> On 24 Jun 2016, at 22:58, Pirmin Braun <[email protected]> wrote: > > On Fri, 24 Jun 2016 05:55:03 +0100 > Richard Frith-Macdonald <[email protected]> wrote: > >>> >>> >>> but then I did the same in plain C (see Test_MariaDB_main.c) and there it >>> works. Or in other words: when I remove the ObjC runtime and the very >>> little ObjC stuff, the crash doesn't occur. >> >> That's not really telling indicative of anything ... different code has >> memory laid out differently, so overruns will write on different parts of >> the memory and cause different crashes (or often no crash at all). >> You therefore have to assume that the problem could be anywhere, and try to >> narrow it down using frequent checks (mcheck_protect etc). >> There is also the problem that adding calls to diagnostic functions could in >> itself hide the bug ... so non-intrusive methods like valgrind are also >> worth trying. >> > > it's indeed the MariaDB Client Library. > > Valgrind reports: > ==2955== Invalid write of size 1 > ==2955== at 0x4E5228D: ??? (in /usr/lib/x86_64-linux-gnu/libmariadb.so.2) > ==2955== by 0x4E5288D: ??? (in /usr/lib/x86_64-linux-gnu/libmariadb.so.2) > ==2955== by 0x4E52B96: mysql_real_query (in > /usr/lib/x86_64-linux-gnu/libmariadb.so.2) > ==2955== by 0x4007B7: executeSQL (Test_MariaDB_main.c:22) > ==2955== by 0x4008C3: main (Test_MariaDB_main.c:55) > ==2955== Address 0x63d4228 is 0 bytes after a block of size 8,152 alloc'd > ==2955== at 0x4C28C20: malloc (vg_replace_malloc.c:296) > ==2955== by 0x4E5AEE8: ??? (in /usr/lib/x86_64-linux-gnu/libmariadb.so.2) > ==2955== by 0x4E58E26: ??? (in /usr/lib/x86_64-linux-gnu/libmariadb.so.2) > ==2955== by 0x4E52216: ??? (in /usr/lib/x86_64-linux-gnu/libmariadb.so.2) > ==2955== by 0x4E5288D: ??? (in /usr/lib/x86_64-linux-gnu/libmariadb.so.2) > ==2955== by 0x4E52B96: mysql_real_query (in > /usr/lib/x86_64-linux-gnu/libmariadb.so.2) > ==2955== by 0x4007B7: executeSQL (Test_MariaDB_main.c:22) > ==2955== by 0x4008C3: main (Test_MariaDB_main.c:55) > > on the version with the crashing query string in both test programs - ObjC > and C. > Only difference is, ObjC program crashes and C doesn't. > With the slightly modified query string valgrind reports no invalid write.
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