[PATCH v2 09/46] chown: Use fchownat if arch does not have the chown syscall

[Markos Chandras]

From: Markos Chandras <markos.chandras at imgtec.com>

Signed-off-by: Markos Chandras <markos.chandras at imgtec.com>
---
 include/unistd.h                     | 1 +
 libc/sysdeps/linux/common/chown.c    | 9 +++++++++
 libc/sysdeps/linux/common/fchownat.c | 1 +
 3 files changed, 11 insertions(+)

diff --git a/include/unistd.h b/include/unistd.h
index e58945d..296ae0a 100644
--- a/include/unistd.h
+++ b/include/unistd.h
@@ -469,6 +469,7 @@ 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.  */
diff --git a/libc/sysdeps/linux/common/chown.c b/libc/sysdeps/linux/common/chown.c
index f2c60e0..edca3f8 100644
--- a/libc/sysdeps/linux/common/chown.c
+++ b/libc/sysdeps/linux/common/chown.c
@@ -8,9 +8,17 @@
  */
 
 #include <sys/syscall.h>
+#include <fcntl.h>
 #include <unistd.h>
 #include <bits/wordsize.h>
 
+#if defined(__NR_fchownat) && !defined(__NR_chown)
+int chown(const char *path, uid_t owner, gid_t group)
+{
+	return fchownat(AT_FDCWD, path, owner, group, 0);
+}
+
+#else
 
 #if (__WORDSIZE == 32 && defined(__NR_chown32)) || __WORDSIZE == 64
 # ifdef __NR_chown32
@@ -37,4 +45,5 @@ int chown(const char *path, uid_t owner, gid_t group)
 }
 #endif
 
+#endif
 libc_hidden_def(chown)
diff --git a/libc/sysdeps/linux/common/fchownat.c b/libc/sysdeps/linux/common/fchownat.c
index 707164d..4ad818b 100644
--- a/libc/sysdeps/linux/common/fchownat.c
+++ b/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
-- 
1.8.0