libdbi-devel — Discussion about development of the core library and DBD interface

Re: [libdbi-devel] dbi_result_next_row() in while() loop

[Eric B. <eb...@ya...>]

Yes, your right.

For some reason, I thought dbi_result_get_XXX() was
flagging BAD_IDX when it calls
dbi_result_get_XXX_idx() with a bad field.


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Re: [libdbi-devel] dbi_result_next_row() in while() loop

[Christian M. S. <chr...@st...>]

=2D----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Hi,

On Tuesday 26 August 2003 06.13, Markus Hoenicka wrote:
: Hi,
:
: I didn't get round to debug the problem, but if the loop below doesn't
: work as expected, it's a libdbi bug. dbi_result_next_row() checks
: whether currowidx is within the bounds of the result set and throws an
: error if it is too high. There is probably a hidden off-by-one
: error in the comparisons that we need to fix.

No It's not a bug. It's a feature ;)=20

Everytime the while loop checks the condition if it should loop one more ti=
me=20
the function dbi_conn_next_row() gets executed.=20

: while (dbi_result_next_row(result))

So say that there are 8 rows, when the 8 row are fetched the while loop=20
executes dbi_conn_next_row() one more time to check if it should go a 9:th=
=20
time, libdbi throws a DABIDX becouse you are trying to fetch row number 9 a=
nd=20
there are only 8 rows, returns 0 so the while loop stops.

So the question here is. Should this error check for BADIDX be taken out of=
=20
dbi_result_next_row() so that you can use it whitout errors thrown in a pla=
in=20
while loop.=20

While looking in to the problem I found something that is a bug.=20

dbi_result_seek_row() doesn't return -1 when dbd_seek_row() returns -1=20
indicating failure. It tryies to fetch the row anyway which is in my eyes a=
n=20
error (if the row can't be seeked we are fetching the wrong row).

=2D --- dbi_result.c.orig   2003-08-26 08:55:37.000000000 +0200
+++ dbi_result.c        2003-08-26 08:56:33.000000000 +0200
@@ -86,6 +86,7 @@
        retval =3D result->conn->driver->functions->goto_row(result, row-1);
        if (retval =3D=3D -1) {
                _error_handler(result->conn, DBI_ERROR_DBD);
+               return -1;
        }
        retval =3D result->conn->driver->functions->fetch_row(result, row-1=
);
        if (retval =3D=3D 0) {

Take it easy,

Christian


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Re: [libdbi-devel] dbi_result_next_row() in while() loop

[Markus H. <mar...@mh...>]

Hi,

I didn't get round to debug the problem, but if the loop below doesn't
work as expected, it's a libdbi bug. dbi_result_next_row() checks
whether currowidx is within the bounds of the result set and throws an
error if it is too high. There is probably a hidden off-by-one
error in the comparisons that we need to fix.

regards,
Markus

Eric Bixby writes:
 > However, we switched to using a while loop to use
 > fewer lines of code, like this:
 > 
 >   while (dbi_result_next_row(result)) {
 >     column = dbi_result_get_string(result, "A");
 >     printf("%s\n", column);
 >   }
 > 

-- 
Markus Hoenicka
mar...@ca...
(Spam-protected email: replace the quadrupeds with "mhoenicka")
http://www.mhoenicka.de

Re: [libdbi-devel] dbi_result_next_row() in while() loop

[Christian M. S. <chr...@st...>]

=2D----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Hi,

Took me some time to understand what you where talking about. (I don't use=
=20
error handlers anywhere)

Not sure what my thought are about removing it, There are other ways then=20
while loops to call dbi_result_next_row() and in some of them the error fee=
ls=20
kosher.

There are  ways to ignore the problem.=20

You could just look at the error_flag ignoring BAD_IDX errors in your error=
=20
handler or change the behavior of your while loops.

In attaching some example code.

Cheers,=20

Christian

Ps.

