src/doc.c

   1 /* Record indices of function doc strings stored in a file.
   2
   3 Copyright (C) 1985-1986, 1993-1995, 1997-2014 Free Software Foundation, Inc.
   4
   5 This file is part of GNU Emacs.
   6
   7 GNU Emacs is free software: you can redistribute it and/or modify
   8 it under the terms of the GNU General Public License as published by
   9 the Free Software Foundation, either version 3 of the License, or
  10 (at your option) any later version.
  11
  12 GNU Emacs is distributed in the hope that it will be useful,
  13 but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 GNU General Public License for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20
  21 #include <config.h>
  22
  23 #include <errno.h>
  24 #include <sys/types.h>
  25 #include <sys/file.h>   /* Must be after sys/types.h for USG.  */
  26 #include <fcntl.h>
  27 #include <unistd.h>
  28
  29 #include <c-ctype.h>
  30
  31 #include "lisp.h"
  32 #include "character.h"
  33 #include "buffer.h"
  34 #include "keyboard.h"
  35 #include "keymap.h"
  36
  37 Lisp_Object Qfunction_documentation;
  38
  39 /* Buffer used for reading from documentation file.  */
  40 static char *get_doc_string_buffer;
  41 static ptrdiff_t get_doc_string_buffer_size;
  42
  43 static unsigned char *read_bytecode_pointer;
  44
  45 /* `readchar' in lread.c calls back here to fetch the next byte.
  46    If UNREADFLAG is 1, we unread a byte.  */
  47
  48 int
  49 read_bytecode_char (bool unreadflag)
  50 {
  51   if (unreadflag)
  52     {
  53       read_bytecode_pointer--;
  54       return 0;
  55     }
  56   return *read_bytecode_pointer++;
  57 }
  58
  59 /* Extract a doc string from a file.  FILEPOS says where to get it.
  60    If it is an integer, use that position in the standard DOC file.
  61    If it is (FILE . INTEGER), use FILE as the file name
  62    and INTEGER as the position in that file.
  63    But if INTEGER is negative, make it positive.
  64    (A negative integer is used for user variables, so we can distinguish
  65    them without actually fetching the doc string.)
  66
  67    If the location does not point to the beginning of a docstring
  68    (e.g. because the file has been modified and the location is stale),
  69    return nil.
  70
  71    If UNIBYTE, always make a unibyte string.
  72
  73    If DEFINITION, assume this is for reading
  74    a dynamic function definition; convert the bytestring
  75    and the constants vector with appropriate byte handling,
  76    and return a cons cell.  */
  77
  78 Lisp_Object
  79 get_doc_string (Lisp_Object filepos, bool unibyte, bool definition)
  80 {
  81   char *from, *to, *name, *p, *p1;
  82   int fd;
  83   ptrdiff_t minsize;
  84   int offset;
  85   EMACS_INT position;
  86   Lisp_Object file, tem, pos;
  87   ptrdiff_t count;
  88   USE_SAFE_ALLOCA;
  89
  90   if (INTEGERP (filepos))
  91     {
  92       file = Vdoc_file_name;
  93       pos = filepos;
  94     }
  95   else if (CONSP (filepos))
  96     {
  97       file = XCAR (filepos);
  98       pos = XCDR (filepos);
  99     }
 100   else
 101     return Qnil;
 102
 103   position = eabs (XINT (pos));
 104
 105   if (!STRINGP (Vdoc_directory))
 106     return Qnil;
 107
 108   if (!STRINGP (file))
 109     return Qnil;
 110
 111   /* Put the file name in NAME as a C string.
 112      If it is relative, combine it with Vdoc_directory.  */
 113
 114   tem = Ffile_name_absolute_p (file);
 115   file = ENCODE_FILE (file);
 116   if (NILP (tem))
 117     {
 118       Lisp_Object docdir = ENCODE_FILE (Vdoc_directory);
 119       minsize = SCHARS (docdir);
 120       /* sizeof ("../etc/") == 8 */
 121       if (minsize < 8)
 122         minsize = 8;
 123       name = SAFE_ALLOCA (minsize + SCHARS (file) + 8);
 124       char *z = lispstpcpy (name, docdir);
 125       strcpy (z, SSDATA (file));
 126     }
 127   else
 128     {
 129       name = SSDATA (file);
 130     }
 131
 132   fd = emacs_open (name, O_RDONLY, 0);
 133   if (fd < 0)
 134     {
 135 #ifndef CANNOT_DUMP
 136       if (!NILP (Vpurify_flag))
 137         {
 138           /* Preparing to dump; DOC file is probably not installed.
