shell/cmdedit.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * Termios command line History and Editting, originally
   4  * intended for NetBSD sh (ash)
   5  * Copyright (c) 1999
   6  *      Main code:            Adam Rogoyski <rogoyski@cs.utexas.edu>
   7  *      Etc:                  Dave Cinege <dcinege@psychosis.com>
   8  *  Majorly adjusted/re-written for busybox:
   9  *                            Erik Andersen <andersee@debian.org>
  10  *
  11  * You may use this code as you wish, so long as the original author(s)
  12  * are attributed in any redistributions of the source code.
  13  * This code is 'as is' with no warranty.
  14  * This code may safely be consumed by a BSD or GPL license.
  15  *
  16  * v 0.5  19990328      Initial release
  17  *
  18  * Future plans: Simple file and path name completion. (like BASH)
  19  *
  20  */
  21
  22 /*
  23    Usage and Known bugs:
  24    Terminal key codes are not extensive, and more will probably
  25    need to be added. This version was created on Debian GNU/Linux 2.x.
  26    Delete, Backspace, Home, End, and the arrow keys were tested
  27    to work in an Xterm and console. Ctrl-A also works as Home.
  28    Ctrl-E also works as End. The binary size increase is <3K.
  29
  30    Editting will not display correctly for lines greater then the
  31    terminal width. (more then one line.) However, history will.
  32  */
  33
  34 #include "busybox.h"
  35 #ifdef BB_FEATURE_SH_COMMAND_EDITING
  36
  37 #include <stdio.h>
  38 #include <errno.h>
  39 #include <unistd.h>
  40 #include <stdlib.h>
  41 #include <string.h>
  42 #include <sys/ioctl.h>
  43 #include <ctype.h>
  44 #include <signal.h>
  45
  46
  47 #define  MAX_HISTORY   15               /* Maximum length of the linked list for the command line history */
  48
  49 #define ESC     27
  50 #define DEL     127
  51 #define member(c, s) ((c) ? ((char *)strchr ((s), (c)) != (char *)NULL) : 0)
  52 #define whitespace(c) (((c) == ' ') || ((c) == '\t'))
  53
  54 static struct history *his_front = NULL;        /* First element in command line list */
  55 static struct history *his_end = NULL;  /* Last element in command line list */
  56
  57 /* ED: sparc termios is broken: revert back to old termio handling. */
  58 #ifdef BB_FEATURE_USE_TERMIOS
  59
  60 #if #cpu(sparc)
  61 #      include <termio.h>
  62 #      define termios termio
  63 #      define setTermSettings(fd,argp) ioctl(fd,TCSETAF,argp)
  64 #      define getTermSettings(fd,argp) ioctl(fd,TCGETA,argp)
  65 #else
  66 #      include <termios.h>
  67 #      define setTermSettings(fd,argp) tcsetattr(fd,TCSANOW,argp)
  68 #      define getTermSettings(fd,argp) tcgetattr(fd, argp);
  69 #endif
  70
  71 /* Current termio and the previous termio before starting sh */
  72 static struct termios initial_settings, new_settings;
  73
  74
  75 #ifndef _POSIX_VDISABLE
  76 #define _POSIX_VDISABLE '\0'
  77 #endif
  78
  79 #endif
  80
  81
  82
  83 static int cmdedit_termw = 80;  /* actual terminal width */
  84 static int cmdedit_scroll = 27; /* width of EOL scrolling region */
  85 static int history_counter = 0; /* Number of commands in history list */
  86 static int reset_term = 0;              /* Set to true if the terminal needs to be reset upon exit */
  87 static int exithandler_set = 0; /* Set to true when atexit() has been called */
  88
  89
  90 /* Link into lash to reset context to 0
  91  * on ^C and such */
  92 extern unsigned int shell_context;
  93
  94
  95 struct history {
  96         char *s;
  97         struct history *p;
  98         struct history *n;
  99 };
 100
 101 #define xwrite write
 102
 103 /*
 104  * TODO: Someday we want to implement 'horizontal scrolling' of the
 105  * command-line when the user has typed more than the current width. This
 106  * would allow the user to see a 'window' of what he has typed.
