src/bin/watch.c

   1 /* watch -- execute a program repeatedly, displaying output fullscreen
   2  *
   3  * Based on the original 1991 'watch' by Tony Rems <rembo@unisoft.com>
   4  * (with mods and corrections by Francois Pinard).
   5  *
   6  * Substantially reworked, new features (differences option, SIGWINCH
   7  * handling, unlimited command length, long line handling) added Apr 1999 by
   8  * Mike Coleman <mkc@acm.org>.
   9  *
  10  * Changes by Albert Cahalan, 2002-2003.
  11  */
  12
  13 #define VERSION "0.2.0"
  14
  15 #include <ctype.h>
  16 #include <getopt.h>
  17 #include <signal.h>
  18 #include <ncurses.h>
  19 #include <stdio.h>
  20 #include <stdlib.h>
  21 #include <string.h>
  22 #include <sys/ioctl.h>
  23 #include <time.h>
  24 #include <unistd.h>
  25 #include <locale.h>
  26 /* #include "proc/procps.h" */
  27
  28 static struct option longopts[] = {
  29         {"differences", optional_argument, 0, 'd'},
  30         {"help", no_argument, 0, 'h'},
  31         {"interval", required_argument, 0, 'n'},
  32         {"no-title", no_argument, 0, 't'},
  33         {"version", no_argument, 0, 'v'},
  34         {0, 0, 0, 0}
  35 };
  36
  37 static char usage[] =
  38     "Usage: %s [-dhntv] [--differences[=cumulative]] [--help] [--interval=<n>] [--no-title] [--version] <command>\n";
  39
  40 static char *progname;
  41
  42 static int curses_started = 0;
  43 static int height = 24, width = 80;
  44 static int screen_size_changed = 0;
  45 static int first_screen = 1;
  46 static int show_title = 2;  // number of lines used, 2 or 0
  47
  48 #define min(x,y) ((x) > (y) ? (y) : (x))
  49
  50 //static void do_usage(void) NORETURN;
  51 static void do_usage(void)
  52 {
  53         fprintf(stderr, usage, progname);
  54         exit(1);
  55 }
  56
  57 //static void do_exit(int status) NORETURN;
  58 static void do_exit(int status)
  59 {
  60         if (curses_started)
  61                 endwin();
  62         exit(status);
  63 }
  64
  65 /* signal handler */
  66 //static void die(int notused) NORETURN;
  67 static void die(int notused)
  68 {
  69         (void) notused;
  70         do_exit(0);
  71 }
  72
  73 static void
  74 winch_handler(int notused)
  75 {
  76         (void) notused;
  77         screen_size_changed = 1;
  78 }
  79
  80 static void
  81 get_terminal_size(void)
  82 {
  83         struct winsize w;
  84         if (ioctl(2, TIOCGWINSZ, &w) == 0) {
  85                 if (w.ws_row > 0)
  86                         height = w.ws_row;
  87                 if (w.ws_col > 0)
  88                         width = w.ws_col;
  89         }
  90 }
  91
  92 int
  93 main(int argc, char *argv[])
  94 {
  95         int optc;
  96         int option_differences = 0,
  97             option_differences_cumulative = 0,
  98             option_help = 0, option_version = 0;
  99         int interval = 2;
 100         char *command;
 101         int command_length = 0; /* not including final \0 */
 102
 103         setlocale(LC_ALL, "");
 104         progname = argv[0];
 105
 106         while ((optc = getopt_long(argc, argv, "+d::hn:vt", longopts, (int *) 0))
 107                != EOF) {
 108                 switch (optc) {
 109                 case 'd':
 110                         option_differences = 1;
 111                         if (optarg)
 112                                 option_differences_cumulative = 1;
 113                         break;
 114                 case 'h':
 115                         option_help = 1;
 116                         break;
 117                 case 't':
 118                         show_title = 0;
 119                         break;
 120                 case 'n':
 121                         {
 122                                 char *str;
 123                                 interval = strtol(optarg, &str, 10);
 124                                 if (!*optarg || *str)
 125                                         do_usage();
 126                         }
 127                         break;
 128                 case 'v':
 129                         option_version = 1;
 130                         break;
 131                 default:
 132                         do_usage();
 133                         break;
 134                 }
 135         }
 136
 137         if (option_version) {
 138                 fprintf(stderr, "%s\n", VERSION);
 139                 if (!option_help)
 140                         exit(0);
 141         }
 142
 143         if (option_help) {
 144                 fprintf(stderr, usage, progname);
 145                 fputs("  -d, --differences[=cumulative]\thighlight changes between updates\n", stderr);
 146                 fputs("\t\t(cumulative means highlighting is cumulative)\n", stderr);
 147                 fputs("  -h, --help\t\t\t\tprint a summary of the options\n", stderr);
 148                 fputs("  -n, --interval=<seconds>\t\tseconds to wait between updates\n", stderr);
 149                 fputs("  -v, --version\t\t\t\tprint the version number\n", stderr);
 150                 fputs("  -t, --no-title\t\t\tturns off showing the header\n", stderr);
 151                 exit(0);
 152         }
 153
 154         if (optind >= argc)
 155                 do_usage();
 156
 157         command = strdup(argv[optind++]);
 158         command_length = strlen(command);
 159         for (; optind < argc; optind++) {
 160                 char *endp;
