dlopen Solaris memory leaks

[Ben Goodwin]

I've been hunting down a memory leak that my library, which gets
dlopened/closed numerous times in any given instance of a program, seems to
incurr.  I've been able to recreate the leak with minimal code.  At first I
thought it was a Solaris bug, but I tried compiling the same code with
SUNWspro (sun's cc) and the leak goes away.  So, naturally, I come here.
Basically the program 'tst' dlopens 'tstlib', runs a routine called 'doit'
from 'tstlib', dlcloses 'tstlib', and repeats.  This causes a memory leak in
'tst'.  I've reproduced this with gcc 2.95.3, 3.0.2, and 3.1 on Solaris
8/x86, Solaris 8/sparc, and Solaris 9/sparc.  Again, SUNWspro (version info
below) doesn't produce a leaking executeable/dlopen library.  Perhaps I'm
doing something wrong (and as such, so is libtool), or perhaps there's
really a bug here.  I'm using the system's 'ld' linker (like libtool does),
though I've tried using gcc -shared with the same results.
Note that not all routines cause this memory leak.  The only one I *know*
about is getservbyname(), but I also know there are others, as dlopening
MySQL (and running mysql_init/close) causes leaks even if I comment out all
getservbyname() calls.  Before I paste version info/code, I'd like to state
I'm willing to do more debugging here, but this goes beyond my immediate
know-how.  Please let me know how I can help more, if necessary.
Note also that this leak does not occur on my RedHat 7.3/intel machine.
I'm attaching the *.i* files as well.
Thanks!

    -=| Ben

====

SUNWspro 'cc -V' output

 > cc -V
ucbcc: Sun WorkShop 6 update 1 C 5.2 2000/09/11
ld: Software Generation Utilities - Solaris Link Editors: 5.8-1.275

Serveral gcc versions; The Solaris 9 box was wiped so I don't have that info
handy - but it was a Sun FreeWare installation.

 /* Sourceforge compile farm - From the path name it's obvious this is a Sun
FreeWare installation.  I don't know anything else about how it was
configured/installed. */
 > gcc -v
Reading specs from /opt/sfw/lib/gcc-lib/sparc-sun-solaris2.8/2.95.3/specs
gcc version 2.95.3 20010315 (release)

 > gcc -v
Reading specs from /usr/local/lib/gcc-lib/i386-pc-solaris2.8/3.1/specs
Configured with:
../configure --with-as=/usr/ccs/bin/as --with-ld=/usr/ccs/bin/ld --disable-n
ls
Thread model: posix
gcc version 3.1

> gcc -v
Reading specs from /usr/local/lib/gcc-lib/sparcv9-sun-solaris2/3.0.2/specs
Configured with:
../gcc-3.0.2/configure --prefix=/usr/local --enable-languages=all
sparcv9-sun-solaris2
Thread model: posix
gcc version 3.0.2



Here's the code.

/* tst.c */
#include <stdio.h>
#include <dlfcn.h>

#define MYLIB "/export/home/ben/dl/tstlib.so.1"

int main (void)
{
  void *handle;
  int (*a)(void);
  char *error;

  while (1)
    {
      handle = dlopen (MYLIB, RTLD_LAZY);
      if (!handle)
        {
          fputs (dlerror(), stderr);
          exit (1);
        }

      a = dlsym (handle, "doit");
      if ((error = dlerror ()) != NULL)
        {
          fprintf (stderr, "%s\n", error);
          exit (1);
        }
        (*a)();

      dlclose (handle);
    }
}

/* tstlib.c */


#include <stdio.h>
#include <stdlib.h>
#include <netdb.h>

static struct servent *serv_ptr;
static char *f;

void doit (void)
{
   if ((serv_ptr = getservbyname("telnet", "tcp")) == NULL)
     {
        printf("oops\n");
     }
}


/* Compiled with */

gcc -g -o tst tst.c -ldl
gcc -g -fPIC -DPIC -c tstlib.c -o tstlib.o

/usr/ccs/bin/ld -G -h tstlib.so.1 -o tstlib.so.1 tstlib.o -lsocket -lnsl

(or 'cc' - Sun's version)


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