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// Copyright © Tavian Barnes <tavianator@tavianator.com>
// SPDX-License-Identifier: 0BSD
/**
* Execute a command in a pseudo-terminal.
*
* $ ptyx [-w WIDTH] [-h HEIGHT] [--] COMMAND [ARGS...]
*/
#include "bfs.h"
#include "bfstd.h"
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/wait.h>
#include <termios.h>
#include <unistd.h>
#if __has_include(<stropts.h>)
# include <stropts.h>
#endif
#if __sun
/**
* Push a STREAMS module, if it's not already there.
*
* See https://www.illumos.org/issues/9042.
*/
static int i_push(int fd, const char *name) {
int ret = ioctl(fd, I_FIND, name);
if (ret < 0) {
return ret;
} else if (ret == 0) {
return ioctl(fd, I_PUSH, name);
} else {
return 0;
}
}
#endif
int main(int argc, char *argv[]) {
const char *cmd = argc > 0 ? argv[0] : "ptyx";
/** Report an error message and exit. */
#define die(...) die_(__VA_ARGS__, )
#define die_(format, ...) \
do { \
fprintf(stderr, "%s: " format "%s", cmd, __VA_ARGS__ "\n"); \
exit(EXIT_FAILURE); \
} while (0)
/** Report an error code and exit. */
#define edie(...) edie_(__VA_ARGS__, )
#define edie_(format, ...) \
do { \
fprintf(stderr, "%s: " format ": %s\n", cmd, __VA_ARGS__ errstr()); \
exit(EXIT_FAILURE); \
} while (0)
unsigned short width = 0;
unsigned short height = 0;
// Parse the command line
int c;
while (c = getopt(argc, argv, "+:w:h:"), c != -1) {
switch (c) {
case 'w':
if (xstrtous(optarg, NULL, 10, &width) != 0) {
edie("Bad width '%s'", optarg);
}
break;
case 'h':
if (xstrtous(optarg, NULL, 10, &height) != 0) {
edie("Bad height '%s'", optarg);
}
break;
case ':':
die("Missing argument to -%c", optopt);
case '?':
die("Unrecognized option -%c", optopt);
}
}
if (optind >= argc) {
die("Missing command");
}
char **args = argv + optind;
// Create a new pty, and set it up
int ptm = posix_openpt(O_RDWR | O_NOCTTY);
if (ptm < 0) {
edie("posix_openpt()");
}
if (grantpt(ptm) != 0) {
edie("grantpt()");
}
if (unlockpt(ptm) != 0) {
edie("unlockpt()");
}
// Get the subsidiary device path
char *name = ptsname(ptm);
if (!name) {
edie("ptsname()");
}
// Open the subsidiary device
int pts = open(name, O_RDWR | O_NOCTTY);
if (pts < 0) {
edie("%s", name);
}
#if __sun
// On Solaris/illumos, a pty doesn't behave like a terminal until we
// push some STREAMS modules (see ptm(4D), ptem(4M), ldterm(4M)).
if (i_push(pts, "ptem") != 0) {
die("ioctl(I_PUSH, ptem)");
}
if (i_push(pts, "ldterm") != 0) {
die("ioctl(I_PUSH, ldterm)");
}
#endif
// A new pty starts at 0x0, which is not very useful. Instead, grab the
// default size from the current controlling terminal, if possible.
if (!width || !height) {
int tty = open_cterm(O_RDONLY | O_CLOEXEC);
if (tty >= 0) {
struct winsize ws;
if (xtcgetwinsize(tty, &ws) != 0) {
edie("tcgetwinsize()");
}
if (!width) {
width = ws.ws_col;
}
if (!height) {
height = ws.ws_row;
}
xclose(tty);
}
}
if (!width) {
width = 80;
}
if (!height) {
height = 24;
}
// Update the pty size
struct winsize ws;
if (xtcgetwinsize(pts, &ws) != 0) {
edie("tcgetwinsize()");
}
ws.ws_col = width;
ws.ws_row = height;
if (xtcsetwinsize(pts, &ws) != 0) {
edie("tcsetwinsize()");
}
// Set custom terminal attributes
struct termios attrs;
if (tcgetattr(pts, &attrs) != 0) {
edie("tcgetattr()");
}
attrs.c_oflag &= ~OPOST; // Don't convert \n to \r\n
if (tcsetattr(pts, TCSANOW, &attrs) != 0) {
edie("tcsetattr()");
}
pid_t pid = fork();
if (pid < 0) {
edie("fork()");
} else if (pid == 0) {
// Child
close(ptm);
// Make ourselves a session leader so we can have our own
// controlling terminal
if (setsid() < 0) {
edie("setsid()");
}
#ifdef TIOCSCTTY
// Set the pty as the controlling terminal
if (ioctl(pts, TIOCSCTTY, 0) != 0) {
edie("ioctl(TIOCSCTTY)");
}
#endif
// Redirect std{in,out,err} to the pty
if (dup2(pts, STDIN_FILENO) < 0
|| dup2(pts, STDOUT_FILENO) < 0
|| dup2(pts, STDERR_FILENO) < 0) {
edie("dup2()");
}
if (pts > STDERR_FILENO) {
xclose(pts);
}
// Run the requested command
execvp(args[0], args);
edie("execvp(): %s", args[0]);
}
// Parent
xclose(pts);
// Read output from the pty and copy it to stdout
char buf[1024];
while (true) {
ssize_t len = read(ptm, buf, sizeof(buf));
if (len > 0) {
if (xwrite(STDOUT_FILENO, buf, len) < 0) {
edie("write()");
}
} else if (len == 0) {
break;
} else if (errno == EINTR) {
continue;
} else if (errno == EIO) {
// Linux reports EIO rather than EOF when pts is closed
break;
} else {
die("read()");
}
}
xclose(ptm);
int wstatus;
if (xwaitpid(pid, &wstatus, 0) < 0) {
edie("waitpid()");
}
if (WIFEXITED(wstatus)) {
return WEXITSTATUS(wstatus);
} else if (WIFSIGNALED(wstatus)) {
int sig = WTERMSIG(wstatus);
fprintf(stderr, "%s: %s: %s\n", cmd, args[0], strsignal(sig));
return 128 + sig;
} else {
return 128;
}
}
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