src/doc.c

   1 /* Record indices of function doc strings stored in a file.
   2
   3 Copyright (C) 1985-1986, 1993-1995, 1997-2013 Free Software Foundation,
   4 Inc.
   5
   6 This file is part of GNU Emacs.
   7
   8 GNU Emacs is free software: you can redistribute it and/or modify
   9 it under the terms of the GNU General Public License as published by
  10 the Free Software Foundation, either version 3 of the License, or
  11 (at your option) any later version.
  12
  13 GNU Emacs is distributed in the hope that it will be useful,
  14 but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 GNU General Public License for more details.
  17
  18 You should have received a copy of the GNU General Public License
  19 along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
  20
  21
  22 #include <config.h>
  23
  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 #include "buildobj.h"
  37
  38 Lisp_Object Qfunction_documentation;
  39
  40 /* Buffer used for reading from documentation file.  */
  41 static char *get_doc_string_buffer;
  42 static ptrdiff_t get_doc_string_buffer_size;
  43
  44 static unsigned char *read_bytecode_pointer;
  45
  46 /* readchar in lread.c calls back here to fetch the next byte.
  47    If UNREADFLAG is 1, we unread a byte.  */
  48
  49 int
  50 read_bytecode_char (bool unreadflag)
  51 {
  52   if (unreadflag)
  53     {
  54       read_bytecode_pointer--;
  55       return 0;
  56     }
  57   return *read_bytecode_pointer++;
  58 }
  59
  60 /* Extract a doc string from a file.  FILEPOS says where to get it.
  61    If it is an integer, use that position in the standard DOC-... file.
  62    If it is (FILE . INTEGER), use FILE as the file name
  63    and INTEGER as the position in that file.
  64    But if INTEGER is negative, make it positive.
  65    (A negative integer is used for user variables, so we can distinguish
  66    them without actually fetching the doc string.)
  67
  68    If the location does not point to the beginning of a docstring
  69    (e.g. because the file has been modified and the location is stale),
  70    return nil.
  71
  72    If UNIBYTE, always make a unibyte string.
  73
  74    If DEFINITION, assume this is for reading
  75    a dynamic function definition; convert the bytestring
  76    and the constants vector with appropriate byte handling,
  77    and return a cons cell.  */
  78
  79 Lisp_Object
  80 get_doc_string (Lisp_Object filepos, bool unibyte, bool definition)
  81 {
  82   char *from, *to, *name, *p, *p1;
  83   int fd;
  84   ptrdiff_t minsize;
  85   int offset;
  86   EMACS_INT position;
  87   Lisp_Object file, tem;
  88   USE_SAFE_ALLOCA;
  89
  90   if (INTEGERP (filepos))
  91     {
  92       file = Vdoc_file_name;
  93       position = XINT (filepos);
  94     }
  95   else if (CONSP (filepos))
  96     {
  97       file = XCAR (filepos);
  98       position = XINT (XCDR (filepos));
  99     }
 100   else
 101     return Qnil;
 102
 103   if (position < 0)
 104     position = - position;
 105
 106   if (!STRINGP (Vdoc_directory))
 107     return Qnil;
 108
 109   if (!STRINGP (file))
 110     return Qnil;
 111
 112   /* Put the file name in NAME as a C string.
 113      If it is relative, combine it with Vdoc_directory.  */
 114
 115   tem = Ffile_name_absolute_p (file);
 116   file = ENCODE_FILE (file);
 117   if (NILP (tem))
 118     {
 119       Lisp_Object docdir = ENCODE_FILE (Vdoc_directory);
 120       minsize = SCHARS (docdir);
 121       /* sizeof ("../etc/") == 8 */
 122       if (minsize < 8)
 123         minsize = 8;
 124       name = SAFE_ALLOCA (minsize + SCHARS (file) + 8);
 125       strcpy (name, SSDATA (docdir));
 126       strcat (name, SSDATA (file));
 127     }
 128   else
 129     {
 130       name = SSDATA (file);
 131     }
 132
 133   fd = emacs_open (name, O_RDONLY, 0);
 134   if (fd < 0)
 135     {
 136 #ifndef CANNOT_DUMP
 137       if (!NILP (Vpurify_flag))
 138         {
 139           /* Preparing to dump; DOC file is probably not installed.