 107  */
 108 static void cmdedit_setwidth(int w)
 109 {
 110         if (w > 20) {
 111                 cmdedit_termw = w;
 112                 cmdedit_scroll = w / 3;
 113         } else {
 114                 error_msg("\n*** Error: minimum screen width is 21\n");
 115         }
 116 }
 117
 118 static void win_changed(int junk)
 119 {
 120         struct winsize win = { 0, 0, 0, 0 };
 121         ioctl(0, TIOCGWINSZ, &win);
 122         if (win.ws_col > 0) {
 123                 cmdedit_setwidth( win.ws_col - 1);
 124         }
 125 }
 126
 127
 128 static void cmdedit_reset_term(void)
 129 {
 130         if (reset_term)
 131                 /* sparc and other have broken termios support: use old termio handling. */
 132                 setTermSettings(fileno(stdin), (void*) &initial_settings);
 133 #ifdef BB_FEATURE_CLEAN_UP
 134         if (his_front) {
 135                 struct history *n;
 136                 //while(his_front!=his_end) {
 137                 while(his_front!=his_end) {
 138                         n = his_front->n;
 139                         free(his_front->s);
 140                         free(his_front);
 141                         his_front=n;
 142                 }
 143         }
 144 #endif
 145 }
 146
 147 static void clean_up_and_die(int sig)
 148 {
 149         cmdedit_reset_term();
 150         fprintf(stdout, "\n");
 151         if (sig!=SIGINT)
 152                 exit(EXIT_SUCCESS);
 153 }
 154
 155 /* Go to HOME position */
 156 static void input_home(int outputFd, int *cursor)
 157 {
 158         while (*cursor > 0) {
 159                 xwrite(outputFd, "\b", 1);
 160                 --*cursor;
 161         }
 162 }
 163
 164 /* Go to END position */
 165 static void input_end(int outputFd, int *cursor, int len)
 166 {
 167         while (*cursor < len) {
 168                 xwrite(outputFd, "\033[C", 3);
 169                 ++*cursor;
 170         }
 171 }
 172
 173 /* Delete the char in back of the cursor */
 174 static void input_backspace(char* command, int outputFd, int *cursor, int *len)
 175 {
 176         int j = 0;
 177
 178 /* Debug crap */
 179 //fprintf(stderr, "\nerik: len=%d, cursor=%d, strlen(command)='%d'\n", *len, *cursor, strlen(command));
 180 //xwrite(outputFd, command, *len);
 181 //*cursor = *len;
 182
 183
 184         if (*cursor > 0) {
 185                 xwrite(outputFd, "\b \b", 3);
 186                 --*cursor;
 187                 memmove(command + *cursor, command + *cursor + 1,
 188                                 BUFSIZ - *cursor + 1);
 189
 190                 for (j = *cursor; j < (BUFSIZ - 1); j++) {
 191                         if (!*(command + j))
 192                                 break;
 193                         else
 194                                 xwrite(outputFd, (command + j), 1);
 195                 }
 196
 197                 xwrite(outputFd, " \b", 2);
 198
 199                 while (j-- > *cursor)
 200                         xwrite(outputFd, "\b", 1);
 201
 202                 --*len;
 203         }
 204 }
 205
 206 /* Delete the char in front of the cursor */
 207 static void input_delete(char* command, int outputFd, int cursor, int *len)
 208 {
 209         int j = 0;
 210
 211         if (cursor == *len)
 212                 return;
 213
 214         memmove(command + cursor, command + cursor + 1,
 215                         BUFSIZ - cursor - 1);
 216         for (j = cursor; j < (BUFSIZ - 1); j++) {
