[glibc] Linux: consolidate dup2 implementation

[Adhemerval Zanella <azanella@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=33ef940302eba1ecf9e98376557af75d7d9c0ed1

commit 33ef940302eba1ecf9e98376557af75d7d9c0ed1
Author: Adhemerval Zanella Netto <adhemerval.zanella@linaro.org>
Date:   Wed Oct 19 19:14:08 2022 -0300

    Linux: consolidate dup2 implementation
    
    Use dup2 syscall if defined, otherwise use dup3.
    
    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 => }/dup2.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/sysdeps/unix/sysv/linux/generic/dup2.c b/sysdeps/unix/sysv/linux/dup2.c
similarity index 83%
rename from sysdeps/unix/sysv/linux/generic/dup2.c
rename to sysdeps/unix/sysv/linux/dup2.c
index 0dc45e9b17..1182780e15 100644
--- a/sysdeps/unix/sysv/linux/generic/dup2.c
+++ b/sysdeps/unix/sysv/linux/dup2.c
@@ -1,4 +1,5 @@
-/* Copyright (C) 2011-2022 Free Software Foundation, Inc.
+/* Duplicate a file descriptor.  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
@@ -24,12 +25,16 @@
 int
 __dup2 (int fd, int fd2)
 {
+#ifdef __NR_dup2
+  return INLINE_SYSCALL_CALL (dup2, fd, fd2);
+#else
   /* For the degenerate case, check if the fd is valid (by trying to
      get the file status flags) and return it, or else return EBADF.  */
   if (fd == fd2)
     return __libc_fcntl (fd, F_GETFL, 0) < 0 ? -1 : fd;
 
-  return INLINE_SYSCALL (dup3, 3, fd, fd2, 0);
+  return INLINE_SYSCALL_CALL (dup3, fd, fd2, 0);
+#endif
 }
 libc_hidden_def (__dup2)
 weak_alias (__dup2, dup2)