Add broadcast

1 files changed, 117 insertions, 0 deletions

diff --git a/broadcast.c b/broadcast.c
new file mode 100644
index 0000000..e5957ae
--- /dev/null
+++ b/broadcast.c
@@ -0,0 +1,117 @@
+/* Copyright (c) 2018, Curtis McEnroe <programble@gmail.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <err.h>
+#include <poll.h>
+#include <pwd.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/ioctl.h>
+#include <sys/wait.h>
+#include <sysexits.h>
+#include <termios.h>
+#include <unistd.h>
+
+#if defined __FreeBSD__
+#include <libutil.h>
+#elif defined __linux__
+#include <pty.h>
+#else
+#include <util.h>
+#endif
+
+static struct termios saveTerm;
+static void restoreTerm(void) {
+    tcsetattr(STDERR_FILENO, TCSADRAIN, &saveTerm);
+}
+
+int main(int argc, char *argv[]) {
+    int error;
+
+    if (argc > 1) {
+        argv++;
+    } else {
+        uid_t uid = getuid();
+        struct passwd *user = getpwuid(uid);
+        if (!user) err(EX_OSFILE, "/etc/passwd");
+        argv[0] = user->pw_shell;
+    }
+
+    int input = STDIN_FILENO;
+    int local = STDERR_FILENO;
+    int remote = STDOUT_FILENO;
+
+    error = tcgetattr(local, &saveTerm);
+    if (error) err(EX_IOERR, "tcgetattr");
+    atexit(restoreTerm);
+
+    struct termios raw;
+    cfmakeraw(&raw);
+    error = tcsetattr(local, TCSADRAIN, &raw);
+    if (error) err(EX_IOERR, "tcsetattr");
+
+    struct winsize window;
+    error = ioctl(local, TIOCGWINSZ, &window);
+    if (error) err(EX_IOERR, "ioctl(%d, TIOCGWINSZ, ...)", local);
+
+    ssize_t size = write(remote, &window, sizeof(window));
+    if (size < 0) err(EX_IOERR, "write(%d)", remote);
+    if ((size_t)size < sizeof(window)) errx(EX_IOERR, "short write(%d)", remote);
+
+    int pty;
+    pid_t pid = forkpty(&pty, NULL, NULL, &window);
+    if (pid < 0) err(EX_OSERR, "forkpty");
+
+    if (!pid) {
+        execvp(*argv, argv);
+        err(EX_USAGE, "%s", *argv);
+    }
+
+    char buf[4096];
+    struct pollfd fds[2] = {
+        { .fd = input, .events = POLLIN },
+        { .fd = pty, .events = POLLIN },
+    };
+    while (0 < poll(fds, 2, -1)) {
+        if (fds[0].revents) {
+            ssize_t readSize = read(input, buf, sizeof(buf));
+            if (readSize < 0) err(EX_IOERR, "read(%d)", input);
+
+            ssize_t writeSize = write(pty, buf, readSize);
+            if (writeSize < 0) err(EX_IOERR, "write(%d)", pty);
+            if (writeSize < readSize) errx(EX_IOERR, "short write(%d)", pty);
+        }
+
+        if (fds[1].revents) {
+            ssize_t readSize = read(pty, buf, sizeof(buf));
+            if (readSize < 0) err(EX_IOERR, "read(%d)", pty);
+
+            ssize_t writeSize = write(local, buf, readSize);
+            if (writeSize < 0) err(EX_IOERR, "write(%d)", local);
+            if (writeSize < readSize) errx(EX_IOERR, "short write(%d)", local);
+
+            writeSize = write(remote, buf, readSize);
+            if (writeSize < 0) err(EX_IOERR, "write(%d)", remote);
+            if (writeSize < readSize) errx(EX_IOERR, "short write(%d)", remote);
+        }
+
+        int status;
+        pid_t dead = waitpid(pid, &status, WNOHANG);
+        if (dead < 0) err(EX_OSERR, "waitpid");
+        if (dead) return WIFEXITED(status) ? WEXITSTATUS(status) : EX_SOFTWARE;
+    }
+    err(EX_IOERR, "poll");
+}