 217                 if (!*(command + j))
 218                         break;
 219                 else
 220                         xwrite(outputFd, (command + j), 1);
 221         }
 222
 223         xwrite(outputFd, " \b", 2);
 224
 225         while (j-- > cursor)
 226                 xwrite(outputFd, "\b", 1);
 227         --*len;
 228 }
 229
 230 /* Move forward one charactor */
 231 static void input_forward(int outputFd, int *cursor, int len)
 232 {
 233         if (*cursor < len) {
 234                 xwrite(outputFd, "\033[C", 3);
 235                 ++*cursor;
 236         }
 237 }
 238
 239 /* Move back one charactor */
 240 static void input_backward(int outputFd, int *cursor)
 241 {
 242         if (*cursor > 0) {
 243                 xwrite(outputFd, "\033[D", 3);
 244                 --*cursor;
 245         }
 246 }
 247
 248
 249
 250 #ifdef BB_FEATURE_SH_TAB_COMPLETION
 251 static char** username_tab_completion(char* command, int *num_matches)
 252 {
 253         char **matches = (char **) NULL;
 254         *num_matches=0;
 255         fprintf(stderr, "\nin username_tab_completion\n");
 256         return (matches);
 257 }
 258
 259 #include <dirent.h>
 260 static char** exe_n_cwd_tab_completion(char* command, int *num_matches)
 261 {
 262         char *dirName;
 263         char **matches;
 264         DIR *dir;
 265         struct dirent *next;
 266
 267         matches = xmalloc( sizeof(char*)*50);
 268
 269         /* Stick a wildcard onto the command, for later use */
 270         strcat( command, "*");
 271
 272         /* Now wall the current directory */
 273         dirName = get_current_dir_name();
 274         dir = opendir(dirName);
 275         if (!dir) {
 276                 /* Don't print an error, just shut up and return */
 277                 *num_matches=0;
 278                 return (matches);
 279         }
 280         while ((next = readdir(dir)) != NULL) {
 281
 282                 /* Some quick sanity checks */
 283                 if ((strcmp(next->d_name, "..") == 0)
 284                         || (strcmp(next->d_name, ".") == 0)) {
 285                         continue;
 286                 }
 287                 /* See if this matches */
 288                 if (check_wildcard_match(next->d_name, command) == TRUE) {
 289                         /* Cool, found a match.  Add it to the list */
 290                         matches[*num_matches] = xmalloc(strlen(next->d_name)+1);
 291                         strcpy( matches[*num_matches], next->d_name);
 292                         ++*num_matches;
 293                         //matches = realloc( matches, sizeof(char*)*(*num_matches));
 294                 }
 295         }
 296
 297         return (matches);
 298 }
 299
 300 static void input_tab(char* command, char* prompt, int outputFd, int *cursor, int *len, int lastWasTab)
 301 {
 302         /* Do TAB completion */
 303         static int num_matches=0;
 304         static char **matches = (char **) NULL;
 305         int pos = *cursor;
 306
 307
 308         if (lastWasTab == FALSE) {
 309                 char *tmp, *tmp1, *matchBuf;
 310
 311                 /* For now, we will not bother with trying to distinguish
 312                  * whether the cursor is in/at a command extression -- we
 313                  * will always try all possible matches.  If you don't like
 314                  * that then feel free to fix it.
