vasnprintf: Optimize bit search operation.

[gnulib.git] / lib / careadlinkat.h

diff --git a/lib/careadlinkat.h b/lib/careadlinkat.h
index c5e4bcf..6576fb2 100644 (file)
--- a/lib/careadlinkat.h
+++ b/lib/careadlinkat.h
@@ -18,6 +18,7 @@
 /* Written by Paul Eggert, Bruno Haible, and Jim Meyering.  */
 
 #ifndef _GL_CAREADLINKAT_H
+#define _GL_CAREADLINKAT_H
 
 #include <fcntl.h>
 #include <unistd.h>
@@ -37,7 +38,10 @@ struct allocator;
    buffer managed by ALLOC.  It is the caller's responsibility to free
    the returned value if it is nonnull and is not BUFFER.
 
-   The PREADLINKAT function specifies how to read links.
+   The PREADLINKAT function specifies how to read links.  It operates
+   like POSIX readlinkat()
+   <http://pubs.opengroup.org/onlinepubs/9699919799/functions/readlink.html>
+   but can assume that its first argument is the same as FD.
 
    If successful, return the buffer address; otherwise return NULL and
    set errno.  */
@@ -49,9 +53,10 @@ char *careadlinkat (int fd, char const *filename,
                                             char *, size_t));
 
 /* Suitable values for careadlinkat's FD and PREADLINKAT arguments,
-   when doing a plain readlink.  */
+   when doing a plain readlink:
+   Pass FD = AT_FDCWD and PREADLINKAT = careadlinkatcwd.  */
 #if HAVE_READLINKAT
-# define careadlinkatcwd readlinkat
+/* AT_FDCWD is declared in <fcntl.h>.  */
 #else
 /* Define AT_FDCWD independently, so that the careadlinkat module does
    not depend on the fcntl-h module.  The value does not matter, since
@@ -60,8 +65,8 @@ char *careadlinkat (int fd, char const *filename,
 # ifndef AT_FDCWD
 #  define AT_FDCWD (-3041965)
 # endif
+#endif
 ssize_t careadlinkatcwd (int fd, char const *filename,
                          char *buffer, size_t buffer_size);
-#endif
 
 #endif /* _GL_CAREADLINKAT_H */