016 04:38:07 +0000 Subject: grep-2.25 --- lib/fdopendir.c | 249 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 249 insertions(+) create mode 100644 lib/fdopendir.c (limited to 'lib/fdopendir.c') diff --git a/lib/fdopendir.c b/lib/fdopendir.c new file mode 100644 index 0000000..c1f4dcb --- /dev/null +++ b/lib/fdopendir.c @@ -0,0 +1,249 @@ +/* provide a replacement fdopendir function + Copyright (C) 2004-2016 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 + the Free Software Foundation; either version 3 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + 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, see . */ + +/* written by Jim Meyering */ + +#include + +#include + +#include +#include + +#if !HAVE_FDOPENDIR + +# include "openat.h" +# include "openat-priv.h" +# include "save-cwd.h" + +# if GNULIB_DIRENT_SAFER +# include "dirent--.h" +# endif + +# ifndef REPLACE_FCHDIR +# define REPLACE_FCHDIR 0 +# endif + +static DIR *fdopendir_with_dup (int, int, struct saved_cwd const *); +static DIR *fd_clone_opendir (int, struct saved_cwd const *); + +/* Replacement for POSIX fdopendir. + + First, try to simulate it via opendir ("/proc/self/fd/..."). Failing + that, simulate it by using fchdir metadata, or 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. + + If successful, the resulting stream is based on FD in + implementations where streams are based on file descriptors and in + applications where no other thread or signal handler allocates or + frees file descriptors. In other cases, consult dirfd on the result + to find out whether FD is still being used. + + Otherwise, this function works just like POSIX fdopendir. + + W A R N I N G: + + Unlike other fd-related functions, this one places constraints on FD. + If this function returns successfully, FD is under control of the + dirent.h system, and the caller should not close or modify the state of + FD other than by the dirent.h functions. */ +# ifdef __KLIBC__ +# include + +DIR * +fdopendir (int fd) +{ + char path[_MAX_PATH]; + DIR *dirp; + + /* Get a path from fd */ + if (__libc_Back_ioFHToPath (fd, path, sizeof (path))) + return NULL; + + dirp = opendir (path); + if (!dirp) + return NULL; + + /* Unregister fd registered by opendir() */ + _gl_unregister_dirp_fd (dirfd (dirp)); + + /* Register our fd */ + if (_gl_register_dirp_fd (fd, dirp)) + { + int saved_errno = errno; + + closedir (dirp); + + errno = saved_errno; + + dirp = NULL; + } + + return dirp; +} +# else +DIR * +fdopendir (int fd) +{ + DIR *dir = fdopendir_with_dup (fd, -1, NULL); + + if (! REPLACE_FCHDIR && ! dir) + { + int saved_errno = errno; + if (EXPECTED_ERRNO (saved_errno)) + { + struct saved_cwd cwd; + if (save_cwd (&cwd) != 0) + openat_save_fail (errno); + dir = fdopendir_with_dup (fd, -1, &cwd); + saved_errno = errno; + free_cwd (&cwd); + errno = saved_errno; + } + } + + return dir; +} +# endif + +/* Like fdopendir, except that if OLDER_DUPFD is not -1, it is known + to be a dup of FD which is less than FD - 1 and which will be + closed by the caller and not otherwise used by the caller. This + function makes sure that FD is closed and all file descriptors less + than FD are open, and then calls fd_clone_opendir on a dup of FD. + That way, barring race conditions, fd_clone_opendir returns a + stream whose file descriptor is FD. + + If REPLACE_FCHDIR or CWD is null, use opendir ("/proc/self/fd/...", + falling back on fchdir metadata. Otherwise, CWD is a saved version + of the working directory; use fchdir/opendir(".")/restore_cwd(CWD). */ +static DIR * +fdopendir_with_dup (int fd, int older_dupfd, struct saved_cwd const *cwd) +{ + int dupfd = dup (fd); + if (dupfd < 0 && errno == EMFILE) + dupfd = older_dupfd; + if (dupfd < 0) + return NULL; + else + { + DIR *dir; + int saved_errno; + if (dupfd < fd - 1 && dupfd != older_dupfd) + { + dir = fdopendir_with_dup (fd, dupfd, cwd); + saved_errno = errno; + } + else + { + close (fd); + dir = fd_clone_opendir (dupfd, cwd); + saved_errno = errno; + if (! dir) + { + int fd1 = dup (dupfd); + if (fd1 != fd) + openat_save_fail (fd1 < 0 ? errno : EBADF); + } + } + + if (dupfd != older_dupfd) + close (dupfd); + errno = saved_errno; + return dir; + } +} + +/* Like fdopendir, except the result controls a clone of FD. It is + the caller's responsibility both to close FD and (if the result is + not null) to closedir the result. */ +static DIR * +fd_clone_opendir (int fd, struct saved_cwd const *cwd) +{ + if (REPLACE_FCHDIR || ! cwd) + { + DIR *dir = NULL; + int saved_errno = EOPNOTSUPP; + char buf[OPENAT_BUFFER_SIZE]; + char *proc_file = openat_proc_name (buf, fd, "."); + if (proc_file) + { + dir = opendir (proc_file); + saved_errno = errno; + if (proc_file != buf) + free (proc_file); + } +# if REPLACE_FCHDIR + if (! dir && EXPECTED_ERRNO (saved_errno)) + { + char const *name = _gl_directory_name (fd); + DIR *dp = name ? opendir (name) : NULL; + + /* The caller has done an elaborate dance to arrange for opendir to + consume just the right file descriptor. If dirfd returns -1, + though, we're on a system like mingw where opendir does not + consume a file descriptor. Consume it via 'dup' instead. */ + if (dp && dirfd (dp) < 0) + dup (fd); + + return dp; + } +# endif + errno = saved_errno; + return dir; + } + else + { + if (fchdir (fd) != 0) + return NULL; + else + { + DIR *dir = opendir ("."); + int saved_errno = errno; + if (restore_cwd (cwd) != 0) + openat_restore_fail (errno); + errno = saved_errno; + return dir; + } + } +} + +#else /* HAVE_FDOPENDIR */ + +# include +# include + +# undef fdopendir + +/* Like fdopendir, but work around GNU/Hurd bug by validating FD. */ + +DIR * +rpl_fdopendir (int fd) +{ + struct stat st; + if (fstat (fd, &st)) + return NULL; + if (!S_ISDIR (st.st_mode)) + { + errno = ENOTDIR; + return NULL; + } + return fdopendir (fd); +} + +#endif /* HAVE_FDOPENDIR */ -- cgit v1.2.1