openat: test for fstatat (..., 0) bug

[gnulib.git] / lib / fstatat.c

diff --git a/lib/fstatat.c b/lib/fstatat.c
index 16d60f6..326ce21 100644 (file)
--- a/lib/fstatat.c
+++ b/lib/fstatat.c
@@ -17,31 +17,53 @@
 
 /* Written by Paul Eggert and Jim Meyering.  */
 
+/* If the user's config.h happens to include <sys/stat.h>, let it include only
+   the system's <sys/stat.h> here, so that orig_fstatat doesn't recurse to
+   rpl_fstatat.  */
+#define __need_system_sys_stat_h
 #include <config.h>
 
+/* Get the original definition of fstatat.  It might be defined as a macro.  */
+#include <sys/types.h>
+#include <sys/stat.h>
+#undef __need_system_sys_stat_h
+
+#if HAVE_FSTATAT
+static inline int
+orig_fstatat (int fd, char const *filename, struct stat *buf, int flags)
+{
+  return fstatat (fd, filename, buf, flags);
+}
+#endif
+
 #include <sys/stat.h>
 
 #include <errno.h>
 #include <fcntl.h>
 #include <string.h>
 
-#if HAVE_FSTATAT
+#if HAVE_FSTATAT && !FSTATAT_ZERO_FLAG_BROKEN
 
-# undef fstatat
+# ifndef LSTAT_FOLLOWS_SLASHED_SYMLINK
+#  define LSTAT_FOLLOWS_SLASHED_SYMLINK 0
+# endif
 
 /* fstatat should always follow symbolic links that end in /, but on
    Solaris 9 it doesn't if AT_SYMLINK_NOFOLLOW is specified.
    Likewise, trailing slash on a non-directory should be an error.
    These are the same problems that lstat.c and stat.c address, so
-   solve it in a similar way.  */
+   solve it in a similar way.
+
+   AIX 7.1 fstatat (AT_FDCWD, ..., 0) always fails, which is a bug.
+   Work around this bug if FSTATAT_AT_FDCWD_0_BROKEN is nonzero.  */
 
 int
 rpl_fstatat (int fd, char const *file, struct stat *st, int flag)
 {
-  int result = fstatat (fd, file, st, flag);
+  int result = orig_fstatat (fd, file, st, flag);
   size_t len;
 
-  if (result != 0)
+  if (LSTAT_FOLLOWS_SLASHED_SYMLINK || result != 0)
     return result;
   len = strlen (file);
   if (flag & AT_SYMLINK_NOFOLLOW)
@@ -54,7 +76,7 @@ rpl_fstatat (int fd, char const *file, struct stat *st, int flag)
           errno = ENOTDIR;
           return -1;
         }
-      result = fstatat (fd, file, st, flag & ~AT_SYMLINK_NOFOLLOW);
+      result = orig_fstatat (fd, file, st, flag & ~AT_SYMLINK_NOFOLLOW);
     }
   /* Fix stat behavior.  */
   if (result == 0 && !S_ISDIR (st->st_mode) && file[len - 1] == '/')
@@ -65,7 +87,7 @@ rpl_fstatat (int fd, char const *file, struct stat *st, int flag)
   return result;
 }
 
-#else /* !HAVE_FSTATAT */
+#else /* !HAVE_FSTATAT || FSTATAT_ZERO_FLAG_BROKEN */
 
 /* On mingw, the gnulib <sys/stat.h> defines `stat' as a function-like
    macro; but using it in AT_FUNC_F2 causes compilation failure
@@ -93,7 +115,11 @@ stat_func (char const *name, struct stat *st)
    then give a diagnostic and exit nonzero.
    Otherwise, this function works just like Solaris' fstatat.  */
 
-# define AT_FUNC_NAME fstatat
+# if FSTATAT_ZERO_FLAG_BROKEN
+#  define AT_FUNC_NAME rpl_fstatat
+# else
+#  define AT_FUNC_NAME fstatat
+# endif
 # define AT_FUNC_F1 lstat
 # define AT_FUNC_F2 stat_func
 # define AT_FUNC_USE_F1_COND AT_SYMLINK_NOFOLLOW