From: Volkan YAZICI <volkan.yazici@gmail.com>
To: David Hinkle <drachs@gmail.com>
Cc: pgsql-interfaces@postgresql.org
Subject: Re: libpq, PQExecParams and the inserting of binary data
Date: Sat, 4 Jun 2005 11:22:38 +0300
Message-ID: <7104a73705060401222c6cc5d2@mail.gmail.com> (raw)
In-Reply-To: <ae830e6c05060310367c37a84a@mail.gmail.com>
References: <ae830e6c05060309182201f85b@mail.gmail.com>
<7104a7370506030943662e4be@mail.gmail.com>
<ae830e6c05060310367c37a84a@mail.gmail.com>
Hi,
On 6/3/05, David Hinkle <drachs@gmail.com> wrote:
> [snipped]
> What I'm asking for is an expample or a document showing me how to do
> it.
While trying to prepare an example for your question, I scracthed sth.
like this:
{{{ Code snippet
const char *command = "INSERT INTO tbl1 VALUES ($1)";
int nParams = 1;
const Oid paramTypes[] = {17}; // 17, for bytea type's OID.
const char * const paramValues[] = {"\\101\\102\\103"}; // "ABC"
const int *paramLengths = NULL; // Letting the backend to
const int *paramFormats = NULL; // deduce these params.
int resultFormat = 0; // Result will be in text format.
conn = PQconnectdb("dbname=test");
if ( PQstatus(conn) != CONNECTION_OK ) {
fprintf(stderr, "Connection failed!\n%s", PQerrorMessage(conn));
exit_nicely(conn);
}
printf("Command: \"%s\",\n", command);
printf("Param. : \"%s\".\n", paramValues[0]);
res = PQexecParams(conn, command, nParams, paramTypes, paramValues,
paramLengths, paramFormats, resultFormat);
if ( PQresultStatus(res) != PGRES_COMMAND_OK ) {
fprintf(stderr, "Insert failed!\n%s", PQresultErrorMessage(res));
PQclear(res);
exit_nicely(conn);
} else {
printf("Insert succeeded.\n");
PQclear(res);
}
}}}
Above code is working well for me. But while trying some other
combinations (out of NULL usage) for PQexecParams parameters, I
realized that when we use "const int paramFormats[] = {1};" execution
dumps SegFault:
{{{ Command output snippet
$ gcc -g -Wall -lpq binIns.c && ./a.out
Command: "INSERT INTO tbl1 VALUES ($1)",
Param. : "\101\102\103".
Segmentation fault
$ gdb ./a.out
[snipped]
Using host libthread_db library "/lib/tls/libthread_db.so.1".
(gdb) run
Starting program: /home/knt/temp/a.out
Command: "INSERT INTO tbl1 VALUES ($1)",
Param. : "\101\102\103".
Program received signal SIGSEGV, Segmentation fault.
0xb7fcee05 in PQsendQueryGuts () from /usr/lib/libpq.so.4
(gdb) bt
#0 0xb7fcee05 in PQsendQueryGuts () from /usr/lib/libpq.so.4
#1 0xb7fce902 in PQsendQueryParams () from /usr/lib/libpq.so.4
#2 0xb7fcf420 in PQexecParams () from /usr/lib/libpq.so.4
#3 0x08048811 in main () at binIns.c:34
}}}
[Line 34: "res = PQexecParams(conn, ..."]
Is this an expected behaviour or did I miss sth. important?
Regards.
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To: pgsql-interfaces@postgresql.org
Cc: volkan.yazici@gmail.com, drachs@gmail.com
Subject: Re: libpq, PQExecParams and the inserting of binary data
In-Reply-To: <7104a73705060401222c6cc5d2@mail.gmail.com>
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