openat: make template easier to use

[gnulib.git] / lib / at-func.c

diff --git a/lib/at-func.c b/lib/at-func.c
index c7963fe..620fdaf 100644 (file)
--- a/lib/at-func.c
+++ b/lib/at-func.c
@@ -1,5 +1,5 @@
 /* Define an at-style functions like fstatat, unlinkat, fchownat, etc.
-   Copyright (C) 2006 Free Software Foundation, Inc.
+   Copyright (C) 2006, 2009 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
@@ -16,14 +16,27 @@
 
 /* written by Jim Meyering */
 
-#define CALL_FUNC(F)                           \
-  (AT_FUNC_USE_F1_COND                         \
+#ifdef AT_FUNC_USE_F1_COND
+# define CALL_FUNC(F)                          \
+  (flag == AT_FUNC_USE_F1_COND                 \
     ? AT_FUNC_F1 (F AT_FUNC_POST_FILE_ARGS)    \
     : AT_FUNC_F2 (F AT_FUNC_POST_FILE_ARGS))
+# define VALIDATE_FLAG(F)                      \
+  if (flag & ~AT_FUNC_USE_F1_COND)             \
+    {                                          \
+      errno = EINVAL;                          \
+      return -1;                               \
+    }
+#else
+# define CALL_FUNC(F) (AT_FUNC_F1 (F AT_FUNC_POST_FILE_ARGS))
+# define VALIDATE_FLAG(F) /* empty */
+#endif
 
-/* Call AT_FUNC_F1 or AT_FUNC_F2 (testing AT_FUNC_USE_F1_COND to
-   determine which) to operate on FILE, which is in the directory
-   open on descriptor FD.  If possible, do it without changing the
+/* Call AT_FUNC_F1 to operate on FILE, which is in the directory
+   open on descriptor FD.  If AT_FUNC_USE_F1_COND is defined to a value,
+   AT_FUNC_POST_FILE_PARAM_DECLS must inlude a parameter named flag;
+   call AT_FUNC_F2 if FLAG is 0 or fail if FLAG contains more bits than
+   AT_FUNC_USE_F1_COND.  If possible, do it without changing the
    working directory.  Otherwise, resort to using save_cwd/fchdir,
    then AT_FUNC_F?/restore_cwd.  If either the save_cwd or the restore_cwd
    fails, then give a diagnostic and exit nonzero.  */
@@ -34,6 +47,8 @@ AT_FUNC_NAME (int fd, char const *file AT_FUNC_POST_FILE_PARAM_DECLS)
   int saved_errno;
   int err;
 
+  VALIDATE_FLAG (flag);
+
   if (fd == AT_FDCWD || IS_ABSOLUTE_FILE_NAME (file))
     return CALL_FUNC (file);