cosmopolitan/libc/calls/setpgid.c

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8                                :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2022 Justine Alexandra Roberts Tunney                              │
│                                                                              │
│ Permission to use, copy, modify, and/or distribute this software for         │
│ any purpose with or without fee is hereby granted, provided that the         │
│ above copyright notice and this permission notice appear in all copies.      │
│                                                                              │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL                │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED                │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE             │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL         │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR        │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER               │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
│ PERFORMANCE OF THIS SOFTWARE.                                                │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/calls/calls.h"
#include "libc/calls/internal.h"
#include "libc/calls/strace.internal.h"
#include "libc/dce.h"
#include "libc/nt/console.h"
#include "libc/sysv/errfuns.h"

/**
 * Changes process group for process.
 */
int setpgid(int pid, int pgid) {
  int rc, me;
  if (!IsWindows()) {
    rc = sys_setpgid(pid, pgid);
  } else {
    me = getpid();
    if (pid == me && pgid == me) {
      /*
       * "When a process is created with CREATE_NEW_PROCESS_GROUP
       *  specified, an implicit call to SetConsoleCtrlHandler(NULL,TRUE)
       *  is made on behalf of the new process; this means that the new
       *  process has CTRL+C disabled. This lets shells handle CTRL+C
       *  themselves, and selectively pass that signal on to
       *  sub-processes. CTRL+BREAK is not disabled, and may be used to
       *  interrupt the process/process group."
       *                           ──Quoth MSDN § CreateProcessW()
       */
      if (SetConsoleCtrlHandler(0, 1)) {
        rc = 0;
      } else {
        rc = __winerr();
      }
    } else {
      // irregular use cases not supported on windows
      rc = einval();
    }
  }
  STRACE("setpgid(%d, %d) → %d% m", pid, pgid, rc);
  return rc;
}