RE: undefined reference to `__errno_location(void)'

RE: undefined reference to `__errno_location(void)'

[Rupert Wood]

Gordon Ellsworth wrote:

> /home/muvie/muvie/src/socket_class.c:211: undefined reference to 
> `__errno_location(void)'
:
>     And when you link make sure to add -lpthread,
>     since the symbol for errno_location is defined
>     in the libpthread library on Linux.
:
> I tried this, but it did not get rid of the problem.

Can I confirm that you tried the '-lpthread' in addition to the #include
in the PR comment? If so, can you confirm that you've got a libpthread.a
or libpthread.so in /lib or /usr/lib and that it contains the symbol
__errno_location?

As you said you haven't upgraded, the system *ought* to work as shipped.
But it's possible (albeit unlikely) that your C library was not build
with threading support or that you're missing the ptherad library -
maybe you need to install it as a separate package?

Good luck,
Rup.

Re: undefined reference to `__errno_location(void)'

[GRE Spam Mail]

On Mon, 2 Sep 2002 07:38:48 +0100
"Rupert Wood" <me@rupey.net> wrote:

> Gordon Ellsworth wrote:
> 
> > /home/muvie/muvie/src/socket_class.c:211: undefined reference to 
> > `__errno_location(void)'
> :
> >     And when you link make sure to add -lpthread,
> >     since the symbol for errno_location is defined
> >     in the libpthread library on Linux.
> :
> > I tried this, but it did not get rid of the problem.
> 
> Can I confirm that you tried the '-lpthread' in addition to the #include
> in the PR comment? 

Which #include would that be? I think I missed it.

> If so, can you confirm that you've got a libpthread.a
> or libpthread.so in /lib or /usr/lib 

Here's what I have:
./usr/lib/libpthread.a
./usr/lib/libpthread_p.a
./lib/libpthread-0.9.so
./usr/lib/libpthread.so

> and that it contains the symbol
> __errno_location?
> 

How do I check for the symbol?

I tried this to see if the symbol was there, I don't know if this is the right
way to check:
[root@vaghn (/)] 01:02:53 $ grep "__errno_location" /usr/lib/libpthread.a
Binary file /usr/lib/libpthread.a matches
[root@vaghn (/)] 01:02:56 $ grep "__errno_location" /usr/lib/libpthread.so
Binary file /usr/lib/libpthread.so matches

> As you said you haven't upgraded, the system *ought* to work as shipped.
> But it's possible (albeit unlikely) that your C library was not build
> with threading support or that you're missing the ptherad library -
> maybe you need to install it as a separate package?

I installed every package that comes with Slackware 8.1 (I did a full install
from the Slackware CD) so there should be nothing missing.

> 
> Good luck,
> Rup.

Thank you for your help.

Sincerely,

Gordon R. Ellsworth, Jr.

Re: undefined reference to `__errno_location(void)'x

[Der Herr Hofrat]

> 
> How do I check for the symbol?
> 
> I tried this to see if the symbol was there, I don't know if this is the right
> way to check:
> [root@vaghn (/)] 01:02:53 $ grep "__errno_location" /usr/lib/libpthread.a
> Binary file /usr/lib/libpthread.a matches
> [root@vaghn (/)] 01:02:56 $ grep "__errno_location" /usr/lib/libpthread.so
> Binary file /usr/lib/libpthread.so matches
>
nm /usr/lib/libpthread.a | grep errno should be safe.

hofrat 

Re: undefined reference to `__errno_location(void)'x

[GRE Spam Mail]

On Mon, 2 Sep 2002 18:18:04 +0200 (CEST)
Der Herr Hofrat <der.herr@mail.hofr.at> wrote:

> > 
> > How do I check for the symbol?
> > 
> > I tried this to see if the symbol was there, I don't know if this is the right
> > way to check:
> > [root@vaghn (/)] 01:02:53 $ grep "__errno_location" /usr/lib/libpthread.a
> > Binary file /usr/lib/libpthread.a matches
> > [root@vaghn (/)] 01:02:56 $ grep "__errno_location" /usr/lib/libpthread.so
> > Binary file /usr/lib/libpthread.so matches
> >
> nm /usr/lib/libpthread.a | grep errno should be safe.
> 
> hofrat 
> 

OK, I did that for libpthread.a and libpthread.so and this is the output:

root@vaghn (~)] 01:51:32 $ nm /usr/lib/libpthread.a | grep errno
         U __errno_location
         U __errno_location
         U __errno_location
         U __errno_location
         U _errno
         U _h_errno
         U __errno_location
         U __errno_location
errno.o:
00000000 T __errno_location
00000054 T __h_errno_location
         U __errno_location

[root@vaghn (~)] 01:51:49 $ nm /usr/lib/libpthread.so | grep errno
00009c24 T __errno_location
00009ca0 T __h_errno_location
         U _errno@@GLIBC_2.0
         U _h_errno@@GLIBC_2.0
         U errno@@GLIBC_2.0
         U h_errno@@GLIBC_2.0

Re: undefined reference to `__errno_location(void)'x

[GRE Spam Mail]

On Mon, 2 Sep 2002 13:54:02 -0400
GRE Spam Mail <gre_spam@anora.org> wrote:

> 
> OK, I did that for libpthread.a and libpthread.so and this is the output:
> 
> root@vaghn (~)] 01:51:32 $ nm /usr/lib/libpthread.a | grep errno
>          U __errno_location
>          U __errno_location
>          U __errno_location
>          U __errno_location
>          U _errno
>          U _h_errno
>          U __errno_location
>          U __errno_location
> errno.o:
> 00000000 T __errno_location
> 00000054 T __h_errno_location
>          U __errno_location
> 
> [root@vaghn (~)] 01:51:49 $ nm /usr/lib/libpthread.so | grep errno
> 00009c24 T __errno_location
> 00009ca0 T __h_errno_location
>          U _errno@@GLIBC_2.0
>          U _h_errno@@GLIBC_2.0
>          U errno@@GLIBC_2.0
>          U h_errno@@GLIBC_2.0
> 

Did you guys forget about me?

Sincerely,
GRE

Re: undefined reference to `__errno_location(void)'x

[bjorn rohde jensen]

Hi Gordon,

  Could you post some (small) code demonstrating the problem?
I think, you might be confusing ld's in its handling of weak/strong
symbols during linking. It would be nice with some code to experiment
with:)

Yours sincerely,

Bjorn

Re: undefined reference to `__errno_location(void)'

[GRE Spam Mail]

On Wed, 04 Sep 2002 09:27:52 +0200
bjorn rohde jensen <bjensen@fastmail.fm> wrote:

> Hi Gordon,
> 
>   Could you post some (small) code demonstrating the problem?
> I think, you might be confusing ld's in its handling of weak/strong
> symbols during linking. It would be nice with some code to experiment
> with:)
> 
> Yours sincerely,
> 
> Bjorn
> 
> 

Sure enough! Here's the smallest code that I've written that has this problem.

===

#include <cstdio>
#include <cerrno>
#include <cstring>

int main(int argc, char **argv)
{
        extern int errno;
        FILE *fp;

        errno = 0;

        if(!(fp=fopen("Somestupidfile.txt","r"))) {
                printf("File error: %s\n",strerror(errno));
        }
        else {
                fclose(fp);
        }

        return 0;
}

===

This is just a stupid little code, but it demonstrates the problem.
If I try to compile it with g++ I get the following errors:

[root@vaghn (~/prog)] 10:42:17 $ g++ -Wall test.c -o test
/tmp/ccka9V3Q.o: In function `main':
/tmp/ccka9V3Q.o(.text+0x8): undefined reference to `__errno_location(void)'
/tmp/ccka9V3Q.o(.text+0x3d): undefined reference to `__errno_location(void)'
collect2: ld returned 1 exit status

Thank you for all your help.

Sincerely,

Gordon R. Ellsworth, Jr.

Re: undefined reference to `__errno_location(void)'

[Claudio Bley]

>>>>> "GRE" == GRE Spam Mail <gre_spam@anora.org> writes:

    GRE> On Wed, 04 Sep 2002 09:27:52 +0200 bjorn rohde jensen
    GRE> <bjensen@fastmail.fm> wrote:

    >> Hi Gordon,
    >> 
    >> Could you post some (small) code demonstrating the problem?  I
    >> think, you might be confusing ld's in its handling of
    >> weak/strong symbols during linking. It would be nice with some
    >> code to experiment with:)
    >> 
    >> Yours sincerely,
    >> 
    >> Bjorn
    >> 
    >> 

    GRE> Sure enough! Here's the smallest code that I've written that
    GRE> has this problem.

