Another libio bug.

[H.J. Lu]

Here is another stdio bug. On glibc 2, I got

# gcc f.c
# a.out
4096, 4120
4120
# a.out 1
fwrite: Resource temporarily unavailable
4096, 4120
0

On Solaris,

# a.out
5120, 5144
5144
# a.out 1
fwrite: Resource temporarily unavailable
5120, 5144
5120

On HP-UX,

# a.out
fwrite: Resource temporarily unavailable
8192, 8216
8192
# a.out 1
fwrite: Resource temporarily unavailable
8192, 8216
8192

I believe glibc 2 is wrong. Either Solaris or HP is ok. Ulrich, could
you please take a look? It seems a nasty bug to me.

Thanks.


-- 
H.J. Lu (hjl@gnu.org)
---
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <fcntl.h>
#include <errno.h>

main (int argc, char **argv)
{
  int pipe_fd [2];
  int flags;
  int pipe_buf;
  int bufsiz1, bufsiz2;
  FILE *fp;
  char *bp;
  int nitems;

  if (pipe(pipe_fd))
    {
      perror ("pipe");
      return 1;
    }

  if ((flags = fcntl(pipe_fd[1], F_GETFL, 0)) == -1)
    {
      perror ("fcntl");
      return 1;
    }

  flags |= O_NONBLOCK;
  if (fcntl(pipe_fd[1], F_SETFL, flags) == -1)
    {
      perror ("fcntl");
      return 1;
    }

  if ((pipe_buf = fpathconf(pipe_fd[1], _PC_PIPE_BUF)) <= 0L)
    {
      perror ("fpathconf");
      return 1;
    }

  bufsiz1 = pipe_buf + 16;
  bufsiz2 = bufsiz1 + 8;

  if (!(fp = fdopen(pipe_fd[1], "w")))
    {
      perror ("fdopen");
      return 1;
    }

  if (argc > 1)
    setbuf(fp, (char *) NULL);
  bp = (char *) malloc(bufsiz2);
  while (write(pipe_fd [1], bp, pipe_buf / 2) == pipe_buf / 2);
  
  read (pipe_fd [0], bp, pipe_buf);

  nitems = fwrite((void *) bp, (size_t) 1, (size_t) bufsiz2, fp);
  if (ferror (fp))
    perror ("fwrite");
  printf ("%d, %d\n", pipe_buf, bufsiz2);
  printf ("%d\n", nitems);
}