 139              So check in ../etc.  */
 140           strcpy (name, "../etc/");
 141           strcat (name, SSDATA (file));
 142
 143           fd = emacs_open (name, O_RDONLY, 0);
 144         }
 145 #endif
 146       if (fd < 0)
 147         {
 148           SAFE_FREE ();
 149           AUTO_STRING (cannot_open, "Cannot open doc string file \"");
 150           AUTO_STRING (quote_nl, "\"\n");
 151           return concat3 (cannot_open, file, quote_nl);
 152         }
 153     }
 154   count = SPECPDL_INDEX ();
 155   record_unwind_protect_int (close_file_unwind, fd);
 156
 157   /* Seek only to beginning of disk block.  */
 158   /* Make sure we read at least 1024 bytes before `position'
 159      so we can check the leading text for consistency.  */
 160   offset = min (position, max (1024, position % (8 * 1024)));
 161   if (TYPE_MAXIMUM (off_t) < position
 162       || lseek (fd, position - offset, 0) < 0)
 163     error ("Position %"pI"d out of range in doc string file \"%s\"",
 164            position, name);
 165
 166   /* Read the doc string into get_doc_string_buffer.
 167      P points beyond the data just read.  */
 168
 169   p = get_doc_string_buffer;
 170   while (1)
 171     {
 172       ptrdiff_t space_left = (get_doc_string_buffer_size - 1
 173                               - (p - get_doc_string_buffer));
 174       int nread;
 175
 176       /* Allocate or grow the buffer if we need to.  */
 177       if (space_left <= 0)
 178         {
 179           ptrdiff_t in_buffer = p - get_doc_string_buffer;
 180           get_doc_string_buffer
 181             = xpalloc (get_doc_string_buffer, &get_doc_string_buffer_size,
 182                        16 * 1024, -1, 1);
 183           p = get_doc_string_buffer + in_buffer;
 184           space_left = (get_doc_string_buffer_size - 1
 185                         - (p - get_doc_string_buffer));
 186         }
 187
 188       /* Read a disk block at a time.
 189          If we read the same block last time, maybe skip this?  */
 190       if (space_left > 1024 * 8)
 191         space_left = 1024 * 8;
 192       nread = emacs_read (fd, p, space_left);
 193       if (nread < 0)
 194         report_file_error ("Read error on documentation file", file);
 195       p[nread] = 0;
 196       if (!nread)
 197         break;
 198       if (p == get_doc_string_buffer)
 199         p1 = strchr (p + offset, '\037');
 200       else
 201         p1 = strchr (p, '\037');
 202       if (p1)
 203         {
 204           *p1 = 0;
 205           p = p1;
 206           break;
 207         }
 208       p += nread;
 209     }
 210   unbind_to (count, Qnil);
 211   SAFE_FREE ();
 212
 213   /* Sanity checking.  */
 214   if (CONSP (filepos))
 215     {
 216       int test = 1;
 217       /* A dynamic docstring should be either at the very beginning of a "#@
 218          comment" or right after a dynamic docstring delimiter (in case we
 219          pack several such docstrings within the same comment).  */
 220       if (get_doc_string_buffer[offset - test] != '\037')
 221         {
 222           if (get_doc_string_buffer[offset - test++] != ' ')
 223             return Qnil;
 224           while (get_doc_string_buffer[offset - test] >= '0'
 225                  && get_doc_string_buffer[offset - test] <= '9')
 226             test++;
 227           if (get_doc_string_buffer[offset - test++] != '@'
 228               || get_doc_string_buffer[offset - test] != '#')
 229             return Qnil;
 230         }
 231     }
 232   else
 233     {
 234       int test = 1;
 235       if (get_doc_string_buffer[offset - test++] != '\n')
 236         return Qnil;
 237       while (get_doc_string_buffer[offset - test] > ' ')
 238         test++;
 239       if (get_doc_string_buffer[offset - test] != '\037')
 240         return Qnil;
 241     }
 242
 243   /* Scan the text and perform quoting with ^A (char code 1).
