std.c

   1 /* See LICENSE file for copyright and license details.
   2  *
   3  * Simple terminal daemon is a terminal emulator. It can be used in
   4  * combination with simple terminal to emulate a mostly VT100-compatible
   5  * terminal.
   6  *
   7  * In this process std works like a filter. It reads data from a
   8  * pseudo-terminal and parses the escape sequences and transforms them
   9  * into an ed(1)-like language. The resulting data is buffered and
  10  * written to stdout.
  11  * Parallely it reads data from stdin and parses and executes the
  12  * commands. The resulting data is written to the pseudo-terminal.
  13  */
  14 #include <sys/types.h>
  15 #include <sys/wait.h>
  16 #include <ctype.h>
  17 #include <err.h>
  18 #include <errno.h>
  19 #include <fcntl.h>
  20 #if !(_POSIX_C_SOURCE >= 200112L || _XOPEN_SOURCE >= 600)
  21 #include <pty.h>
  22 #endif
  23 #include <signal.h>
  24 #include <stdarg.h>
  25 #include <stdio.h>
  26 #include <stdlib.h>
  27 #include <string.h>
  28 #include <unistd.h>
  29
  30 #define LENGTH(x)       (sizeof(x) / sizeof((x)[0]))
  31 #define MAX(a,b)        (((a) > (b)) ? (a) : (b))
  32 #define MIN(a,b)        (((a) < (b)) ? (a) : (b))
  33
  34 typedef struct {
  35         unsigned char data[BUFSIZ];
  36         int s, e;
  37         int n;
  38 } RingBuffer;
  39
  40 static void buffer(char c);
  41 static void cmd(const char *cmdstr, ...);
  42 static void getpty(void);
  43 static void movea(int x, int y);
  44 static void mover(int x, int y);
  45 static void parsecmd(void);
  46 static void parseesc(void);
  47 static void scroll(int l);
  48 static void shell(void);
  49 static void sigchld(int n);
  50 static char unbuffer(void);
  51
  52 static int cols = 80, lines = 25;
  53 static int cx = 0, cy = 0;
  54 static int c;
  55 static int ptm, pts;
  56 static _Bool bold, digit, qmark;
  57 static pid_t pid;
  58 static RingBuffer buf;
  59 static FILE *fptm;
  60
  61 void
  62 buffer(char c) {
  63         if(buf.n < LENGTH(buf.data))
  64                 buf.n++;
  65         else
  66                 buf.s = (buf.s + 1) % LENGTH(buf.data);
  67         buf.data[buf.e++] = c;
  68         buf.e %= LENGTH(buf.data);
  69 }
  70
  71 void
  72 cmd(const char *cmdstr, ...) {
  73         va_list ap;
  74
  75         putchar('\n');
  76         putchar(':');
  77         va_start(ap, cmdstr);
  78         vfprintf(stdout, cmdstr, ap);
  79         va_end(ap);
  80 }
  81
  82 void
  83 movea(int x, int y) {
  84         x = MAX(x, cols);
  85         y = MAX(y, lines);
  86         cx = x;
  87         cy = y;
  88         cmd("seek(%d,%d)", x, y);
  89 }
  90
  91 void
  92 mover(int x, int y) {
  93         movea(cx + x, cy + y);
  94 }
  95
  96 void
  97 parsecmd(void) {
  98 }
  99
 100 void
 101 parseesc(void) {
 102         int i, j;
 103         int arg[16];
 104
 105         memset(arg, 0, LENGTH(arg));
 106         c = getc(fptm);
 107         switch(c) {
 108         case '[':
 109                 c = getc(fptm);
 110                 for(j = 0; j < LENGTH(arg);) {
 111                         if(isdigit(c)) {
 112                                 digit = 1;
 113                                 arg[j] *= 10;
 114                                 arg[j] += c - '0';
 115                         }
 116                         else if(c == '?')
