-/* macros used by openat-like functions
- Copyright (C) 2005 Free Software Foundation, Inc.
+/* Internals for openat-like functions.
- This program is free software; you can redistribute it and/or modify
+ Copyright (C) 2005-2006, 2009-2013 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 2, or (at your option)
- any later version.
+ 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
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, write to the Free Software Foundation,
- Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
+ along with this program. If not, see <http://www.gnu.org/licenses/>. */
/* written by Jim Meyering */
-#include <stdio.h>
-#include <string.h>
-#include "alloca.h"
-#include "intprops.h"
-
-/* Set PROC_FD_FILENAME to the expansion of "/proc/self/fd/%d/%s" in
- alloca'd memory, using FD and FILE, respectively for %d and %s. */
-#define BUILD_PROC_NAME(Proc_fd_filename, Fd, File) \
- do \
- { \
- size_t filelen = strlen (File); \
- static const char procfd[] = "/proc/self/fd/%d/%s"; \
- /* Buffer for the file name we are going to use. It consists of \
- - the string /proc/self/fd/ \
- - the file descriptor number \
- - the file name provided. \
- The final NUL is included in the sizeof. \
- Subtract 4 to account for %d and %s. */ \
- size_t buflen = sizeof (procfd) - 4 + INT_STRLEN_BOUND (Fd) + filelen; \
- (Proc_fd_filename) = alloca (buflen); \
- snprintf ((Proc_fd_filename), buflen, procfd, (Fd), (File)); \
- } \
- while (0)
+#ifndef _GL_HEADER_OPENAT_PRIV
+#define _GL_HEADER_OPENAT_PRIV
+
+#include <errno.h>
+#include <limits.h>
+#include <stdlib.h>
+
+/* Maximum number of bytes that it is safe to allocate as a single
+ array on the stack, and that is known as a compile-time constant.
+ The assumption is that we'll touch the array very quickly, or a
+ temporary very near the array, provoking an out-of-memory trap. On
+ some operating systems, there is only one guard page for the stack,
+ and a page size can be as small as 4096 bytes. Subtract 64 in the
+ hope that this will let the compiler touch a nearby temporary and
+ provoke a trap. */
+#define SAFER_ALLOCA_MAX (4096 - 64)
+
+#define SAFER_ALLOCA(m) ((m) < SAFER_ALLOCA_MAX ? (m) : SAFER_ALLOCA_MAX)
+
+#if defined PATH_MAX
+# define OPENAT_BUFFER_SIZE SAFER_ALLOCA (PATH_MAX)
+#elif defined _XOPEN_PATH_MAX
+# define OPENAT_BUFFER_SIZE SAFER_ALLOCA (_XOPEN_PATH_MAX)
+#else
+# define OPENAT_BUFFER_SIZE SAFER_ALLOCA (1024)
+#endif
+
+char *openat_proc_name (char buf[OPENAT_BUFFER_SIZE], int fd, char const *file);
/* Trying to access a BUILD_PROC_NAME file will fail on systems without
/proc support, and even on systems *with* ProcFS support. Return
nonzero if the failure may be legitimate, e.g., because /proc is not
readable, or the particular .../fd/N directory is not present. */
-#define EXPECTED_ERRNO(Errno) \
- ((Errno) == ENOTDIR || (Errno) == ENOENT \
- || (Errno) == EPERM || (Errno) == EACCES \
- || (Errno) == ENOSYS /* Solaris 8 */ \
+#define EXPECTED_ERRNO(Errno) \
+ ((Errno) == ENOTDIR || (Errno) == ENOENT \
+ || (Errno) == EPERM || (Errno) == EACCES \
+ || (Errno) == ENOSYS /* Solaris 8 */ \
|| (Errno) == EOPNOTSUPP /* FreeBSD */)
+
+/* Wrapper function shared among linkat and renameat. */
+int at_func2 (int fd1, char const *file1,
+ int fd2, char const *file2,
+ int (*func) (char const *file1, char const *file2));
+
+#endif /* _GL_HEADER_OPENAT_PRIV */
projects / gnulib.git / blobdiff