 244      ^A^A becomes ^A, ^A0 becomes a null char, and ^A_ becomes a ^_.  */
 245   from = get_doc_string_buffer + offset;
 246   to = get_doc_string_buffer + offset;
 247   while (from != p)
 248     {
 249       if (*from == 1)
 250         {
 251           int c;
 252
 253           from++;
 254           c = *from++;
 255           if (c == 1)
 256             *to++ = c;
 257           else if (c == '0')
 258             *to++ = 0;
 259           else if (c == '_')
 260             *to++ = 037;
 261           else
 262             {
 263               unsigned char uc = c;
 264               error ("\
 265 Invalid data in documentation file -- %c followed by code %03o",
 266                      1, uc);
 267             }
 268         }
 269       else
 270         *to++ = *from++;
 271     }
 272
 273   /* If DEFINITION, read from this buffer
 274      the same way we would read bytes from a file.  */
 275   if (definition)
 276     {
 277       read_bytecode_pointer = (unsigned char *) get_doc_string_buffer + offset;
 278       return Fread (Qlambda);
 279     }
 280
 281   if (unibyte)
 282     return make_unibyte_string (get_doc_string_buffer + offset,
 283                                 to - (get_doc_string_buffer + offset));
 284   else
 285     {
 286       /* The data determines whether the string is multibyte.  */
 287       ptrdiff_t nchars
 288         = multibyte_chars_in_text (((unsigned char *) get_doc_string_buffer
 289                                     + offset),
 290                                    to - (get_doc_string_buffer + offset));
 291       return make_string_from_bytes (get_doc_string_buffer + offset,
 292                                      nchars,
 293                                      to - (get_doc_string_buffer + offset));
 294     }
 295 }
 296
 297 /* Get a string from position FILEPOS and pass it through the Lisp reader.
 298    We use this for fetching the bytecode string and constants vector
 299    of a compiled function from the .elc file.  */
 300
 301 Lisp_Object
 302 read_doc_string (Lisp_Object filepos)
 303 {
 304   return get_doc_string (filepos, 0, 1);
 305 }
 306
 307 static bool
 308 reread_doc_file (Lisp_Object file)
 309 {
 310 #if 0
 311   Lisp_Object reply, prompt[3];
 312   struct gcpro gcpro1;
 313   GCPRO1 (file);
 314   prompt[0] = build_string ("File ");
 315   prompt[1] = NILP (file) ? Vdoc_file_name : file;
 316   prompt[2] = build_string (" is out of sync.  Reload? ");
 317   reply = Fy_or_n_p (Fconcat (3, prompt));
 318   UNGCPRO;
 319   if (NILP (reply))
 320     return 0;
 321 #endif
 322
 323   if (NILP (file))
 324     Fsnarf_documentation (Vdoc_file_name);
 325   else
 326     Fload (file, Qt, Qt, Qt, Qnil);
 327
 328   return 1;
 329 }
 330
 331 DEFUN ("documentation", Fdocumentation, Sdocumentation, 1, 2, 0,
 332        doc: /* Return the documentation string of FUNCTION.
 333 Unless a non-nil second argument RAW is given, the
 334 string is passed through `substitute-command-keys'.  */)
 335   (Lisp_Object function, Lisp_Object raw)
 336 {
 337   Lisp_Object fun;
 338   Lisp_Object funcar;
 339   Lisp_Object doc;
 340   bool try_reload = 1;
 341
 342  documentation:
 343
 344   doc = Qnil;
 345
 346   if (SYMBOLP (function))
 347     {
 348       Lisp_Object tem = Fget (function, Qfunction_documentation);
 349       if (!NILP (tem))
 350         return Fdocumentation_property (function, Qfunction_documentation,
 351                                         raw);
 352     }
 353
 354   fun = Findirect_function (function, Qnil);
 355   if (CONSP (fun) && EQ (XCAR (fun), Qmacro))
 356     fun = XCDR (fun);
 357   if (SUBRP (fun))
 358     {
 359       if (XSUBR (fun)->doc == 0)
 360         return Qnil;
 361       /* FIXME: This is not portable, as it assumes that string
 362          pointers have the top bit clear.  */
 363       else if ((intptr_t) XSUBR (fun)->doc >= 0)
 364         doc = build_string (XSUBR (fun)->doc);
 365       else
 366         doc = make_number ((intptr_t) XSUBR (fun)->doc);
 367     }
 368   else if (COMPILEDP (fun))
 369     {
 370       if ((ASIZE (fun) & PSEUDOVECTOR_SIZE_MASK) <= COMPILED_DOC_STRING)
 371         return Qnil;
 372       else
 373         {
 374           Lisp_Object tem = AREF (fun, COMPILED_DOC_STRING);
 375           if (STRINGP (tem))
 376             doc = tem;
 377           else if (NATNUMP (tem) || CONSP (tem))
 378             doc = tem;
 379           else
 380             return Qnil;
 381         }
 382     }
 383   else if (STRINGP (fun) || VECTORP (fun))
 384     {
