| |
| /*--------------------------------------------------------------------*/ |
| /*--- Semaphore stuff. sema.c ---*/ |
| /*--------------------------------------------------------------------*/ |
| |
| /* |
| This file is part of Valgrind, a dynamic binary instrumentation |
| framework. |
| |
| Copyright (C) 2000-2005 Julian Seward |
| jseward@acm.org |
| |
| This program is free software; you can redistribute it and/or |
| modify it under the terms of the GNU General Public License as |
| published by the Free Software Foundation; either version 2 of the |
| License, or (at your option) any later version. |
| |
| This program is distributed in the hope that it will be useful, but |
| WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with this program; if not, write to the Free Software |
| Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA |
| 02111-1307, USA. |
| |
| The GNU General Public License is contained in the file COPYING. |
| */ |
| |
| #include "pub_core_basics.h" |
| #include "pub_core_libcassert.h" |
| #include "pub_core_libcfile.h" |
| #include "pub_core_libcproc.h" |
| #include "priv_sema.h" |
| |
| /* |
| Slower (than the removed futex-based sema scheme) but more portable |
| pipe-based token passing scheme. |
| */ |
| |
| void VG_(sema_init)(vg_sema_t *sema) |
| { |
| VG_(pipe)(sema->pipe); |
| sema->pipe[0] = VG_(safe_fd)(sema->pipe[0]); |
| sema->pipe[1] = VG_(safe_fd)(sema->pipe[1]); |
| |
| sema->owner_thread = -1; |
| |
| /* create initial token */ |
| VG_(write)(sema->pipe[1], "T", 1); |
| } |
| |
| void VG_(sema_deinit)(vg_sema_t *sema) |
| { |
| VG_(close)(sema->pipe[0]); |
| VG_(close)(sema->pipe[1]); |
| sema->pipe[0] = sema->pipe[1] = -1; |
| } |
| |
| /* get a token */ |
| void VG_(sema_down)(vg_sema_t *sema) |
| { |
| Char buf[2] = { 'x' }; |
| Int ret; |
| Int lwpid = VG_(gettid)(); |
| |
| vg_assert(sema->owner_thread != lwpid); /* can't have it already */ |
| |
| again: |
| ret = VG_(read)(sema->pipe[0], buf, 2); |
| |
| if (ret == -VKI_EINTR) |
| goto again; |
| |
| vg_assert(ret == 1); /* should get exactly 1 token */ |
| vg_assert(buf[0] == 'T'); |
| |
| sema->owner_thread = lwpid; |
| } |
| |
| /* put token back */ |
| void VG_(sema_up)(vg_sema_t *sema) |
| { |
| Int ret; |
| |
| vg_assert(sema->owner_thread == VG_(gettid)()); /* must have it */ |
| |
| sema->owner_thread = 0; |
| |
| ret = VG_(write)(sema->pipe[1], "T", 1); |
| |
| vg_assert(ret == 1); |
| } |
| |
| /*--------------------------------------------------------------------*/ |
| /*--- end ---*/ |
| /*--------------------------------------------------------------------*/ |
| |
| |