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

   1 /* runpty.c - Run a process under a pseudo-tty
   2  *
   3  * This code is Copyright (c) 2017, by the authors of nmh.  See the
   4  * COPYRIGHT file in the root directory of the nmh distribution for
   5  * complete copyright information.
   6  */
   7
   8 #include <stdio.h>
   9 #include <stdlib.h>
  10 #include <string.h>
  11 #include <stdarg.h>
  12 #include <fcntl.h>
  13 #include <termios.h>
  14 #include <unistd.h>
  15 #include <sys/types.h>
  16 #include <sys/wait.h>
  17 #include <sys/select.h>
  18 #include <time.h>
  19 #include <errno.h>
  20
  21 #define COMMAND_TIMEOUT 30
  22
  23 static void run_command(char *argv[], int master_in, int master_out);
  24 static int open_master_pty(const char *desc);
  25 static void die(const char *fmt, ...);
  26
  27 int
  28 main(int argc, char *argv[])
  29 {
  30     int master_in, master_out, cc, status;
  31     time_t starttime, now;
  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     master_in = open_master_pty("input");
  43     master_out = open_master_pty("output");
  44
  45     if ((child = fork()) == -1) {
  46         die("fork() failed: %s\n", strerror(errno));
  47     }
  48     if (child == 0) {
  49         run_command(argv + 2, master_in, master_out); /* Does not return. */
  50     }
  51
  52     if (!(output = fopen(argv[1], "w"))) {
  53         die("Unable to open \"%s\" for output: %s\n", argv[1],
  54             strerror(errno));
  55     }
  56
  57     starttime = time(NULL);
  58
  59     for (;;) {
  60         fd_set readfds;
  61         struct timeval tv;
  62
  63         FD_ZERO(&readfds);
  64
  65         FD_SET(master_out, &readfds);
  66
  67         /*
  68          * After we get our first bit of data, close the master pty
  69          * connected to standard input on our slave; that will generate
  70          * an EOF.
  71          */
  72
  73         tv.tv_sec = starttime + COMMAND_TIMEOUT - time(NULL);
  74         if (tv.tv_sec < 0)
  75             tv.tv_sec = 0;
  76         tv.tv_usec = 0;
  77
  78         cc = select(master_out + 1, &readfds, NULL, NULL, &tv);
  79
  80         if (cc < 0) {
  81             die("select() failed: %s\n", strerror(errno));
  82         }
  83
  84         if (cc > 0 && FD_ISSET(master_out, &readfds)) {
  85             cc = read(master_out, readbuf, sizeof(readbuf));
  86
  87             if (cc <= 0)
  88                 break;
  89
  90             fwrite(readbuf, 1, cc, output);
  91
  92             if (master_in != -1) {
  93                 close(master_in);
  94                 master_in = -1;
  95             }
  96         }
  97
  98         now = time(NULL);
  99         if (now >= starttime + COMMAND_TIMEOUT) {
 100             fprintf(stderr, "Command execution timed out: %ld to %ld: %d\n",
 101                 starttime, now, cc);
 102             break;
 103         }
 104     }
 105
 106     if (master_in != -1)
 107         close(master_in);
 108     close(master_out);
 109     fclose(output);
 110
 111     waitpid(child, &status, 0);
 112
 113     exit(0);
 114 }
 115
 116 static void
 117 run_command(char *argv[], int master_in, int master_out)
 118 {
 119     const char *slavename;
 120     int slave;
 121
 122     /* Open the two slave pseudo-ttys and close the masters after we are
 123      * done with them. */
 124
 125     if (!(slavename = ptsname(master_in))) {
 126         die("Unable to determine name of slave pty: %s\n",
 127             strerror(errno));
 128     }
 129
 130     if ((slave = open(slavename, O_RDWR)) == -1) {
 131         die("Unable to open slave pty \"%s\": %s\n", slavename,
 132             strerror(errno));
 133     }
 134
 135     dup2(slave, STDIN_FILENO);
 136     close(slave);
 137     close(master_in);
 138
 139     if (!(slavename = ptsname(master_out))) {
 140         die("Unable to determine name of slave pty: %s\n",
 141             strerror(errno));
 142     }
 143
 144     if ((slave = open(slavename, O_RDWR | O_NOCTTY)) < 0) {
 145         die("Unable to open slave pty \"%s\": %s\n", slavename,
 146             strerror(errno));
 147     }
 148
 149     dup2(slave, STDOUT_FILENO);
 150     dup2(slave, STDERR_FILENO);
 151     close(slave);
 152     close(master_out);
 153
 154     execvp(*argv, argv);
 155
 156     die("execvp(%s) failed: %s\n", *argv, strerror(errno));
 157 }
 158
 159 static int
 160 open_master_pty(const char *desc)
 161 {
 162     int fd;
 163
 164     if ((fd = posix_openpt(O_RDWR | O_NOCTTY)) == -1) {
 165         die("Unable to open master %s pseudo-tty: %s\n", desc, strerror(errno));
 166     }
 167     if (grantpt(fd) == -1) {
 168         die("Unable to grant permissions to master %s pty: %s\n", desc,
 169             strerror(errno));
 170     }
 171     if (unlockpt(fd) == -1) {
 172         die("Unable to unlock master %s pty: %s\n", desc, strerror(errno));
 173     }
 174
 175     return fd;
 176 }
 177
 178 static void
 179 die(const char *fmt, ...)
 180 {
 181     va_list args;
 182
 183     va_start(args, fmt);
 184     vfprintf(stderr, fmt, args);
 185     va_end(args);
 186
 187     exit(1);
 188 }