Message-ID: <000401c2f9d3$ee3c9a80$6600a8c0@JAMES>
From: "James Williamson" <james@nameonthe.net>
To: <pgsql-interfaces@postgresql.org>
References: <3E8C19B5.6050106@rodos.fzk.de>
Subject: Re: Segmentation Fault
Date: Thu, 3 Apr 2003 12:26:54 +0100
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----- Original Message -----
From: "Christoph Haller" <ch@rodos.fzk.de>
> >
>  > Oh, I'm so sorry....
>  > I've made a stupid mistake... and this mistake is at the cost of 3 days
>  > work.
>  > The segmentation fault is totally irrelevant to the time functions in
>  > previous thread.
>  >
> Keep your head.
> AFAICT segmentation faults are every C programmer's nightmare
> and best known for hard to find. I know of people searching for
> mistakes even longer and I've seen mistakes more stupid than yours.
>
>  >
>  > Here I have one more question, is there any debugging tools other
> than GDB?
>  > I'm not quite used to it, debugging segmentation fault is really a
> pain. :-(
>  >

Have you looked at efence, purify and valgrind?

Regards,

James Williamson
www.nameonthe.net
Tel: +44 208 7415453
Fax: + 44 208 7411615


> I don't know of one. I'm using xdb on HP-UX, which is quite similar I
> suppose.
> I've found it useful when trying to track down, do not trace, but let it
> simply run
> within the debugger and then use the "down" command to find your code
area.
> There is also a function called memorymap(int show_stats) which often
> detects
> memory faults before the operating systems does.
>
>  >    len =strlen(PQgetvalue(res, 0, i)) * 2 + 1;  // <=========
> Why not using PQgetlength(res, 0, i)?
>  >    PQescapeString(tmp2, PQgetvalue(res, 0, i), len); // <=========
> One last question:
> Why are you using PQescapeString on PQgetvalue?
>
> The doc says:
> If you want to include strings that have been received from a source
> that is not trustworthy (for example, because a random user entered
> them), you cannot directly include them in SQL queries for security
> reasons. Instead, you have to quote special characters that are
> otherwise interpreted by the SQL parser.
>
> So PQgetvalue is trustworthy. There should be no need to call
> PQescapeString,
> except you were using a binary cursor. But if you were using one, then why
> would you want to escape the result instead of just using a normal cursor?
>
> Regards, Christoph
>
>
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