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Full Discussion: A weird problem with POSIX function
Top Forums Programming A weird problem with POSIX function Post 302556185 by NH2 on Saturday 17th of September 2011 04:09:25 AM
Old 09-17-2011
Hi!

Quote:
Originally Posted by bus147
Hi all,

Sorry for the title because I didn't find a proper name for it. My question is about POSIX functions, such as timer_create(), mq_open() and pthread_create().

[...]

If I put the above function in main.c, there will have no problem. The queue is successfully created. But if I put in a file, let say foo.c. This file is compiled into libFOO.a and linked with main.c. Then I got the following error: errno(2: No such file or directory)

The other POSIX functions are also same if put in libFOO.a, for example, timer_create() failed with "Invalid argument" errro, pthread_create() succeeds but it is never run.

Is there any difference between running in main.c and foo.c? If you ever experienced such problem then please give me some hints

Thank you very much
Strange. Can you check if the following works on your platform:

Code:
/* foo.c */
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "foo.h" 

static pthread_t tid;

void* my_thread(void* ignore)
{
   int i;
   printf("Hello from thread\n");
   for (i=0; i<10; i++) {
      printf ("%d ", i); 
      fflush(stdout);
      sleep(1);
   }
}

void init(void)
{
   int rc;
   
   rc = pthread_create(&tid, NULL, my_thread, NULL);
   if (rc!=0) {
      fprintf(stderr,"pthread_create failed: %s (%d)\n", strerror(rc), rc);
      exit(1);
   }
}

Code:
/* foo.h */
#ifndef __FOO_H_
#define __FOO_H_
void init(void);
#endif

Code:
//myprog.c
#include <unistd.h>
#include "foo.h"

int
main()
{
   int val; 
   init();
   sleep(6);
}

Compile as follows:
Code:
cc -c foo.c
ar rcs libfoo.a foo.o
cc -pthread -static myprog.c -o myprog -L. -lfoo

If everything works as expected, you should see the following output:
Code:
Hello from thread
0 1 2 3 4 5

/Lew
 

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LEARN ABOUT DEBIAN

undocumented

UNDOCUMENTED(7) 					     Linux Programmer's Manual						   UNDOCUMENTED(7)

NAME

       undocumented - No manpage for this program, utility or function.

DESCRIPTION

       This  program,  utility	or function does not have a useful manpage.  Before opening a bug to report this, please check with the Debian Bug
       Tracking System (BTS) at <http://bugs.debian.org/> if a bug has already been reported.  If not, you can submit a wishlist bug if you want.

       If you are a competent and accurate writer and are willing to spend the time reading the source code and writing good manpages please write
       a  better  man page than this one.  Please contact the package maintainer and copy man-pages@qa.debian.org in order to avoid several people
       working on the same manpage.

       Even if you are not an accurate writer, your input may be helpful.  Writing manual pages is quite easy, the format is described in  man(7).
       The most important and time-consuming task is to collect the information to be put in the new manpage.

DIAGNOSTICS

       It  is  possible  that  the man page for the command you specified is installed and that your manual page index caches are out of sync. You
       should try running mandb(8).

       Try the following options if you want more information:

       foo --help, foo -h, foo -?

       info foo

       whatis foo, apropos foo

       dpkg --listfiles foo, dpkg --search foo

       locate '*foo*'

       find / -name '*foo*'

       Additionally, check the directories /usr/share/doc/foo, /usr/lib/foo.

       The documentation might be in a package starting with the same name as the package the software belongs to, but ending with -doc or -docs.

       If you still didn't find the information you are looking for you might consider posting a call for help to debian-user@lists.debian.org.

SEE ALSO

       info(1), whatis(1), apropos(1), dpkg(8), locate(1), find(1), updatedb(1), undocumented(3), man(7), mandb(8), missing(7).

Debian GNU/Linux						 August 24th, 2003						   UNDOCUMENTED(7)
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