zircon/third_party/ulib/musl/src/process/posix_spawn.c

#define _GNU_SOURCE
#include <fcntl.h>
#include <sched.h>
#include <spawn.h>
#include <sys/wait.h>
#include <unistd.h>

#include "fdop.h"
#include "libc.h"
#include "threads_impl.h"

struct args {
  int p[2];
  sigset_t oldmask;
  const char* path;
  int (*exec)(const char*, char* const*, char* const*);
  const posix_spawn_file_actions_t* fa;
  const posix_spawnattr_t* restrict attr;
  char *const *argv, *const *envp;
};

int __posix_spawnx(pid_t* restrict res, const char* restrict path,
                   int (*exec)(const char*, char* const*, char* const*),
                   const posix_spawn_file_actions_t* fa, const posix_spawnattr_t* restrict attr,
                   char* const argv[restrict], char* const envp[restrict]) {
  pid_t pid;
  int ec = 0;
  struct args args;

  if (pipe2(args.p, O_CLOEXEC))
    return errno;

  args.path = path;
  args.exec = exec;
  args.fa = fa;
  args.attr = attr ? attr : &(const posix_spawnattr_t){};
  args.argv = argv;
  args.envp = envp;
  pthread_sigmask(SIG_BLOCK, SIGALL_SET, &args.oldmask);

  // TODO(kulakowski) Launchpad up a process here.
  pid = -ENOSYS;
  close(args.p[1]);

  if (pid > 0) {
    if (read(args.p[0], &ec, sizeof ec) != sizeof ec)
      ec = 0;
    else
      waitpid(pid, &(int){0}, 0);
  } else {
    ec = -pid;
  }

  close(args.p[0]);

  if (!ec && res)
    *res = pid;

  pthread_sigmask(SIG_SETMASK, &args.oldmask, 0);

  return ec;
}

int posix_spawn(pid_t* restrict res, const char* restrict path,
                const posix_spawn_file_actions_t* fa, const posix_spawnattr_t* restrict attr,
                char* const argv[restrict], char* const envp[restrict]) {
  return __posix_spawnx(res, path, execve, fa, attr, argv, envp);
}