    GRE> extern int errno; 
         ^^^^^^^^^^^^^^^^^

Remove this line from your source. You get the error because errno is
defined as a macro and the line is expanded to 

extern int (*__errno_location ());


Claudio

Re: undefined reference to `__errno_location(void)'

[Rupert Wood]

Claudio Bley wrote:

>     GRE> extern int errno;
>          ^^^^^^^^^^^^^^^^^
>
> Remove this line from your source. You get the error because errno is
> defined as a macro and the line is expanded to
>
> extern int (*__errno_location ());

Which, in that scope, is defined as a C++ symbol. Which is why it
didn't match the C __errno_location in libpthread.

The "d'oh" here is that the clue was in the title: it wouldn't have said
"(void)" if it was trying to match a C symbol because it wouldn't have
that information.

Oh well, we learn. (And good spot, Claudio!)

Rup.

Re: undefined reference to `__errno_location(void)'

[GRE Spam Mail]

On Wed, 4 Sep 2002 12:20:11 -0400 (EDT)
Rupert Wood <rup@kanat.pair.com> wrote:

> Claudio Bley wrote:
> 
> >     GRE> extern int errno;
> >          ^^^^^^^^^^^^^^^^^
> >
> > Remove this line from your source. You get the error because errno is
> > defined as a macro and the line is expanded to
> >
> > extern int (*__errno_location ());
> 
> Which, in that scope, is defined as a C++ symbol. Which is why it
> didn't match the C __errno_location in libpthread.
> 
> The "d'oh" here is that the clue was in the title: it wouldn't have said
> "(void)" if it was trying to match a C symbol because it wouldn't have
> that information.
> 
> Oh well, we learn. (And good spot, Claudio!)
> 
> Rup.
> 
> 

I just wanted to thank you all for your help. The problem seems resolved.
I also want to thank the others that helped me that I didn't reply to in
this message, Such as Der Herr Hofrat.

Sincerely,

Gordon R. Ellsworth, Jr.

P.S. Now I feel stupid. "d'oh!"

Re: undefined reference to `__errno_location(void)'

[GRE Spam Mail]

On Mon, 2 Sep 2002 07:38:48 +0100
"Rupert Wood" <me@rupey.net> wrote:

> Gordon Ellsworth wrote:
> 
> > /home/muvie/muvie/src/socket_class.c:211: undefined reference to 
> > `__errno_location(void)'
> :
> >     And when you link make sure to add -lpthread,
> >     since the symbol for errno_location is defined
> >     in the libpthread library on Linux.
> :
> > I tried this, but it did not get rid of the problem.
> 
> Can I confirm that you tried the '-lpthread' in addition to the #include
> in the PR comment? 

Which #include would that be? I think I missed it.

> If so, can you confirm that you've got a libpthread.a
> or libpthread.so in /lib or /usr/lib 

Here's what I have:
./usr/lib/libpthread.a
./usr/lib/libpthread_p.a
./lib/libpthread-0.9.so
./usr/lib/libpthread.so

> and that it contains the symbol
> __errno_location?
> 

How do I check for the symbol?

I tried this to see if the symbol was there, I don't know if this is the right
way to check:
[root@vaghn (/)] 01:02:53 $ grep "__errno_location" /usr/lib/libpthread.a
Binary file /usr/lib/libpthread.a matches
[root@vaghn (/)] 01:02:56 $ grep "__errno_location" /usr/lib/libpthread.so
Binary file /usr/lib/libpthread.so matches

> As you said you haven't upgraded, the system *ought* to work as shipped.
> But it's possible (albeit unlikely) that your C library was not build
> with threading support or that you're missing the ptherad library -
> maybe you need to install it as a separate package?

I installed every package that comes with Slackware 8.1 (I did a full install
from the Slackware CD) so there should be nothing missing.

> 
> Good luck,
> Rup.

Thank you for your help.

Sincerely,

Gordon R. Ellsworth, Jr.