sysdeps/unix/sysv/linux/personality.c

   1 /* Copyright (C) 2015-2017 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <http://www.gnu.org/licenses/>.  */
  17
  18 #include <sys/personality.h>
  19 #include <sysdep.h>
  20
  21 extern __typeof (personality) __personality;
  22
  23 int
  24 __personality (unsigned long persona)
  25 {
  26 #ifdef PERSONALITY_TRUNCATE_ARGUMENT
  27   /* Starting with kernel commit v2.6.21-3117-g97dc32c, the type of
  28      task_struct->pesonality is "unsigned int".
  29      Starting with kernel commit v2.6.35-rc1-372-g485d527, the personality
  30      syscall accepts "unsigned int" instead of "long unsigned int".
  31      Inbetween, a personality argument that does not fit into "unsigned int"
  32      would result to system call returning -EINVAL.
  33      We explicitly truncate the personality argument to "unsigned int"
  34      to eliminate the uncertainty.  */
  35   persona = (unsigned int) persona;
  36 #endif
  37
  38   INTERNAL_SYSCALL_DECL (err);
  39   long ret = INTERNAL_SYSCALL (personality, err, 1, persona);
  40
  41   /* Starting with kernel commit v2.6.29-6609-g11d06b2, the personality syscall
  42      never fails.  However, 32-bit kernels might flag valid values as errors, so
  43      we need to reverse the error setting.  We can't use the raw result as some
  44      arches split the return/error values.  */
  45   if (__glibc_unlikely (INTERNAL_SYSCALL_ERROR_P (ret, err)))
  46     ret = -INTERNAL_SYSCALL_ERRNO (ret, err);
  47   return ret;
  48 }
  49 weak_alias (__personality, personality)