Mostly NULL-merge 5.1 => 5.5 of

Bug#11761576 54082: HANDLE_SEGFAULT MAKES USE OF UNSAFE FUNCTIONS

sql/signal_handler.cc

+/* Copyright (c) 2011, Oracle and/or its affiliates. All rights reserved.
+
+   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 St, Fifth Floor, Boston, MA  02111-1307  USA */
+
+#include "my_global.h"
+#include <signal.h>
+
+#include "mysql_priv.h"
+#include "my_stacktrace.h"
+
+#ifdef __WIN__
+#include <crtdbg.h>
+#define SIGNAL_FMT "exception 0x%x"
+#else
+#define SIGNAL_FMT "signal %d"
+#endif
+
+/*
+  We are handling signals in this file.
+  Any global variables we read should be 'volatile sig_atomic_t'
+  to guarantee that we read some consistent value.
+ */
+static volatile sig_atomic_t segfaulted= 0;
+extern ulong max_used_connections;
+extern volatile sig_atomic_t calling_initgroups;
+#ifdef HAVE_NPTL
+extern volatile sig_atomic_t ld_assume_kernel_is_set;
+#endif
+
+/**
+ * Handler for fatal signals
+ *
+ * Fatal events (seg.fault, bus error etc.) will trigger
+ * this signal handler.  The handler will try to dump relevant
+ * debugging information to stderr and dump a core image.
+ *
+ * Signal handlers can only use a set of 'safe' system calls
+ * and library functions.  A list of safe calls in POSIX systems
+ * are available at:
+ *  http://pubs.opengroup.org/onlinepubs/009695399/functions/xsh_chap02_04.html
+ * For MS Windows, guidelines are available at:
+ *  http://msdn.microsoft.com/en-us/library/xdkz3x12(v=vs.71).aspx
+ *
+ * @param sig Signal number
+*/
+extern "C" sig_handler handle_fatal_signal(int sig)
+{
+  if (segfaulted)
+  {
+    my_safe_printf_stderr("Fatal " SIGNAL_FMT " while backtracing\n", sig);
+    _exit(1); /* Quit without running destructors */
+  }
+
+  segfaulted = 1;
+
+#ifdef __WIN__
+  SYSTEMTIME utc_time;
+  GetSystemTime(&utc_time);
+  const long hrs=  utc_time.wHour;
+  const long mins= utc_time.wMinute;
+  const long secs= utc_time.wSecond;
+#else
+  /* Using time() instead of my_time() to avoid looping */
+  const time_t curr_time= time(NULL);
+  /* Calculate time of day */
+  const long tmins = curr_time / 60;
+  const long thrs  = tmins / 60;
+  const long hrs   = thrs  % 24;
+  const long mins  = tmins % 60;
+  const long secs  = curr_time % 60;
+#endif
+
+  char hrs_buf[3]= "00";
+  char mins_buf[3]= "00";
+  char secs_buf[3]= "00";
+  my_safe_itoa(10, hrs, &hrs_buf[2]);
+  my_safe_itoa(10, mins, &mins_buf[2]);
+  my_safe_itoa(10, secs, &secs_buf[2]);
+
+  my_safe_printf_stderr("%s:%s:%s UTC - mysqld got " SIGNAL_FMT " ;\n",
+                        hrs_buf, mins_buf, secs_buf, sig);
+
+  my_safe_printf_stderr("%s",
+    "This could be because you hit a bug. It is also possible that this binary\n"
+    "or one of the libraries it was linked against is corrupt, improperly built,\n"
+    "or misconfigured. This error can also be caused by malfunctioning hardware.\n");
+
+  my_safe_printf_stderr("%s",
+    "We will try our best to scrape up some info that will hopefully help\n"
+    "diagnose the problem, but since we have already crashed, \n"
+    "something is definitely wrong and this may fail.\n\n");
+
+  my_safe_printf_stderr("key_buffer_size=%lu\n",
+                        (ulong) dflt_key_cache->key_cache_mem_size);
+
+  my_safe_printf_stderr("read_buffer_size=%ld\n",
+                        (long) global_system_variables.read_buff_size);
+
+  my_safe_printf_stderr("max_used_connections=%lu\n",
+                        (ulong) max_used_connections);
+
+  my_safe_printf_stderr("max_threads=%u\n",
+                        (uint) thread_scheduler.max_threads);
+
+  my_safe_printf_stderr("thread_count=%u\n", (uint) thread_count);
+
+  my_safe_printf_stderr("connection_count=%u\n", (uint) connection_count);
+
+  my_safe_printf_stderr("It is possible that mysqld could use up to \n"
+                        "key_buffer_size + "
+                        "(read_buffer_size + sort_buffer_size)*max_threads = "
+                        "%lu K  bytes of memory\n",
+                        ((ulong) dflt_key_cache->key_cache_mem_size +
+                         (global_system_variables.read_buff_size +
+                          global_system_variables.sortbuff_size) *
+                         thread_scheduler.max_threads +
+                         max_connections * sizeof(THD)) / 1024);
+
+  my_safe_printf_stderr("%s",
+    "Hope that's ok; if not, decrease some variables in the equation.\n\n");
