fopen/malloc MT bug

[Wojciech Piechowski]

hello!

I have not found this one in archives.

In a multithreaded program (Linux 2.2.15, glibc 2.2-5, gcc 2.96) I noticed
the following problem: memory gets corrupted when one thread calls
malloc() and another calls fopen() at the same time. Everything goes fine
when I replace fopen() with open().

Please let me know if you know some other workarounds, a real solution or
anything about this bug (or is it my mistake?) because replacing
fopen() with open() is not what I really need.

This test program drops core:

/* compile with:
   gcc -o test test.cc -g -lpthread -lmcheck -lrt

   Some includes (and possibly linking with librt) are redundant and come
   from tests with open() and attempts with async I/O but they shouldn't
   bother.
*/

#define _REENTRANT
#define _THREAD_SAFE

#include <unistd.h>
#include <pthread.h>
#include <stdio.h>
#include <malloc.h>
#include <mcheck.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

void *allocator (void *arg) {
   while (true) {
      new char [(int)arg];
      if ((int)arg==10) {
         FILE *in = fopen ("/etc/passwd","r");
         if (in)
            fclose (in);
      }
   } 
   return 0;
}

main () {
   pthread_t t;
   mcheck_pedantic (0);
   pthread_create (&t, 0, allocator, (void*)10);
   pthread_create (&t, 0, allocator, (void*)100);
   pthread_create (&t, 0, allocator, (void*)30);
   pthread_create (&t, 0, allocator, (void*)80);
   pthread_create (&t, 0, allocator, (void*)1000);
   pthread_create (&t, 0, allocator, (void*)3000);
   pthread_create (&t, 0, allocator, (void*)5000);
   pthread_create (&t, 0, allocator, (void*)4);
   allocator ((void*)99);
   return 0;
}


-- 
-- Wojciech Piechowski - address@hidden - Gadu-Gadu 494156 --