 140              So check in ../etc.  */
 141           strcpy (name, "../etc/");
 142           strcat (name, SSDATA (file));
 143
 144           fd = emacs_open (name, O_RDONLY, 0);
 145         }
 146 #endif
 147       if (fd < 0)
 148         return concat3 (build_string ("Cannot open doc string file \""),
 149                         file, build_string ("\"\n"));
 150     }
 151
 152   /* Seek only to beginning of disk block.  */
 153   /* Make sure we read at least 1024 bytes before `position'
 154      so we can check the leading text for consistency.  */
 155   offset = min (position, max (1024, position % (8 * 1024)));
 156   if (TYPE_MAXIMUM (off_t) < position
 157       || lseek (fd, position - offset, 0) < 0)
 158     {
 159       emacs_close (fd);
 160       error ("Position %"pI"d out of range in doc string file \"%s\"",
 161              position, name);
 162     }
 163
 164   SAFE_FREE ();
 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         {
 195           emacs_close (fd);
 196           error ("Read error on documentation file");
 197         }
 198       p[nread] = 0;
 199       if (!nread)
 200         break;
 201       if (p == get_doc_string_buffer)
 202         p1 = strchr (p + offset, '\037');
 203       else
 204         p1 = strchr (p, '\037');
 205       if (p1)
 206         {
 207           *p1 = 0;
 208           p = p1;
 209           break;
 210         }
 211       p += nread;
 212     }
 213   emacs_close (fd);
 214
 215   /* Sanity checking.  */
 216   if (CONSP (filepos))
 217     {
 218       int test = 1;
 219       if (get_doc_string_buffer[offset - test++] != ' ')
 220         return Qnil;
 221       while (get_doc_string_buffer[offset - test] >= '0'
 222              && get_doc_string_buffer[offset - test] <= '9')
 223         test++;
 224       if (get_doc_string_buffer[offset - test++] != '@'
 225           || get_doc_string_buffer[offset - test] != '#')
 226         return Qnil;
 227     }
 228   else
 229     {
 230       int test = 1;
 231       if (get_doc_string_buffer[offset - test++] != '\n')
 232         return Qnil;
 233       while (get_doc_string_buffer[offset - test] > ' ')
 234         test++;
 235       if (get_doc_string_buffer[offset - test] != '\037')
 236         return Qnil;
 237     }
 238
 239   /* Scan the text and perform quoting with ^A (char code 1).
 240      ^A^A becomes ^A, ^A0 becomes a null char, and ^A_ becomes a ^_.  */
 241   from = get_doc_string_buffer + offset;
 242   to = get_doc_string_buffer + offset;
 243   while (from != p)
 244     {
 245       if (*from == 1)
 246         {
 247           int c;
 248
 249           from++;
 250           c = *from++;
 251           if (c == 1)
 252             *to++ = c;
 253           else if (c == '0')
 254             *to++ = 0;
 255           else if (c == '_')
 256             *to++ = 037;
 257           else
 258             {
 259               unsigned char uc = c;
 260               error ("\
 261 Invalid data in documentation file -- %c followed by code %03o",
 262                      1, uc);
 263             }
 264         }
 265       else
 266         *to++ = *from++;
 267     }
 268
 269   /* If DEFINITION, read from this buffer
 270      the same way we would read bytes from a file.  */
 271   if (definition)
 272     {
 273       read_bytecode_pointer = (unsigned char *) get_doc_string_buffer + offset;
 274       return Fread (Qlambda);
 275     }
 276
 277   if (unibyte)
 278     return make_unibyte_string (get_doc_string_buffer + offset,
 279                                 to - (get_doc_string_buffer + offset));
 280   else
 281     {
 282       /* The data determines whether the string is multibyte.  */
 283       ptrdiff_t nchars =
 284         multibyte_chars_in_text (((unsigned char *) get_doc_string_buffer
 285                                   + offset),
 286                                  to - (get_doc_string_buffer + offset));
 287       return make_string_from_bytes (get_doc_string_buffer + offset,
 288                                      nchars,
 289                                      to - (get_doc_string_buffer + offset));
 290     }
 291 }
 292
 293 /* Get a string from position FILEPOS and pass it through the Lisp reader.