While looking into the problem I found that dbi_result_seek_row()  don't=20
return -1 when retval is -1 from dbd_goto_row() it continues along trying t=
o=20
fetch the row (This is a bug and should be changed even though we don't=20
remove the error handler, guess it hasn't been found yet becouse all driver=
s=20
always return 1 from dbd_goto_row()).



On Friday 22 August 2003 20.13, Eric Bixby wrote:
: I'm using the error handler feature to catch bad db
: queries.
:
: Calling dbi_result_next_row() in a while loop causes
: _error_handler() to get called.  I think it would be
: better to ignore this condition rather than report it
: as an error.  This isn't an error in the context of a
: while loop.  Ignoring this error in my error handler
: doesn't work because I need to trap when someone
: requests a bad fields name which is the same error
: code.
:
: Can the call to _error_handler() be taken out of the
: baseline for this function?
:
:
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Re: [libdbi-devel] dbi_result_next_row() in while() loop

[Christian M. S. <chr...@st...>]

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On Monday 25 August 2003 20.39, Eric Bixby wrote:
[..]

: The problem with ignoring BAD_IDX is that it's the
: same error code that occurs in a while loop and the
: same error code that occurs in the example I just
: gave.

I'm talking about the error flags, they are diffrent for BADIDX and BADNAME
use dbi_conn_error_flag(conn) to fetch the error flag.
errno is from the db error_flag is from libdbi.

Cheers,

Christian
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Re: [libdbi-devel] dbi_result_next_row() in while() loop

[Eric B. <eb...@ya...>]

Christian,

I should've included some example code to help explain
what I was talking about.  However, I'm glad you where
able to understand what I was saying.

Error handling is great because it helps find sloppy
mistakes that the compiler will not find.  For
example,  I was able to find mistakes where someone
did a query like "SELECT x FROM y", then did a
dbi_result_get_long("x_nm").

My error handler does an assert() so that it forces
the developers to fix the problem rather than ignoring
it or not realizing that it occurred.

The problem with ignoring BAD_IDX is that it's the
same error code that occurs in a while loop and the
same error code that occurs in the example I just
gave.

Usually, we used a for loop, like this:

  rows = dbi_result_get_numrows(result);
  for (row = 0; row < rows; row++) {
    dbi_result_next_row(result);
    column = dbi_result_get_string(result, "A");
    printf("%s\n", column);
  }

However, we switched to using a while loop to use
fewer lines of code, like this:

  while (dbi_result_next_row(result)) {
    column = dbi_result_get_string(result, "A");
    printf("%s\n", column);
  }

The quick fix I came up with, to avoid rewriting the
while loops back to for loops, was to create a wrapper
function:

  int DbiResultNextRow(dbi_result Result)
  {
   dbi_result_t *result = Result;

   if ((result != NULL) && (result->currowidx <
       dbi_result_get_numrows(Result)))
   {
    return dbi_result_next_row(result);
   }
   else
   {
    return 0;
   }
  }

Thanks for your help.


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[libdbi-devel] dbi_result_next_row() in while() loop

[Markus H. <mar...@mh...>]

Hi Eric,

could you please provide a code example? It is not obvious to me why
_error_handler() is called unless the loop goes too far. If it really
does, this is probably a bug somewhere else that needs to be fixed.

regards,
Markus

Eric Bixby writes:
 > I'm using the error handler feature to catch bad db
 > queries.
 > 
 > Calling dbi_result_next_row() in a while loop causes
 > _error_handler() to get called.  I think it would be
 > better to ignore this condition rather than report it
 > as an error.  This isn't an error in the context of a
 > while loop.  Ignoring this error in my error handler
 > doesn't work because I need to trap when someone
 > requests a bad fields name which is the same error
 > code.
 > 
 > Can the call to _error_handler() be taken out of the
 > baseline for this function?
 > 

-- 
Markus Hoenicka
mar...@ca...
(Spam-protected email: replace the quadrupeds with "mhoenicka")
http://www.mhoenicka.de

[libdbi-devel] dbi_result_next_row() in while() loop

[Eric B. <eb...@ya...>]

I'm using the error handler feature to catch bad db
queries.