 385       return build_string ("Keyboard macro.");
 386     }
 387   else if (CONSP (fun))
 388     {
 389       funcar = XCAR (fun);
 390       if (!SYMBOLP (funcar))
 391         xsignal1 (Qinvalid_function, fun);
 392       else if (EQ (funcar, Qkeymap))
 393         return build_string ("Prefix command (definition is a keymap associating keystrokes with commands).");
 394       else if (EQ (funcar, Qlambda)
 395                || (EQ (funcar, Qclosure) && (fun = XCDR (fun), 1))
 396                || EQ (funcar, Qautoload))
 397         {
 398           Lisp_Object tem1 = Fcdr (Fcdr (fun));
 399           Lisp_Object tem = Fcar (tem1);
 400           if (STRINGP (tem))
 401             doc = tem;
 402           /* Handle a doc reference--but these never come last
 403              in the function body, so reject them if they are last.  */
 404           else if ((NATNUMP (tem) || (CONSP (tem) && INTEGERP (XCDR (tem))))
 405                    && !NILP (XCDR (tem1)))
 406             doc = tem;
 407           else
 408             return Qnil;
 409         }
 410       else
 411         goto oops;
 412     }
 413   else
 414     {
 415     oops:
 416       xsignal1 (Qinvalid_function, fun);
 417     }
 418
 419   /* If DOC is 0, it's typically because of a dumped file missing
 420      from the DOC file (bug in src/Makefile.in).  */
 421   if (EQ (doc, make_number (0)))
 422     doc = Qnil;
 423   if (INTEGERP (doc) || CONSP (doc))
 424     {
 425       Lisp_Object tem;
 426       tem = get_doc_string (doc, 0, 0);
 427       if (NILP (tem) && try_reload)
 428         {
 429           /* The file is newer, we need to reset the pointers.  */
 430           struct gcpro gcpro1, gcpro2;
 431           GCPRO2 (function, raw);
 432           try_reload = reread_doc_file (Fcar_safe (doc));
 433           UNGCPRO;
 434           if (try_reload)
 435             {
 436               try_reload = 0;
 437               goto documentation;
 438             }
 439         }
 440       else
 441         doc = tem;
 442     }
 443
 444   if (NILP (raw))
 445     doc = Fsubstitute_command_keys (doc);
 446   return doc;
 447 }
 448
 449 DEFUN ("documentation-property", Fdocumentation_property,
 450        Sdocumentation_property, 2, 3, 0,
 451        doc: /* Return the documentation string that is SYMBOL's PROP property.
 452 Third argument RAW omitted or nil means pass the result through
 453 `substitute-command-keys' if it is a string.
 454
 455 This differs from `get' in that it can refer to strings stored in the
 456 `etc/DOC' file; and that it evaluates documentation properties that
 457 aren't strings.  */)
 458   (Lisp_Object symbol, Lisp_Object prop, Lisp_Object raw)
 459 {
 460   bool try_reload = 1;
 461   Lisp_Object tem;
 462
 463  documentation_property:
 464
 465   tem = Fget (symbol, prop);
 466   if (EQ (tem, make_number (0)))
 467     tem = Qnil;
 468   if (INTEGERP (tem) || (CONSP (tem) && INTEGERP (XCDR (tem))))
 469     {
 470       Lisp_Object doc = tem;
 471       tem = get_doc_string (tem, 0, 0);
 472       if (NILP (tem) && try_reload)
 473         {
 474           /* The file is newer, we need to reset the pointers.  */
 475           struct gcpro gcpro1, gcpro2, gcpro3;
 476           GCPRO3 (symbol, prop, raw);
 477           try_reload = reread_doc_file (Fcar_safe (doc));
 478           UNGCPRO;
 479           if (try_reload)
 480             {
 481               try_reload = 0;
 482               goto documentation_property;
 483             }
 484         }
 485     }
 486   else if (!STRINGP (tem))
 487     /* Feval protects its argument.  */
 488     tem = Feval (tem, Qnil);
 489
 490   if (NILP (raw) && STRINGP (tem))
 491     tem = Fsubstitute_command_keys (tem);
 492   return tem;
 493 }
 494 \f
 495 /* Scanning the DOC files and placing docstring offsets into functions.  */
 496
 497 static void
 498 store_function_docstring (Lisp_Object obj, ptrdiff_t offset)
 499 {
 500   /* Don't use indirect_function here, or defaliases will apply their
 501      docstrings to the base functions (Bug#2603).  */
 502   Lisp_Object fun = SYMBOLP (obj) ? XSYMBOL (obj)->function : obj;
 503
 504   /* The type determines where the docstring is stored.  */
 505
 506   /* Lisp_Subrs have a slot for it.  */
 507   if (SUBRP (fun))
 508     {
 509       intptr_t negative_offset = - offset;
 510       XSUBR (fun)->doc = (char *) negative_offset;
 511     }
 512
 513   /* If it's a lisp form, stick it in the form.  */
 514   else if (CONSP (fun))
 515     {
 516       Lisp_Object tem;
 517
