355 lines
9.4 KiB
C
Executable file
355 lines
9.4 KiB
C
Executable file
#define _GNU_SOURCE 1
|
|
#include <errno.h>
|
|
#include <fcntl.h>
|
|
#include <signal.h>
|
|
#include <stdarg.h>
|
|
#include <stdbool.h>
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <string.h>
|
|
#include <stropts.h>
|
|
#include <sys/ioctl.h>
|
|
#include <sys/stat.h>
|
|
#include <sys/time.h>
|
|
#include <sys/types.h>
|
|
#include <sys/wait.h>
|
|
#include <termios.h>
|
|
#include <unistd.h>
|
|
|
|
static void
|
|
fail_io (const char *msg, ...)
|
|
__attribute__ ((noreturn))
|
|
__attribute__ ((format (printf, 1, 2)));
|
|
|
|
/* Prints MSG, formatting as with printf(),
|
|
plus an error message based on errno,
|
|
and exits. */
|
|
static void
|
|
fail_io (const char *msg, ...)
|
|
{
|
|
va_list args;
|
|
|
|
va_start (args, msg);
|
|
vfprintf (stderr, msg, args);
|
|
va_end (args);
|
|
|
|
if (errno != 0)
|
|
fprintf (stderr, ": %s", strerror (errno));
|
|
putc ('\n', stderr);
|
|
exit (EXIT_FAILURE);
|
|
}
|
|
|
|
/* If FD is a terminal, configures it for noncanonical input mode
|
|
with VMIN and VTIME set as indicated.
|
|
If FD is not a terminal, has no effect. */
|
|
static void
|
|
make_noncanon (int fd, int vmin, int vtime)
|
|
{
|
|
if (isatty (fd))
|
|
{
|
|
struct termios termios;
|
|
if (tcgetattr (fd, &termios) < 0)
|
|
fail_io ("tcgetattr");
|
|
termios.c_lflag &= ~(ICANON | ECHO);
|
|
termios.c_cc[VMIN] = vmin;
|
|
termios.c_cc[VTIME] = vtime;
|
|
if (tcsetattr (fd, TCSANOW, &termios) < 0)
|
|
fail_io ("tcsetattr");
|
|
}
|
|
}
|
|
|
|
/* Make FD non-blocking if NONBLOCKING is true,
|
|
or blocking if NONBLOCKING is false. */
|
|
static void
|
|
make_nonblocking (int fd, bool nonblocking)
|
|
{
|
|
int flags = fcntl (fd, F_GETFL);
|
|
if (flags < 0)
|
|
fail_io ("fcntl");
|
|
if (nonblocking)
|
|
flags |= O_NONBLOCK;
|
|
else
|
|
flags &= ~O_NONBLOCK;
|
|
if (fcntl (fd, F_SETFL, flags) < 0)
|
|
fail_io ("fcntl");
|
|
}
|
|
|
|
/* Handle a read or write on *FD, which is the pty if FD_IS_PTY
|
|
is true, that returned end-of-file or error indication RETVAL.
|
|
The system call is named CALL, for use in error messages.
|
|
Returns true if processing may continue, false if we're all
|
|
done. */
|
|
static bool
|
|
handle_error (ssize_t retval, int *fd, bool fd_is_pty, const char *call)
|
|
{
|
|
if (fd_is_pty)
|
|
{
|
|
if (retval < 0)
|
|
{
|
|
if (errno == EIO)
|
|
{
|
|
/* Slave side of pty has been closed. */
|
|
return false;
|
|
}
|
|
else
|
|
fail_io (call);
|
|
}
|
|
else
|
|
return true;
|
|
}
|
|
else
|
|
{
|
|
if (retval == 0)
|
|
{
|
|
close (*fd);
|
|
*fd = -1;
|
|
return true;
|
|
}
|
|
else
|
|
fail_io (call);
|
|
}
|
|
}
|
|
|
|
/* Copies data from stdin to PTY and from PTY to stdout until no
|
|
more data can be read or written. */
|
|
static void
|
|
relay (int pty, int dead_child_fd)
|
|
{
|
|
struct pipe
|
|
{
|
|
int in, out;
|
|
char buf[BUFSIZ];
|
|
size_t size, ofs;
|
|
bool active;
|
|
};
|
|
struct pipe pipes[2];
|
|
|
|