 294    We use this for fetching the bytecode string and constants vector
 295    of a compiled function from the .elc file.  */
 296
 297 Lisp_Object
 298 read_doc_string (Lisp_Object filepos)
 299 {
 300   return get_doc_string (filepos, 0, 1);
 301 }
 302
 303 static bool
 304 reread_doc_file (Lisp_Object file)
 305 {
 306 #if 0
 307   Lisp_Object reply, prompt[3];
 308   struct gcpro gcpro1;
 309   GCPRO1 (file);
 310   prompt[0] = build_string ("File ");
 311   prompt[1] = NILP (file) ? Vdoc_file_name : file;
 312   prompt[2] = build_string (" is out of sync.  Reload? ");
 313   reply = Fy_or_n_p (Fconcat (3, prompt));
 314   UNGCPRO;
 315   if (NILP (reply))
 316     return 0;
 317 #endif
 318
 319   if (NILP (file))
 320     Fsnarf_documentation (Vdoc_file_name);
 321   else
 322     Fload (file, Qt, Qt, Qt, Qnil);
 323
 324   return 1;
 325 }
 326
 327 DEFUN ("documentation", Fdocumentation, Sdocumentation, 1, 2, 0,
 328        doc: /* Return the documentation string of FUNCTION.
 329 Unless a non-nil second argument RAW is given, the
 330 string is passed through `substitute-command-keys'.  */)
 331   (Lisp_Object function, Lisp_Object raw)
 332 {
 333   Lisp_Object fun;
 334   Lisp_Object funcar;
 335   Lisp_Object doc;
 336   bool try_reload = 1;
 337
 338  documentation:
 339
 340   doc = Qnil;
 341
 342   if (SYMBOLP (function))
 343     {
 344       Lisp_Object tem = Fget (function, Qfunction_documentation);
 345       if (!NILP (tem))
 346         return Fdocumentation_property (function, Qfunction_documentation,
 347                                         raw);
 348     }
 349
 350   fun = Findirect_function (function, Qnil);
 351   if (SUBRP (fun))
 352     {
 353       if (XSUBR (fun)->doc == 0)
 354         return Qnil;
 355       /* FIXME: This is not portable, as it assumes that string
 356          pointers have the top bit clear.  */
 357       else if ((intptr_t) XSUBR (fun)->doc >= 0)
 358         doc = build_string (XSUBR (fun)->doc);
 359       else
 360         doc = make_number ((intptr_t) XSUBR (fun)->doc);
 361     }
 362   else if (COMPILEDP (fun))
 363     {
 364       if ((ASIZE (fun) & PSEUDOVECTOR_SIZE_MASK) <= COMPILED_DOC_STRING)
 365         return Qnil;
 366       else
 367         {
 368           Lisp_Object tem = AREF (fun, COMPILED_DOC_STRING);
 369           if (STRINGP (tem))
 370             doc = tem;
 371           else if (NATNUMP (tem) || CONSP (tem))
 372             doc = tem;
 373           else
 374             return Qnil;
 375         }
 376     }
 377   else if (STRINGP (fun) || VECTORP (fun))
 378     {
 379       return build_string ("Keyboard macro.");
 380     }
 381   else if (CONSP (fun))
 382     {
 383       funcar = XCAR (fun);
 384       if (!SYMBOLP (funcar))
 385         xsignal1 (Qinvalid_function, fun);
 386       else if (EQ (funcar, Qkeymap))
 387         return build_string ("Prefix command (definition is a keymap associating keystrokes with commands).");
 388       else if (EQ (funcar, Qlambda)
 389                || (EQ (funcar, Qclosure) && (fun = XCDR (fun), 1))
 390                || EQ (funcar, Qautoload))
 391         {
 392           Lisp_Object tem1 = Fcdr (Fcdr (fun));
 393           Lisp_Object tem = Fcar (tem1);
 394           if (STRINGP (tem))
 395             doc = tem;
 396           /* Handle a doc reference--but these never come last
 397              in the function body, so reject them if they are last.  */
 398           else if ((NATNUMP (tem) || (CONSP (tem) && INTEGERP (XCDR (tem))))
 399                    && !NILP (XCDR (tem1)))
 400             doc = tem;
 401           else
 402             return Qnil;
 403         }
 404       else if (EQ (funcar, Qmacro))
 405         return Fdocumentation (Fcdr (fun), raw);
 406       else
 407         goto oops;
 408     }
 409   else
 410     {
 411     oops:
 412       xsignal1 (Qinvalid_function, fun);
 413     }
 414
 415   /* Check for an advised function.  Its doc string
 416      has an `ad-advice-info' text property.  */
 417   if (STRINGP (doc))
 418     {
 419       Lisp_Object innerfunc;
 420       innerfunc = Fget_text_property (make_number (0),
 421                                       intern ("ad-advice-info"),
 422                                       doc);
 423       if (! NILP (innerfunc))
 424         doc = call1 (intern ("ad-make-advised-docstring"), innerfunc);
 425     }
 426