 518       tem = XCAR (fun);
 519       if (EQ (tem, Qlambda) || EQ (tem, Qautoload)
 520           || (EQ (tem, Qclosure) && (fun = XCDR (fun), 1)))
 521         {
 522           tem = Fcdr (Fcdr (fun));
 523           if (CONSP (tem) && INTEGERP (XCAR (tem)))
 524             /* FIXME: This modifies typically pure hash-cons'd data, so its
 525                correctness is quite delicate.  */
 526             XSETCAR (tem, make_number (offset));
 527         }
 528       else if (EQ (tem, Qmacro))
 529         store_function_docstring (XCDR (fun), offset);
 530     }
 531
 532   /* Bytecode objects sometimes have slots for it.  */
 533   else if (COMPILEDP (fun))
 534     {
 535       /* This bytecode object must have a slot for the
 536          docstring, since we've found a docstring for it.  */
 537       if ((ASIZE (fun) & PSEUDOVECTOR_SIZE_MASK) > COMPILED_DOC_STRING)
 538         ASET (fun, COMPILED_DOC_STRING, make_number (offset));
 539       else
 540         message ("No docstring slot for %s",
 541                  SYMBOLP (obj) ? SSDATA (SYMBOL_NAME (obj)) : "<anonymous>");
 542     }
 543 }
 544
 545
 546 DEFUN ("Snarf-documentation", Fsnarf_documentation, Ssnarf_documentation,
 547        1, 1, 0,
 548        doc: /* Used during Emacs initialization to scan the `etc/DOC...' file.
 549 This searches the `etc/DOC...' file for doc strings and
 550 records them in function and variable definitions.
 551 The function takes one argument, FILENAME, a string;
 552 it specifies the file name (without a directory) of the DOC file.
 553 That file is found in `../etc' now; later, when the dumped Emacs is run,
 554 the same file name is found in the `doc-directory'.  */)
 555   (Lisp_Object filename)
 556 {
 557   int fd;
 558   char buf[1024 + 1];
 559   int filled;
 560   EMACS_INT pos;
 561   Lisp_Object sym;
 562   char *p, *name;
 563   bool skip_file = 0;
 564   ptrdiff_t count;
 565   char const *dirname;
 566   ptrdiff_t dirlen;
 567   /* Preloaded defcustoms using custom-initialize-delay are added to
 568      this list, but kept unbound.  See http://debbugs.gnu.org/11565  */
 569   Lisp_Object delayed_init =
 570     find_symbol_value (intern ("custom-delayed-init-variables"));
 571
 572   if (EQ (delayed_init, Qunbound)) delayed_init = Qnil;
 573
 574   CHECK_STRING (filename);
 575
 576   if
 577 #ifndef CANNOT_DUMP
 578     (!NILP (Vpurify_flag))
 579 #else /* CANNOT_DUMP */
 580       (0)
 581 #endif /* CANNOT_DUMP */
 582     {
 583       static char const sibling_etc[] = "../etc/";
 584       dirname = sibling_etc;
 585       dirlen = sizeof sibling_etc - 1;
 586     }
 587   else
 588     {
 589       CHECK_STRING (Vdoc_directory);
 590       dirname = SSDATA (Vdoc_directory);
 591       dirlen = SBYTES (Vdoc_directory);
 592     }
 593
 594   count = SPECPDL_INDEX ();
 595   USE_SAFE_ALLOCA;
 596   name = SAFE_ALLOCA (dirlen + SBYTES (filename) + 1);
 597   strcpy (name, dirname);
 598   strcat (name, SSDATA (filename));     /*** Add this line ***/
 599
 600   /* Vbuild_files is nil when temacs is run, and non-nil after that.  */
 601   if (NILP (Vbuild_files))
 602     {
 603       static char const *const buildobj[] =
 604         {
 605           #include "buildobj.h"
 606         };
 607       int i = ARRAYELTS (buildobj);
 608       while (0 <= --i)
 609         Vbuild_files = Fcons (build_string (buildobj[i]), Vbuild_files);
 610       Vbuild_files = Fpurecopy (Vbuild_files);
 611     }
 612
 613   fd = emacs_open (name, O_RDONLY, 0);
 614   if (fd < 0)
 615     {
 616       int open_errno = errno;
 617       report_file_errno ("Opening doc string file", build_string (name),
 618                          open_errno);
 619     }
 620   record_unwind_protect_int (close_file_unwind, fd);
 621   Vdoc_file_name = filename;
 622   filled = 0;
 623   pos = 0;
 624   while (1)
 625     {
 626       register char *end;
 627       if (filled < 512)
 628         filled += emacs_read (fd, &buf[filled], sizeof buf - 1 - filled);
 629       if (!filled)
 630         break;
 631
 632       buf[filled] = 0;
 633       end = buf + (filled < 512 ? filled : filled - 128);
 634       p = memchr (buf, '\037', end - buf);
 635       /* p points to ^_Ffunctionname\n or ^_Vvarname\n or ^_Sfilename\n.  */
 636       if (p)
 637         {
 638           end = strchr (p, '\n');
 639
 640           /* See if this is a file name, and if it is a file in build-files.  */
 641           if (p[1] == 'S')
 642             {
 643               skip_file = 0;
 644               if (end - p > 4 && end[-2] == '.'
