Fix error in ECPG while connection handling - Mailing list pgsql-hackers

From Jeevan Ladhe
Subject Fix error in ECPG while connection handling
Date
Msg-id CAOgcT0Pnh8UUGYke16At+Fy77nq2Wb6aZFzhJ8nzONKLuO=EYw@mail.gmail.com
Whole thread Raw
Responses Re: Fix error in ECPG while connection handling  (Michael Meskes <meskes@postgresql.org>)
List pgsql-hackers
Hi,

I came across following error while working on ecpg client program.

$ install/bin/ecpg ecpg_connection_ptr.pgc 
ecpg_connection_ptr.pgc:26: ERROR: AT option not allowed in WHENEVER statement

I have attached simple ecpg program 'ecpg_connection_ptr_issue.pgc' that
reproduces the above issue.

After doing some investigation I could see that, in preproc.y, in rule of
'ClosePortalStmt', function output_statement() is called, which in turn frees
the connection pointer. Here is the relevant trailing snippet from the
output_statement() function.

  whenever_action(whenever_mode | 2);
free(stmt);
if (connection != NULL)
free(connection);
}

Now, when the ecpg parses following statement using rule 'ECPGWhenever':
     EXEC SQL WHENEVER SQLERROR CONTINUE;
it checks if the connection is set, if it is then throws an error as below:

if (connection)
mmerror(PARSE_ERROR, ET_ERROR, "AT option not allowed in WHENEVER statement");

Now, ideally the connection would have been null here, but, as the 'ClosePortalStmt'
rule freed the connection but did not set it to NULL, it still sees that there
is a connection(which is actually having garbage in it) and throws an error.

I see similarly there are other places, which are freeing this global connection
but not setting to NULL, and all those should be fixed. I have attached a patch
ecpg_connection_ptr_issue_fix.patch to fix these places.

Regards,
Jeevan Ladhe
Attachment

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