 315                  */
 316
 317                 /* Make a local copy of the string -- up
 318                  * to the position of the cursor */
 319                 matchBuf = (char *) xcalloc(BUFSIZ, sizeof(char));
 320                 strncpy(matchBuf, command, *cursor);
 321                 tmp=matchBuf;
 322
 323                 /* skip past any command seperator tokens */
 324                 while (*tmp && (tmp1=strpbrk(tmp, ";|&{(`")) != NULL) {
 325                         tmp=++tmp1;
 326                         /* skip any leading white space */
 327                         while (*tmp && isspace(*tmp))
 328                                 ++tmp;
 329                 }
 330
 331                 /* skip any leading white space */
 332                 while (*tmp && isspace(*tmp))
 333                         ++tmp;
 334
 335                 /* Free up any memory already allocated */
 336                 if (matches) {
 337                         free(matches);
 338                         matches = (char **) NULL;
 339                 }
 340
 341                 /* If the word starts with `~' and there is no slash in the word,
 342                  * then try completing this word as a username. */
 343
 344                 /* FIXME -- this check is broken! */
 345                 if (*tmp == '~' && !strchr(tmp, '/'))
 346                         matches = username_tab_completion(tmp, &num_matches);
 347
 348                 /* Try to match any executable in our path and everything
 349                  * in the current working directory that matches.  */
 350                 if (!matches)
 351                         matches = exe_n_cwd_tab_completion(tmp, &num_matches);
 352
 353                 /* Don't leak memory */
 354                 free( matchBuf);
 355
 356                 /* Did we find exactly one match? */
 357                 if (matches && num_matches==1) {
 358                         /* write out the matched command */
 359                         strncpy(command+pos, matches[0]+pos, strlen(matches[0])-pos);
 360                         *len=strlen(command);
 361                         *cursor=*len;
 362                         xwrite(outputFd, matches[0]+pos, strlen(matches[0])-pos);
 363                         return;
 364                 }
 365         } else {
 366                 /* Ok -- the last char was a TAB.  Since they
 367                  * just hit TAB again, print a list of all the
 368                  * available choices... */
 369                 if ( matches && num_matches>0 ) {
 370                         int i, col;
 371
 372                         /* Go to the next line */
 373                         xwrite(outputFd, "\n", 1);
 374                         /* Print the list of matches */
 375                         for (i=0,col=0; i<num_matches; i++) {
 376                                 char foo[17];
 377                                 sprintf(foo, "%-14s  ", matches[i]);
 378                                 col += xwrite(outputFd, foo, strlen(foo));
 379                                 if (col > 60 && matches[i+1] != NULL) {
 380                                         xwrite(outputFd, "\n", 1);
 381                                         col = 0;
 382                                 }
 383                         }
 384                         /* Go to the next line */
 385                         xwrite(outputFd, "\n", 1);
 386                         /* Rewrite the prompt */
 387                         xwrite(outputFd, prompt, strlen(prompt));
 388                         /* Rewrite the command */
 389                         xwrite(outputFd, command, *len);
 390                         /* Put the cursor back to where it used to be */
 391                         for (cursor=len; *cursor > pos; cursor--)
 392                                 xwrite(outputFd, "\b", 1);
 393                 }
 394         }
 395 }
 396 #endif
 397
 398 static void get_previous_history(struct history **hp, char* command)
 399 {
 400         if ((*hp)->s)
 401                 free((*hp)->s);
 402         (*hp)->s = strdup(command);
 403         *hp = (*hp)->p;
 404 }
 405
 406 static void get_next_history(struct history **hp, char* command)
 407 {
 408         if ((*hp)->s)
 409                 free((*hp)->s);
 410         (*hp)->s = strdup(command);
 411         *hp = (*hp)->n;
 412 }
 413
 414 /*
 415  * This function is used to grab a character buffer
 416  * from the input file descriptor and allows you to
 417  * a string with full command editing (sortof like
 418  * a mini readline).
 419  *
 420  * The following standard commands are not implemented:
 421  * ESC-b -- Move back one word
 422  * ESC-f -- Move forward one word
 423  * ESC-d -- Delete back one word
 424  * ESC-h -- Delete forward one word
 425  * CTL-t -- Transpose two characters
 426  *
 427  * Furthermore, the "vi" command editing keys are not implemented.
