socketpair() syscall ignores non-blocking request (SOCK_NONBLOCK, O_NONBLOCK)

[christianparpart]

Hi,

(windows version: 10.0.17133.73)

I found out that the syscall socketpair is litereally ignoring the SOCK_NONBLOCK argument.
Also is fcntl's attempt to make socketpair's sockets non-blocking ignored.

Here's a minimal example program that proofs both cases. On original Linux it immediately quits as expected with the appropriate error message (EAGAIN), but on WSL/Linux it freezes after having filled one end with 163840 bytes.

#include <sys/socket.h>
#include <sys/types.h>
#include <fcntl.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <unistd.h>

int reportError(const char* syscall, int ec) {
  printf("%s: %s\n", syscall, strerror(ec));
  return 1;
}

int main(int argc, const char* argv[]) {
  int sv[2];
  int typeMask = 0;
  int flags = 0;

  if (argc == 2 && strcmp(argv[1], "-f") == 0) {
    flags |= O_NONBLOCK;
  } else {
    typeMask |= SOCK_NONBLOCK;
  }

  if (socketpair(PF_LOCAL, SOCK_STREAM | typeMask, 0, sv) < 0)
    return reportError("socketpair", errno);

  if (flags) {
    if (fcntl(sv[0], F_SETFL, flags) < 0)
      return reportError("fcntl", errno);
    if (fcntl(sv[1], F_SETFL, flags) < 0)
      return reportError("fcntl", errno);
  }

  static const char buf[4096] = {0};
  for (;;) {
    int rv = write(sv[0], buf, sizeof(buf));
    if (rv < 0) {
      reportError("write", errno);
      break;
    }
  }
  close(sv[0]);
  close(sv[1]);
  return 0;
}

[Biswa96]

Mention Windows build version.

[christianparpart]

@Biswa96 added. thx!

[therealkenc]

Rare; +1 (I was loosing faith). Not even sure it is a dupe (too hard to search).

[christianparpart]

That is why I am dog-clear in subject and description, including example-code to reproduce. No other ticket came close to it, that's why I created a dedicated one.

[therealkenc]

It's #2949, I think (right?). Don't quibble on the flags. Won't dupe ya.

[Brian-Perkins]

This should be fixed in build 17666.