 427   /* If DOC is 0, it's typically because of a dumped file missing
 428      from the DOC file (bug in src/Makefile.in).  */
 429   if (EQ (doc, make_number (0)))
 430     doc = Qnil;
 431   if (INTEGERP (doc) || CONSP (doc))
 432     {
 433       Lisp_Object tem;
 434       tem = get_doc_string (doc, 0, 0);
 435       if (NILP (tem) && try_reload)
 436         {
 437           /* The file is newer, we need to reset the pointers.  */
 438           struct gcpro gcpro1, gcpro2;
 439           GCPRO2 (function, raw);
 440           try_reload = reread_doc_file (Fcar_safe (doc));
 441           UNGCPRO;
 442           if (try_reload)
 443             {
 444               try_reload = 0;
 445               goto documentation;
 446             }
 447         }
 448       else
 449         doc = tem;
 450     }
 451
 452   if (NILP (raw))
 453     doc = Fsubstitute_command_keys (doc);
 454   return doc;
 455 }
 456
 457 DEFUN ("documentation-property", Fdocumentation_property,
 458        Sdocumentation_property, 2, 3, 0,
 459        doc: /* Return the documentation string that is SYMBOL's PROP property.
 460 Third argument RAW omitted or nil means pass the result through
 461 `substitute-command-keys' if it is a string.
 462
 463 This differs from `get' in that it can refer to strings stored in the
 464 `etc/DOC' file; and that it evaluates documentation properties that
 465 aren't strings.  */)
 466   (Lisp_Object symbol, Lisp_Object prop, Lisp_Object raw)
 467 {
 468   bool try_reload = 1;
 469   Lisp_Object tem;
 470
 471  documentation_property:
 472
 473   tem = Fget (symbol, prop);
 474   if (EQ (tem, make_number (0)))
 475     tem = Qnil;
 476   if (INTEGERP (tem) || (CONSP (tem) && INTEGERP (XCDR (tem))))
 477     {
 478       Lisp_Object doc = tem;
 479       tem = get_doc_string (tem, 0, 0);
 480       if (NILP (tem) && try_reload)
 481         {
 482           /* The file is newer, we need to reset the pointers.  */
 483           struct gcpro gcpro1, gcpro2, gcpro3;
 484           GCPRO3 (symbol, prop, raw);
 485           try_reload = reread_doc_file (Fcar_safe (doc));
 486           UNGCPRO;
 487           if (try_reload)
 488             {
 489               try_reload = 0;
 490               goto documentation_property;
 491             }
 492         }
 493     }
 494   else if (!STRINGP (tem))
 495     /* Feval protects its argument.  */
 496     tem = Feval (tem, Qnil);
 497
 498   if (NILP (raw) && STRINGP (tem))
 499     tem = Fsubstitute_command_keys (tem);
 500   return tem;
 501 }
 502 \f
 503 /* Scanning the DOC files and placing docstring offsets into functions.  */
 504
 505 static void
 506 store_function_docstring (Lisp_Object obj, ptrdiff_t offset)
 507 {
 508   /* Don't use indirect_function here, or defaliases will apply their
 509      docstrings to the base functions (Bug#2603).  */
 510   Lisp_Object fun = SYMBOLP (obj) ? XSYMBOL (obj)->function : obj;
 511
 512   /* The type determines where the docstring is stored.  */
 513
 514   /* Lisp_Subrs have a slot for it.  */
 515   if (SUBRP (fun))
 516     {
 517       intptr_t negative_offset = - offset;
 518       XSUBR (fun)->doc = (char *) negative_offset;
 519     }
 520
 521   /* If it's a lisp form, stick it in the form.  */
 522   else if (CONSP (fun))
 523     {
 524       Lisp_Object tem;
 525
 526       tem = XCAR (fun);
 527       if (EQ (tem, Qlambda) || EQ (tem, Qautoload)
 528           || (EQ (tem, Qclosure) && (fun = XCDR (fun), 1)))
 529         {
 530           tem = Fcdr (Fcdr (fun));
 531           if (CONSP (tem) && INTEGERP (XCAR (tem)))
 532             XSETCAR (tem, make_number (offset));
 533         }
 534       else if (EQ (tem, Qmacro))
 535         store_function_docstring (XCDR (fun), offset);
 536     }
 537
 538   /* Bytecode objects sometimes have slots for it.  */
 539   else if (COMPILEDP (fun))
 540     {
 541       /* This bytecode object must have a slot for the
 542          docstring, since we've found a docstring for it.  */
 543       if ((ASIZE (fun) & PSEUDOVECTOR_SIZE_MASK) > COMPILED_DOC_STRING)
 544         ASET (fun, COMPILED_DOC_STRING, make_number (offset));
 545     }
 546 }
 547
 548 static const char buildobj[] = BUILDOBJ;
 549
 550 DEFUN ("Snarf-documentation", Fsnarf_documentation, Ssnarf_documentation,
 551        1, 1, 0,
 552        doc: /* Used during Emacs initialization to scan the `etc/DOC...' file.
