diplodocus.org Git - nmh/blob - test/runpty.c

   1 /*
   2  * runpty.c - Run a process under a pseudo-tty
   3  *
   4  * This code is Copyright (c) 2017, by the authors of nmh.  See the
   5  * COPYRIGHT file in the root directory of the nmh distribution for
   6  * complete copyright information.
   7  */
   8
   9 #include <stdio.h>
  10 #include <stdlib.h>
  11 #include <string.h>
  12 #include <stdarg.h>
  13 #include <fcntl.h>
  14 #include <termios.h>
  15 #include <unistd.h>
  16 #include <sys/types.h>
  17 #include <sys/wait.h>
  18 #include <sys/select.h>
  19 #include <time.h>
  20 #include <errno.h>
  21
  22 #define COMMAND_TIMEOUT 30
  23
  24 static void die(const char *fmt, ...);
  25
  26 int
  27 main(int argc, char *argv[])
  28 {
  29     int master_in, master_out, slave, cc, status;
  30     time_t starttime, now;
  31     const char *slavename;
  32     pid_t child;
  33     unsigned char readbuf[1024];
  34     FILE *output;
  35
  36     if (argc < 3) {
  37         die("%s: too few arguments\n"
  38             "usage: %s output-filename command [arguments...]\n",
  39             *argv, *argv);
  40     }
  41
  42     if ((master_in = posix_openpt(O_RDWR | O_NOCTTY)) < 0) {
  43         die("Unable to open master pseudo-tty: %s\n", strerror(errno));
  44     }
  45
  46     if ((master_out = posix_openpt(O_RDWR | O_NOCTTY)) < 0) {
  47         die("Unable to open master pseudo-tty: %s\n", strerror(errno));
  48     }
  49
  50     if (grantpt(master_in) < 0) {
  51         die("Unable to grant permissions to master pty: %s\n",
  52             strerror(errno));
  53     }
  54
  55     if (grantpt(master_out) < 0) {
  56         die("Unable to grant permissions to master pty: %s\n",
  57             strerror(errno));
  58     }
  59
  60     if (unlockpt(master_in) < 0) {
  61         die("Unable to unlock master pty: %s\n", strerror(errno));
  62     }
  63
  64     if (unlockpt(master_out) < 0) {
  65         die("Unable to unlock master pty: %s\n", strerror(errno));
  66     }
  67
  68     child = fork();
  69
  70     /*
  71      * Start the child process if we are in the child; open the two
  72      * slave pseudo-ttys and close the masters after we are done with them.
  73      */
  74
  75     if (child == 0) {
  76         if (!(slavename = ptsname(master_in))) {
  77             die("Unable to determine name of slave pty: %s\n",
  78                 strerror(errno));
  79         }
  80
  81         if ((slave = open(slavename, O_RDWR)) < 0) {
  82             die("Unable to open slave pty \"%s\": %s\n", slavename,
  83                 strerror(errno));
  84         }
  85
  86         dup2(slave, STDIN_FILENO);
  87         close(slave);
  88         close(master_in);
  89
  90         if (!(slavename = ptsname(master_out))) {
  91             die("Unable to determine name of slave pty: %s\n",
  92                 strerror(errno));
  93         }
  94
  95         if ((slave = open(slavename, O_RDWR | O_NOCTTY)) < 0) {
  96             die("Unable to open slave pty \"%s\": %s\n", slavename,
  97                 strerror(errno));
  98         }
  99
 100         dup2(slave, STDOUT_FILENO);
 101         dup2(slave, STDERR_FILENO);
 102         close(slave);
 103         close(master_out);
 104
 105         execvp(argv[2], argv + 2);
 106
 107         die("execvp(%s) failed: %s\n", argv[2], strerror(errno));
 108
 109     } else if (child < 0) {
 110         die("fork() failed: %s\n", strerror(errno));
 111     }
 112
 113     if (!(output = fopen(argv[1], "w"))) {
 114         die("Unable to open \"%s\" for output: %s\n", argv[1],
 115             strerror(errno));
 116     }
 117
 118     starttime = time(NULL);
 119
 120     for (;;) {
 121         fd_set readfds;
 122         struct timeval tv;
 123
 124         FD_ZERO(&readfds);
 125
 126         FD_SET(master_out, &readfds);
 127
 128         /*
 129          * After we get our first bit of data, close the master pty
 130          * connected to standard input on our slave; that will generate
 131          * an EOF.
 132          */
 133
 134         tv.tv_sec = starttime + COMMAND_TIMEOUT - time(NULL);
 135         if (tv.tv_sec < 0)
 136             tv.tv_sec = 0;
 137         tv.tv_usec = 0;
 138
 139         cc = select(master_out + 1, &readfds, NULL, NULL, &tv);
 140
 141         if (cc < 0) {
 142             die("select() failed: %s\n", strerror(errno));
 143         }
 144
 145         if (cc > 0 && FD_ISSET(master_out, &readfds)) {
 146             cc = read(master_out, readbuf, sizeof(readbuf));
 147
 148             if (cc <= 0)
 149                 break;
 150
 151             fwrite(readbuf, 1, cc, output);
 152
 153             if (master_in != -1) {
 154                 close(master_in);
 155                 master_in = -1;
 156             }
 157         }
 158
 159         now = time(NULL);
 160         if (now >= starttime + COMMAND_TIMEOUT) {
 161             fprintf(stderr, "Command execution timed out: %ld to %ld: %d\n",
 162                 starttime, now, cc);
 163             break;
 164         }
 165     }
 166
 167     if (master_in != -1)
 168         close(master_in);
 169     close(master_out);
 170     fclose(output);
 171
 172     waitpid(child, &status, 0);
 173
 174     exit(0);
 175 }
 176
 177 static void
 178 die(const char *fmt, ...)
 179 {
 180     va_list args;
 181
 182     va_start(args, fmt);
 183     vfprintf(stderr, fmt, args);
 184     va_end(args);
 185
 186     exit(1);
 187 }