Hi Carsten, I have just had a similar experience, which Jorge from Mysql support helped me sort out (successfully) - here is his advice to me.....
Hi! Which compiler / version are you using ? If it is any from 2.96 series, you'd be better off using any in the 2.95 or 3 series, as 2.96 is still buggy. Another question, was the libmysqlclient you're using downloaded from us, or was it the one shipped with the Red Hat CD ? If it's the one from the Red Hat CD, then it's the same thing .... Buggy compiler ! Regards, Jorge Robin. -----Original Message----- From: Carsten H. Pedersen [mailto:[EMAIL PROTECTED]] Sent: 27 October 2001 23:07 To: mysql mailing list Subject: C API - mysql_store_result segfaulting I'm having some trouble moving a C application from a test machine to production. The program, which uses the small wrapper around mysql_query() shown below, runs flawlessly on the test machine (hours of runtime; tens of thousands if not a million+ queries). On the production machine, the program will execute exactly 10 queries, then segfault. The 10 queries which are executed before the fault are a mix of INSERT, DELETE, and SELECTs which return both empty and non-empty sets. The last query is a SELECT which returns (well -- is *supposed* to return) an empty set. The problem is twofold: The call to mysql_field_count() returns 1 (should be 0) and upon reaching the mysql_store_result() function call, the program segfaults. I have tried switching around the two statements (as per the examples in the docs), to no avail. Both machines run RH Linux 7.1, and use GCC 2.96-85 Test machine: - MySQL 3.23.39-1 RPM from mysql.com - glibc-2.2-12 - kernel v. 2.2 (as included in RH 7.1) Production machine: - MySQL 3.23.43-1 RPM from mysql.com - glibc-2.2.4-19 - updated kernel (2.4) I've been trying all kinds of up- and downgrades of gcc and the MySQL packages, different levels of compiler optimizations, etc., but can't seem to get around this problem. If anyone has any hint as to what is wrong, I would appreciate hearing from you. [code snippet below] / Carsten MYSQL_RES *mysql_query_e(char *query, char* message, int lineno) { int result; char *errmsg; MYSQL_RES *resultset; // Do the query if (mysql_query(mysql, query)) { printf("----------------------------------------\n" "ERROR: Error when querying database on line %d.\n" "--\n%s\n\nQuery:\n %s\n\nError message:\n%d: %s\n", lineno, message, query, mysql_errno(mysql), mysql_error(mysql)); fflush(stdout); exit(2); } // Check whether we should expect any data if (mysql_field_count(mysql)) { // On the 11th query... // ... this line prints "1" where it should say "0": printf ("%d fields in result\n", mysql_field_count(mysql)); // ... and the following line segfaults: resultset = mysql_store_result(mysql); if (NULL == resultset) { printf("Error: Could not get result for query on line %d\n" "--\nExpected %d columns\n" "%s\n\nQuery:\n %s\n\nError message:\n%d:\n%s\n", lineno, mysql_field_count(mysql), message, query, mysql_errno(mysql), mysql_error(mysql)); fflush(stdout); exit(2); } // yes, there is data. Return the the result to caller return resultset; } // No data, no columns. That's fine return NULL; } --- Incoming mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.282 / Virus Database: 150 - Release Date: 25/09/01 --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.282 / Virus Database: 150 - Release Date: 25/09/01 --------------------------------------------------------------------- Before posting, please check: http://www.mysql.com/manual.php (the manual) http://lists.mysql.com/ (the list archive) To request this thread, e-mail <[EMAIL PROTECTED]> To unsubscribe, e-mail <[EMAIL PROTECTED]> Trouble unsubscribing? Try: http://lists.mysql.com/php/unsubscribe.php
