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 run_command(char *argv[], int master_in, int master_out);
  25 static int open_master_pty(const char *desc);
  26 static void die(const char *fmt, ...);
  27
  28 int
  29 main(int argc, char *argv[])
  30 {
  31     int master_in, master_out, cc, status;
  32     time_t starttime, now;
  33     pid_t child;
  34     unsigned char readbuf[1024];
  35     FILE *output;
  36
  37     if (argc < 3) {
  38         die("%s: too few arguments\n"
  39             "usage: %s output-filename command [arguments...]\n",
  40             *argv, *argv);
  41     }
  42
  43     master_in = open_master_pty("input");
  44     master_out = open_master_pty("output");
  45
  46     if ((child = fork()) == -1) {
  47         die("fork() failed: %s\n", strerror(errno));
  48     }
  49     if (child == 0) {
  50         run_command(argv + 2, master_in, master_out); /* Does not return. */
  51     }
  52
  53     if (!(output = fopen(argv[1], "w"))) {
  54         die("Unable to open \"%s\" for output: %s\n", argv[1],
  55             strerror(errno));
  56     }
  57
  58     starttime = time(NULL);
  59
  60     for (;;) {
  61         fd_set readfds;
  62         struct timeval tv;
  63
  64         FD_ZERO(&readfds);
  65
  66         FD_SET(master_out, &readfds);
  67
  68         /*
  69          * After we get our first bit of data, close the master pty
  70          * connected to standard input on our slave; that will generate
  71          * an EOF.
  72          */
  73
  74         tv.tv_sec = starttime + COMMAND_TIMEOUT - time(NULL);
  75         if (tv.tv_sec < 0)
  76             tv.tv_sec = 0;
  77         tv.tv_usec = 0;
  78
  79         cc = select(master_out + 1, &readfds, NULL, NULL, &tv);
  80
  81         if (cc < 0) {
  82             die("select() failed: %s\n", strerror(errno));
  83         }
  84
  85         if (cc > 0 && FD_ISSET(master_out, &readfds)) {
  86             cc = read(master_out, readbuf, sizeof(readbuf));
  87
  88             if (cc <= 0)
  89                 break;
  90
  91             fwrite(readbuf, 1, cc, output);
  92
  93             if (master_in != -1) {
  94                 close(master_in);
  95                 master_in = -1;
  96             }
  97         }
  98
  99         now = time(NULL);
 100         if (now >= starttime + COMMAND_TIMEOUT) {
 101             fprintf(stderr, "Command execution timed out: %ld to %ld: %d\n",
 102                 starttime, now, cc);
 103             break;
 104         }
 105     }
 106
 107     if (master_in != -1)
 108         close(master_in);
 109     close(master_out);
 110     fclose(output);
 111
 112     waitpid(child, &status, 0);
 113
 114     exit(0);
 115 }
 116
 117 static void
 118 run_command(char *argv[], int master_in, int master_out)
 119 {
 120     const char *slavename;
 121     int slave;
 122
 123     /* Open the two slave pseudo-ttys and close the masters after we are
 124      * done with them. */
 125
 126     if (!(slavename = ptsname(master_in))) {
 127         die("Unable to determine name of slave pty: %s\n",
 128             strerror(errno));
 129     }
 130
 131     if ((slave = open(slavename, O_RDWR)) == -1) {
 132         die("Unable to open slave pty \"%s\": %s\n", slavename,
 133             strerror(errno));
 134     }
 135
 136     dup2(slave, STDIN_FILENO);
 137     close(slave);
 138     close(master_in);
 139
 140     if (!(slavename = ptsname(master_out))) {
 141         die("Unable to determine name of slave pty: %s\n",
 142             strerror(errno));
 143     }
 144
 145     if ((slave = open(slavename, O_RDWR | O_NOCTTY)) < 0) {
 146         die("Unable to open slave pty \"%s\": %s\n", slavename,
 147             strerror(errno));
 148     }
 149
 150     dup2(slave, STDOUT_FILENO);
 151     dup2(slave, STDERR_FILENO);
 152     close(slave);
 153     close(master_out);
 154
 155     execvp(*argv, argv);
 156
 157     die("execvp(%s) failed: %s\n", *argv, strerror(errno));
 158 }
 159
 160 static int
 161 open_master_pty(const char *desc)
 162 {
 163     int fd;
 164
 165     if ((fd = posix_openpt(O_RDWR | O_NOCTTY)) == -1) {
 166         die("Unable to open master %s pseudo-tty: %s\n", desc, strerror(errno));
 167     }
 168     if (grantpt(fd) == -1) {
 169         die("Unable to grant permissions to master %s pty: %s\n", desc,
 170             strerror(errno));
 171     }
 172     if (unlockpt(fd) == -1) {
 173         die("Unable to unlock master %s pty: %s\n", desc, strerror(errno));
 174     }
 175
 176     return fd;
 177 }
 178
 179 static void
 180 die(const char *fmt, ...)
 181 {
 182     va_list args;
 183
 184     va_start(args, fmt);
 185     vfprintf(stderr, fmt, args);
 186     va_end(args);
 187
 188     exit(1);
 189 }