ecpg crash

Hi,

While i'm working on a ecpg patch I found a bug in ecpg code. The simple
program above could reproduce it. But basically it crashes (segfault)
because it's trying to use a inexistent connection when we're preparing
a statement. Don't know if it deserves a ecpg_log() message. A possible
fix is attached.

#include <stdio.h>

exec sql whenever sqlerror sqlprint;

int main(void)
{
    exec sql begin declare section;
    char cmd[128];
    exec sql end declare section;

    exec sql connect to euler as main;
    sprintf(cmd, "select * from foo");
    exec sql prepare f from :cmd;
    exec sql disconnect;

    return 0;
}


(gdb) bt
#0  0xb7ebd9cd in find_prepared_statement (name=0x8048819 "f", con=0x0,
prev_=0xbfccc6dc) at
/a/pgsql/dev/pgsql/src/interfaces/ecpg/ecpglib/prepare.c:187
#1  0xb7ebd79f in ECPGprepare (lineno=15, connection_name=0x0,
questionmarks=0, name=0x8048819 "f", variable=0xbfccc72c "select * from
foo limit 1,2")
     at /a/pgsql/dev/pgsql/src/interfaces/ecpg/ecpglib/prepare.c:128
#2  0x0804865d in main ()


--
   Euler Taveira de Oliveira
   http://www.timbira.com/
Index: src/interfaces/ecpg/ecpglib/prepare.c
===================================================================
RCS file: /a/pgsql/dev/anoncvs/pgsql/src/interfaces/ecpg/ecpglib/prepare.c,v
retrieving revision 1.26
diff -c -r1.26 prepare.c
*** src/interfaces/ecpg/ecpglib/prepare.c    7 Feb 2008 11:09:13 -0000    1.26
--- src/interfaces/ecpg/ecpglib/prepare.c    10 May 2008 02:58:36 -0000
***************
*** 124,129 ****
--- 124,132 ----

      con = ecpg_get_connection(connection_name);

+     if (!con)
+         return false;
+
      /* check if we already have prepared this statement */
      this = find_prepared_statement(name, con, &prev);
      if (this && !deallocate_one(lineno, ECPG_COMPAT_PGSQL, con, prev, this))