This is xnu-11215.1.10. See this file in:
#include <darwintest.h>
#include <errno.h>
#include <libproc.h>
#include <signal.h>
#include <spawn.h>
#include <spawn_private.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/proc_info.h>
#include <sys/spawn_internal.h>
#include <sys/sysctl.h>
#include <sysexits.h>
#include <unistd.h>
#include <sys/fileport.h>
T_GLOBAL_META(T_META_RUN_CONCURRENTLY(true));
T_DECL(posix_spawn_file_actions_add_fileportdup2_np,
"Check posix_spawnattr for posix_spawn_file_actions_add_fileportdup2_np",
T_META_ASROOT(true), T_META_TAG_VM_PREFERRED)
{
posix_spawnattr_t attr;
posix_spawn_file_actions_t fact;
int ret, pipes[2];
mach_port_t mp;
ret = pipe(pipes);
T_QUIET; T_ASSERT_POSIX_SUCCESS(ret, "pipe");
ret = fileport_makeport(pipes[1], &mp);
T_QUIET; T_ASSERT_POSIX_SUCCESS(ret, "fileport_makefd");
ret = posix_spawnattr_init(&attr);
T_QUIET; T_ASSERT_POSIX_SUCCESS(ret, "posix_spawnattr_init");
ret = posix_spawn_file_actions_init(&fact);
T_QUIET; T_ASSERT_POSIX_SUCCESS(ret, "posix_spawn_file_actions_init");
ret = posix_spawn_file_actions_add_fileportdup2_np(&fact, mp, STDOUT_FILENO);
T_ASSERT_POSIX_SUCCESS(ret, "posix_spawn_file_actions_add_fileportdup2_np");
char * const prog = "/bin/echo";
char * const argv_child[] = { prog, "1", NULL };
pid_t child_pid;
extern char **environ;
ret = posix_spawn(&child_pid, prog, &fact, &attr, argv_child, environ);
T_ASSERT_POSIX_SUCCESS(ret, "posix_spawn");
ret = posix_spawn_file_actions_destroy(&fact);
T_QUIET; T_ASSERT_POSIX_SUCCESS(ret, "posix_spawn_file_actions_destroy");
ret = posix_spawnattr_destroy(&attr);
T_QUIET; T_ASSERT_POSIX_SUCCESS(ret, "posix_spawnattr_destroy");
T_LOG("parent: spawned child with pid %d\n", child_pid);
int status = 0;
int waitpid_result = waitpid(child_pid, &status, 0);
T_ASSERT_POSIX_SUCCESS(waitpid_result, "waitpid");
T_ASSERT_EQ(waitpid_result, child_pid, "waitpid should return child we spawned");
T_ASSERT_EQ(WIFEXITED(status), 1, "child should have exited normally");
T_ASSERT_EQ(WEXITSTATUS(status), EX_OK, "child should have exited with success");
char buf[1];
ssize_t rc = read(pipes[0], buf, sizeof(buf));
T_ASSERT_POSIX_SUCCESS(rc, "read");
T_ASSERT_EQ(rc, 1l, "should have read one byte");
T_ASSERT_EQ(buf[0], '1', "should have read '1'");
}