 553 This searches the `etc/DOC...' file for doc strings and
 554 records them in function and variable definitions.
 555 The function takes one argument, FILENAME, a string;
 556 it specifies the file name (without a directory) of the DOC file.
 557 That file is found in `../etc' now; later, when the dumped Emacs is run,
 558 the same file name is found in the `doc-directory'.  */)
 559   (Lisp_Object filename)
 560 {
 561   int fd;
 562   char buf[1024 + 1];
 563   int filled;
 564   EMACS_INT pos;
 565   Lisp_Object sym;
 566   char *p, *name;
 567   bool skip_file = 0;
 568
 569   CHECK_STRING (filename);
 570
 571   if
 572 #ifndef CANNOT_DUMP
 573     (!NILP (Vpurify_flag))
 574 #else /* CANNOT_DUMP */
 575       (0)
 576 #endif /* CANNOT_DUMP */
 577     {
 578       name = alloca (SCHARS (filename) + 14);
 579       strcpy (name, "../etc/");
 580     }
 581   else
 582     {
 583       CHECK_STRING (Vdoc_directory);
 584       name = alloca (SCHARS (filename) + SCHARS (Vdoc_directory) + 1);
 585       strcpy (name, SSDATA (Vdoc_directory));
 586     }
 587   strcat (name, SSDATA (filename));     /*** Add this line ***/
 588
 589   /* Vbuild_files is nil when temacs is run, and non-nil after that.  */
 590   if (NILP (Vbuild_files))
 591   {
 592     const char *beg, *end;
 593
 594     for (beg = buildobj; *beg; beg = end)
 595       {
 596         ptrdiff_t len;
 597
 598         while (*beg && c_isspace (*beg)) ++beg;
 599
 600         for (end = beg; *end && ! c_isspace (*end); ++end)
 601           if (*end == '/') beg = end+1;  /* skip directory part  */
 602
 603         len = end - beg;
 604         if (len > 4 && end[-4] == '.' && end[-3] == 'o')
 605           len -= 2;  /* Just take .o if it ends in .obj  */
 606
 607         if (len > 0)
 608           Vbuild_files = Fcons (make_string (beg, len), Vbuild_files);
 609       }
 610     Vbuild_files = Fpurecopy (Vbuild_files);
 611   }
 612
 613   fd = emacs_open (name, O_RDONLY, 0);
 614   if (fd < 0)
 615     report_file_error ("Opening doc string file",
 616                        Fcons (build_string (name), Qnil));
 617   Vdoc_file_name = filename;
 618   filled = 0;
 619   pos = 0;
 620   while (1)
 621     {
 622       register char *end;
 623       if (filled < 512)
 624         filled += emacs_read (fd, &buf[filled], sizeof buf - 1 - filled);
 625       if (!filled)
 626         break;
 627
 628       buf[filled] = 0;
 629       p = buf;
 630       end = buf + (filled < 512 ? filled : filled - 128);
 631       while (p != end && *p != '\037') p++;
 632       /* p points to ^_Ffunctionname\n or ^_Vvarname\n or ^_Sfilename\n.  */
 633       if (p != end)
 634         {
 635           end = strchr (p, '\n');
 636
 637           /* See if this is a file name, and if it is a file in build-files.  */
 638           if (p[1] == 'S')
 639             {
 640               skip_file = 0;
 641               if (end - p > 4 && end[-2] == '.'