+
+#if defined(HAVE_LINUXTHREADS)
+  if (sizeof(char*) == 4 && thread_count > UNSAFE_DEFAULT_LINUX_THREADS)
+  {
+    my_safe_printf_stderr(
+      "You seem to be running 32-bit Linux and have "
+      "%d concurrent connections.\n"
+      "If you have not changed STACK_SIZE in LinuxThreads "
+      "and built the binary \n"
+      "yourself, LinuxThreads is quite likely to steal "
+      "a part of the global heap for\n"
+      "the thread stack. Please read "
+      "http://dev.mysql.com/doc/mysql/en/linux-installation.html\n\n"
+      thread_count);
+  }
+#endif /* HAVE_LINUXTHREADS */
+
+#ifdef HAVE_STACKTRACE
+  THD *thd=current_thd;
+
+  if (!(test_flags & TEST_NO_STACKTRACE))
+  {
+    my_safe_printf_stderr("Thread pointer: 0x%p\n", thd);
+    my_safe_printf_stderr("%s",
+      "Attempting backtrace. You can use the following "
+      "information to find out\n"
+      "where mysqld died. If you see no messages after this, something went\n"
+      "terribly wrong...\n");
+    my_print_stacktrace(thd ? (uchar*) thd->thread_stack : NULL,
+                        my_thread_stack_size);
+  }
+  if (thd)
+  {
+    const char *kreason= "UNKNOWN";
+    switch (thd->killed) {
+    case THD::NOT_KILLED:
+      kreason= "NOT_KILLED";
+      break;
+    case THD::KILL_BAD_DATA:
+      kreason= "KILL_BAD_DATA";
+      break;
+    case THD::KILL_CONNECTION:
+      kreason= "KILL_CONNECTION";
+      break;
+    case THD::KILL_QUERY:
+      kreason= "KILL_QUERY";
+      break;
+    case THD::KILLED_NO_VALUE:
+      kreason= "KILLED_NO_VALUE";
+      break;
+    }
+    my_safe_printf_stderr("%s", "\n"
+      "Trying to get some variables.\n"
+      "Some pointers may be invalid and cause the dump to abort.\n");
+
+    my_safe_printf_stderr("Query (%p): ", thd->query());
+    my_safe_print_str(thd->query(), min(1024U, thd->query_length()));
+    my_safe_printf_stderr("Connection ID (thread ID): %lu\n",
+                          (ulong) thd->thread_id);
+    my_safe_printf_stderr("Status: %s\n\n", kreason);
+  }
+  my_safe_printf_stderr("%s",
+    "The manual page at "
+    "http://dev.mysql.com/doc/mysql/en/crashing.html contains\n"
+    "information that should help you find out what is causing the crash.\n");
+
+#endif /* HAVE_STACKTRACE */
+
+#ifdef HAVE_INITGROUPS
+  if (calling_initgroups)
+  {
+    my_safe_printf_stderr("%s", "\n"
+      "This crash occured while the server was calling initgroups(). This is\n"
+      "often due to the use of a mysqld that is statically linked against \n"
+      "glibc and configured to use LDAP in /etc/nsswitch.conf.\n"
+      "You will need to either upgrade to a version of glibc that does not\n"
+      "have this problem (2.3.4 or later when used with nscd),\n"
+      "disable LDAP in your nsswitch.conf, or use a "
+      "mysqld that is not statically linked.\n");
+  }
+#endif
+
+#ifdef HAVE_NPTL
+  if (thd_lib_detected == THD_LIB_LT && !ld_assume_kernel_is_set)
+  {
+    my_safe_printf_stderr("%s",
+      "You are running a statically-linked LinuxThreads binary on an NPTL\n"
+      "system. This can result in crashes on some distributions due to "
+      "LT/NPTL conflicts.\n"
+      "You should either build a dynamically-linked binary, "
+      "or force LinuxThreads\n"
+      "to be used with the LD_ASSUME_KERNEL environment variable.\n"
+      "Please consult the documentation for your distribution "
+      "on how to do that.\n");
+  }
+#endif
+
+  if (locked_in_memory)
+  {
+    my_safe_printf_stderr("%s", "\n"
+      "The \"--memlock\" argument, which was enabled, "
+      "uses system calls that are\n"
+      "unreliable and unstable on some operating systems and "
+      "operating-system versions (notably, some versions of Linux).\n"
+      "This crash could be due to use of those buggy OS calls.\n"
+      "You should consider whether you really need the "
+      "\"--memlock\" parameter and/or consult the OS distributer about "
+      "\"mlockall\" bugs.\n");
+  }
+
+#ifdef HAVE_WRITE_CORE
+  if (test_flags & TEST_CORE_ON_SIGNAL)
+  {
+    my_safe_printf_stderr("%s", "Writing a core file\n");
+    my_write_core(sig);
+  }
+#endif
+
+#ifndef __WIN__
+  /*
+     Quit, without running destructors (etc.)
+     On Windows, do not terminate, but pass control to exception filter.
+  */
+  _exit(1);  // Using _exit(), since exit() is not async signal safe
+#endif
+}