#include <assert.h>
#include <pty.h>
#include <poll.h>
+#include <sys/stat.h>
#define LENGTH(x) (sizeof (x) / sizeof (*(x)))
static const char *progname;
-static volatile int signal_child_hit = 0;
+static volatile pid_t child;
-/* We use it to race-safely emulate ppoll(2) by poll(2). */
-static int pipefd[2];
-
-static void signal_child (int signo)
+static void signal_chld (int signo)
{
- int i;
-
- signal_child_hit = 1;
-
- assert (pipefd[1] != -1);
- i = close (pipefd[1]);
- assert (i == 0);
- pipefd[1] = -1;
}
-static volatile int signal_alarm_hit = 0;
+static volatile int signal_alrm_hit = 0;
-static void signal_alarm (int signo)
+static void signal_alrm (int signo)
{
- signal_alarm_hit = 1;
+ signal_alrm_hit = 1;
}
static char childptyname[LINE_MAX];
-static pid_t child;
static void print_child_error (const char *reason, char **argv)
{
fputc ('\n', stderr);
}
+static int read_out (int amaster)
+{
+ char buf[LINE_MAX];
+ ssize_t buf_got;
+
+ buf_got = read (amaster, buf, sizeof buf);
+ if (buf_got == 0)
+ return 0;
+ /* Weird but at least after POLLHUP we get EIO instead of just EOF. */
+ if (buf_got == -1 && errno == EIO)
+ return 0;
+ if (buf_got == -1 && errno == EAGAIN)
+ return 0;
+ if (buf_got < 0)
+ {
+ perror ("read (amaster)");
+ exit (EXIT_FAILURE);
+ }
+ if (write (STDOUT_FILENO, buf, buf_got) != buf_got)
+ {
+ perror ("write(2)");
+ exit (EXIT_FAILURE);
+ }
+ return 1;
+}
+
+/* kill (child, 0) ==0 sometimes even when CHILD's state is already Z. */
+
+static int child_exited (void)
+{
+ char buf[200];
+ int fd, i, retval;
+ ssize_t got;
+ char *state;
+
+ snprintf (buf, sizeof (buf), "/proc/%ld/stat", (long) child);
+ fd = open (buf, O_RDONLY);
+ if (fd == -1)
+ {
+ perror ("open (/proc/CHILD/stat)");
+ exit (EXIT_FAILURE);
+ }
+ got = read (fd, buf, sizeof(buf));
+ if (got <= 0)
+ {
+ perror ("read (/proc/CHILD/stat)");
+ exit (EXIT_FAILURE);
+ }
+ if (close (fd) != 0)
+ {
+ perror ("close (/proc/CHILD/stat)");
+ exit (EXIT_FAILURE);
+ }
+ i = sscanf (buf, "%*d%*s%ms", &state);
+ if (i != 1)
+ {
+ perror ("sscanf (/proc/CHILD/stat)");
+ exit (EXIT_FAILURE);
+ }
+ retval = strcmp (state, "Z") == 0;
+ free (state);
+ return retval;
+}
+
static int spawn (char **argv, int timeout)
{
pid_t child_got;
int status, amaster, i, rc;
struct sigaction act;
+ sigset_t set;
struct termios termios;
unsigned alarm_orig;
- i = pipe (pipefd);
- assert (i == 0);
-
- /* We do not use signal(2) to be sure we have SA_RESTART set. */
+ /* We do not use signal(2) to be sure we do not have SA_RESTART. */
memset (&act, 0, sizeof (act));
- act.sa_handler = signal_child;
+ act.sa_handler = signal_chld;
i = sigemptyset (&act.sa_mask);
assert (i == 0);
- act.sa_flags = SA_RESTART;
+ act.sa_flags = 0; /* !SA_RESTART */
i = sigaction (SIGCHLD, &act, NULL);
assert (i == 0);
+ i = sigemptyset (&set);
+ assert (i == 0);
+ i = sigaddset (&set, SIGCHLD);
+ assert (i == 0);
+ i = sigprocmask (SIG_SETMASK, &set, NULL);
+ assert (i == 0);
+
/* With TERMP passed as NULL we get "\n" -> "\r\n". */
termios.c_iflag = IGNBRK | IGNPAR;
termios.c_oflag = 0;
perror ("forkpty(3)");
exit (EXIT_FAILURE);
case 0:
- i = close (pipefd[0]);
- assert (i == 0);
- i = close (pipefd[1]);
- assert (i == 0);
-