 161                 int s = strlen(argv[optind]);
 162                 command = realloc(command, command_length + s + 2);     /* space and \0 */
 163                 endp = command + command_length;
 164                 *endp = ' ';
 165                 memcpy(endp + 1, argv[optind], s);
 166                 command_length += 1 + s;        /* space then string length */
 167                 command[command_length] = '\0';
 168         }
 169
 170         get_terminal_size();
 171
 172         /* Catch keyboard interrupts so we can put tty back in a sane state.  */
 173         signal(SIGINT, die);
 174         signal(SIGTERM, die);
 175         signal(SIGHUP, die);
 176         signal(SIGWINCH, winch_handler);
 177
 178         /* Set up tty for curses use.  */
 179         curses_started = 1;
 180         initscr();
 181         nonl();
 182         noecho();
 183         cbreak();
 184
 185         for (;;) {
 186                 time_t t = time(NULL);
 187                 char *ts = ctime(&t);
 188                 int tsl = strlen(ts);
 189                 char *header;
 190                 FILE *p;
 191                 int x, y;
 192                 int oldeolseen = 1;
 193
 194                 if (screen_size_changed) {
 195                         get_terminal_size();
 196                         resizeterm(height, width);
 197                         clear();
 198                         /* redrawwin(stdscr); */
 199                         screen_size_changed = 0;
 200                         first_screen = 1;
 201                 }
 202
 203                 if (show_title) {
 204                         // left justify interval and command,
 205                         // right justify time, clipping all to fit window width
 206                         asprintf(&header, "Every %ds: %.*s",
 207                                  interval, min(width - 1, command_length), command);
 208                         mvaddstr(0, 0, header);
 209                         if (strlen(header) > (size_t) (width - tsl - 1))
 210                                 mvaddstr(0, width - tsl - 4, "...  ");
 211                         mvaddstr(0, width - tsl + 1, ts);
 212                         free(header);
 213                 }
 214
 215                 if (!(p = popen(command, "r"))) {
 216                         perror("popen");
 217                         do_exit(2);
 218                 }
 219
 220                 for (y = show_title; y < height; y++) {
 221                         int eolseen = 0, tabpending = 0;
 222                         for (x = 0; x < width; x++) {
 223                                 int c = ' ';
 224                                 int attr = 0;
 225
 226                                 if (!eolseen) {
 227                                         /* if there is a tab pending, just spit spaces until the
 228                                            next stop instead of reading characters */
 229                                         if (!tabpending)
 230                                                 do
 231                                                         c = getc(p);
 232                                                 while (c != EOF && !isprint(c)
 233                                                        && c != '\n'
 234                                                        && c != '\t');
 235                                         if (c == '\n')
 236                                                 if (!oldeolseen && x == 0) {
 237                                                         x = -1;
 238                                                         continue;
 239                                                 } else
 240                                                         eolseen = 1;
 241                                         else if (c == '\t')
 242                                                 tabpending = 1;
 243                                         if (c == EOF || c == '\n' || c == '\t')
 244                                                 c = ' ';
 245                                         if (tabpending && (((x + 1) % 8) == 0))
 246                                                 tabpending = 0;
 247                                 }
 248                                 move(y, x);
 249                                 if (option_differences) {
 250                                         int oldch = inch();
 251                                         char oldc = oldch & A_CHARTEXT;
 252                                         attr = !first_screen
 253                                             && (c != oldc
 254                                                 ||
 255                                                 (option_differences_cumulative
 256                                                  && (oldch & A_ATTRIBUTES)));
 257                                 }
 258                                 if (attr)
 259                                         standout();
 260                                 addch(c);
 261                                 if (attr)
 262                                         standend();
 263                         }
 264                         oldeolseen = eolseen;
 265                 }
 266
 267                 pclose(p);
 268
 269                 first_screen = 0;
 270                 refresh();
 271                 sleep(interval);
 272         }
 273
 274         endwin();
 275
 276         return 0;
 277 }