cosmopolitan/libc/sysv/strace.greg.c

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│ vi: set et ft=c ts=2 sts=2 sw=2 fenc=utf-8                               :vi │
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│ Copyright 2021 Justine Alexandra Roberts Tunney                              │
│                                                                              │
│ Permission to use, copy, modify, and/or distribute this software for         │
│ any purpose with or without fee is hereby granted, provided that the         │
│ above copyright notice and this permission notice appear in all copies.      │
│                                                                              │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL                │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED                │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE             │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL         │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR        │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER               │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
│ PERFORMANCE OF THIS SOFTWARE.                                                │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/atomic.h"
#include "libc/runtime/runtime.h"

/**
 * System call logging enabled state.
 *
 * If Cosmopolitan was compiled with the `SYSDEBUG` macro (this is the
 * default behavior, except in tiny and release modes) then `__strace`
 * shall control whether or not system calls are logged to fd 2. If it's
 * greater than zero, syscalls are logged. Otherwise, they're aren't.
 *
 * By convention, functions wishing to disable syscall tracing for a
 * short time period should say:
 *
 *     void foo() {
 *       strace_enabled(-1);
 *       bar();
 *       strace_enabled(+1);
 *     }
 *
 * This way you still have some flexibility to force syscall tracing, by
 * setting `__strace` to a higher number like `2` or `200`. Even though
 * under normal circumstances, `__strace` should only be either zero or
 * one.
 */
int __strace;