 642                   && (end[-1] == 'o' || end[-1] == 'c'))
 643                 {
 644                   ptrdiff_t len = end - p - 2;
 645                   char *fromfile = alloca (len + 1);
 646                   memcpy (fromfile, &p[2], len);
 647                   fromfile[len] = 0;
 648                   if (fromfile[len-1] == 'c')
 649                     fromfile[len-1] = 'o';
 650
 651                   skip_file = NILP (Fmember (build_string (fromfile),
 652                                              Vbuild_files));
 653                 }
 654             }
 655
 656           sym = oblookup (Vobarray, p + 2,
 657                           multibyte_chars_in_text ((unsigned char *) p + 2,
 658                                                    end - p - 2),
 659                           end - p - 2);
 660           /* Check skip_file so that when a function is defined several
 661              times in different files (typically, once in xterm, once in
 662              w32term, ...), we only pay attention to the one that
 663              matters.  */
 664           if (! skip_file && SYMBOLP (sym))
 665             {
 666               /* Attach a docstring to a variable?  */
 667               if (p[1] == 'V')
 668                 {
 669                   /* Install file-position as variable-documentation property
 670                      and make it negative for a user-variable
 671                      (doc starts with a `*').  */
 672                   if (!NILP (Fboundp (sym)))
 673                     Fput (sym, Qvariable_documentation,
 674                           make_number ((pos + end + 1 - buf)
 675                                        * (end[1] == '*' ? -1 : 1)));
 676                 }
 677
 678               /* Attach a docstring to a function?  */
 679               else if (p[1] == 'F')
 680                 {
 681                   if (!NILP (Ffboundp (sym)))
 682                     store_function_docstring (sym, pos + end + 1 - buf);
 683                 }
 684               else if (p[1] == 'S')
 685                 ; /* Just a source file name boundary marker.  Ignore it.  */
 686
 687               else
 688                 error ("DOC file invalid at position %"pI"d", pos);
 689             }
 690         }
 691       pos += end - buf;
 692       filled -= end - buf;
 693       memmove (buf, end, filled);
 694     }
 695   emacs_close (fd);
 696   return Qnil;
 697 }
 698 \f
 699 DEFUN ("substitute-command-keys", Fsubstitute_command_keys,
 700        Ssubstitute_command_keys, 1, 1, 0,
 701        doc: /* Substitute key descriptions for command names in STRING.
 702 Each substring of the form \\=\\[COMMAND] is replaced by either a
 703 keystroke sequence that invokes COMMAND, or "M-x COMMAND" if COMMAND
 704 is not on any keys.
 705
 706 Each substring of the form \\=\\{MAPVAR} is replaced by a summary of
 707 the value of MAPVAR as a keymap.  This summary is similar to the one
 708 produced by `describe-bindings'.  The summary ends in two newlines
 709 \(used by the helper function `help-make-xrefs' to find the end of the
 710 summary).
 711
 712 Each substring of the form \\=\\<MAPVAR> specifies the use of MAPVAR
 713 as the keymap for future \\=\\[COMMAND] substrings.
 714 \\=\\= quotes the following character and is discarded;
 715 thus, \\=\\=\\=\\= puts \\=\\= into the output, and \\=\\=\\=\\[ puts \\=\\[ into the output.