 645                   && (end[-1] == 'o' || end[-1] == 'c'))
 646                 {
 647                   ptrdiff_t len = end - p - 2;
 648                   char *fromfile = SAFE_ALLOCA (len + 1);
 649                   memcpy (fromfile, &p[2], len);
 650                   fromfile[len] = 0;
 651                   if (fromfile[len-1] == 'c')
 652                     fromfile[len-1] = 'o';
 653
 654                   skip_file = NILP (Fmember (build_string (fromfile),
 655                                              Vbuild_files));
 656                 }
 657             }
 658
 659           sym = oblookup (Vobarray, p + 2,
 660                           multibyte_chars_in_text ((unsigned char *) p + 2,
 661                                                    end - p - 2),
 662                           end - p - 2);
 663           /* Check skip_file so that when a function is defined several
 664              times in different files (typically, once in xterm, once in
 665              w32term, ...), we only pay attention to the one that
 666              matters.  */
 667           if (! skip_file && SYMBOLP (sym))
 668             {
 669               /* Attach a docstring to a variable?  */
 670               if (p[1] == 'V')
 671                 {
 672                   /* Install file-position as variable-documentation property
 673                      and make it negative for a user-variable
 674                      (doc starts with a `*').  */
 675                   if (!NILP (Fboundp (sym))
 676                       || !NILP (Fmemq (sym, delayed_init)))
 677                     Fput (sym, Qvariable_documentation,
 678                           make_number ((pos + end + 1 - buf)
 679                                        * (end[1] == '*' ? -1 : 1)));
 680                 }
 681
 682               /* Attach a docstring to a function?  */
 683               else if (p[1] == 'F')
 684                 {
 685                   if (!NILP (Ffboundp (sym)))
 686                     store_function_docstring (sym, pos + end + 1 - buf);
 687                 }
 688               else if (p[1] == 'S')
 689                 ; /* Just a source file name boundary marker.  Ignore it.  */
 690
 691               else
 692                 error ("DOC file invalid at position %"pI"d", pos);
 693             }
 694         }
 695       pos += end - buf;
 696       filled -= end - buf;
 697       memmove (buf, end, filled);
 698     }
 699
 700   SAFE_FREE ();
 701   return unbind_to (count, Qnil);
 702 }
 703 \f
 704 DEFUN ("substitute-command-keys", Fsubstitute_command_keys,
 705        Ssubstitute_command_keys, 1, 1, 0,
 706        doc: /* Substitute key descriptions for command names in STRING.
 707 Each substring of the form \\=\\[COMMAND] is replaced by either a
 708 keystroke sequence that invokes COMMAND, or "M-x COMMAND" if COMMAND
 709 is not on any keys.
 710
 711 Each substring of the form \\=\\{MAPVAR} is replaced by a summary of
 712 the value of MAPVAR as a keymap.  This summary is similar to the one
 713 produced by `describe-bindings'.  The summary ends in two newlines
 714 \(used by the helper function `help-make-xrefs' to find the end of the
 715 summary).
 716
 717 Each substring of the form \\=\\<MAPVAR> specifies the use of MAPVAR
 718 as the keymap for future \\=\\[COMMAND] substrings.
 719 \\=\\= quotes the following character and is discarded;
 720 thus, \\=\\=\\=\\= puts \\=\\= into the output, and \\=\\=\\=\\[ puts \\=\\[ into the output.
