Initial import

libc/log/showcrashreports.c

@@ -0,0 +1,78 @@
+/*-*- 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]);
+    }
+  }
+}