 716
 717 Return the original STRING if no substitutions are made.
 718 Otherwise, return a new string, without any text properties.  */)
 719   (Lisp_Object string)
 720 {
 721   char *buf;
 722   bool changed = 0;
 723   unsigned char *strp;
 724   char *bufp;
 725   ptrdiff_t idx;
 726   ptrdiff_t bsize;
 727   Lisp_Object tem;
 728   Lisp_Object keymap;
 729   unsigned char *start;
 730   ptrdiff_t length, length_byte;
 731   Lisp_Object name;
 732   struct gcpro gcpro1, gcpro2, gcpro3, gcpro4;
 733   bool multibyte;
 734   ptrdiff_t nchars;
 735
 736   if (NILP (string))
 737     return Qnil;
 738
 739   CHECK_STRING (string);
 740   tem = Qnil;
 741   keymap = Qnil;
 742   name = Qnil;
 743   GCPRO4 (string, tem, keymap, name);
 744
 745   multibyte = STRING_MULTIBYTE (string);
 746   nchars = 0;
 747
 748   /* KEYMAP is either nil (which means search all the active keymaps)
 749      or a specified local map (which means search just that and the
 750      global map).  If non-nil, it might come from Voverriding_local_map,
 751      or from a \\<mapname> construct in STRING itself..  */
 752   keymap = KVAR (current_kboard, Voverriding_terminal_local_map);
 753   if (NILP (keymap))
 754     keymap = Voverriding_local_map;
 755
 756   bsize = SBYTES (string);
 757   bufp = buf = xmalloc (bsize);
 758
 759   strp = SDATA (string);
 760   while (strp < SDATA (string) + SBYTES (string))
 761     {
 762       if (strp[0] == '\\' && strp[1] == '=')
 763         {
 764           /* \= quotes the next character;
 765              thus, to put in \[ without its special meaning, use \=\[.  */
 766           changed = 1;
 767           strp += 2;
 768           if (multibyte)
 769             {
 770               int len;
 771
 772               STRING_CHAR_AND_LENGTH (strp, len);
 773               if (len == 1)
 774                 *bufp = *strp;
 775               else
 776                 memcpy (bufp, strp, len);
 777               strp += len;
 778               bufp += len;
 779               nchars++;
 780             }
 781           else
 782             *bufp++ = *strp++, nchars++;
 783         }
 784       else if (strp[0] == '\\' && strp[1] == '[')
 785         {
 786           ptrdiff_t start_idx;
 787           bool follow_remap = 1;
 788
 789           changed = 1;
 790           strp += 2;            /* skip \[ */
 791           start = strp;
 792           start_idx = start - SDATA (string);
 793
 794           while ((strp - SDATA (string)
 795                   < SBYTES (string))
 796                  && *strp != ']')
 797             strp++;
 798           length_byte = strp - start;
 799
 800           strp++;               /* skip ] */
 801
 802           /* Save STRP in IDX.  */
 803           idx = strp - SDATA (string);
 804           name = Fintern (make_string ((char *) start, length_byte), Qnil);
 805
 806         do_remap:
 807           tem = Fwhere_is_internal (name, keymap, Qt, Qnil, Qnil);
 808
 809           if (VECTORP (tem) && ASIZE (tem) > 1
 810               && EQ (AREF (tem, 0), Qremap) && SYMBOLP (AREF (tem, 1))
 811               && follow_remap)
 812             {
 813               name = AREF (tem, 1);
 814               follow_remap = 0;
 815               goto do_remap;
 816             }
 817
 818           /* Note the Fwhere_is_internal can GC, so we have to take
 819              relocation of string contents into account.  */
 820           strp = SDATA (string) + idx;
 821           start = SDATA (string) + start_idx;
 822
 823           if (NILP (tem))       /* but not on any keys */
 824             {
 825               ptrdiff_t offset = bufp - buf;
 826               if (STRING_BYTES_BOUND - 4 < bsize)
 827                 string_overflow ();
 828               buf = xrealloc (buf, bsize += 4);
 829               bufp = buf + offset;
 830               memcpy (bufp, "M-x ", 4);
 831               bufp += 4;
 832               nchars += 4;
 833               if (multibyte)
 834                 length = multibyte_chars_in_text (start, length_byte);
 835               else
 836                 length = length_byte;
 837               goto subst;
 838             }
 839           else
 840             {                   /* function is on a key */
 841               tem = Fkey_description (tem, Qnil);
 842               goto subst_string;
 843             }
 844         }
 845       /* \{foo} is replaced with a summary of the keymap (symbol-value foo).
 846          \<foo> just sets the keymap used for \[cmd].  */
 847       else if (strp[0] == '\\' && (strp[1] == '{' || strp[1] == '<'))
 848         {
 849           struct buffer *oldbuf;
 850           ptrdiff_t start_idx;
 851           /* This is for computing the SHADOWS arg for describe_map_tree.  */
 852           Lisp_Object active_maps = Fcurrent_active_maps (Qnil, Qnil);
 853           Lisp_Object earlier_maps;
 854
 855           changed = 1;
 856           strp += 2;            /* skip \{ or \< */
 857           start = strp;
 858           start_idx = start - SDATA (string);
 859
 860           while ((strp - SDATA (string) < SBYTES (string))
 861                  && *strp != '}' && *strp != '>')
 862             strp++;
 863
 864           length_byte = strp - start;
 865           strp++;                       /* skip } or > */
 866
 867           /* Save STRP in IDX.  */
 868           idx = strp - SDATA (string);
 869
 870           /* Get the value of the keymap in TEM, or nil if undefined.