 721
 722 Return the original STRING if no substitutions are made.
 723 Otherwise, return a new string.  */)
 724   (Lisp_Object string)
 725 {
 726   char *buf;
 727   bool changed = 0;
 728   unsigned char *strp;
 729   char *bufp;
 730   ptrdiff_t idx;
 731   ptrdiff_t bsize;
 732   Lisp_Object tem;
 733   Lisp_Object keymap;
 734   unsigned char *start;
 735   ptrdiff_t length, length_byte;
 736   Lisp_Object name;
 737   struct gcpro gcpro1, gcpro2, gcpro3, gcpro4;
 738   bool multibyte;
 739   ptrdiff_t nchars;
 740
 741   if (NILP (string))
 742     return Qnil;
 743
 744   CHECK_STRING (string);
 745   tem = Qnil;
 746   keymap = Qnil;
 747   name = Qnil;
 748   GCPRO4 (string, tem, keymap, name);
 749
 750   multibyte = STRING_MULTIBYTE (string);
 751   nchars = 0;
 752
 753   /* KEYMAP is either nil (which means search all the active keymaps)
 754      or a specified local map (which means search just that and the
 755      global map).  If non-nil, it might come from Voverriding_local_map,
 756      or from a \\<mapname> construct in STRING itself..  */
 757   keymap = Voverriding_local_map;
 758
 759   bsize = SBYTES (string);
 760   bufp = buf = xmalloc (bsize);
 761
 762   strp = SDATA (string);
 763   while (strp < SDATA (string) + SBYTES (string))
 764     {
 765       if (strp[0] == '\\' && strp[1] == '=')
 766         {
 767           /* \= quotes the next character;
 768              thus, to put in \[ without its special meaning, use \=\[.  */
 769           changed = 1;
 770           strp += 2;
 771           if (multibyte)
 772             {
 773               int len;
 774
 775               STRING_CHAR_AND_LENGTH (strp, len);
 776               if (len == 1)
 777                 *bufp = *strp;
 778               else
 779                 memcpy (bufp, strp, len);
 780               strp += len;
 781               bufp += len;
 782               nchars++;
 783             }
 784           else
 785             *bufp++ = *strp++, nchars++;
 786         }
 787       else if (strp[0] == '\\' && strp[1] == '[')
 788         {
 789           ptrdiff_t start_idx;
 790           bool follow_remap = 1;
 791
 792           changed = 1;
 793           strp += 2;            /* skip \[ */
 794           start = strp;
 795           start_idx = start - SDATA (string);
 796
 797           while ((strp - SDATA (string)
 798                   < SBYTES (string))
 799                  && *strp != ']')
 800             strp++;
 801           length_byte = strp - start;
 802
 803           strp++;               /* skip ] */
 804
 805           /* Save STRP in IDX.  */
 806           idx = strp - SDATA (string);
 807           name = Fintern (make_string ((char *) start, length_byte), Qnil);
 808
 809         do_remap:
 810           tem = Fwhere_is_internal (name, keymap, Qt, Qnil, Qnil);
 811
 812           if (VECTORP (tem) && ASIZE (tem) > 1
 813               && EQ (AREF (tem, 0), Qremap) && SYMBOLP (AREF (tem, 1))
 814               && follow_remap)
 815             {
 816               name = AREF (tem, 1);
 817               follow_remap = 0;
 818               goto do_remap;
 819             }
 820
 821           /* Note the Fwhere_is_internal can GC, so we have to take
 822              relocation of string contents into account.  */
 823           strp = SDATA (string) + idx;
 824           start = SDATA (string) + start_idx;
 825
 826           if (NILP (tem))       /* but not on any keys */
 827             {
 828               ptrdiff_t offset = bufp - buf;
 829               if (STRING_BYTES_BOUND - 4 < bsize)
 830                 string_overflow ();
 831               buf = xrealloc (buf, bsize += 4);
 832               bufp = buf + offset;
 833               memcpy (bufp, "M-x ", 4);
 834               bufp += 4;
 835               nchars += 4;
 836               if (multibyte)
 837                 length = multibyte_chars_in_text (start, length_byte);
 838               else
 839                 length = length_byte;
 840               goto subst;
 841             }
 842           else
 843             {                   /* function is on a key */
 844               tem = Fkey_description (tem, Qnil);
 845               goto subst_string;
 846             }
 847         }
 848       /* \{foo} is replaced with a summary of the keymap (symbol-value foo).
 849          \<foo> just sets the keymap used for \[cmd].  */
 850       else if (strp[0] == '\\' && (strp[1] == '{' || strp[1] == '<'))
 851         {
 852           struct buffer *oldbuf;
 853           ptrdiff_t start_idx;
 854           /* This is for computing the SHADOWS arg for describe_map_tree.  */
 855           Lisp_Object active_maps = Fcurrent_active_maps (Qnil, Qnil);
 856           Lisp_Object earlier_maps;
 857           ptrdiff_t count = SPECPDL_INDEX ();
 858
 859           changed = 1;
 860           strp += 2;            /* skip \{ or \< */
 861           start = strp;
 862           start_idx = start - SDATA (string);
 863
 864           while ((strp - SDATA (string) < SBYTES (string))
 865                  && *strp != '}' && *strp != '>')
 866             strp++;
 867
 868           length_byte = strp - start;
 869           strp++;                       /* skip } or > */
 870
 871           /* Save STRP in IDX.  */
 872           idx = strp - SDATA (string);
 873
 874           /* Get the value of the keymap in TEM, or nil if undefined.