 117                                 qmark = 1;
 118                         else if(c == ';') {
 119                                 if(!digit)
 120                                         errx(EXIT_FAILURE, "syntax error");
 121                                 digit = 0;
 122                                 j++;
 123                         }
 124                         else {
 125                                 if(digit) {
 126                                         digit = 0;
 127                                         j++;
 128                                 }
 129                                 break;
 130                         }
 131                         c = getc(fptm);
 132                 }
 133                 switch(c) {
 134                 case '@':
 135                         break;
 136                 case 'A':
 137                         mover(0, j ? arg[0] : 1);
 138                         break;
 139                 case 'B':
 140                         mover(0, j ? -arg[0] : -1);
 141                         break;
 142                 case 'C':
 143                         mover(j ? arg[0] : 1, 0);
 144                         break;
 145                 case 'D':
 146                         mover(j ? -arg[0] : -1, 0);
 147                         break;
 148                 case 'E':
 149                         /* movel(j ? arg[0] : 1); */
 150                         break;
 151                 case 'F':
 152                         /* movel(j ? -arg[0] : -1); */
 153                         break;
 154                 case '`':
 155                 case 'G':
 156                         movea(j ? arg[0] : 1, cy);
 157                         break;
 158                 case 'f':
 159                 case 'H':
 160                         movea(arg[1] ? arg[1] : 1, arg[0] ? arg[0] : 1);
 161                 case 'L':
 162                         /* insline(j ? arg[0] : 1); */
 163                         break;
 164                 case 'M':
 165                         /* delline(j ? arg[0] : 1); */
 166                         break;
 167                 case 'P':
 168                         break;
 169                 case 'S':
 170                         scroll(j ? arg[0] : 1);
 171                         break;
 172                 case 'T':
 173                         scroll(j ? -arg[0] : -1);
 174                         break;
 175                 case 'd':
 176                         movea(cx, j ? arg[0] : 1);
 177                         break;
 178                 case 'm':
 179                         for(i = 0; i < j; i++) {
 180                                 if(arg[i] >= 30 && arg[i] <= 37)
 181                                         cmd("#%d", arg[i] - 30);
 182                                 if(arg[i] >= 40 && arg[i] <= 47)
 183                                         cmd("|%d", arg[i] - 40);
 184                                 /* xterm bright colors */
 185                                 if(arg[i] >= 90 && arg[i] <= 97)
 186                                         cmd("#%d", arg[i] - 90);
 187                                 if(arg[i] >= 100 && arg[i] <= 107)
 188                                         cmd("|%d", arg[i] - 100);
 189                                 switch(arg[i]) {
 190                                 case 0:
 191                                 case 22:
 192                                         if(bold)
 193                                                 cmd("bold");
 194                                 case 1:
 195                                         if(!bold)
 196                                                 cmd("bold");
 197                                         break;
 198                                 }
 199                         }
 200                         break;
 201                 }
 202                 break;
 203         default:
 204                 putchar('\033');
 205                 ungetc(c, fptm);
 206         }
 207 }
 208
 209 void
 210 scroll(int l) {
 211         cmd("seek(%d,%d)", cx, cy + l);
 212 }
 213
 214 void
 215 getpty(void) {
 216         char *ptsdev;
 217
 218 #if defined(_GNU_SOURCE)
 219         ptm = getpt();
 220 #elif _POSIX_C_SOURCE >= 200112L || _XOPEN_SOURCE >= 600
 221         ptm = posix_openpt(O_RDWR);
 222 #else
 223         ptm = open("/dev/ptmx", O_RDWR);
 224         if(ptm == -1)
 225                 if(openpty(&ptm, &pts, NULL, NULL, NULL) == -1)
 226                         err(EXIT_FAILURE, "cannot open pty");
 227 #endif
 228 #if defined(_XOPEN_SOURCE)
 229         if(ptm != -1) {
 230                 if(grantpt(ptm) == -1)
 231                         err(EXIT_FAILURE, "cannot grant access to pty");
 232                 if(unlockpt(ptm) == -1)
 233                         err(EXIT_FAILURE, "cannot unlock pty");
 234                 ptsdev = ptsname(ptm);
 235                 if(!ptsdev)
 236                         err(EXIT_FAILURE, "slave pty name undefined");
 237                 pts = open(ptsdev, O_RDWR);
