From: Chris Jewell <vs0u8055@liv.ac.uk>
To: pgsql-interfaces@postgresql.org
Subject: Seg fault on completing query
Date: Thu, 13 Mar 2003 15:28:20 +0000
Message-ID: <3E70A394.9080802@liv.ac.uk> (raw)
Hi,
I'm working on a frontend to a Postgresql database. I've chosen C in
which to work, mainly because I wanted to learn the language. So, I'm
using the pqlib frontend library. The C source I have is below. I
compile it (on linux) with gcc -g -Wall -lpq -oantibug antibug.c. When
I run the executable, it prints out the query to the screen ok, but also
prints a "Segmentation Fault" on completion of the list. Does anyone
know why? How can I prevent this?
Thanks,
Chris J
Source:
/**************************************************************
* A test C program to perform a SELECT query on tblantibiotic*
* on the bugswat database. *
**************************************************************/
#include <stdio.h>
#include <libpq-fe.h>
#include <stdlib.h>
void exit_nicely(PGconn * conn) {
PQfinish(conn);
printf("Abnormal exit");
exit(1);
}
int main() {
/* Declare variables for the connection and getting results */
int num_records;
PGconn *connect;
PGresult *res;
int i;
char *name;
/* Connect to the database */
connect = PQconnectdb("host = linux.chrisdomain dbname=antibugdb
user=cjewell");
if (PQstatus(connect) == CONNECTION_BAD) {
fprintf(stderr, "Could not connect to database");
fprintf(stderr, "Error: %s\n", PQerrorMessage(connect));
exit_nicely(connect);
}
/* Perform our query */
res = PQexec(connect, "SELECT * FROM tblactivity;");
if ((!res) || (PQresultStatus(res) != PGRES_TUPLES_OK)) {
fprintf(stderr, "SELECT query failed, error: %d\n",
PQresultStatus(res));
fprintf(stderr, "Server error: %s\n", PQerrorMessage(connect));
PQclear(res);
exit_nicely(connect);
}
num_records = PQntuples(res); /* put the number of tuples into
num_records */
/* Now print out the results to the screen */
for(i=0; i < num_records; ++i) {
sprintf(name, "%s", PQgetvalue(res, i, 0));
printf("%s\n", name);
}
PQclear(res);
PQfinish(connect);
return(0);
}
Output:
[cjewell@chris cprogs]$ ./antibug
good
some
poor
none
unknown
Segmentation fault
[cjewell@chris cprogs]$
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Subject: Re: Seg fault on completing query
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