 428  *
 429  * TODO: implement TAB command completion. :)
 430  */
 431 extern void cmdedit_read_input(char* prompt, char command[BUFSIZ])
 432 {
 433
 434         int inputFd=fileno(stdin);
 435         int outputFd=fileno(stdout);
 436         int nr = 0;
 437         int len = 0;
 438         int j = 0;
 439         int cursor = 0;
 440         int break_out = 0;
 441         int ret = 0;
 442         int lastWasTab = FALSE;
 443         char c = 0;
 444         struct history *hp = his_end;
 445
 446         if (!reset_term) {
 447
 448                 getTermSettings(inputFd, (void*) &initial_settings);
 449                 memcpy(&new_settings, &initial_settings, sizeof(struct termios));
 450                 new_settings.c_cc[VMIN] = 1;
 451                 new_settings.c_cc[VTIME] = 0;
 452                 new_settings.c_cc[VINTR] = _POSIX_VDISABLE; /* Turn off CTRL-C, so we can trap it */
 453                 new_settings.c_lflag &= ~ICANON;        /* unbuffered input */
 454                 new_settings.c_lflag &= ~(ECHO|ECHOCTL|ECHONL); /* Turn off echoing */
 455                 reset_term = 1;
 456         }
 457         setTermSettings(inputFd, (void*) &new_settings);
 458
 459         memset(command, 0, BUFSIZ);
 460
 461         /* Print out the command prompt */
 462         xwrite(outputFd, prompt, strlen(prompt));
 463
 464         while (1) {
 465
 466                 if ((ret = read(inputFd, &c, 1)) < 1)
 467                         return;
 468                 //fprintf(stderr, "got a '%c' (%d)\n", c, c);
 469
 470                 switch (c) {
 471                 case '\n':
 472                 case '\r':
 473                         /* Enter */
 474                         *(command + len++ + 1) = c;
 475                         xwrite(outputFd, &c, 1);
 476                         break_out = 1;
 477                         break;
 478                 case 1:
 479                         /* Control-a -- Beginning of line */
 480                         input_home(outputFd, &cursor);
 481                 case 2:
 482                         /* Control-b -- Move back one character */
 483                         input_backward(outputFd, &cursor);
 484                         break;
 485                 case 3:
 486                         /* Control-c -- stop gathering input */
 487
 488                         /* Link into lash to reset context to 0 on ^C and such */
 489                         shell_context = 0;
 490
 491                         /* Go to the next line */
 492                         xwrite(outputFd, "\n", 1);
 493
 494 #if 0
 495                         /* Rewrite the prompt */
 496                         xwrite(outputFd, prompt, strlen(prompt));
 497
 498                         /* Reset the command string */
 499                         memset(command, 0, BUFSIZ);
 500                         len = cursor = 0;
 501 #endif
 502                         return;
 503
 504                 case 4:
 505                         /* Control-d -- Delete one character, or exit
 506                          * if the len=0 and no chars to delete */
 507                         if (len == 0) {
 508                                 xwrite(outputFd, "exit", 4);
 509                                 clean_up_and_die(0);
 510                         } else {
 511                                 input_delete(command, outputFd, cursor, &len);
 512                         }
 513                         break;
 514                 case 5:
 515                         /* Control-e -- End of line */
 516                         input_end(outputFd, &cursor, len);
 517                         break;
 518                 case 6:
 519                         /* Control-f -- Move forward one character */
 520                         input_forward(outputFd, &cursor, len);
 521                         break;
 522                 case '\b':
 523                 case DEL:
 524                         /* Control-h and DEL */
 525                         input_backspace(command, outputFd, &cursor, &len);
 526                         break;
 527                 case '\t':
 528 #ifdef BB_FEATURE_SH_TAB_COMPLETION
 529                         input_tab(command, prompt, outputFd, &cursor,
 530 &len, lastWasTab);
 531 #endif
 532                         break;
 533                 case 14:
 534                         /* Control-n -- Get next command in history */
 535                         if (hp && hp->n && hp->n->s) {
 536                                 get_next_history(&hp, command);
 537                                 goto rewrite_line;
 538                         } else {
 539                                 xwrite(outputFd, "\007", 1);
 540                         }
 541                         break;
 542                 case 16:
 543                         /* Control-p -- Get previous command from history */
 544                         if (hp && hp->p) {
 545                                 get_previous_history(&hp, command);
 546                                 goto rewrite_line;
 547                         } else {
 548                                 xwrite(outputFd, "\007", 1);
 549                         }
 550                         break;
 551                 case ESC:{
 552                                 /* escape sequence follows */
 553                                 if ((ret = read(inputFd, &c, 1)) < 1)