Calling dbi_result_next_row() in a while loop causes
_error_handler() to get called.  I think it would be
better to ignore this condition rather than report it
as an error.  This isn't an error in the context of a
while loop.  Ignoring this error in my error handler
doesn't work because I need to trap when someone
requests a bad fields name which is the same error
code.

Can the call to _error_handler() be taken out of the
baseline for this function?


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Re: [libdbi-devel] packaging libdbi, libdbi-drivers for Cygwin

[David P. <da...@ne...>]

Markus Hoenicka <mar...@mh...> said:

> All that's missing is the libdbi-drivers cygwin package that you might
> want to add to the download page and subdir. I've uploaded the package
> to
> 
> http://libdbi-drivers.sourceforge.net/libdbi-drivers-cygwin-bin-0.7.0.tar.bz2
> 
> thanks
> Markus

I just downloaded this file to http://libdbi.sourceforge.net/downloads/

Do you also want me to add a note about it to the downloads page or should it
just continue to refer to http://libdbi-drivers.sf.net? (You should also be
able to edit the libdbi website files if that's what you want to do... it's
now group writable like it's supposed to be)

David

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Re: [libdbi-devel] packaging libdbi, libdbi-drivers for Cygwin

[Markus H. <mar...@mh...>]

David Parker writes:
 > > Sounds ok to me. I'll upload the drivers package to the same location,
 > > so once you're at it you may include that as well.
 > 
 > All done... I put up your libdbi binary tarball, and thanks for reminding me
 > to add Mac OS X to the download page. What else did you want me to include?
 > Maybe I missed an email somewhere.
 > 

All that's missing is the libdbi-drivers cygwin package that you might
want to add to the download page and subdir. I've uploaded the package
to

http://libdbi-drivers.sourceforge.net/libdbi-drivers-cygwin-bin-0.7.0.tar.bz2

thanks
Markus

-- 
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mar...@ca...
(Spam-protected email: replace the quadrupeds with "mhoenicka")
http://www.mhoenicka.de

Re: [libdbi-devel] packaging libdbi, libdbi-drivers for Cygwin

[David P. <da...@ne...>]

On Wed, 23 Jul 2003 23:58:20 +0200, Markus Hoenicka wrote:

> Actually Cygwin does have a packaging system, but they've got a strict
> rule that no package may depend on external packages. PostgreSQL is
> the only officially packaged database engine supported by
> libdbi. However, offering libdbi and the PostgreSQL driver alone is a
> bit lame. This is why I'm currently not willing to create an official
> package.

Fair enough :) What I meant by that is it makes little sense, for example, to
offer a binary tarball for Red Hat instead of RPMs.

> Sounds ok to me. I'll upload the drivers package to the same location,
> so once you're at it you may include that as well.

All done... I put up your libdbi binary tarball, and thanks for reminding me
to add Mac OS X to the download page. What else did you want me to include?
Maybe I missed an email somewhere.

David

-------
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Re: [libdbi-devel] packaging libdbi, libdbi-drivers for Cygwin

[Markus H. <mar...@mh...>]

Hi David,

David Parker writes:
 > On Tue, 15 Jul 2003 00:39:10 +0200, Markus Hoenicka wrote:
 > 
 > > - does anyone have objections against providing binary packages on SF?
 > 
 > Not I, at least for platforms where compiling from source is impractical (and
 > no viable packaging system is supported).
 > 

Actually Cygwin does have a packaging system, but they've got a strict
rule that no package may depend on external packages. PostgreSQL is
the only officially packaged database engine supported by
libdbi. However, offering libdbi and the PostgreSQL driver alone is a
bit lame. This is why I'm currently not willing to create an official
package.