 875              Do this while still in the user's current buffer
 876              in case it is a local variable.  */
 877           name = Fintern (make_string ((char *) start, length_byte), Qnil);
 878           tem = Fboundp (name);
 879           if (! NILP (tem))
 880             {
 881               tem = Fsymbol_value (name);
 882               if (! NILP (tem))
 883                 {
 884                   tem = get_keymap (tem, 0, 1);
 885                   /* Note that get_keymap can GC.  */
 886                   strp = SDATA (string) + idx;
 887                   start = SDATA (string) + start_idx;
 888                 }
 889             }
 890
 891           /* Now switch to a temp buffer.  */
 892           oldbuf = current_buffer;
 893           set_buffer_internal (XBUFFER (Vprin1_to_string_buffer));
 894           /* This is for an unusual case where some after-change
 895              function uses 'format' or 'prin1' or something else that
 896              will thrash Vprin1_to_string_buffer we are using.  */
 897           specbind (Qinhibit_modification_hooks, Qt);
 898
 899           if (NILP (tem))
 900             {
 901               name = Fsymbol_name (name);
 902               insert_string ("\nUses keymap `");
 903               insert_from_string (name, 0, 0,
 904                                   SCHARS (name),
 905                                   SBYTES (name), 1);
 906               insert_string ("', which is not currently defined.\n");
 907               if (start[-1] == '<') keymap = Qnil;
 908             }
 909           else if (start[-1] == '<')
 910             keymap = tem;
 911           else
 912             {
 913               /* Get the list of active keymaps that precede this one.
 914                  If this one's not active, get nil.  */
 915               earlier_maps = Fcdr (Fmemq (tem, Freverse (active_maps)));
 916               describe_map_tree (tem, 1, Fnreverse (earlier_maps),
 917                                  Qnil, 0, 1, 0, 0, 1);
 918             }
 919           tem = Fbuffer_string ();
 920           Ferase_buffer ();
 921           set_buffer_internal (oldbuf);
 922           unbind_to (count, Qnil);
 923
 924         subst_string:
 925           start = SDATA (tem);
 926           length = SCHARS (tem);
 927           length_byte = SBYTES (tem);
 928         subst:
 929           {
 930             ptrdiff_t offset = bufp - buf;
 931             if (STRING_BYTES_BOUND - length_byte < bsize)
 932               string_overflow ();
 933             buf = xrealloc (buf, bsize += length_byte);
 934             bufp = buf + offset;
 935             memcpy (bufp, start, length_byte);
 936             bufp += length_byte;
 937             nchars += length;
 938             /* Check STRING again in case gc relocated it.  */
 939             strp = SDATA (string) + idx;
 940           }
 941         }
 942       else if (! multibyte)             /* just copy other chars */
 943         *bufp++ = *strp++, nchars++;
 944       else
 945         {
 946           int len;
 947
 948           STRING_CHAR_AND_LENGTH (strp, len);
 949           if (len == 1)
 950             *bufp = *strp;
 951           else
 952             memcpy (bufp, strp, len);
 953           strp += len;
 954           bufp += len;
 955           nchars++;
 956         }
 957     }
 958
 959   if (changed)                  /* don't bother if nothing substituted */
 960     tem = make_string_from_bytes (buf, nchars, bufp - buf);
 961   else
 962     tem = string;
 963   xfree (buf);
 964   RETURN_UNGCPRO (tem);
 965 }
 966 \f
 967 void
 968 syms_of_doc (void)
 969 {
 970   DEFSYM (Qfunction_documentation, "function-documentation");
 971
 972   DEFVAR_LISP ("internal-doc-file-name", Vdoc_file_name,
 973                doc: /* Name of file containing documentation strings of built-in symbols.  */);
 974   Vdoc_file_name = Qnil;
 975
 976   DEFVAR_LISP ("build-files", Vbuild_files,
 977                doc: /* A list of files used to build this Emacs binary.  */);
 978   Vbuild_files = Qnil;
 979
 980   defsubr (&Sdocumentation);
 981   defsubr (&Sdocumentation_property);
 982   defsubr (&Ssnarf_documentation);
 983   defsubr (&Ssubstitute_command_keys);
 984 }