summaryrefslogtreecommitdiffstats
path: root/lib/open.c
diff options
context:
space:
mode:
Diffstat (limited to 'lib/open.c')
-rw-r--r--lib/open.c208
1 files changed, 208 insertions, 0 deletions
diff --git a/lib/open.c b/lib/open.c
new file mode 100644
index 0000000..792e258
--- /dev/null
+++ b/lib/open.c
@@ -0,0 +1,208 @@
+/* Open a descriptor to a file.
+ Copyright (C) 2007-2018 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 <https://www.gnu.org/licenses/>. */
+
+/* Written by Bruno Haible <bruno@clisp.org>, 2007. */
+
+/* If the user's config.h happens to include <fcntl.h>, let it include only
+ the system's <fcntl.h> here, so that orig_open doesn't recurse to
+ rpl_open. */
+#define __need_system_fcntl_h
+#include <config.h>
+
+/* Get the original definition of open. It might be defined as a macro. */
+#include <fcntl.h>
+#include <sys/types.h>
+#undef __need_system_fcntl_h
+
+static int
+orig_open (const char *filename, int flags, mode_t mode)
+{
+ return open (filename, flags, mode);
+}
+
+/* Specification. */
+/* Write "fcntl.h" here, not <fcntl.h>, otherwise OSF/1 5.1 DTK cc eliminates
+ this include because of the preliminary #include <fcntl.h> above. */
+#include "fcntl.h"
+
+#include "cloexec.h"
+
+#include <errno.h>
+#include <stdarg.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+#ifndef REPLACE_OPEN_DIRECTORY
+# define REPLACE_OPEN_DIRECTORY 0
+#endif
+
+int
+open (const char *filename, int flags, ...)
+{
+ /* 0 = unknown, 1 = yes, -1 = no. */
+#if GNULIB_defined_O_CLOEXEC
+ int have_cloexec = -1;
+#else
+ static int have_cloexec;
+#endif
+
+ mode_t mode;
+ int fd;
+
+ mode = 0;
+ if (flags & O_CREAT)
+ {
+ va_list arg;
+ va_start (arg, flags);
+
+ /* We have to use PROMOTED_MODE_T instead of mode_t, otherwise GCC 4
+ creates crashing code when 'mode_t' is smaller than 'int'. */
+ mode = va_arg (arg, PROMOTED_MODE_T);
+
+ va_end (arg);
+ }
+
+#if GNULIB_defined_O_NONBLOCK
+ /* The only known platform that lacks O_NONBLOCK is mingw, but it
+ also lacks named pipes and Unix sockets, which are the only two
+ file types that require non-blocking handling in open().
+ Therefore, it is safe to ignore O_NONBLOCK here. It is handy
+ that mingw also lacks openat(), so that is also covered here. */
+ flags &= ~O_NONBLOCK;
+#endif
+
+#if defined _WIN32 && ! defined __CYGWIN__
+ if (strcmp (filename, "/dev/null") == 0)
+ filename = "NUL";
+#endif
+
+#if OPEN_TRAILING_SLASH_BUG
+ /* If the filename ends in a slash and one of O_CREAT, O_WRONLY, O_RDWR
+ is specified, then fail.
+ Rationale: POSIX <http://www.opengroup.org/susv3/basedefs/xbd_chap04.html>
+ says that
+ "A pathname that contains at least one non-slash character and that
+ ends with one or more trailing slashes shall be resolved as if a
+ single dot character ( '.' ) were appended to the pathname."
+ and
+ "The special filename dot shall refer to the directory specified by
+ its predecessor."
+ If the named file already exists as a directory, then
+ - if O_CREAT is specified, open() must fail because of the semantics
+ of O_CREAT,
+ - if O_WRONLY or O_RDWR is specified, open() must fail because POSIX
+ <http://www.opengroup.org/susv3/functions/open.html> says that it
+ fails with errno = EISDIR in this case.
+ If the named file does not exist or does not name a directory, then
+ - if O_CREAT is specified, open() must fail since open() cannot create
+ directories,
+ - if O_WRONLY or O_RDWR is specified, open() must fail because the
+ file does not contain a '.' directory. */
+ if (flags & (O_CREAT | O_WRONLY | O_RDWR))
+ {
+ size_t len = strlen (filename);
+ if (len > 0 && filename[len - 1] == '/')
+ {
+ errno = EISDIR;
+ return -1;
+ }
+ }
+#endif
+
+ fd = orig_open (filename,
+ flags & ~(have_cloexec <= 0 ? O_CLOEXEC : 0), mode);
+
+ if (flags & O_CLOEXEC)
+ {
+ if (! have_cloexec)
+ {
+ if (0 <= fd)
+ have_cloexec = 1;
+ else if (errno == EINVAL)
+ {
+ fd = orig_open (filename, flags & ~O_CLOEXEC, mode);
+ have_cloexec = -1;
+ }
+ }
+ if (have_cloexec < 0 && 0 <= fd)
+ set_cloexec_flag (fd, true);
+ }
+
+
+#if REPLACE_FCHDIR
+ /* Implementing fchdir and fdopendir requires the ability to open a
+ directory file descriptor. If open doesn't support that (as on
+ mingw), we use a dummy file that behaves the same as directories
+ on Linux (ie. always reports EOF on attempts to read()), and
+ override fstat() in fchdir.c to hide the fact that we have a
+ dummy. */
+ if (REPLACE_OPEN_DIRECTORY && fd < 0 && errno == EACCES
+ && ((flags & O_ACCMODE) == O_RDONLY
+ || (O_SEARCH != O_RDONLY && (flags & O_ACCMODE) == O_SEARCH)))
+ {
+ struct stat statbuf;
+ if (stat (filename, &statbuf) == 0 && S_ISDIR (statbuf.st_mode))
+ {
+ /* Maximum recursion depth of 1. */
+ fd = open ("/dev/null", flags, mode);
+ if (0 <= fd)
+ fd = _gl_register_fd (fd, filename);
+ }
+ else
+ errno = EACCES;
+ }
+#endif
+
+#if OPEN_TRAILING_SLASH_BUG
+ /* If the filename ends in a slash and fd does not refer to a directory,
+ then fail.
+ Rationale: POSIX <http://www.opengroup.org/susv3/basedefs/xbd_chap04.html>
+ says that
+ "A pathname that contains at least one non-slash character and that
+ ends with one or more trailing slashes shall be resolved as if a
+ single dot character ( '.' ) were appended to the pathname."
+ and
+ "The special filename dot shall refer to the directory specified by
+ its predecessor."
+ If the named file without the slash is not a directory, open() must fail
+ with ENOTDIR. */
+ if (fd >= 0)
+ {
+ /* We know len is positive, since open did not fail with ENOENT. */
+ size_t len = strlen (filename);
+ if (filename[len - 1] == '/')
+ {
+ struct stat statbuf;
+
+ if (fstat (fd, &statbuf) >= 0 && !S_ISDIR (statbuf.st_mode))
+ {
+ close (fd);
+ errno = ENOTDIR;
+ return -1;
+ }
+ }
+ }
+#endif
+
+#if REPLACE_FCHDIR
+ if (!REPLACE_OPEN_DIRECTORY && 0 <= fd)
+ fd = _gl_register_fd (fd, filename);
+#endif
+
+ return fd;
+}