[glibc] Linux: consolidate readlink implementation

[glibc] Linux: consolidate readlink implementation

[Adhemerval Zanella]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=2fc81f6ca56f1df5323fc849f3f8dc40f38fc5b2

commit 2fc81f6ca56f1df5323fc849f3f8dc40f38fc5b2
Author: Adhemerval Zanella Netto <adhemerval.zanella@linaro.org>
Date:   Wed Oct 19 19:14:14 2022 -0300

    Linux: consolidate readlink implementation
    
    Use readlink syscall if defined, otherwise readlinkat.
    
    Checked on x86_64-linux-gnu.
    Reviewed-by: Carlos O'Donell <carlos@redhat.com>
    Tested-by: Carlos O'Donell <carlos@redhat.com>

Diff:
---
 sysdeps/unix/sysv/linux/{generic => }/readlink.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/sysdeps/unix/sysv/linux/generic/readlink.c b/sysdeps/unix/sysv/linux/readlink.c
similarity index 80%
rename from sysdeps/unix/sysv/linux/generic/readlink.c
rename to sysdeps/unix/sysv/linux/readlink.c
index 9f25811a35..083dcaf502 100644
--- a/sysdeps/unix/sysv/linux/generic/readlink.c
+++ b/sysdeps/unix/sysv/linux/readlink.c
@@ -1,4 +1,5 @@
-/* Copyright (C) 2011-2022 Free Software Foundation, Inc.
+/* Read value of a symbolic link.  Linux version.
+   Copyright (C) 2011-2022 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
    The GNU C Library is free software; you can redistribute it and/or
@@ -25,6 +26,10 @@
 ssize_t
 __readlink (const char *path, char *buf, size_t len)
 {
-  return INLINE_SYSCALL (readlinkat, 4, AT_FDCWD, path, buf, len);
+#ifdef __NR_readlink
+  return INLINE_SYSCALL_CALL (readlink, path, buf, len);
+#else
+  return INLINE_SYSCALL_CALL (readlinkat, AT_FDCWD, path, buf, len);
+#endif
 }
 weak_alias (__readlink, readlink)