+/* Code executed by the child process. argv[1] = "child". */
+static int
+child_main (int argc, char *argv[])
+{
+ char buffer[2] = { 's', 't' };
+ int fd;
+ int ret;
+
+ ASSERT (argc == 3);
+
+ /* Read one byte from fd 0, and write its value plus one to fd 1.
+ fd 2 should be closed iff the argument is 1. Check that no other file
+ descriptors leaked. */
+
+ ASSERT (read (STDIN_FILENO, buffer, 2) == 1);
+
+ buffer[0]++;
+ ASSERT (write (STDOUT_FILENO, buffer, 1) == 1);
+
+ errno = 0;
+ ret = dup2 (STDERR_FILENO, STDERR_FILENO);
+ switch (atoi (argv[2]))
+ {
+ case 0:
+ /* Expect fd 2 is open. */
+ ASSERT (ret == STDERR_FILENO);
+ break;
+ case 1:
+ /* Expect fd 2 is closed. */
+ ASSERT (ret == -1);
+ ASSERT (errno == EBADF);
+ break;
+ default:
+ ASSERT (false);
+ }
+
+ for (fd = 3; fd < 7; fd++)
+ {
+ errno = 0;
+ ASSERT (close (fd) == -1);
+ ASSERT (errno == EBADF);
+ }
+
+ return 0;
+}
+