Hi SQLite Team
I added callback function pointers for my sqlite database and the
program crashed in the function sqlite3DbMallocSize. Same code works
fine with older release such as 3.6.15.
I debugged and got the place where the exception was thrown.
in 3.7.4
SQLITE_PRIVATE int sqlite3DbMallocSize(sqlite3 *db, void *p){
assert( db==0 || sqlite3_mutex_held(db->mutex) );
else if( db && isLookaside(db, p) ){
return db->lookaside.sz;
}else{
assert( sqlite3MemdebugHasType(p, MEMTYPE_DB) );
assert( sqlite3MemdebugHasType(p,
MEMTYPE_LOOKASIDE|MEMTYPE_HEAP) );
assert( db!=0 || sqlite3MemdebugNoType(p,
MEMTYPE_LOOKASIDE) );
return sqlite3GlobalConfig.m.xSize(p);
}
}
while in 3.6.15 it was implemented as
SQLITE_PRIVATE int sqlite3DbMallocSize(sqlite3 *db, void *p){
assert( db==0 || sqlite3_mutex_held(db->mutex) );
if( p==0 ){
return 0;
}else if( isLookaside(db, p) ){
return db->lookaside.sz;
}else{
return sqlite3GlobalConfig.m.xSize(p);
}
}
So, in order to get my app fly, I modified 3.7.4 sqlite code by adding a
few more lines (in red):
SQLITE_PRIVATE int sqlite3DbMallocSize(sqlite3 *db, void *p){
assert( db==0 || sqlite3_mutex_held(db->mutex) );
if( p == 0 ) // youfei fixed to prevent illegal memory
access when callbacks get called
{
return 0;
}
else if( db && isLookaside(db, p) ){
return db->lookaside.sz;
}else{
assert( sqlite3MemdebugHasType(p, MEMTYPE_DB) );
assert( sqlite3MemdebugHasType(p,
MEMTYPE_LOOKASIDE|MEMTYPE_HEAP) );
assert( db!=0 || sqlite3MemdebugNoType(p,
MEMTYPE_LOOKASIDE) );
return sqlite3GlobalConfig.m.xSize(p);
}
}
In my code, *p is 0 when sqlite3DbMallocSize gets called, so a memory
access violation exception is thrown by "return
sqlite3GlobalConfig.m.xSize(p);". Previous release covers it well while
the latest does not. After the modification my program gets back to
work. Please verify my change and let me know if it's a bug missed by
you experts?
Thanks,
Youfei
Youfei Chen | EMC Corporation <http://www.emc.com/> | 176 South Street
Hopkinton, MA 01748
<http://maps.google.com/maps?f=q&hl=en&geocode=&q=176+South+Street+Hopki
nton,+MA+01748> | Direct #: (508)293-6402 | Extension: 76402 | Email:
youfei.c...@emc.com <mailto:chen_you...@emc.com>
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