libc/sysdeps/linux/i386/__syscall_error.c

   1 /* Wrapper for setting errno.
   2  *
   3  * Copyright (C) 2000-2006 Erik Andersen <andersen@uclibc.org>
   4  *
   5  * Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball.
   6  */
   7
   8 /* This routine is jumped to by all the syscall handlers, to stash
   9  * an error number into errno.  */
  10
  11 /* This version uses a lot of magic and relies heavily on x86
  12  * calling convention ... The advantage is that this is the same
  13  * size as the previous __syscall_error() but all the .S functions
  14  * need just one instruction.
  15  *
  16  * Local .S files have to set %eax to the negative errno value
  17  * and then jump to this function.  The neglected return to caller
  18  * and return value of -1 is taken care of here so we don't have to
  19  * worry about it in the .S functions.
  20  *
  21  * We have to stash the errno from %eax in a local stack var because
  22  * __set_errno will prob call a function thus clobbering %eax on us.
  23  */
  24
  25 #include <errno.h>
  26 #include <features.h>
  27
  28 int __syscall_error(void) attribute_hidden;
  29 int __syscall_error(void)
  30 {
  31         register int eax __asm__ ("%eax");
  32         int _errno = -eax;
  33         __set_errno (_errno);
  34         return -1;
  35 }