Hello,
I seem to have a problem with the C API, briefly I try to select something
into a temporary table and then do three selects, two of which are from the
temporary table created. Program segfaults.
When I comment all but temp table creation, program works, and same happens
for a non-temp table select, but when both are present, the program simply
refuses to run.
code details (complete queries ommitted for clarity, queries are not problematic
- they were tested with the standalone mysql client):
query_len = sprintf(query, "CREATE TEMPORARY TABLE temp SELECT ....");
fprintf(stderr, "QUERY: %s\nLEN: %d\n", query, query_len);
if (mysql_real_query(db_read, query, query_len)) {
free(query);
b_abort("CREATE TABLE temp unsuccessful: %s", mysql_error(db_read));
}
if (mysql_affected_rows(db_read) == 0) { /* no rows transferred to the temp table,
skip entry */
fprintf(stderr, "CREATE TABLE selected no rows, skipping id %d\n", id);
free(query);
return 1; /* no self score found, but the query was OK */
}
fprintf(stderr, "Created table with results for id %d, affected rows %lu, errcode
%d\n", id, (unsigned long) mysql_affected_rows(db_read), mysql_errno(db_read));
/* get group and self-score */
query_len = sprintf(query, "SELECT a1, a2 FROM t1,t2 GROUP BY ...");
fprintf(stderr, "QUERY: %s\nLEN: %d\n", query, query_len);
if (mysql_query(db_read, query)) {
b_abort("SELECT from BRP, Map unsuccessful: %s", mysql_error(db_read));
}
res_set = mysql_store_result(db_read);
fprintf(stderr, "SELECT FROM ResultPairs, affected rows %lu, result_set %lu rows\n",
(unsigned long) mysql_affected_rows(db_read), (unsigned long) mysql_num_rows(res_set));
if (res_set && mysql_num_rows(res_set)){
if ((row = mysql_fetch_row(res_set)) != NULL){
mygrp = (unsigned long) atol(row[0]);
selfscore = (unsigned long) atol(row[1]);
}
mysql_free_result(res_set);
} else {
fprintf(stderr, "SELF SCORE selected no rows, skipping id %d", id);
free(query);
return 1; /* no self sacore found, but the query was OK */
}
fprintf(stderr, "selected group (%d) & selfscore (%d) results for id %d\n", mygrp,
selfscore, id);
when both queries are uncommented the program segfaults in:
Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 1024 (LWP 11049)]
chunk_alloc (ar_ptr=0x401d0a00, nb=49) at malloc.c:2929
2929 malloc.c: No such file or directory.
in malloc.c
(gdb) where
#0 chunk_alloc (ar_ptr=0x401d0a00, nb=49) at malloc.c:2929
#1 0x4011c108 in __libc_malloc (bytes=40) at malloc.c:2811
#2 0x4003c12d in my_malloc () from /usr/lib/mysql/libmysqlclient.so.10
#3 0x40037e4c in read_rows () from /usr/lib/mysql/libmysqlclient.so.10
#4 0x40039554 in mysql_read_query_result () from
/usr/lib/mysql/libmysqlclient.so.10
#5 0x400395ff in mysql_real_query () from
/usr/lib/mysql/libmysqlclient.so.10
#6 0x400393bb in mysql_query () from /usr/lib/mysql/libmysqlclient.so.10
#7 0x0804b285 in do_statistics (db_read=0x805c800, db_write=0x805fbf8,
id=102, type=3) at Stattest.c:291
#8 0x0804b82a in main (argc=6, argv=0xbffffb24) at Stattest.c:552
#9 0x400b8627 in __libc_start_main (main=0x804b3ec <main>, argc=6,
ubp_av=0xbffffb24, init=0x8049a6c <_init>,
fini=0x8056d00 <_fini>, rtld_fini=0x4000dcd4 <_dl_fini>,
stack_end=0xbffffb1c)
at ../sysdeps/generic/libc-start.c:129
when I comment either ow the two, the program runs OK. Any ideas?
Kristian
--
Dr. sc. Kristian Vlahovicek
Protein structure & bioinformatics Phone: +39 0403757354
ICGEB Fax: +39 040226555
Padriciano 99 E-mail: kristian(at)icgeb(dot)trieste(dot)it
Trieste 34012 Italy Web: http://www.icgeb.trieste.it/dna
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