X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=lib%2Fopenat-priv.h;h=948b220c7ef82cb064a3368f55381cac140b1050;hb=cd19e83484e2c0ff9fd68e7439dd97128c6a2703;hp=9254f6bbad85cf37ca17770e91c422abd0f3210d;hpb=57fdfd3f8ec62b105c53bcdf6f127c35c7fe7391;p=gnulib.git

diff --git a/lib/openat-priv.h b/lib/openat-priv.h
index 9254f6bba..948b220c7 100644
--- a/lib/openat-priv.h
+++ b/lib/openat-priv.h
@@ -1,6 +1,6 @@
 /* Internals for openat-like functions.
 
-   Copyright (C) 2005, 2006 Free Software Foundation, Inc.
+   Copyright (C) 2005-2006, 2009-2011 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
@@ -17,38 +17,48 @@
 
 /* written by Jim Meyering */
 
+#ifndef _GL_HEADER_OPENAT_PRIV
+#define _GL_HEADER_OPENAT_PRIV
+
 #include <errno.h>
+#include <limits.h>
 #include <stdlib.h>
 
-#define OPENAT_BUFFER_SIZE 512
-char *openat_proc_name (char buf[OPENAT_BUFFER_SIZE], int fd, char const *file);
+/* 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)
 
-/* Some systems don't have ENOSYS.  */
-#ifndef ENOSYS
-# ifdef ENOTSUP
-#  define ENOSYS ENOTSUP
-# else
-/* Some systems don't have ENOTSUP either.  */
-#  define ENOSYS EINVAL
-# endif
-#endif
+#define SAFER_ALLOCA(m) ((m) < SAFER_ALLOCA_MAX ? (m) : SAFER_ALLOCA_MAX)
 
-/* Some systems don't have EOPNOTSUPP.  */
-#ifndef EOPNOTSUPP
-# ifdef ENOTSUP
-#  define EOPNOTSUPP ENOTSUP
-# else
-/* Some systems don't have ENOTSUP either.  */
-#  define EOPNOTSUPP EINVAL
-# endif
+#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 */