 > > - is it ok to release binary packages that are built from CVS instead
 > >   of from the latest source release? Should we release the fixed
 > >   sources first?
 > 
 > I think this is fine when CVS has changes needed for binary ports to work, but
 > maybe we should just include a plain file download link as opposed to making
 > an official sourceforge file release.
 > 
 > Does this sound ok? If so I'll go ahead and put up the release you sent
 > yesterday.
 > 

Sounds ok to me. I'll upload the drivers package to the same location,
so once you're at it you may include that as well.

regards,
Markus

-- 
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(Spam-protected email: replace the quadrupeds with "mhoenicka")
http://www.mhoenicka.de

Re: [libdbi-devel] packaging libdbi, libdbi-drivers for Cygwin

[David P. <da...@ne...>]

On Tue, 15 Jul 2003 00:39:10 +0200, Markus Hoenicka wrote:

> - does anyone have objections against providing binary packages on SF?

Not I, at least for platforms where compiling from source is impractical (and
no viable packaging system is supported).

> - is it ok to release binary packages that are built from CVS instead
>   of from the latest source release? Should we release the fixed
>   sources first?

I think this is fine when CVS has changes needed for binary ports to work, but
maybe we should just include a plain file download link as opposed to making
an official sourceforge file release.

Does this sound ok? If so I'll go ahead and put up the release you sent
yesterday.

David

-------
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[libdbi-devel] libdbi Cygwin package ready for release

[Markus H. <mar...@mh...>]

Hi David,

would you please release the following binary package at your earliest
convenience:

http://libdbi-drivers.sourceforge.net/libdbi-cygwin-bin-0.7.1.tar.bz2

I'll release the matching libdbi-drivers package as soon as the libdbi
package is available.

thanks,
Markus

-- 
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[libdbi-devel] packaging libdbi, libdbi-drivers for Cygwin

[Markus H. <mar...@mh...>]

Hi,

I'm currently fiddling with libdbi and libdbi-drivers on Cygwin (a
Unix layer on top of Windows, for those not familiar with it). I've
added a couple of small fixes to the sources in order to get both
packages up and running on Cygwin. I'm planning to create binary
packages, but I've got a couple of questions:

- does anyone have objections against providing binary packages on SF?

- is it ok to release binary packages that are built from CVS instead
  of from the latest source release? Should we release the fixed
  sources first?

- the Cygwin libdbi-drivers package currently contains only the MySQL
  and PostgreSQL drivers. SQLite doesn't work yet on Cygwin due to
  some file locking stuff that is not supported yet. I don't know
  about the status of mSQL on Cygwin. Did anyone try?

Let me know what you think.

regards,
Markus

-- 
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mar...@ca...
(Spam-protected email: replace the quadrupeds with "mhoenicka")
http://www.mhoenicka.de

[libdbi-devel] dbi_conn_error asprintf leak

[David P. <da...@ne...>]

Don Kinzer pointed out that dbi_conn_error is leaking memory. It produces the
error string with asprintf, but never frees it and the documentation
explicitly says not to free the string. Is anyone already freeing it on their
own, or is it safe to make the string remembered statically and freed the next
time dbi_conn_error is called? Any reason to do neither and force the user to
free the returned string?

David

-------
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[libdbi-devel] mailing lists

[David P. <da...@ne...>]

A while ago I created the libdbi-devel mailing list, but forgot to start
using it. Copied from http://libdbi.sourceforge.net/maillists.php:

* libdbi-users
Go here if you have any general questions, ideas, or problems with using
libdbi in your program.
 
* libdbi-devel
Discussion about development of the core library and DBD interface.
 
* libdbi-cvs
Automated CVS diffs and log entries are sent to this address. Subscribe here
if you want to track libdbi's progress at the source-code level.

libdbi-drivers doesn't have a similar webpage yet (hopefully sometime
tonight), but right now there's libdbi-drivers-cvs and libdbi-drivers-devel. 

I'll try to keep development-related stuff posted to libdbi-devel and/or
libdbi-drivers/devel from now on. If you're on the libdbi-users mailing list
and want to continue receiving development discussion, you'll need to
subscribe yourself if you haven't already (click the link at the top of this
message).

Thanks,
David

-------
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