 554                                         return;
 555
 556                                 if (c == '[') { /* 91 */
 557                                         if ((ret = read(inputFd, &c, 1)) < 1)
 558                                                 return;
 559
 560                                         switch (c) {
 561                                         case 'A':
 562                                                 /* Up Arrow -- Get previous command from history */
 563                                                 if (hp && hp->p) {
 564                                                         get_previous_history(&hp, command);
 565                                                         goto rewrite_line;
 566                                                 } else {
 567                                                         xwrite(outputFd, "\007", 1);
 568                                                 }
 569                                                 break;
 570                                         case 'B':
 571                                                 /* Down Arrow -- Get next command in history */
 572                                                 if (hp && hp->n && hp->n->s) {
 573                                                         get_next_history(&hp, command);
 574                                                         goto rewrite_line;
 575                                                 } else {
 576                                                         xwrite(outputFd, "\007", 1);
 577                                                 }
 578                                                 break;
 579
 580                                                 /* Rewrite the line with the selected history item */
 581                                           rewrite_line:
 582                                                 /* erase old command from command line */
 583                                                 len = strlen(command)-strlen(hp->s);
 584
 585                                                 while (len>cursor)
 586                                                         input_delete(command, outputFd, cursor, &len);
 587                                                 while (cursor>0)
 588                                                         input_backspace(command, outputFd, &cursor, &len);
 589                                                 input_home(outputFd, &cursor);
 590
 591                                                 /* write new command */
 592                                                 strcpy(command, hp->s);
 593                                                 len = strlen(hp->s);
 594                                                 xwrite(outputFd, command, len);
 595                                                 cursor = len;
 596                                                 break;
 597                                         case 'C':
 598                                                 /* Right Arrow -- Move forward one character */
 599                                                 input_forward(outputFd, &cursor, len);
 600                                                 break;
 601                                         case 'D':
 602                                                 /* Left Arrow -- Move back one character */
 603                                                 input_backward(outputFd, &cursor);
 604                                                 break;
 605                                         case '3':
 606                                                 /* Delete */
 607                                                 input_delete(command, outputFd, cursor, &len);
 608                                                 break;
 609                                         case '1':
 610                                                 /* Home (Ctrl-A) */
 611                                                 input_home(outputFd, &cursor);
 612                                                 break;
 613                                         case '4':
 614                                                 /* End (Ctrl-E) */
 615                                                 input_end(outputFd, &cursor, len);
 616                                                 break;
 617                                         default:
 618                                                 xwrite(outputFd, "\007", 1);
 619                                         }
 620                                         if (c == '1' || c == '3' || c == '4')
 621                                                 if ((ret = read(inputFd, &c, 1)) < 1)
 622                                                         return; /* read 126 (~) */
 623                                 }
 624                                 if (c == 'O') {
 625                                         /* 79 */
 626                                         if ((ret = read(inputFd, &c, 1)) < 1)
 627                                                 return;
 628                                         switch (c) {
 629                                         case 'H':
 630                                                 /* Home (xterm) */
 631                                                 input_home(outputFd, &cursor);
 632                                                 break;