/* Make PTY, stdin, and stdout non-blocking. */
|
|
make_nonblocking (pty, true);
|
|
make_nonblocking (STDIN_FILENO, true);
|
|
make_nonblocking (STDOUT_FILENO, true);
|
|
|
|
/* Configure noncanonical mode on PTY and stdin to avoid
|
|
waiting for end-of-line. We want to minimize context
|
|
switching on PTY (for efficiency) and minimize latency on
|
|
stdin to avoid a laggy user experience. */
|
|
make_noncanon (pty, 16, 1);
|
|
make_noncanon (STDIN_FILENO, 1, 0);
|
|
|
|
memset (pipes, 0, sizeof pipes);
|
|
pipes[0].in = STDIN_FILENO;
|
|
pipes[0].out = pty;
|
|
pipes[1].in = pty;
|
|
pipes[1].out = STDOUT_FILENO;
|
|
|
|
while (pipes[0].in != -1 || pipes[1].in != -1)
|
|
{
|
|
fd_set read_fds, write_fds;
|
|
int retval;
|
|
int i;
|
|
|
|
FD_ZERO (&read_fds);
|
|
FD_ZERO (&write_fds);
|
|
for (i = 0; i < 2; i++)
|
|
{
|
|
struct pipe *p = &pipes[i];
|
|
|
|
/* Don't do anything with the stdin->pty pipe until we
|
|
have some data for the pty->stdout pipe. If we get
|
|
too eager, Bochs will throw away our input. */
|
|
if (i == 0 && !pipes[1].active)
|
|
continue;
|
|
|
|
if (p->in != -1 && p->size + p->ofs < sizeof p->buf)
|
|
FD_SET (p->in, &read_fds);
|
|
if (p->out != -1 && p->size > 0)
|
|
FD_SET (p->out, &write_fds);
|
|
}
|
|
FD_SET (dead_child_fd, &read_fds);
|
|
|
|
do
|
|
{
|
|
retval = select (FD_SETSIZE, &read_fds, &write_fds, NULL, NULL);
|
|
}
|
|
while (retval < 0 && errno == EINTR);
|
|
if (retval < 0)
|
|
fail_io ("select");
|
|
|
|
if (FD_ISSET (dead_child_fd, &read_fds))
|
|
{
|
|
/* Child died. Do final relaying. */
|
|
struct pipe *p = &pipes[1];
|
|
if (p->out == -1)
|
|
return;
|
|
make_nonblocking (STDOUT_FILENO, false);
|
|
for (;;)
|
|
{
|
|
ssize_t n;
|
|
|
|
/* Write buffer. */
|
|
while (p->size > 0)
|
|
{
|
|
n = write (p->out, p->buf + p->ofs, p->size);
|
|
if (n < 0)
|
|
fail_io ("write");
|
|
else if (n == 0)
|
|
fail_io ("zero-length write");
|
|
p->ofs += n;
|
|
p->size -= n;
|
|
}
|
|
p->ofs = 0;
|
|
|
|
p->size = n = read (p->in, p->buf, sizeof p->buf);
|
|
if (n <= 0)
|
|
return;
|
|
}
|
|
}
|
|
|
|
for (i = 0; i < 2; i++)
|
|
{
|
|
struct pipe *p = &pipes[i];
|
|
if (p->in != -1 && FD_ISSET (p->in, &read_fds))
|
|
{
|
|
ssize_t n = read (p->in, p->buf + p->ofs + p->size,
|
|
sizeof p->buf - p->ofs - p->size);
|
|
if (n > 0)
|
|
{
|
|
p->active = true;
|
|
p->size += n;
|
|
if (p->size == BUFSIZ && p->ofs != 0)
|
|
{
|
|
memmove (p->buf, p->buf + p->ofs, p->size);
|
|
p->ofs = 0;
|
|
}
|
|
}
|
|
else if (!handle_error (n, &p->in, p->in == pty, "read"))
|
|
return;
|
|
}
|
|
if (p->out != -1 && FD_ISSET (p->out, &write_fds))
|
|
{
|
|
ssize_t n = write (p->out, p->buf + p->ofs, p->size);
|
|
if (n > 0)
|
|
{
|
|
p->ofs += n;
|
|
p->size -= n;
|
|
if (p->size == 0)
|
|
p->ofs = 0;
|
|
}
|
|
else if (!handle_error (n, &p->out, p->out == pty, "write"))
|
|
return;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
static int dead_child_fd;
|
|
|
|
static void
|
|
sigchld_handler (int signo __attribute__ ((unused)))
|
|
{
|
|
