Description of problem:

getpwuid_r() on RH-9 can return zero, indicating success, when in fact 
there was an error.

Version-Release number of selected component (if applicable):

stock RH-9, glibc-2.3.2-11.9

How reproducible:

always

Steps to Reproduce:
1. Compile and run this program, make sure limit on file descriptors
   is less than 1024 (so getpwuid_r should fail with EMFILE):

#include <stdio.h>
#include <pwd.h>
#include <unistd.h>
#include <sys/types.h>
#include <errno.h>
#include <string.h>
 
int main(void) {
  FILE *fd[1024];
  int i;
                                                                                
  for(i = 0; i < 1024; i++) {
    char buf[256];
    sprintf(buf, "/tmp/f%d", i);
    fd[i] = fopen(buf, "w");
  }
 
  int uid = geteuid();
 
  struct passwd pwent;
  struct passwd* p;
  char pwbuf[1024];
 
  errno = 0;
  int result = getpwuid_r(uid, &pwent, pwbuf, sizeof(pwbuf), &p);
 
  if (result == 0 && p == NULL)
    printf("getpwuid_r returns %d, but p is %p and errno = %d\n", result, p, errno);
  if (result != 0) { printf("getpwuid_r: %s\n", strerror(result)); }
 
  return 0;
}
    
Actual results:

on RH-9:

fez:~> g++ tstgetpwuid_r.cpp
fez:~> ./a.out
getpwuid_r returns 0, but p is (nil) and errno = 24

Expected results:

getpwuid_r should return non-zero value to indicate failure, for example,
on RH-7.3:

screen:~> ./a.out
getpwuid_r: Too many open files

Additional info: