contrib/less/cmdbuf.c

   1 /*
   2  * Copyright (C) 1984-2015  Mark Nudelman
   3  *
   4  * You may distribute under the terms of either the GNU General Public
   5  * License or the Less License, as specified in the README file.
   6  *
   7  * For more information, see the README file.
   8  */
   9
  10
  11 /*
  12  * Functions which manipulate the command buffer.
  13  * Used only by command() and related functions.
  14  */
  15
  16 #include "less.h"
  17 #include "cmd.h"
  18 #include "charset.h"
  19 #if HAVE_STAT
  20 #include <sys/stat.h>
  21 #endif
  22
  23 extern int sc_width;
  24 extern int utf_mode;
  25
  26 static char cmdbuf[CMDBUF_SIZE]; /* Buffer for holding a multi-char command */
  27 static int cmd_col;             /* Current column of the cursor */
  28 static int prompt_col;          /* Column of cursor just after prompt */
  29 static char *cp;                /* Pointer into cmdbuf */
  30 static int cmd_offset;          /* Index into cmdbuf of first displayed char */
  31 static int literal;             /* Next input char should not be interpreted */
  32 static int updown_match = -1;   /* Prefix length in up/down movement */
  33
  34 #if TAB_COMPLETE_FILENAME
  35 static int cmd_complete();
  36 /*
  37  * These variables are statics used by cmd_complete.
  38  */
  39 static int in_completion = 0;
  40 static char *tk_text;
  41 static char *tk_original;
  42 static char *tk_ipoint;
  43 static char *tk_trial;
  44 static struct textlist tk_tlist;
  45 #endif
  46
  47 static int cmd_left();
  48 static int cmd_right();
  49
  50 #if SPACES_IN_FILENAMES
  51 public char openquote = '"';
  52 public char closequote = '"';
  53 #endif
  54
  55 #if CMD_HISTORY
  56
  57 /* History file */
  58 #define HISTFILE_FIRST_LINE      ".less-history-file:"
  59 #define HISTFILE_SEARCH_SECTION  ".search"
  60 #define HISTFILE_SHELL_SECTION   ".shell"
  61
  62 /*
  63  * A mlist structure represents a command history.
  64  */
  65 struct mlist
  66 {
  67         struct mlist *next;
  68         struct mlist *prev;
  69         struct mlist *curr_mp;
  70         char *string;
  71         int modified;
  72 };
  73
  74 /*
  75  * These are the various command histories that exist.
  76  */
  77 struct mlist mlist_search =
  78         { &mlist_search,  &mlist_search,  &mlist_search,  NULL, 0 };
  79 public void * constant ml_search = (void *) &mlist_search;
  80
  81 struct mlist mlist_examine =
  82         { &mlist_examine, &mlist_examine, &mlist_examine, NULL, 0 };
  83 public void * constant ml_examine = (void *) &mlist_examine;
  84
  85 #if SHELL_ESCAPE || PIPEC
  86 struct mlist mlist_shell =
  87         { &mlist_shell,   &mlist_shell,   &mlist_shell,   NULL, 0 };
  88 public void * constant ml_shell = (void *) &mlist_shell;
  89 #endif
  90
  91 #else /* CMD_HISTORY */
  92
  93 /* If CMD_HISTORY is off, these are just flags. */
  94 public void * constant ml_search = (void *)1;
  95 public void * constant ml_examine = (void *)2;
  96 #if SHELL_ESCAPE || PIPEC
  97 public void * constant ml_shell = (void *)3;
  98 #endif
  99
 100 #endif /* CMD_HISTORY */
 101
 102 /*
 103  * History for the current command.
 104  */
 105 static struct mlist *curr_mlist = NULL;
 106 static int curr_cmdflags;
 107
 108 static char cmd_mbc_buf[MAX_UTF_CHAR_LEN];
 109 static int cmd_mbc_buf_len;
 110 static int cmd_mbc_buf_index;
 111
 112
 113 /*
 114  * Reset command buffer (to empty).
 115  */
 116         public void
 117 cmd_reset()
 118 {
 119         cp = cmdbuf;
 120         *cp = '\0';
 121         cmd_col = 0;
 122         cmd_offset = 0;
 123         literal = 0;
 124         cmd_mbc_buf_len = 0;
 125         updown_match = -1;
 126 }
 127
 128 /*
 129  * Clear command line.
 130  */
 131         public void
 132 clear_cmd()
 133 {
 134         cmd_col = prompt_col = 0;
 135         cmd_mbc_buf_len = 0;
 136         updown_match = -1;
 137 }
 138
 139 /*
 140  * Display a string, usually as a prompt for input into the command buffer.
 141  */
 142         public void
 143 cmd_putstr(s)
 144         char *s;
 145 {
 146         LWCHAR prev_ch = 0;
 147         LWCHAR ch;
 148         char *endline = s + strlen(s);
 149         while (*s != '\0')
 150         {
 151                 char *ns = s;
 152                 ch = step_char(&ns, +1, endline);
 153                 while (s < ns)
 154                         putchr(*s++);
 155                 if (!utf_mode)
 156                 {
 157                         cmd_col++;
 158                         prompt_col++;
 159                 } else if (!is_composing_char(ch) &&
 160                            !is_combining_char(prev_ch, ch))
 161                 {
 162                         int width = is_wide_char(ch) ? 2 : 1;
 163                         cmd_col += width;
 164                         prompt_col += width;
 165                 }
 166                 prev_ch = ch;
 167         }
 168 }
 169
 170 /*
 171  * How many characters are in the command buffer?
 172  */
 173         public int
 174 len_cmdbuf()
 175 {
 176         char *s = cmdbuf;
 177         char *endline = s + strlen(s);
 178         int len = 0;
 179
 180         while (*s != '\0')
 181         {
 182                 step_char(&s, +1, endline);
 183                 len++;
 184         }
 185         return (len);
 186 }
 187
 188 /*
 189  * Common part of cmd_step_right() and cmd_step_left().
 190  */
 191         static char *
 192 cmd_step_common(p, ch, len, pwidth, bswidth)
 193         char *p;
 194         LWCHAR ch;
 195         int len;
 196         int *pwidth;
 197         int *bswidth;
 198 {
 199         char *pr;
 200
 201         if (len == 1)
 202         {
 203                 pr = prchar((int) ch);
 204                 if (pwidth != NULL || bswidth != NULL)
 205                 {
 206                         int len = (int) strlen(pr);
 207                         if (pwidth != NULL)
 208                                 *pwidth = len;
 209                         if (bswidth != NULL)
 210                                 *bswidth = len;
 211                 }
 212         } else
 213         {
 214                 pr = prutfchar(ch);
 215                 if (pwidth != NULL || bswidth != NULL)
 216                 {
 217                         if (is_composing_char(ch))
 218                         {
 219                                 if (pwidth != NULL)
 220                                         *pwidth = 0;
 221                                 if (bswidth != NULL)
 222                                         *bswidth = 0;
 223                         } else if (is_ubin_char(ch))
 224                         {
 225                                 int len = (int) strlen(pr);
 226                                 if (pwidth != NULL)
 227                                         *pwidth = len;
 228                                 if (bswidth != NULL)
 229                                         *bswidth = len;
 230                         } else
 231                         {
 232                                 LWCHAR prev_ch = step_char(&p, -1, cmdbuf);
 233                                 if (is_combining_char(prev_ch, ch))
 234                                 {
 235                                         if (pwidth != NULL)
 236                                                 *pwidth = 0;
 237                                         if (bswidth != NULL)
 238                                                 *bswidth = 0;
 239                                 } else
 240                                 {
 241                                         if (pwidth != NULL)
 242                                                 *pwidth = is_wide_char(ch)
 243                                                         ?       2
 244                                                         :       1;
 245                                         if (bswidth != NULL)
 246                                                 *bswidth = 1;
 247                                 }
 248                         }
 249                 }
 250         }
 251
 252         return (pr);
 253 }
 254
 255 /*
 256  * Step a pointer one character right in the command buffer.
 257  */
 258         static char *
 259 cmd_step_right(pp, pwidth, bswidth)
 260         char **pp;
 261         int *pwidth;
 262         int *bswidth;
 263 {
 264         char *p = *pp;
 265         LWCHAR ch = step_char(pp, +1, p + strlen(p));
 266
 267         return cmd_step_common(p, ch, *pp - p, pwidth, bswidth);
 268 }
 269
 270 /*
 271  * Step a pointer one character left in the command buffer.
 272  */
 273         static char *
 274 cmd_step_left(pp, pwidth, bswidth)
 275         char **pp;
 276         int *pwidth;
 277         int *bswidth;
 278 {
 279         char *p = *pp;
 280         LWCHAR ch = step_char(pp, -1, cmdbuf);
 281
 282         return cmd_step_common(*pp, ch, p - *pp, pwidth, bswidth);
 283 }
 284
 285 /*
 286  * Repaint the line from cp onwards.
 287  * Then position the cursor just after the char old_cp (a pointer into cmdbuf).
 288  */
 289         static void
 290 cmd_repaint(old_cp)
 291         char *old_cp;
 292 {
 293         /*
 294          * Repaint the line from the current position.
 295          */
 296         clear_eol();
 297         while (*cp != '\0')
 298         {
 299                 char *np = cp;
 300                 int width;
 301                 char *pr = cmd_step_right(&np, &width, NULL);
 302                 if (cmd_col + width >= sc_width)
 303                         break;
 304                 cp = np;
 305                 putstr(pr);
 306                 cmd_col += width;
 307         }
 308         while (*cp != '\0')
 309         {
 310                 char *np = cp;
 311                 int width;
 312                 char *pr = cmd_step_right(&np, &width, NULL);
 313                 if (width > 0)
 314                         break;
 315                 cp = np;
 316                 putstr(pr);
 317         }
 318
 319         /*
 320          * Back up the cursor to the correct position.
 321          */
 322         while (cp > old_cp)
 323                 cmd_left();
 324 }
 325
 326 /*
 327  * Put the cursor at "home" (just after the prompt),
 328  * and set cp to the corresponding char in cmdbuf.
 329  */
 330         static void
 331 cmd_home()
 332 {
 333         while (cmd_col > prompt_col)
 334         {
 335                 int width, bswidth;
 336
 337                 cmd_step_left(&cp, &width, &bswidth);
 338                 while (bswidth-- > 0)
 339                         putbs();
 340                 cmd_col -= width;
 341         }
 342
 343         cp = &cmdbuf[cmd_offset];
 344 }
 345
 346 /*
 347  * Shift the cmdbuf display left a half-screen.
 348  */
 349         static void
 350 cmd_lshift()
 351 {
 352         char *s;
 353         char *save_cp;
 354         int cols;
 355
 356         /*
 357          * Start at the first displayed char, count how far to the
 358          * right we'd have to move to reach the center of the screen.
 359          */
 360         s = cmdbuf + cmd_offset;
 361         cols = 0;
 362         while (cols < (sc_width - prompt_col) / 2 && *s != '\0')
 363         {
 364                 int width;
 365                 cmd_step_right(&s, &width, NULL);
 366                 cols += width;
 367         }
 368         while (*s != '\0')
 369         {
 370                 int width;
 371                 char *ns = s;
 372                 cmd_step_right(&ns, &width, NULL);
 373                 if (width > 0)
 374                         break;
 375                 s = ns;
 376         }
 377
 378         cmd_offset = (int) (s - cmdbuf);
 379         save_cp = cp;
 380         cmd_home();
 381         cmd_repaint(save_cp);
 382 }
 383
 384 /*
 385  * Shift the cmdbuf display right a half-screen.
 386  */
 387         static void
 388 cmd_rshift()
 389 {
 390         char *s;
 391         char *save_cp;
 392         int cols;
 393
 394         /*
 395          * Start at the first displayed char, count how far to the
 396          * left we'd have to move to traverse a half-screen width
 397          * of displayed characters.
 398          */
 399         s = cmdbuf + cmd_offset;
 400         cols = 0;
 401         while (cols < (sc_width - prompt_col) / 2 && s > cmdbuf)
 402         {
 403                 int width;
 404                 cmd_step_left(&s, &width, NULL);
 405                 cols += width;
 406         }
 407
 408         cmd_offset = (int) (s - cmdbuf);
 409         save_cp = cp;
 410         cmd_home();
 411         cmd_repaint(save_cp);
 412 }
 413
 414 /*
 415  * Move cursor right one character.
 416  */
 417         static int
 418 cmd_right()
 419 {
 420         char *pr;
 421         char *ncp;
 422         int width;
 423
 424         if (*cp == '\0')
 425         {
 426                 /* Already at the end of the line. */
 427                 return (CC_OK);
 428         }
 429         ncp = cp;
 430         pr = cmd_step_right(&ncp, &width, NULL);
 431         if (cmd_col + width >= sc_width)
 432                 cmd_lshift();
 433         else if (cmd_col + width == sc_width - 1 && cp[1] != '\0')
 434                 cmd_lshift();
 435         cp = ncp;
 436         cmd_col += width;
 437         putstr(pr);
 438         while (*cp != '\0')
 439         {
 440                 pr = cmd_step_right(&ncp, &width, NULL);
 441                 if (width > 0)
 442                         break;
 443                 putstr(pr);
 444                 cp = ncp;
 445         }
 446         return (CC_OK);
 447 }
 448
 449 /*
 450  * Move cursor left one character.
 451  */
 452         static int
 453 cmd_left()
 454 {
 455         char *ncp;
 456         int width, bswidth;
 457
 458         if (cp <= cmdbuf)
 459         {
 460                 /* Already at the beginning of the line */
 461                 return (CC_OK);
 462         }
 463         ncp = cp;
 464         while (ncp > cmdbuf)
 465         {
 466                 cmd_step_left(&ncp, &width, &bswidth);
 467                 if (width > 0)
 468                         break;
 469         }
 470         if (cmd_col < prompt_col + width)
 471                 cmd_rshift();
 472         cp = ncp;
 473         cmd_col -= width;
 474         while (bswidth-- > 0)
 475                 putbs();
 476         return (CC_OK);
 477 }
 478
 479 /*
 480  * Insert a char into the command buffer, at the current position.
 481  */
 482         static int
 483 cmd_ichar(cs, clen)
 484         char *cs;
 485         int clen;
 486 {
 487         char *s;
 488
 489         if (strlen(cmdbuf) + clen >= sizeof(cmdbuf)-1)
 490         {
 491                 /* No room in the command buffer for another char. */
 492                 bell();
 493                 return (CC_ERROR);
 494         }
 495
 496         /*
 497          * Make room for the new character (shift the tail of the buffer right).
 498          */
 499         for (s = &cmdbuf[strlen(cmdbuf)];  s >= cp;  s--)
 500                 s[clen] = s[0];
 501         /*
 502          * Insert the character into the buffer.
 503          */
 504         for (s = cp;  s < cp + clen;  s++)
 505                 *s = *cs++;
 506         /*
 507          * Reprint the tail of the line from the inserted char.
 508          */
 509         updown_match = -1;
 510         cmd_repaint(cp);
 511         cmd_right();
 512         return (CC_OK);
 513 }
 514
 515 /*
 516  * Backspace in the command buffer.
 517  * Delete the char to the left of the cursor.
 518  */
 519         static int
 520 cmd_erase()
 521 {
 522         register char *s;
 523         int clen;
 524
 525         if (cp == cmdbuf)
 526         {
 527                 /*
 528                  * Backspace past beginning of the buffer:
 529                  * this usually means abort the command.
 530                  */
 531                 return (CC_QUIT);
 532         }
 533         /*
 534          * Move cursor left (to the char being erased).
 535          */
 536         s = cp;
 537         cmd_left();
 538         clen = (int) (s - cp);
 539
 540         /*
 541          * Remove the char from the buffer (shift the buffer left).
 542          */
 543         for (s = cp;  ;  s++)
 544         {
 545                 s[0] = s[clen];
 546                 if (s[0] == '\0')
 547                         break;
 548         }
 549
 550         /*
 551          * Repaint the buffer after the erased char.
 552          */
 553         updown_match = -1;
 554         cmd_repaint(cp);
 555
 556         /*
 557          * We say that erasing the entire command string causes us
 558          * to abort the current command, if CF_QUIT_ON_ERASE is set.
 559          */
 560         if ((curr_cmdflags & CF_QUIT_ON_ERASE) && cp == cmdbuf && *cp == '\0')
 561                 return (CC_QUIT);
 562         return (CC_OK);
 563 }
 564
 565 /*
 566  * Delete the char under the cursor.
 567  */
 568         static int
 569 cmd_delete()
 570 {
 571         if (*cp == '\0')
 572         {
 573                 /* At end of string; there is no char under the cursor. */
 574                 return (CC_OK);
 575         }
 576         /*
 577          * Move right, then use cmd_erase.
 578          */
 579         cmd_right();
 580         cmd_erase();
 581         return (CC_OK);
 582 }
 583
 584 /*
 585  * Delete the "word" to the left of the cursor.
 586  */
 587         static int
 588 cmd_werase()
 589 {
 590         if (cp > cmdbuf && cp[-1] == ' ')
 591         {
 592                 /*
 593                  * If the char left of cursor is a space,
 594                  * erase all the spaces left of cursor (to the first non-space).
 595                  */
 596                 while (cp > cmdbuf && cp[-1] == ' ')
 597                         (void) cmd_erase();
 598         } else
 599         {
 600                 /*
 601                  * If the char left of cursor is not a space,
 602                  * erase all the nonspaces left of cursor (the whole "word").
 603                  */
 604                 while (cp > cmdbuf && cp[-1] != ' ')
 605                         (void) cmd_erase();
 606         }
 607         return (CC_OK);
 608 }
 609
 610 /*
 611  * Delete the "word" under the cursor.
 612  */
 613         static int
 614 cmd_wdelete()
 615 {
 616         if (*cp == ' ')
 617         {
 618                 /*
 619                  * If the char under the cursor is a space,
 620                  * delete it and all the spaces right of cursor.
 621                  */
 622                 while (*cp == ' ')
 623                         (void) cmd_delete();
 624         } else
 625         {
 626                 /*
 627                  * If the char under the cursor is not a space,
 628                  * delete it and all nonspaces right of cursor (the whole word).
 629                  */
 630                 while (*cp != ' ' && *cp != '\0')
 631                         (void) cmd_delete();
 632         }
 633         return (CC_OK);
 634 }
 635
 636 /*
 637  * Delete all chars in the command buffer.
 638  */
 639         static int
 640 cmd_kill()
 641 {
 642         if (cmdbuf[0] == '\0')
 643         {
 644                 /* Buffer is already empty; abort the current command. */
 645                 return (CC_QUIT);
 646         }
 647         cmd_offset = 0;
 648         cmd_home();
 649         *cp = '\0';
 650         updown_match = -1;
 651         cmd_repaint(cp);
 652
 653         /*
 654          * We say that erasing the entire command string causes us
 655          * to abort the current command, if CF_QUIT_ON_ERASE is set.
 656          */
 657         if (curr_cmdflags & CF_QUIT_ON_ERASE)
 658                 return (CC_QUIT);
 659         return (CC_OK);
 660 }
 661
 662 /*
 663  * Select an mlist structure to be the current command history.
 664  */
 665         public void
 666 set_mlist(mlist, cmdflags)
 667         void *mlist;
 668         int cmdflags;
 669 {
 670 #if CMD_HISTORY
 671         curr_mlist = (struct mlist *) mlist;
 672         curr_cmdflags = cmdflags;
 673
 674         /* Make sure the next up-arrow moves to the last string in the mlist. */
 675         if (curr_mlist != NULL)
 676                 curr_mlist->curr_mp = curr_mlist;
 677 #endif
 678 }
 679
 680 #if CMD_HISTORY
 681 /*
 682  * Move up or down in the currently selected command history list.
 683  * Only consider entries whose first updown_match chars are equal to
 684  * cmdbuf's corresponding chars.
 685  */
 686         static int
 687 cmd_updown(action)
 688         int action;
 689 {
 690         char *s;
 691         struct mlist *ml;
 692
 693         if (curr_mlist == NULL)
 694         {
 695                 /*
 696                  * The current command has no history list.
 697                  */
 698                 bell();
 699                 return (CC_OK);
 700         }
 701
 702         if (updown_match < 0)
 703         {
 704                 updown_match = (int) (cp - cmdbuf);
 705         }
 706
 707         /*
 708          * Find the next history entry which matches.
 709          */
 710         for (ml = curr_mlist->curr_mp;;)
 711         {
 712                 ml = (action == EC_UP) ? ml->prev : ml->next;
 713                 if (ml == curr_mlist)
 714                 {
 715                         /*
 716                          * We reached the end (or beginning) of the list.
 717                          */
 718                         break;
 719                 }
 720                 if (strncmp(cmdbuf, ml->string, updown_match) == 0)
 721                 {
 722                         /*
 723                          * This entry matches; stop here.
 724                          * Copy the entry into cmdbuf and echo it on the screen.
 725                          */
 726                         curr_mlist->curr_mp = ml;
 727                         s = ml->string;
 728                         if (s == NULL)
 729                                 s = "";
 730                         cmd_home();
 731                         clear_eol();
 732                         strcpy(cmdbuf, s);
 733                         for (cp = cmdbuf;  *cp != '\0';  )
 734                                 cmd_right();
 735                         return (CC_OK);
 736                 }
 737         }
 738         /*
 739          * We didn't find a history entry that matches.
 740          */
 741         bell();
 742         return (CC_OK);
 743 }
 744 #endif
 745
 746 /*
 747  * Add a string to an mlist.
 748  */
 749         public void
 750 cmd_addhist(mlist, cmd, modified)
 751         struct mlist *mlist;
 752         char *cmd;
 753         int modified;
 754 {
 755 #if CMD_HISTORY
 756         struct mlist *ml;
 757
 758         /*
 759          * Don't save a trivial command.
 760          */
 761         if (strlen(cmd) == 0)
 762                 return;
 763
 764         /*
 765          * Save the command unless it's a duplicate of the
 766          * last command in the history.
 767          */
 768         ml = mlist->prev;
 769         if (ml == mlist || strcmp(ml->string, cmd) != 0)
 770         {
 771                 /*
 772                  * Did not find command in history.
 773                  * Save the command and put it at the end of the history list.
 774                  */
 775                 ml = (struct mlist *) ecalloc(1, sizeof(struct mlist));
 776                 ml->string = save(cmd);
 777                 ml->modified = modified;
 778                 ml->next = mlist;
 779                 ml->prev = mlist->prev;
 780                 mlist->prev->next = ml;
 781                 mlist->prev = ml;
 782         }
 783         /*
 784          * Point to the cmd just after the just-accepted command.
 785          * Thus, an UPARROW will always retrieve the previous command.
 786          */
 787         mlist->curr_mp = ml->next;
 788 #endif
 789 }
 790
 791 /*
 792  * Accept the command in the command buffer.
 793  * Add it to the currently selected history list.
 794  */
 795         public void
 796 cmd_accept()
 797 {
 798 #if CMD_HISTORY
 799         /*
 800          * Nothing to do if there is no currently selected history list.
 801          */
 802         if (curr_mlist == NULL)
 803                 return;
 804         cmd_addhist(curr_mlist, cmdbuf, 1);
 805         curr_mlist->modified = 1;
 806 #endif
 807 }
 808
 809 /*
 810  * Try to perform a line-edit function on the command buffer,
 811  * using a specified char as a line-editing command.
 812  * Returns:
 813  *      CC_PASS The char does not invoke a line edit function.
 814  *      CC_OK   Line edit function done.
 815  *      CC_QUIT The char requests the current command to be aborted.
 816  */
 817         static int
 818 cmd_edit(c)
 819         int c;
 820 {
 821         int action;
 822         int flags;
 823
 824 #if TAB_COMPLETE_FILENAME
 825 #define not_in_completion()     in_completion = 0
 826 #else
 827 #define not_in_completion()
 828 #endif
 829
 830         /*
 831          * See if the char is indeed a line-editing command.
 832          */
 833         flags = 0;
 834 #if CMD_HISTORY
 835         if (curr_mlist == NULL)
 836                 /*
 837                  * No current history; don't accept history manipulation cmds.
 838                  */
 839                 flags |= EC_NOHISTORY;
 840 #endif
 841 #if TAB_COMPLETE_FILENAME
 842         if (curr_mlist == ml_search)
 843                 /*
 844                  * In a search command; don't accept file-completion cmds.
 845                  */
 846                 flags |= EC_NOCOMPLETE;
 847 #endif
 848
 849         action = editchar(c, flags);
 850
 851         switch (action)
 852         {
 853         case EC_RIGHT:
 854                 not_in_completion();
 855                 return (cmd_right());
 856         case EC_LEFT:
 857                 not_in_completion();
 858                 return (cmd_left());
 859         case EC_W_RIGHT:
 860                 not_in_completion();
 861                 while (*cp != '\0' && *cp != ' ')
 862                         cmd_right();
 863                 while (*cp == ' ')
 864                         cmd_right();
 865                 return (CC_OK);
 866         case EC_W_LEFT:
 867                 not_in_completion();
 868                 while (cp > cmdbuf && cp[-1] == ' ')
 869                         cmd_left();
 870                 while (cp > cmdbuf && cp[-1] != ' ')
 871                         cmd_left();
 872                 return (CC_OK);
 873         case EC_HOME:
 874                 not_in_completion();
 875                 cmd_offset = 0;
 876                 cmd_home();
 877                 cmd_repaint(cp);
 878                 return (CC_OK);
 879         case EC_END:
 880                 not_in_completion();
 881                 while (*cp != '\0')
 882                         cmd_right();
 883                 return (CC_OK);
 884         case EC_INSERT:
 885                 not_in_completion();
 886                 return (CC_OK);
 887         case EC_BACKSPACE:
 888                 not_in_completion();
 889                 return (cmd_erase());
 890         case EC_LINEKILL:
 891                 not_in_completion();
 892                 return (cmd_kill());
 893         case EC_ABORT:
 894                 not_in_completion();
 895                 (void) cmd_kill();
 896                 return (CC_QUIT);
 897         case EC_W_BACKSPACE:
 898                 not_in_completion();
 899                 return (cmd_werase());
 900         case EC_DELETE:
 901                 not_in_completion();
 902                 return (cmd_delete());
 903         case EC_W_DELETE:
 904                 not_in_completion();
 905                 return (cmd_wdelete());
 906         case EC_LITERAL:
 907                 literal = 1;
 908                 return (CC_OK);
 909 #if CMD_HISTORY
 910         case EC_UP:
 911         case EC_DOWN:
 912                 not_in_completion();
 913                 return (cmd_updown(action));
 914 #endif
 915 #if TAB_COMPLETE_FILENAME
 916         case EC_F_COMPLETE:
 917         case EC_B_COMPLETE:
 918         case EC_EXPAND:
 919                 return (cmd_complete(action));
 920 #endif
 921         case EC_NOACTION:
 922                 return (CC_OK);
 923         default:
 924                 not_in_completion();
 925                 return (CC_PASS);
 926         }
 927 }
 928
 929 #if TAB_COMPLETE_FILENAME
 930 /*
 931  * Insert a string into the command buffer, at the current position.
 932  */
 933         static int
 934 cmd_istr(str)
 935         char *str;
 936 {
 937         char *s;
 938         int action;
 939         char *endline = str + strlen(str);
 940
 941         for (s = str;  *s != '\0';  )
 942         {
 943                 char *os = s;
 944                 step_char(&s, +1, endline);
 945                 action = cmd_ichar(os, s - os);
 946                 if (action != CC_OK)
 947                 {
 948                         bell();
 949                         return (action);
 950                 }
 951         }
 952         return (CC_OK);
 953 }
 954
 955 /*
 956  * Find the beginning and end of the "current" word.
 957  * This is the word which the cursor (cp) is inside or at the end of.
 958  * Return pointer to the beginning of the word and put the
 959  * cursor at the end of the word.
 960  */
 961         static char *
 962 delimit_word()
 963 {
 964         char *word;
 965 #if SPACES_IN_FILENAMES
 966         char *p;
 967         int delim_quoted = 0;
 968         int meta_quoted = 0;
 969         char *esc = get_meta_escape();
 970         int esclen = (int) strlen(esc);
 971 #endif
 972
 973         /*
 974          * Move cursor to end of word.
 975          */
 976         if (*cp != ' ' && *cp != '\0')
 977         {
 978                 /*
 979                  * Cursor is on a nonspace.
 980                  * Move cursor right to the next space.
 981                  */
 982                 while (*cp != ' ' && *cp != '\0')
 983                         cmd_right();
 984         } else if (cp > cmdbuf && cp[-1] != ' ')
 985         {
 986                 /*
 987                  * Cursor is on a space, and char to the left is a nonspace.
 988                  * We're already at the end of the word.
 989                  */
 990                 ;
 991 #if 0
 992         } else
 993         {
 994                 /*
 995                  * Cursor is on a space and char to the left is a space.
 996                  * Huh? There's no word here.
 997                  */
 998                 return (NULL);
 999 #endif
1000         }
1001         /*
1002          * Find the beginning of the word which the cursor is in.
1003          */
1004         if (cp == cmdbuf)
1005                 return (NULL);
1006 #if SPACES_IN_FILENAMES
1007         /*
1008          * If we have an unbalanced quote (that is, an open quote
1009          * without a corresponding close quote), we return everything
1010          * from the open quote, including spaces.
1011          */
1012         for (word = cmdbuf;  word < cp;  word++)
1013                 if (*word != ' ')
1014                         break;
1015         if (word >= cp)
1016                 return (cp);
1017         for (p = cmdbuf;  p < cp;  p++)
1018         {
1019                 if (meta_quoted)
1020                 {
1021                         meta_quoted = 0;
1022                 } else if (esclen > 0 && p + esclen < cp &&
1023                            strncmp(p, esc, esclen) == 0)
1024                 {
1025                         meta_quoted = 1;
1026                         p += esclen - 1;
1027                 } else if (delim_quoted)
1028                 {
1029                         if (*p == closequote)
1030                                 delim_quoted = 0;
1031                 } else /* (!delim_quoted) */
1032                 {
1033                         if (*p == openquote)
1034                                 delim_quoted = 1;
1035                         else if (*p == ' ')
1036                                 word = p+1;
1037                 }
1038         }
1039 #endif
1040         return (word);
1041 }
1042
1043 /*
1044  * Set things up to enter completion mode.
1045  * Expand the word under the cursor into a list of filenames
1046  * which start with that word, and set tk_text to that list.
1047  */
1048         static void
1049 init_compl()
1050 {
1051         char *word;
1052         char c;
1053
1054         /*
1055          * Get rid of any previous tk_text.
1056          */
1057         if (tk_text != NULL)
1058         {
1059                 free(tk_text);
1060                 tk_text = NULL;
1061         }
1062         /*
1063          * Find the original (uncompleted) word in the command buffer.
1064          */
1065         word = delimit_word();
1066         if (word == NULL)
1067                 return;
1068         /*
1069          * Set the insertion point to the point in the command buffer
1070          * where the original (uncompleted) word now sits.
1071          */
1072         tk_ipoint = word;
1073         /*
1074          * Save the original (uncompleted) word
1075          */
1076         if (tk_original != NULL)
1077                 free(tk_original);
1078         tk_original = (char *) ecalloc(cp-word+1, sizeof(char));
1079         strncpy(tk_original, word, cp-word);
1080         /*
1081          * Get the expanded filename.
1082          * This may result in a single filename, or
1083          * a blank-separated list of filenames.
1084          */
1085         c = *cp;
1086         *cp = '\0';
1087         if (*word != openquote)
1088         {
1089                 tk_text = fcomplete(word);
1090         } else
1091         {
1092 #if MSDOS_COMPILER
1093                 char *qword = NULL;
1094 #else
1095                 char *qword = shell_quote(word+1);
1096 #endif
1097                 if (qword == NULL)
1098                         tk_text = fcomplete(word+1);
1099                 else
1100                 {
1101                         tk_text = fcomplete(qword);
1102                         free(qword);
1103                 }
1104         }
1105         *cp = c;
1106 }
1107
1108 /*
1109  * Return the next word in the current completion list.
1110  */
1111         static char *
1112 next_compl(action, prev)
1113         int action;
1114         char *prev;
1115 {
1116         switch (action)
1117         {
1118         case EC_F_COMPLETE:
1119                 return (forw_textlist(&tk_tlist, prev));
1120         case EC_B_COMPLETE:
1121                 return (back_textlist(&tk_tlist, prev));
1122         }
1123         /* Cannot happen */
1124         return ("?");
1125 }
1126
1127 /*
1128  * Complete the filename before (or under) the cursor.
1129  * cmd_complete may be called multiple times.  The global in_completion
1130  * remembers whether this call is the first time (create the list),
1131  * or a subsequent time (step thru the list).
1132  */
1133         static int
1134 cmd_complete(action)
1135         int action;
1136 {
1137         char *s;
1138
1139         if (!in_completion || action == EC_EXPAND)
1140         {
1141                 /*
1142                  * Expand the word under the cursor and
1143                  * use the first word in the expansion
1144                  * (or the entire expansion if we're doing EC_EXPAND).
1145                  */
1146                 init_compl();
1147                 if (tk_text == NULL)
1148                 {
1149                         bell();
1150                         return (CC_OK);
1151                 }
1152                 if (action == EC_EXPAND)
1153                 {
1154                         /*
1155                          * Use the whole list.
1156                          */
1157                         tk_trial = tk_text;
1158                 } else
1159                 {
1160                         /*
1161                          * Use the first filename in the list.
1162                          */
1163                         in_completion = 1;
1164                         init_textlist(&tk_tlist, tk_text);
1165                         tk_trial = next_compl(action, (char*)NULL);
1166                 }
1167         } else
1168         {
1169                 /*
1170                  * We already have a completion list.
1171                  * Use the next/previous filename from the list.
1172                  */
1173                 tk_trial = next_compl(action, tk_trial);
1174         }
1175
1176         /*
1177          * Remove the original word, or the previous trial completion.
1178          */
1179         while (cp > tk_ipoint)
1180                 (void) cmd_erase();
1181
1182         if (tk_trial == NULL)
1183         {
1184                 /*
1185                  * There are no more trial completions.
1186                  * Insert the original (uncompleted) filename.
1187                  */
1188                 in_completion = 0;
1189                 if (cmd_istr(tk_original) != CC_OK)
1190                         goto fail;
1191         } else
1192         {
1193                 /*
1194                  * Insert trial completion.
1195                  */
1196                 if (cmd_istr(tk_trial) != CC_OK)
1197                         goto fail;
1198                 /*
1199                  * If it is a directory, append a slash.
1200                  */
1201                 if (is_dir(tk_trial))
1202                 {
1203                         if (cp > cmdbuf && cp[-1] == closequote)
1204                                 (void) cmd_erase();
1205                         s = lgetenv("LESSSEPARATOR");
1206                         if (s == NULL)
1207                                 s = PATHNAME_SEP;
1208                         if (cmd_istr(s) != CC_OK)
1209                                 goto fail;
1210                 }
1211         }
1212
1213         return (CC_OK);
1214
1215 fail:
1216         in_completion = 0;
1217         bell();
1218         return (CC_OK);
1219 }
1220
1221 #endif /* TAB_COMPLETE_FILENAME */
1222
1223 /*
1224  * Process a single character of a multi-character command, such as
1225  * a number, or the pattern of a search command.
1226  * Returns:
1227  *      CC_OK           The char was accepted.
1228  *      CC_QUIT         The char requests the command to be aborted.
1229  *      CC_ERROR        The char could not be accepted due to an error.
1230  */
1231         public int
1232 cmd_char(c)
1233         int c;
1234 {
1235         int action;
1236         int len;
1237
1238         if (!utf_mode)
1239         {
1240                 cmd_mbc_buf[0] = c;
1241                 len = 1;
1242         } else
1243         {
1244                 /* Perform strict validation in all possible cases.  */
1245                 if (cmd_mbc_buf_len == 0)
1246                 {
1247                  retry:
1248                         cmd_mbc_buf_index = 1;
1249                         *cmd_mbc_buf = c;
1250                         if (IS_ASCII_OCTET(c))
1251                                 cmd_mbc_buf_len = 1;
1252                         else if (IS_UTF8_LEAD(c))
1253                         {
1254                                 cmd_mbc_buf_len = utf_len(c);
1255                                 return (CC_OK);
1256                         } else
1257                         {
1258                                 /* UTF8_INVALID or stray UTF8_TRAIL */
1259                                 bell();
1260                                 return (CC_ERROR);
1261                         }
1262                 } else if (IS_UTF8_TRAIL(c))
1263                 {
1264                         cmd_mbc_buf[cmd_mbc_buf_index++] = c;
1265                         if (cmd_mbc_buf_index < cmd_mbc_buf_len)
1266                                 return (CC_OK);
1267                         if (!is_utf8_well_formed(cmd_mbc_buf, cmd_mbc_buf_index))
1268                         {
1269                                 /* complete, but not well formed (non-shortest form), sequence */
1270                                 cmd_mbc_buf_len = 0;
1271                                 bell();
1272                                 return (CC_ERROR);
1273                         }
1274                 } else
1275                 {
1276                         /* Flush incomplete (truncated) sequence.  */
1277                         cmd_mbc_buf_len = 0;
1278                         bell();
1279                         /* Handle new char.  */
1280                         goto retry;
1281                 }
1282
1283                 len = cmd_mbc_buf_len;
1284                 cmd_mbc_buf_len = 0;
1285         }
1286
1287         if (literal)
1288         {
1289                 /*
1290                  * Insert the char, even if it is a line-editing char.
1291                  */
1292                 literal = 0;
1293                 return (cmd_ichar(cmd_mbc_buf, len));
1294         }
1295
1296         /*
1297          * See if it is a line-editing character.
1298          */
1299         if (in_mca() && len == 1)
1300         {
1301                 action = cmd_edit(c);
1302                 switch (action)
1303                 {
1304                 case CC_OK:
1305                 case CC_QUIT:
1306                         return (action);
1307                 case CC_PASS:
1308                         break;
1309                 }
1310         }
1311
1312         /*
1313          * Insert the char into the command buffer.
1314          */
1315         return (cmd_ichar(cmd_mbc_buf, len));
1316 }
1317
1318 /*
1319  * Return the number currently in the command buffer.
1320  */
1321         public LINENUM
1322 cmd_int(frac)
1323         long *frac;
1324 {
1325         char *p;
1326         LINENUM n = 0;
1327         int err;
1328
1329         for (p = cmdbuf;  *p >= '0' && *p <= '9';  p++)
1330                 n = (n * 10) + (*p - '0');
1331         *frac = 0;
1332         if (*p++ == '.')
1333         {
1334                 *frac = getfraction(&p, NULL, &err);
1335                 /* {{ do something if err is set? }} */
1336         }
1337         return (n);
1338 }
1339
1340 /*
1341  * Return a pointer to the command buffer.
1342  */
1343         public char *
1344 get_cmdbuf()
1345 {
1346         return (cmdbuf);
1347 }
1348
1349 #if CMD_HISTORY
1350 /*
1351  * Return the last (most recent) string in the current command history.
1352  */
1353         public char *
1354 cmd_lastpattern()
1355 {
1356         if (curr_mlist == NULL)
1357                 return (NULL);
1358         return (curr_mlist->curr_mp->prev->string);
1359 }
1360 #endif
1361
1362 #if CMD_HISTORY
1363 /*
1364  */
1365         static int
1366 mlist_size(ml)
1367         struct mlist *ml;
1368 {
1369         int size = 0;
1370         for (ml = ml->next;  ml->string != NULL;  ml = ml->next)
1371                 ++size;
1372         return size;
1373 }
1374
1375 /*
1376  * Get the name of the history file.
1377  */
1378         static char *
1379 histfile_name()
1380 {
1381         char *home;
1382         char *name;
1383         int len;
1384
1385         /* See if filename is explicitly specified by $LESSHISTFILE. */
1386         name = lgetenv("LESSHISTFILE");
1387         if (name != NULL && *name != '\0')
1388         {
1389                 if (strcmp(name, "-") == 0 || strcmp(name, "/dev/null") == 0)
1390                         /* $LESSHISTFILE == "-" means don't use a history file. */
1391                         return (NULL);
1392                 return (save(name));
1393         }
1394
1395         /* See if history file is disabled in the build. */
1396         if (strcmp(LESSHISTFILE, "") == 0 || strcmp(LESSHISTFILE, "-") == 0)
1397                 return (NULL);
1398
1399         /* Otherwise, file is in $HOME. */
1400         home = lgetenv("HOME");
1401         if (home == NULL || *home == '\0')
1402         {
1403 #if OS2
1404                 home = lgetenv("INIT");
1405                 if (home == NULL || *home == '\0')
1406 #endif
1407                         return (NULL);
1408         }
1409         len = (int) (strlen(home) + strlen(LESSHISTFILE) + 2);
1410         name = (char *) ecalloc(len, sizeof(char));
1411         SNPRINTF2(name, len, "%s/%s", home, LESSHISTFILE);
1412         return (name);
1413 }
1414
1415 /*
1416  * Read a .lesshst file and call a callback for each line in the file.
1417  */
1418         static void
1419 read_cmdhist2(action, uparam, skip_search, skip_shell)
1420         void (*action)(void*,struct mlist*,char*);
1421         void *uparam;
1422         int skip_search;
1423         int skip_shell;
1424 {
1425         struct mlist *ml = NULL;
1426         char line[CMDBUF_SIZE];
1427         char *filename;
1428         FILE *f;
1429         char *p;
1430         int *skip = NULL;
1431
1432         filename = histfile_name();
1433         if (filename == NULL)
1434                 return;
1435         f = fopen(filename, "r");
1436         free(filename);
1437         if (f == NULL)
1438                 return;
1439         if (fgets(line, sizeof(line), f) == NULL ||
1440             strncmp(line, HISTFILE_FIRST_LINE, strlen(HISTFILE_FIRST_LINE)) != 0)
1441         {
1442                 fclose(f);
1443                 return;
1444         }
1445         while (fgets(line, sizeof(line), f) != NULL)
1446         {
1447                 for (p = line;  *p != '\0';  p++)
1448                 {
1449                         if (*p == '\n' || *p == '\r')
1450                         {
1451                                 *p = '\0';
1452                                 break;
1453                         }
1454                 }
1455                 if (strcmp(line, HISTFILE_SEARCH_SECTION) == 0)
1456                 {
1457                         ml = &mlist_search;
1458                         skip = &skip_search;
1459                 } else if (strcmp(line, HISTFILE_SHELL_SECTION) == 0)
1460                 {
1461 #if SHELL_ESCAPE || PIPEC
1462                         ml = &mlist_shell;
1463                         skip = &skip_shell;
1464 #else
1465                         ml = NULL;
1466                         skip = NULL;
1467 #endif
1468                 } else if (*line == '"')
1469                 {
1470                         if (ml != NULL)
1471                         {
1472                                 if (skip != NULL && *skip > 0)
1473                                         --(*skip);
1474                                 else
1475                                         (*action)(uparam, ml, line+1);
1476                         }
1477                 }
1478         }
1479         fclose(f);
1480 }
1481
1482         static void
1483 read_cmdhist(action, uparam, skip_search, skip_shell)
1484         void (*action)(void*,struct mlist*,char*);
1485         void *uparam;
1486         int skip_search;
1487         int skip_shell;
1488 {
1489         read_cmdhist2(action, uparam, skip_search, skip_shell);
1490         (*action)(uparam, NULL, NULL); /* signal end of file */
1491 }
1492
1493         static void
1494 addhist_init(void *uparam, struct mlist *ml, char *string)
1495 {
1496         if (ml == NULL || string == NULL)
1497                 return;
1498         cmd_addhist(ml, string, 0);
1499 }
1500 #endif /* CMD_HISTORY */
1501
1502 /*
1503  * Initialize history from a .lesshist file.
1504  */
1505         public void
1506 init_cmdhist()
1507 {
1508 #if CMD_HISTORY
1509         read_cmdhist(&addhist_init, NULL, 0, 0);
1510 #endif /* CMD_HISTORY */
1511 }
1512
1513 /*
1514  * Write the header for a section of the history file.
1515  */
1516 #if CMD_HISTORY
1517         static void
1518 write_mlist_header(ml, f)
1519         struct mlist *ml;
1520         FILE *f;
1521 {
1522         if (ml == &mlist_search)
1523                 fprintf(f, "%s\n", HISTFILE_SEARCH_SECTION);
1524 #if SHELL_ESCAPE || PIPEC
1525         else if (ml == &mlist_shell)
1526                 fprintf(f, "%s\n", HISTFILE_SHELL_SECTION);
1527 #endif
1528 }
1529
1530 /*
1531  * Write all modified entries in an mlist to the history file.
1532  */
1533         static void
1534 write_mlist(ml, f)
1535         struct mlist *ml;
1536         FILE *f;
1537 {
1538         for (ml = ml->next;  ml->string != NULL;  ml = ml->next)
1539         {
1540                 if (!ml->modified)
1541                         continue;
1542                 fprintf(f, "\"%s\n", ml->string);
1543                 ml->modified = 0;
1544         }
1545         ml->modified = 0; /* entire mlist is now unmodified */
1546 }
1547
1548 /*
1549  * Make a temp name in the same directory as filename.
1550  */
1551         static char *
1552 make_tempname(filename)
1553         char *filename;
1554 {
1555         char lastch;
1556         char *tempname = ecalloc(1, strlen(filename)+1);
1557         strcpy(tempname, filename);
1558         lastch = tempname[strlen(tempname)-1];
1559         tempname[strlen(tempname)-1] = (lastch == 'Q') ? 'Z' : 'Q';
1560         return tempname;
1561 }
1562
1563 struct save_ctx
1564 {
1565         struct mlist *mlist;
1566         FILE *fout;
1567 };
1568
1569 /*
1570  * Copy entries from the saved history file to a new file.
1571  * At the end of each mlist, append any new entries
1572  * created during this session.
1573  */
1574         static void
1575 copy_hist(void *uparam, struct mlist *ml, char *string)
1576 {
1577         struct save_ctx *ctx = (struct save_ctx *) uparam;
1578
1579         if (ml != ctx->mlist) {
1580                 /* We're changing mlists. */
1581                 if (ctx->mlist)
1582                         /* Append any new entries to the end of the current mlist. */
1583                         write_mlist(ctx->mlist, ctx->fout);
1584                 /* Write the header for the new mlist. */
1585                 ctx->mlist = ml;
1586                 write_mlist_header(ctx->mlist, ctx->fout);
1587         }
1588         if (string != NULL)
1589         {
1590                 /* Copy the entry. */
1591                 fprintf(ctx->fout, "\"%s\n", string);
1592         }
1593         if (ml == NULL) /* End of file */
1594         {
1595                 /* Write any sections that were not in the original file. */
1596                 if (mlist_search.modified)
1597                 {
1598                         write_mlist_header(&mlist_search, ctx->fout);
1599                         write_mlist(&mlist_search, ctx->fout);
1600                 }
1601 #if SHELL_ESCAPE || PIPEC
1602                 if (mlist_shell.modified)
1603                 {
1604                         write_mlist_header(&mlist_shell, ctx->fout);
1605                         write_mlist(&mlist_shell, ctx->fout);
1606                 }
1607 #endif
1608         }
1609 }
1610 #endif /* CMD_HISTORY */
1611
1612 /*
1613  * Make a file readable only by its owner.
1614  */
1615         static void
1616 make_file_private(f)
1617         FILE *f;
1618 {
1619 #if HAVE_FCHMOD
1620         int do_chmod = 1;
1621 #if HAVE_STAT
1622         struct stat statbuf;
1623         int r = fstat(fileno(f), &statbuf);
1624         if (r < 0 || !S_ISREG(statbuf.st_mode))
1625                 /* Don't chmod if not a regular file. */
1626                 do_chmod = 0;
1627 #endif
1628         if (do_chmod)
1629                 fchmod(fileno(f), 0600);
1630 #endif
1631 }
1632
1633 /*
1634  * Does the history file need to be updated?
1635  */
1636         static int
1637 histfile_modified()
1638 {
1639         if (mlist_search.modified)
1640                 return 1;
1641 #if SHELL_ESCAPE || PIPEC
1642         if (mlist_shell.modified)
1643                 return 1;
1644 #endif
1645         return 0;
1646 }
1647
1648 /*
1649  * Update the .lesshst file.
1650  */
1651         public void
1652 save_cmdhist()
1653 {
1654 #if CMD_HISTORY
1655         char *histname;
1656         char *tempname;
1657         int skip_search;
1658         int skip_shell;
1659         struct save_ctx ctx;
1660         char *s;
1661         FILE *fout = NULL;
1662         int histsize = 0;
1663
1664         if (!histfile_modified())
1665                 return;
1666         histname = histfile_name();
1667         if (histname == NULL)
1668                 return;
1669         tempname = make_tempname(histname);
1670         fout = fopen(tempname, "w");
1671         if (fout != NULL)
1672         {
1673                 make_file_private(fout);
1674                 s = lgetenv("LESSHISTSIZE");
1675                 if (s != NULL)
1676                         histsize = atoi(s);
1677                 if (histsize <= 0)
1678                         histsize = 100;
1679                 skip_search = mlist_size(&mlist_search) - histsize;
1680 #if SHELL_ESCAPE || PIPEC
1681                 skip_shell = mlist_size(&mlist_shell) - histsize;
1682 #endif
1683                 fprintf(fout, "%s\n", HISTFILE_FIRST_LINE);
1684                 ctx.fout = fout;
1685                 ctx.mlist = NULL;
1686                 read_cmdhist(copy_hist, &ctx, skip_search, skip_shell);
1687                 fclose(fout);
1688 #if MSDOS_COMPILER==WIN32C
1689                 /*
1690                  * Windows rename doesn't remove an existing file,
1691                  * making it useless for atomic operations. Sigh.
1692                  */
1693                 remove(histname);
1694 #endif
1695                 rename(tempname, histname);
1696         }
1697         free(tempname);
1698         free(histname);
1699 #endif /* CMD_HISTORY */
1700 }