Update.

1998-07-16 20:01  Ulrich Drepper  <drepper@cygnus.com>

	* debug/Makefile (routines): Add backtracesymsfd.
	Add rules to generate libSegFault.
	* debug/Versions: Add __backtrace_symbols_fd and backtrace_symbols_fd.
	* debug/execinfo.h: Declare backtrace_symbols_fd.
	* sysdeps/generic/backtracesymsfd.c: New file.
	* sysdeps/generic/elf/backtracesymsfd.c: New file.
	* sysdeps/generic/segfault.c: New file.
	* sysdeps/generic/sigcontextinfo.h: New file.
	* sysdeps/unix/sysv/linux/i386/sigcontextinfo.h: New file.

	* sysdeps/generic/elf/backtracesyms.c: Remove unneeded +.

sysdeps/generic/segfault.c

@@ -0,0 +1,165 @@
+/* Catch segmentation faults and print backtrace.
+   Copyright (C) 1998 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1998.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Library General Public License as
+   published by the Free Software Foundation; either version 2 of the
+   License, or (at your option) any later version.
+
+   The GNU C Library 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
+   Library General Public License for more details.
+
+   You should have received a copy of the GNU Library General Public
+   License along with the GNU C Library; see the file COPYING.LIB.  If not,
+   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+   Boston, MA 02111-1307, USA.  */
+
+#include <execinfo.h>
+#include <fcntl.h>
+#include <signal.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+/* This file defines macros to access the content of the sigcontext element
+   passed up by the signal handler.  */
+#include <sigcontextinfo.h>
+
+/* This is a global variable set at program start time.  It marks the
+   highest used stack address.  */
+extern void *__libc_stack_end;
+
+
+/* This implementation assumes a stack layout that matches the defaults
+   used by gcc's `__builtin_frame_address' and `__builtin_return_address'
+   (FP is the frame pointer register):
+
+	  +-----------------+     +-----------------+
+    FP -> | previous FP --------> | previous FP ------>...
+	  |                 |     |                 |
+	  | return address  |     | return address  |
+	  +-----------------+     +-----------------+
+
+  */
+
+/* Get some notion of the current stack.  Need not be exactly the top
+   of the stack, just something somewhere in the current frame.  */
+#ifndef CURRENT_STACK_FRAME
+# define CURRENT_STACK_FRAME  ({ char __csf; &__csf; })
+#endif
+
+/* By default we assume that the stack grows downward.  */
+#ifndef INNER_THAN
+# define INNER_THAN <
+#endif
+
+struct layout
+{
+  struct layout *next;
+  void *return_address;
+};
+
+
+static void
+handle (int fd, void *addr)
+{
+}
+
+
+/* This function is called when a segmentation fault is caught.  The system
+   is in an instable state now.  This means especially that malloc() might
+   not work anymore.  */
+static void
+catch_segfault (int signal, SIGCONTEXT ctx)
+{
+  struct layout *current;
+  void *top_frame;
+  void *top_stack;
+  const char *fname;
+  int fd;
+  void **arr;
+  size_t cnt;
+
+  /* This is the name of the file we are writing to.  If none is given
+     or we cannot write to this file write to stderr.  */
+  fd = 2;
+  fname = getenv ("SEGFAULT_OUTPUT_NAME");
+  if (fname != NULL && fname[0] != '\0')
+    {
+      fd = open (fname, O_TRUNC | O_WRONLY | O_CREAT);
+      if (fd == -1)
+	fd = 2;
+    }
+
+#define WRITE_STRING(s) write (fd, s, sizeof (s) - 1)
+  WRITE_STRING ("*** Segmentation Fault\n");
+  WRITE_STRING ("Backtrace:\n");
+
+  top_frame = GET_FRAME (ctx);
+  top_stack = GET_STACK (ctx);
+
+  /* First count how many entries we'll have.  */
+  cnt = 1;
+  current = (struct layout *) top_frame;
+  while (!((void *) current INNER_THAN top_stack
+	   || !((void *) current INNER_THAN __libc_stack_end)))
+    {
+      ++cnt;
+
+      current = current->next;
+    }
+
+  arr = alloca (cnt * sizeof (void *));
+
+  /* First handle the program counter from the structure.  */
+  arr[0] = GET_EIP (ctx);
+
+  current = (struct layout *) top_frame;
+  cnt = 1;
+  while (!((void *) current INNER_THAN top_stack
+	   || !((void *) current INNER_THAN __libc_stack_end)))
+    {
+      arr[cnt++] = current->return_address;
+
+      current = current->next;
+    }
+
+  /* Now generate nicely formatted output.  */
+  __backtrace_symbols_fd (arr, cnt, fd);
+
+  /* Nothing else to do.  */
+  _exit (128 + SIGSEGV);
+}
+
+
+static void
+__attribute__ ((constructor))
+install_handler (void)
+{
+  struct sigaction sa;
+
+  sa.sa_handler = (void *) catch_segfault;
+  sigemptyset (&sa.sa_mask);
+  sa.sa_flags = SA_RESTART;
+
+  sigaction (SIGSEGV, &sa, NULL);
+
+  /* Maybe we are expected to use an alternative stack.  */
+  if (getenv ("SEGFAULT_USE_ALTSTACK") != 0)
+    {
+      void *stack_mem = malloc (2 * SIGSTKSZ);
+      struct sigaltstack ss;
+
+      if (stack_mem != NULL)
+	{
+	  ss.ss_sp = stack_mem;
+	  ss.ss_flags = SS_ONSTACK;
+	  ss.ss_size = 2 * SIGSTKSZ;
+
+	  sigaltstack (&ss, NULL);
+	}
+    }
+}