 871              Do this while still in the user's current buffer
 872              in case it is a local variable.  */
 873           name = Fintern (make_string ((char *) start, length_byte), Qnil);
 874           tem = Fboundp (name);
 875           if (! NILP (tem))
 876             {
 877               tem = Fsymbol_value (name);
 878               if (! NILP (tem))
 879                 {
 880                   tem = get_keymap (tem, 0, 1);
 881                   /* Note that get_keymap can GC.  */
 882                   strp = SDATA (string) + idx;
 883                   start = SDATA (string) + start_idx;
 884                 }
 885             }
 886
 887           /* Now switch to a temp buffer.  */
 888           oldbuf = current_buffer;
 889           set_buffer_internal (XBUFFER (Vprin1_to_string_buffer));
 890
 891           if (NILP (tem))
 892             {
 893               name = Fsymbol_name (name);
 894               insert_string ("\nUses keymap `");
 895               insert_from_string (name, 0, 0,
 896                                   SCHARS (name),
 897                                   SBYTES (name), 1);
 898               insert_string ("', which is not currently defined.\n");
 899               if (start[-1] == '<') keymap = Qnil;
 900             }
 901           else if (start[-1] == '<')
 902             keymap = tem;
 903           else
 904             {
 905               /* Get the list of active keymaps that precede this one.
 906                  If this one's not active, get nil.  */
 907               earlier_maps = Fcdr (Fmemq (tem, Freverse (active_maps)));
 908               describe_map_tree (tem, 1, Fnreverse (earlier_maps),
 909                                  Qnil, (char *)0, 1, 0, 0, 1);
 910             }
 911           tem = Fbuffer_string ();
 912           Ferase_buffer ();
 913           set_buffer_internal (oldbuf);
 914
 915         subst_string:
 916           start = SDATA (tem);
 917           length = SCHARS (tem);
 918           length_byte = SBYTES (tem);
 919         subst:
 920           {
 921             ptrdiff_t offset = bufp - buf;
 922             if (STRING_BYTES_BOUND - length_byte < bsize)
 923               string_overflow ();
 924             buf = xrealloc (buf, bsize += length_byte);
 925             bufp = buf + offset;
 926             memcpy (bufp, start, length_byte);
 927             bufp += length_byte;
 928             nchars += length;
 929             /* Check STRING again in case gc relocated it.  */
 930             strp = SDATA (string) + idx;
 931           }
 932         }
 933       else if (! multibyte)             /* just copy other chars */
 934         *bufp++ = *strp++, nchars++;
 935       else
 936         {
 937           int len;
 938
 939           STRING_CHAR_AND_LENGTH (strp, len);
 940           if (len == 1)
 941             *bufp = *strp;
 942           else
 943             memcpy (bufp, strp, len);
 944           strp += len;
 945           bufp += len;
 946           nchars++;
 947         }
 948     }
 949
 950   if (changed)                  /* don't bother if nothing substituted */
 951     tem = make_string_from_bytes (buf, nchars, bufp - buf);
 952   else
 953     tem = string;
 954   xfree (buf);
 955   RETURN_UNGCPRO (tem);
 956 }
 957 \f
 958 void
 959 syms_of_doc (void)
 960 {
 961   DEFSYM (Qfunction_documentation, "function-documentation");
 962
 963   DEFVAR_LISP ("internal-doc-file-name", Vdoc_file_name,
 964                doc: /* Name of file containing documentation strings of built-in symbols.  */);
 965   Vdoc_file_name = Qnil;
 966
 967   DEFVAR_LISP ("build-files", Vbuild_files,
 968                doc: /* A list of files used to build this Emacs binary.  */);
 969   Vbuild_files = Qnil;
 970
 971   defsubr (&Sdocumentation);
 972   defsubr (&Sdocumentation_property);
 973   defsubr (&Ssnarf_documentation);
 974   defsubr (&Ssubstitute_command_keys);
 975 }