if (write (dead_child_fd, "", 1) < 0)
|
|
_exit (1);
|
|
}
|
|
|
|
int
|
|
main (int argc __attribute__ ((unused)), char *argv[])
|
|
{
|
|
int master, slave;
|
|
char *name;
|
|
pid_t pid;
|
|
struct sigaction sa;
|
|
int pipe_fds[2];
|
|
struct itimerval zero_itimerval, old_itimerval;
|
|
|
|
if (argc < 2)
|
|
{
|
|
fprintf (stderr,
|
|
"usage: squish-pty COMMAND [ARG]...\n"
|
|
"Squishes both stdin and stdout into a single pseudoterminal,\n"
|
|
"which is passed as stdout to run the specified COMMAND.\n");
|
|
return EXIT_FAILURE;
|
|
}
|
|
|
|
/* Open master side of pty and get ready to open slave. */
|
|
master = open ("/dev/ptmx", O_RDWR | O_NOCTTY);
|
|
if (master < 0)
|
|
fail_io ("open \"/dev/ptmx\"");
|
|
if (grantpt (master) < 0)
|
|
fail_io ("grantpt");
|
|
if (unlockpt (master) < 0)
|
|
fail_io ("unlockpt");
|
|
|
|
/* Open slave side of pty. */
|
|
name = ptsname (master);
|
|
if (name == NULL)
|
|
fail_io ("ptsname");
|
|
slave = open (name, O_RDWR);
|
|
if (slave < 0)
|
|
fail_io ("open \"%s\"", name);
|
|
|
|
/* System V implementations need STREAMS configuration for the
|
|
slave. */
|
|
if (isastream (slave))
|
|
{
|
|
if (ioctl (slave, I_PUSH, "ptem") < 0
|
|
|| ioctl (slave, I_PUSH, "ldterm") < 0)
|
|
fail_io ("ioctl");
|
|
}
|
|
|
|
/* Arrange to get notified when a child dies, by writing a byte
|
|
to a pipe fd. We really want to use pselect() and
|
|
sigprocmask(), but Solaris 2.7 doesn't have it. */
|
|
if (pipe (pipe_fds) < 0)
|
|
fail_io ("pipe");
|
|
dead_child_fd = pipe_fds[1];
|
|
|
|
memset (&sa, 0, sizeof sa);
|
|
sa.sa_handler = sigchld_handler;
|
|
sigemptyset (&sa.sa_mask);
|
|
sa.sa_flags = SA_RESTART;
|
|
if (sigaction (SIGCHLD, &sa, NULL) < 0)
|
|
fail_io ("sigaction");
|
|
|
|
/* Save the virtual interval timer, which might have been set
|
|
by the process that ran us. It really should be applied to
|
|
our child process. */
|
|
memset (&zero_itimerval, 0, sizeof zero_itimerval);
|
|
if (setitimer (ITIMER_VIRTUAL, &zero_itimerval, &old_itimerval) < 0)
|
|
fail_io ("setitimer");
|
|
|
|
pid = fork ();
|
|
if (pid < 0)
|
|
fail_io ("fork");
|
|
else if (pid != 0)
|
|
{
|
|
/* Running in parent process. */
|
|
int status;
|
|
close (slave);
|
|
relay (master, pipe_fds[0]);
|
|
|
|
/* If the subprocess has died, die in the same fashion.
|
|
In particular, dying from SIGVTALRM tells the pintos
|
|
script that we ran out of CPU time. */
|
|
if (waitpid (pid, &status, WNOHANG) > 0)
|
|
{
|
|
if (WIFEXITED (status))
|
|
return WEXITSTATUS (status);
|
|
else if (WIFSIGNALED (status))
|
|
raise (WTERMSIG (status));
|
|
}
|
|
return 0;
|
|
}
|
|
else
|
|
{
|
|
/* Running in child process. */
|
|
if (setitimer (ITIMER_VIRTUAL, &old_itimerval, NULL) < 0)
|
|
fail_io ("setitimer");
|
|
if (dup2 (slave, STDOUT_FILENO) < 0)
|
|
fail_io ("dup2");
|
|
if (close (pipe_fds[0]) < 0 || close (pipe_fds[1]) < 0
|
|
|| close (slave) < 0 || close (master) < 0)
|
|
fail_io ("close");
|
|
execvp (argv[1], argv + 1);
|
|
fail_io ("exec");
|
|
}
|
|
}
|