chown: Use fchownat if arch does not have the chown syscall

Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>

Signed-off-by: Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>

include/unistd.h

@@ -518,6 +518,7 @@ extern int lchown (const char *__file, __uid_t __owner, __gid_t __group)
 extern int fchownat (int __fd, const char *__file, __uid_t __owner,
 		     __gid_t __group, int __flag)
      __THROW __nonnull ((2)) __wur;
+libc_hidden_proto(fchownat)
 #endif /* Use GNU.  */
 
 /* Change the process's working directory to PATH.  */

libc/sysdeps/linux/common/chown.c

@@ -11,18 +11,26 @@
 #include <unistd.h>
 #include <bits/wordsize.h>
 
+#if defined __NR_fchownat && !defined __NR_chown
+# include <fcntl.h>
+int chown(const char *path, uid_t owner, gid_t group)
+{
+	return fchownat(AT_FDCWD, path, owner, group, 0);
+}
 
-#if (__WORDSIZE == 32 && defined(__NR_chown32)) || __WORDSIZE == 64
-# ifdef __NR_chown32
-#  undef __NR_chown
-#  define __NR_chown __NR_chown32
-# endif
+#else
+
+# if (__WORDSIZE == 32 && defined(__NR_chown32)) || __WORDSIZE == 64
+#  ifdef __NR_chown32
+#   undef __NR_chown
+#   define __NR_chown __NR_chown32
+#  endif
 
 _syscall3(int, chown, const char *, path, uid_t, owner, gid_t, group)
 
-#else
+# else
 
-# define __NR___syscall_chown __NR_chown
+#  define __NR___syscall_chown __NR_chown
 static __inline__ _syscall3(int, __syscall_chown, const char *, path,
 		__kernel_uid_t, owner, __kernel_gid_t, group)
 
@@ -35,6 +43,7 @@ int chown(const char *path, uid_t owner, gid_t group)
 	}
 	return (__syscall_chown(path, owner, group));
 }
-#endif
+# endif
 
+#endif
 libc_hidden_def(chown)

libc/sysdeps/linux/common/fchownat.c

@@ -11,6 +11,7 @@
 
 #ifdef __NR_fchownat
 _syscall5(int, fchownat, int, fd, const char *, file, uid_t, owner, gid_t, group, int, flag)
+libc_hidden_def(fchownat)
 #else
 /* should add emulation with fchown() and /proc/self/fd/ ... */
 #endif