 633                                         case 'F':
 634                                                 /* End (xterm) */
 635                                                 input_end(outputFd, &cursor, len);
 636                                                 break;
 637                                         default:
 638                                                 xwrite(outputFd, "\007", 1);
 639                                         }
 640                                 }
 641                                 c = 0;
 642                                 break;
 643                         }
 644
 645                 default:                                /* If it's regular input, do the normal thing */
 646
 647                         if (!isprint(c)) {      /* Skip non-printable characters */
 648                                 break;
 649                         }
 650
 651                         if (len >= (BUFSIZ - 2))        /* Need to leave space for enter */
 652                                 break;
 653
 654                         len++;
 655
 656                         if (cursor == (len - 1)) {      /* Append if at the end of the line */
 657                                 *(command + cursor) = c;
 658                         } else {                        /* Insert otherwise */
 659                                 memmove(command + cursor + 1, command + cursor,
 660                                                 len - cursor - 1);
 661
 662                                 *(command + cursor) = c;
 663
 664                                 for (j = cursor; j < len; j++)
 665                                         xwrite(outputFd, command + j, 1);
 666                                 for (; j > cursor; j--)
 667                                         xwrite(outputFd, "\033[D", 3);
 668                         }
 669
 670                         cursor++;
 671                         xwrite(outputFd, &c, 1);
 672                         break;
 673                 }
 674                 if (c == '\t')
 675                         lastWasTab = TRUE;
 676                 else
 677                         lastWasTab = FALSE;
 678
 679                 if (break_out)                  /* Enter is the command terminator, no more input. */
 680                         break;
 681         }
 682
 683         nr = len + 1;
 684         setTermSettings(inputFd, (void *) &initial_settings);
 685         reset_term = 0;
 686
 687
 688         /* Handle command history log */
 689         if (*(command)) {
 690
 691                 struct history *h = his_end;
 692
 693                 if (!h) {
 694                         /* No previous history -- this memory is never freed */
 695                         h = his_front = xmalloc(sizeof(struct history));
 696                         h->n = xmalloc(sizeof(struct history));
 697
 698                         h->p = NULL;
 699                         h->s = strdup(command);
 700                         h->n->p = h;
 701                         h->n->n = NULL;
 702                         h->n->s = NULL;
 703                         his_end = h->n;
 704                         history_counter++;
 705                 } else {
 706                         /* Add a new history command -- this memory is never freed */
 707                         h->n = xmalloc(sizeof(struct history));
 708
 709                         h->n->p = h;
 710                         h->n->n = NULL;
 711                         h->n->s = NULL;
 712                         h->s = strdup(command);
 713                         his_end = h->n;
 714
 715                         /* After max history, remove the oldest command */
 716                         if (history_counter >= MAX_HISTORY) {
 717
 718                                 struct history *p = his_front->n;
 719
 720                                 p->p = NULL;
 721                                 free(his_front->s);
 722                                 free(his_front);
 723                                 his_front = p;
 724                         } else {
 725                                 history_counter++;
 726                         }
 727                 }
 728         }
 729
 730         return;
 731 }
 732
 733 extern void cmdedit_init(void)
 734 {
 735         win_changed(0);
 736         signal(SIGWINCH, win_changed);
 737
 738         if(exithandler_set == 0) {
 739                 atexit(cmdedit_reset_term);     /* be sure to do this only once */
 740                 exithandler_set = 1;
 741         }
 742         signal(SIGKILL, clean_up_and_die);
 743         signal(SIGINT, clean_up_and_die);
 744         signal(SIGQUIT, clean_up_and_die);
 745         signal(SIGTERM, clean_up_and_die);
 746 }
 747
 748 /*
 749 ** Undo the effects of cmdedit_init() as good as we can:
 750 ** I am not aware of a way to revoke an atexit() handler,
 751 ** but, fortunately, our particular handler can be made
 752 ** a no-op by setting reset_term = 0.
 753 */
 754 extern void cmdedit_terminate(void)
 755 {
 756         cmdedit_reset_term();
 757         reset_term = 0;
 758         signal(SIGKILL, SIG_DFL);
 759         signal(SIGINT, SIG_DFL);
 760         signal(SIGQUIT, SIG_DFL);
 761         signal(SIGTERM, SIG_DFL);
 762         signal(SIGWINCH, SIG_DFL);
 763 }
 764
 765
 766
 767 #endif                                                  /* BB_FEATURE_SH_COMMAND_EDITING */