/* Do not replace STDIN as inferiors query its termios. */
#if 0
i = close (STDIN_FILENO);
assert (i == STDIN_FILENO);
#endif
+ i = sigemptyset (&set);
+ assert (i == 0);
+ i = sigprocmask (SIG_SETMASK, &set, NULL);
+ assert (i == 0);
+
/* Do not setpgrp(2) in the parent process as the process-group
is shared for the whole sh(1) pipeline we could be a part
of. The process-group is set according to PID of the first
exit (EXIT_FAILURE);
}
- /* We do not use signal(2) to be sure we have SA_RESTART set. */
- act.sa_handler = signal_alarm;
- act.sa_flags &= ~SA_RESTART;
+ /* We do not use signal(2) to be sure we do not have SA_RESTART. */
+ act.sa_handler = signal_alrm;
i = sigaction (SIGALRM, &act, NULL);
assert (i == 0);
alarm_orig = alarm (timeout);
assert (alarm_orig == 0);
- while (!signal_alarm_hit)
+ i = sigemptyset (&set);
+ assert (i == 0);
+
+ while (!signal_alrm_hit)
{
- struct pollfd pollfd[2];
- char buf[LINE_MAX];
- ssize_t buf_got;
+ struct pollfd pollfd;
- pollfd[0].fd = amaster;
- pollfd[0].events = POLLIN;
- pollfd[1].fd = pipefd[0];
- pollfd[1].events = POLLIN;
- i = poll (pollfd, LENGTH (pollfd), -1);
+ pollfd.fd = amaster;
+ pollfd.events = POLLIN;
+ i = ppoll (&pollfd, 1, NULL, &set);
if (i == -1 && errno == EINTR)
- {
- /* Weird but SA_RESTART sometimes does not work. */
+ {
+ if (child_exited ())
+ break;
+ /* Non-CHILD child may have exited. */
continue;
}
- assert (i >= 1);
+ assert (i == 1);
/* Data available? Process it first. */
- if (pollfd[0].revents & POLLIN)
+ if (pollfd.revents & POLLIN)
{
- buf_got = read (amaster, buf, sizeof buf);
- if (buf_got <= 0)
+ if (!read_out (amaster))
{
- perror ("read (amaster)");
- exit (EXIT_FAILURE);
- }
- if (write (STDOUT_FILENO, buf, buf_got) != buf_got)
- {
- perror ("write(2)");
+ fprintf (stderr, "%s: Unexpected EOF\n", progname);
exit (EXIT_FAILURE);
}
}
- if (pollfd[0].revents & POLLHUP)
+ if (pollfd.revents & POLLHUP)
break;
- if ((pollfd[0].revents &= ~POLLIN) != 0)
+ if ((pollfd.revents &= ~POLLIN) != 0)
{
fprintf (stderr, "%s: ppoll(2): revents 0x%x\n", progname,
- (unsigned) pollfd[0].revents);
+ (unsigned) pollfd.revents);
exit (EXIT_FAILURE);
}
/* Child exited? */
- if (pollfd[1].revents & POLLHUP)
+ if (child_exited ())
break;
- assert (pollfd[1].revents == 0);
}
- if (signal_alarm_hit)
+ if (signal_alrm_hit)
{
i = kill (child, SIGKILL);
assert (i == 0);
fprintf (stderr, "waitpid (%d) = %d: %m\n", (int) child, (int) child_got);
exit (EXIT_FAILURE);
}
- if (signal_alarm_hit)
+ if (signal_alrm_hit)
{
char *buf;
exit (EXIT_FAILURE);
}
- assert (signal_child_hit != 0);
-
- assert (pipefd[1] == -1);
- i = close (pipefd[0]);
+ /* Not used in fact. */
+ i = sigprocmask (SIG_SETMASK, &set, NULL);
assert (i == 0);
+ /* Do not unset O_NONBLOCK as a stale child (the whole purpose of this
+ program) having open its output pty would block us in read_out. */
+#if 0
+ i = fcntl (amaster, F_SETFL, O_RDONLY /* !O_NONBLOCK */);
+ if (i != 0)
+ {
+ perror ("fcntl (amaster, F_SETFL, O_RDONLY /* !O_NONBLOCK */)");
+ exit (EXIT_FAILURE);
+ }
+#endif
+
+ while (read_out (amaster));
+
/* Do not close the master FD as the child would have `/dev/pts/23 (deleted)'
entries which are not expected (and expecting ` (deleted)' would be
a race. */