 238                 if(pts == -1)
 239                         err(EXIT_FAILURE, "cannot open slave pty");
 240         }
 241         else
 242                 err(EXIT_FAILURE, "cannot open pty");
 243 #endif
 244 }
 245
 246 void
 247 shell(void) {
 248         static char *shell = NULL;
 249
 250         if(!shell && !(shell = getenv("SHELL")))
 251                 shell = "/bin/sh";
 252         pid = fork();
 253         switch(pid) {
 254         case -1:
 255                 err(EXIT_FAILURE, "cannot fork");
 256         case 0:
 257                 setsid();
 258                 dup2(pts, STDIN_FILENO);
 259                 dup2(pts, STDOUT_FILENO);
 260                 dup2(pts, STDERR_FILENO);
 261                 close(ptm);
 262                 putenv("TERM=vt102");
 263                 execvp(shell, NULL);
 264                 break;
 265         default:
 266                 close(pts);
 267                 signal(SIGCHLD, sigchld);
 268         }
 269 }
 270
 271 void
 272 sigchld(int n) {
 273         int ret;
 274
 275         if(waitpid(pid, &ret, 0) == -1)
 276                 err(EXIT_FAILURE, "waiting for child failed");
 277         if(WIFEXITED(ret))
 278                 exit(WEXITSTATUS(ret));
 279         else
 280                 exit(EXIT_SUCCESS);
 281 }
 282
 283 char
 284 unbuffer(void) {
 285         char c;
 286
 287         c = buf.data[buf.s++];
 288         buf.s %= LENGTH(buf.data);
 289         buf.n--;
 290         return c;
 291 }
 292
 293 int
 294 main(int argc, char *argv[]) {
 295         fd_set rfds;
 296
 297         if(argc == 2 && !strcmp("-v", argv[1]))
 298                 errx(EXIT_SUCCESS, "std-"VERSION", © 2008 Matthias-Christian Ott");
 299         else if(argc == 1)
 300                 errx(EXIT_FAILURE, "usage: std [-v]");
 301         getpty();
 302         shell();
 303         FD_ZERO(&rfds);
 304         FD_SET(STDIN_FILENO, &rfds);
 305         FD_SET(ptm, &rfds);
 306         if(!(fptm = fdopen(ptm, "r+")))
 307                 err(EXIT_FAILURE, "cannot open pty");
 308         if(fcntl(ptm, F_SETFL, O_NONBLOCK) == -1)
 309                 err(EXIT_FAILURE, "cannot set pty to non-blocking mode");
 310         if(fcntl(STDIN_FILENO, F_SETFL, O_NONBLOCK) == -1)
 311                 err(EXIT_FAILURE, "cannot set stdin to non-blocking mode");
 312         for(;;) {
 313                 if(select(MAX(ptm, STDIN_FILENO) + 1, &rfds, NULL, NULL, NULL) == -1)
 314                         err(EXIT_FAILURE, "cannot select");
 315                 if(FD_ISSET(ptm, &rfds)) {
 316                         for(;;) {
 317                                 if((c = getc(fptm)) == EOF) {
 318                                         if(feof(fptm)) {
 319                                                 FD_CLR(ptm, &rfds);
 320                                                 fflush(fptm);
 321                                                 break;
 322                                         }
 323                                         if(errno != EAGAIN)
 324                                                 err(EXIT_FAILURE, "cannot read from pty");
 325                                         fflush(stdout);
 326                                         break;
 327                                 }
 328                                 switch(c) {
 329                                 case '\033':
 330                                         parseesc();
 331                                         break;
 332                                 default:
 333                                         putchar(c);
 334                                 }
 335                         }
 336                         fflush(stdout);
 337                 }
 338                 if(FD_ISSET(STDIN_FILENO, &rfds)) {
 339                         for(;;) {
 340                                 if((c = getchar()) == EOF) {
 341                                         if(feof(stdin)) {
 342                                                 FD_CLR(STDIN_FILENO, &rfds);
 343                                                 fflush(fptm);
 344                                                 break;
 345                                         }
 346                                         if(errno != EAGAIN)
 347                                                 err(EXIT_FAILURE, "cannot read from stdin");
 348                                         fflush(fptm);
 349                                         break;
 350                                 }
 351                                 switch(c) {
 352                                 case ':':
 353                                         parsecmd();
 354                                         break;
 355                                 default:
 356                                         putc(c, fptm);
 357                                 }
 358                         }
 359                         fflush(fptm);
 360                 }
 361         }
 362         return 0;
 363 }