+/*
+ * runpty.c - Run a process under a pseudo-tty
+ *
+ * This code is Copyright (c) 2017, by the authors of nmh. See the
+ * COPYRIGHT file in the root directory of the nmh distribution for
+ * complete copyright information.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <fcntl.h>
+#include <termios.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <sys/select.h>
+#include <time.h>
+#include <errno.h>
+
+#define COMMAND_TIMEOUT 30
+
+int
+main(int argc, char *argv[])
+{
+ int master, slave, cc, sendeof = 0, status;
+ time_t starttime;
+ const char *slavename;
+ pid_t child;
+ unsigned char readbuf[1024];
+ FILE *output;
+
+ if (argc < 3) {
+ fprintf(stderr, "Usage: %s output-filename command [arguments ...]\n",
+ argv[0]);
+ exit(1);
+ }
+
+ if ((master = posix_openpt(O_RDWR | O_NOCTTY)) < 0) {
+ fprintf(stderr, "Unable to open master pseudo-tty: %s\n",
+ strerror(errno));
+ exit(1);
+ }
+
+ if (grantpt(master) < 0) {
+ fprintf(stderr, "Unable to grant permissions to master pty: %s\n",
+ strerror(errno));
+ exit(1);
+ }
+
+ if (unlockpt(master) < 0) {
+ fprintf(stderr, "Unable to unlock master pty: %s\n", strerror(errno));
+ exit(1);
+ }
+
+ if (!(slavename = ptsname(master))) {
+ fprintf(stderr, "Unable to determine name of slave pty: %s\n",
+ strerror(errno));
+ exit(1);
+ }
+
+ if ((slave = open(slavename, O_RDWR | O_NOCTTY)) < 0) {
+ fprintf(stderr, "Unable to open slave pty \"%s\": %s\n", slavename,
+ strerror(errno));
+ exit(1);
+ }
+
+ child = fork();
+
+ /*
+ * Start the child process if we are in the child; close the master
+ * as we are supposed to only use the slave ptys here.
+ */
+
+ if (child == 0) {
+ close(master);
+ dup2(slave, STDIN_FILENO);
+ dup2(slave, STDOUT_FILENO);
+ dup2(slave, STDERR_FILENO);
+ close(slave);
+
+ execvp(argv[2], argv + 2);
+
+ fprintf(stderr, "execvp(%s) failed: %s\n", argv[2], strerror(errno));
+ } else if (child < 0) {
+ fprintf(stderr, "fork() failed: %s\n", strerror(errno));
+ exit(1);
+ }
+
+ close(slave);
+
+ if (!(output = fopen(argv[1], "w"))) {
+ fprintf(stderr, "Unable to open \"%s\" for output: %s\n", argv[1],
+ strerror(errno));
+ exit(1);
+ }
+
+ starttime = time(NULL);
+
+ for (;;) {
+ fd_set readfds;
+ struct timeval tv;
+
+ FD_ZERO(&readfds);
+
+ FD_SET(master, &readfds);
+
+ /*
+ * Okay, what's going on here?
+ *
+ * We want to send the EOF character (to simulate a "end of file",
+ * as if we redirected stdin to /dev/null). We can't just close
+ * master, because we won't be able to get any data back. So,
+ * after we get SOME data, set sendeof, and that will cause us to
+ * send the EOF character after the first select call. If we are
+ * doing sendeof, set the timeout to 1 second; otherwise, set the
+ * timeout to COMMAND_TIMEOUT seconds remaining.
+ */
+
+ if (sendeof) {
+ tv.tv_sec = 1;
+ } else {
+ tv.tv_sec = starttime + COMMAND_TIMEOUT - time(NULL);
+ if (tv.tv_sec < 0)
+ tv.tv_sec = 0;
+ }
+ tv.tv_usec = 0;
+
+ cc = select(master + 1, &readfds, NULL, NULL, &tv);
+
+ if (cc < 0) {
+ fprintf(stderr, "select() failed: %s\n", strerror(errno));
+ exit(1);
+ }
+
+ if (cc > 0 && FD_ISSET(master, &readfds)) {
+ cc = read(master, readbuf, sizeof(readbuf));
+
+ if (cc < 0) {
+ fprintf(stderr, "read() failed: %s\n", strerror(errno));
+ exit(1);
+ }
+
+ if (cc == 0)
+ break;
+
+ fwrite(readbuf, 1, cc, output);
+ }
+
+ if (cc == 0 && sendeof) {
+ struct termios rtty;
+
+ if (tcgetattr(master, &rtty) < 0) {
+ fprintf(stderr, "tcgetattr() failed: %s\n", strerror(errno));
+ exit(1);
+ }
+
+ if (rtty.c_lflag & ICANON)
+ write(master, &rtty.c_cc[VEOF], 1);
+ } else if (!sendeof)
+ sendeof = 1;
+
+ if (time(NULL) > starttime + COMMAND_TIMEOUT) {
+ fprintf(stderr, "Command execution timed out\n");
+ break;
+ }
+ }
+
+ close(master);
+ fclose(output);
+
+ waitpid(child, &status, 0);
+
+ exit(0);
+}
projects / nmh / commitdiff