cosmopolitan/libc/intrin/exit.c
Justine Tunney ff77f2a6af
Make improvements
- This change fixes a bug that allowed unbuffered printf() output (to
  streams like stderr) to be truncated. This regression was introduced
  some time between now and the last release.

- POSIX specifies all functions as thread safe by default. This change
  works towards cleaning up our use of the @threadsafe / @threadunsafe
  documentation annotations to reflect that. The goal is (1) to use
  @threadunsafe to document functions which POSIX say needn't be thread
  safe, and (2) use @threadsafe to document functions that we chose to
  implement as thread safe even though POSIX didn't mandate it.

- Tidy up the clock_gettime() implementation. We're now trying out a
  cleaner approach to system call support that aims to maintain the
  Linux errno convention as long as possible. This also fixes bugs that
  existed previously, where the vDSO errno wasn't being translated
  properly. The gettimeofday() system call is now a wrapper for
  clock_gettime(), which reduces bloat in apps that use both.

- The recently-introduced improvements to the execute bit on Windows has
  had bugs fixed. access(X_OK) on a directory on Windows now succeeds.
  fstat() will now perform the MZ/#! ReadFile() operation correctly.

- Windows.h is no longer included in libc/isystem/, because it confused
  PCRE's build system into thinking Cosmopolitan is a WIN32 platform.
  Cosmo's Windows.h polyfill was never even really that good, since it
  only defines a subset of the subset of WIN32 APIs that Cosmo defines.

- The setlongerjmp() / longerjmp() APIs are removed. While they're nice
  APIs that are superior to the standardized setjmp / longjmp functions,
  they weren't superior enough to not be dead code in the monorepo. If
  you use these APIs, please file an issue and they'll be restored.

- The .com appending magic has now been removed from APE Loader.
2023-10-03 06:17:16 -07:00

118 lines
5.3 KiB
C

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ 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/dce.h"
#include "libc/intrin/promises.internal.h"
#include "libc/intrin/strace.internal.h"
#include "libc/intrin/weaken.h"
#include "libc/nexgen32e/vendor.internal.h"
#include "libc/nt/enum/status.h"
#include "libc/nt/runtime.h"
#include "libc/nt/thunk/msabi.h"
#include "libc/runtime/internal.h"
#include "libc/runtime/runtime.h"
#include "libc/sysv/consts/nr.h"
#include "libc/sysv/consts/sig.h"
/**
* Terminates process, ignoring destructors and atexit() handlers.
*
* Exit codes are narrowed to an unsigned char on most platforms. The
* exceptions would be Windows, NetBSD, and OpenBSD, which should let
* you have larger exit codes.
*
* When running on bare metal, this function will reboot your computer
* by hosing the interrupt descriptors and triple faulting the system.
*
* @asyncsignalsafe
* @vforksafe
* @noreturn
*/
wontreturn void _Exit(int exitcode) {
STRACE("_Exit(%d)", exitcode);
if (!IsWindows() && !IsMetal()) {
// On Linux _Exit1 (exit) must be called in pledge("") mode. If we
// call _Exit (exit_group) when we haven't used pledge("stdio") then
// it'll terminate the process instead. On OpenBSD we must not call
// _Exit1 (__threxit) because only _Exit (exit) is whitelisted when
// operating in pledge("") mode.
if (!(IsLinux() && !PLEDGED(STDIO))) {
#ifdef __x86_64__
asm volatile("syscall"
: /* no outputs */
: "a"(__NR_exit_group), "D"(exitcode)
: "rcx", "r11", "memory");
#elif defined(__aarch64__)
register long x0 asm("x0") = exitcode;
asm volatile("mov\tx8,%0\n\t"
"mov\tx16,%1\n\t"
"svc\t0"
: /* no outputs */
: "i"(94), "i"(1), "r"(x0)
: "x8", "x16", "memory");
#else
#error "unsupported architecture"
#endif
}
// Inline _Exit1() just in case _Exit() isn't allowed by pledge()
#ifdef __x86_64__
asm volatile("syscall"
: /* no outputs */
: "a"(__NR_exit), "D"(exitcode)
: "rcx", "r11", "memory");
#else
register long r0 asm("x0") = exitcode;
asm volatile("mov\tx8,%0\n\t"
"mov\tx16,%1\n\t"
"svc\t0"
: /* no outputs */
: "i"(93), "i"(0x169), "r"(r0)
: "x8", "memory");
#endif
} else if (IsWindows()) {
uint32_t waitstatus;
// What Microsoft calls an exit code, POSIX calls a status code. See
// also the WEXITSTATUS() and WIFEXITED() macros that POSIX defines.
waitstatus = exitcode;
waitstatus <<= 8;
// "The GetExitCodeProcess function returns a valid error code
// defined by the application only after the thread terminates.
// Therefore, an application should not use kNtStillActive (259) as
// an error code (kNtStillActive is a macro for kNtStatusPending).
// If a thread returns kNtStillActive (259) as an error code, then
// applications that test for that value could interpret it to mean
// that the thread is still running, and continue to test for the
// completion of the thread after the thread has terminated, which
// could put the application into an infinite loop." -Quoth MSDN
if (waitstatus == kNtStillActive) {
waitstatus = 0xc9af3d51u;
}
TerminateThisProcess(waitstatus);
}
#ifdef __x86_64__
asm("push\t$0\n\t"
"push\t$0\n\t"
"cli\n\t"
"lidt\t(%rsp)");
for (;;) asm("ud2");
#else
__builtin_unreachable();
#endif
}
__strong_reference(_Exit, _exit);