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