cosmopolitan/libc/log/showcrashreports.c

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2020-06-15 14:18:57 +00:00
/*-*- 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 2020 Justine Alexandra Roberts Tunney
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; version 2 of the License.
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., 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301 USA
*/
#include "libc/bits/bits.h"
#include "libc/calls/calls.h"
#include "libc/calls/sigbits.h"
#include "libc/calls/typedef/sigaction_f.h"
#include "libc/dce.h"
#include "libc/log/internal.h"
#include "libc/log/log.h"
#include "libc/macros.h"
#include "libc/nt/signals.h"
#include "libc/str/str.h"
#include "libc/sysv/consts/sa.h"
#include "libc/sysv/consts/sig.h"
extern const unsigned char kOncrashThunks[7][11];
/**
* Installs crash signal handlers.
*
* Normally, only functions calling die() will print backtraces. This
* function may be called at program startup to install handlers that
* will display similar information, for most types of crashes.
*
* - Backtraces
* - CPU state printout
* - Automatic debugger attachment
*
* Another trick this function enables, is you can press CTRL+\ to open
* the debugger GUI at any point while the program is running. It can be
* useful, for example, if a program is caught in an infinite loop.
*
* @see callexitontermination()
*/
optimizesize void showcrashreports(void) {
size_t i;
struct sigaction sa;
if (IsModeDbg()) STATIC_YOINK("__ubsan_abort");
if (!NoDebug()) STATIC_YOINK("die");
/* <SYNC-LIST>: oncrashthunks.S */
kCrashSigs[0] = SIGQUIT; /* ctrl+\ aka ctrl+break */
kCrashSigs[1] = SIGFPE; /* 1 / 0 */
kCrashSigs[2] = SIGILL; /* illegal instruction */
kCrashSigs[3] = SIGSEGV; /* bad memory access */
kCrashSigs[4] = SIGTRAP; /* bad system call */
kCrashSigs[5] = SIGABRT; /* abort() called */
kCrashSigs[6] = SIGBUS; /* misaligned, noncanonical ptr, etc. */
/* </SYNC-LIST>: oncrashthunks.S */
memset(&sa, 0, sizeof(sa));
sa.sa_flags = SA_RESETHAND;
sigfillset(&sa.sa_mask);
for (i = 0; i < ARRAYLEN(kCrashSigs); ++i) {
sigdelset(&sa.sa_mask, kCrashSigs[i]);
}
for (i = 0; i < ARRAYLEN(kCrashSigs); ++i) {
if (kCrashSigs[i]) {
sa.sa_sigaction = (sigaction_f)kOncrashThunks[i];
sigaction(kCrashSigs[i], &sa, &g_oldcrashacts[i]);
}
}
}