Re: detection of functional openat() for usage inside getcwd.c

[Jim Meyering]

Petr Salinger <address@hidden> wrote:
> getcwd.c uses *at() function family iff AT_FDCWD is defined.
> This approach does not work on GNU/kFreeBSD - FreeBSD kernel + GNU libc.
> The kernel does not provide needed interfaces, and therefore glibc
> provides only stub version for function from *at() family.
> But the AT_FDCWD is declared and getwdc.c uses only native i.e. openat().
>
> Please, could you change detection whether really use *at() function
> family in getcwd.

Here's an untested patch.
Please test it.

        Port to GNU/kFreeBSD - FreeBSD kernel + GNU libc,
        which has no openat syscall, yet <fcntl.h> does define AT_FDCWD.
        * lib/getcwd.c: Undef AT_FDCWD if there is no openat function.
        * modules/getcwd (Depends-on): Add openat.
        Reported by Petr Salinger.

diff --git a/lib/getcwd.c b/lib/getcwd.c
index b8e9989..98df8bf 100644
--- a/lib/getcwd.c
+++ b/lib/getcwd.c
@@ -29,6 +29,11 @@

 #include <fcntl.h> /* For AT_FDCWD on Solaris 9.  */

+/* On a system without the openat function, undefine AT_FDCWD.  */
+#if ! HAVE_OPENAT
+# undef AT_FDCWD
+#endif
+
 #ifndef __set_errno
 # define __set_errno(val) (errno = (val))
 #endif
diff --git a/modules/getcwd b/modules/getcwd
index 17687e7..46ecb03 100644
--- a/modules/getcwd
+++ b/modules/getcwd
@@ -12,6 +12,7 @@ mempcpy
 d-ino
 dirfd
 extensions
+openat
 stdbool
 unistd
 malloc-posix