Bug#11761576 54082: HANDLE_SEGFAULT MAKES USE OF UNSAFE FUNCTIONS

handle_segfault is the signal handler code of mysqld.  however, it makes
calls to potentially unsafe functions localtime_r, fprintf, fflush.



include/my_stacktrace.h:
  Add safe versions of itoa() write() and snprintf().
libmysqld/CMakeLists.txt:
  Move signal handler to separate file.
mysys/stacktrace.c:
  Remove unsafe function calls.
sql/CMakeLists.txt:
  Move signal handler to separate file.
sql/Makefile.am:
  Move signal handler to separate file.
sql/mysqld.cc:
  Move signal handler to separate file.
sql/signal_handler.cc:
  Remove unsafe function calls.

1 files changed, 65 insertions, 4 deletions

diff --git a/include/my_stacktrace.h b/include/my_stacktrace.h
index e7713f46fc3..30cac3871c5 100644
--- a/include/my_stacktrace.h
+++ b/include/my_stacktrace.h
@@ -1,5 +1,4 @@
-/*
-   Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved.
+/* Copyright (c) 2001, 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
@@ -12,8 +11,7 @@
 
    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 02110-1301  USA
-*/
+   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */
 
 #ifndef _my_stacktrace_h_
 #define _my_stacktrace_h_
@@ -63,6 +61,69 @@ void my_set_exception_pointers(EXCEPTION_POINTERS *ep);
 void my_write_core(int sig);
 #endif
 
+
+
+/**
+  Async-signal-safe utility functions used by signal handler routines.
+  Declared here in order to unit-test them.
+  These are not general-purpose, but tailored to the signal handling routines.
+*/
+/**
+  Converts a longlong value to string.
+  @param   base 10 for decimal, 16 for hex values (0..9a..f)
+  @param   val  The value to convert
+  @param   buf  Assumed to point to the *end* of the buffer.
+  @returns Pointer to the first character of the converted string.
+           Negative values:
+           for base-10 the return string will be prepended with '-'
+           for base-16 the return string will contain 16 characters
+  Implemented with simplicity, and async-signal-safety in mind.
+*/
+char *my_safe_itoa(int base, longlong val, char *buf);
+
+/**
+  Converts a ulonglong value to string.
+  @param   base 10 for decimal, 16 for hex values (0..9a..f)
+  @param   val  The value to convert
+  @param   buf  Assumed to point to the *end* of the buffer.
+  @returns Pointer to the first character of the converted string.
+  Implemented with simplicity, and async-signal-safety in mind.
+*/
+char *my_safe_utoa(int base, ulonglong val, char *buf);
+
+/**
+  A (very) limited version of snprintf.
+  @param   to   Destination buffer.
+  @param   n    Size of destination buffer.
+  @param   fmt  printf() style format string.
+  @returns Number of bytes written, including terminating '\0'
+  Supports 'd' 'i' 'u' 'x' 'p' 's' conversion.
+  Supports 'l' and 'll' modifiers for integral types.
+  Does not support any width/precision.
+  Implemented with simplicity, and async-signal-safety in mind.
+*/
+size_t my_safe_snprintf(char* to, size_t n, const char* fmt, ...)
+  ATTRIBUTE_FORMAT(printf, 3, 4);
+
+/**
+  A (very) limited version of snprintf, which writes the result to STDERR.
+  @sa my_safe_snprintf
+  Implemented with simplicity, and async-signal-safety in mind.
+  @note Has an internal buffer capacity of 512 bytes,
+  which should suffice for our signal handling routines.
+*/
+size_t my_safe_printf_stderr(const char* fmt, ...)
+  ATTRIBUTE_FORMAT(printf, 1, 2);
+
+/**
+  Writes up to count bytes from buffer to STDERR.
+  Implemented with simplicity, and async-signal-safety in mind.
+  @param   buf   Buffer containing data to be written.
+  @param   count Number of bytes to write.
+  @returns Number of bytes written.
+*/
+size_t my_write_stderr(const void *buf, size_t count);
+
 C_MODE_END
 
 #endif /* _my_stacktrace_h_ */