WL#4828 and BUG#45747

NOTE: Backporting the patch to next-mr.

WL#4828 Augment DBUG_ENTER/DBUG_EXIT to crash MySQL in different functions
-------

The assessment of the replication code in the presence of faults is extremely
import to increase reliability. In particular, one needs to know if servers
will either correctly recovery or print out appropriate error messages thus
avoiding unexpected problems in a production environment.

In order to accomplish this, the current patch refactories the debug macros
already provided in the source code and introduces three new macros that
allows to inject faults, specifically crashes, while entering or exiting a
function or method. For instance, to crash a server while returning from
the init_slave function (see module sql/slave.cc), one needs to do what
follows:

1 - Modify the source replacing DBUG_RETURN by DBUG_CRASH_RETURN;

  DBUG_CRASH_RETURN(0);

2 - Use the debug variable to activate dbug instructions:

  SET SESSION debug="+d,init_slave_crash_return";

The new macros are briefly described below:

DBUG_CRASH_ENTER (function) is equivalent to DBUG_ENTER which registers the
beginning of a function but in addition to it allows for crashing the server
while entering the function if the appropriate dbug instruction is activate.
In this case, the dbug instruction should be "+d,function_crash_enter".

DBUG_CRASH_RETURN (value) is equivalent to DBUG_RETURN which notifies the
end of a function but in addition to it allows for crashing the server
while returning from the function if the appropriate dbug instruction is
activate. In this case, the dbug instruction should be
"+d,function_crash_return". Note that "function" should be the same string
used by either the DBUG_ENTER or DBUG_CRASH_ENTER.

DBUG_CRASH_VOID_RETURN (value) is equivalent to DBUG_VOID_RETURN which
notifies the end of a function but in addition to it allows for crashing
the server while returning from the function if the appropriate dbug
instruction is activate. In this case, the dbug instruction should be
"+d,function_crash_return". Note that "function" should be the same string
used by either the DBUG_ENTER or DBUG_CRASH_ENTER.

To inject other faults, for instance, wrong return values, one should rely
on the macros already available. The current patch also removes a set of
macros that were either not being used or were redundant as other macros
could be used to provide the same feature. In the future, we also consider
dynamic instrumentation of the code.


BUG#45747 DBUG_CRASH_* is not setting the strict option
---------
      
When combining DBUG_CRASH_* with "--debug=d:t:i:A,file" the server crashes
due to a call to the abort function in the DBUG_CRASH_* macro althought the
appropriate keyword has not been set.

1 files changed, 19 insertions, 0 deletions

diff --git a/include/my_dbug.h b/include/my_dbug.h
index a77e439b5db..7df080bee72 100644
--- a/include/my_dbug.h
+++ b/include/my_dbug.h
@@ -22,6 +22,7 @@ extern "C" {
 #if !defined(DBUG_OFF) && !defined(_lint)
 struct _db_code_state_;
 extern	int _db_keyword_(struct _db_code_state_ *cs, const char *keyword);
+extern  int _db_keywords_(const char *, const char *);
 extern  int _db_strict_keyword_(const char *keyword);
 extern  int _db_explain_(struct _db_code_state_ *cs, char *buf, size_t len);
 extern  int _db_explain_init_(char *buf, size_t len);
@@ -46,6 +47,7 @@ extern	void _db_end_(void);
 extern	void _db_lock_file_(void);
 extern	void _db_unlock_file_(void);
 extern FILE *_db_fp_(void);
+extern  const char* _db_get_func_(void);
 
 #define DBUG_ENTER(a) const char *_db_func_, *_db_file_; uint _db_level_; \
 	char **_db_framep_; \
@@ -81,6 +83,20 @@ extern FILE *_db_fp_(void);
 #define DBUG_EXPLAIN(buf,len) _db_explain_(0, (buf),(len))
 #define DBUG_EXPLAIN_INITIAL(buf,len) _db_explain_init_((buf),(len))
 #define IF_DBUG(A) A
+#define _DBUG_MAX_FUNC_NAME_ 255
+#define DBUG_CHECK_CRASH(func, op) \
+        do { \
+          if (_db_keywords_((func), (op))) \
+            { abort(); } \
+        } while (0)
+#define DBUG_CRASH_ENTER(func) \
+  DBUG_ENTER(func); DBUG_CHECK_CRASH(func, "_crash_enter")
+#define DBUG_CRASH_RETURN(val) \
+  do {DBUG_CHECK_CRASH(_db_get_func_(), "_crash_return"); \
+    DBUG_RETURN(val);} while(0)
+#define DBUG_CRASH_VOID_RETURN \
+  do {DBUG_CHECK_CRASH (_db_get_func_(), "_crash_return"); \
+    DBUG_VOID_RETURN;} while(0)
 #else						/* No debugger */
 
 #define DBUG_ENTER(a1)
@@ -108,6 +124,9 @@ extern FILE *_db_fp_(void);
 #define DBUG_EXPLAIN(buf,len)
 #define DBUG_EXPLAIN_INITIAL(buf,len)
 #define IF_DBUG(A)
+#define DBUG_CRASH_ENTER(func)
+#define DBUG_CRASH_RETURN(val)      do { return(val); } while(0)
+#define DBUG_CRASH_VOID_RETURN      do { return; } while(0)
 #endif
 #ifdef	__cplusplus
 }