src/w16select.c

   1 /* 16-bit Windows Selection processing for emacs on MS-Windows
   2    Copyright (C) 1996, 1997, 2001, 2002, 2003, 2004,
   3                  2005, 2006, 2007, 2008 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 /* These functions work by using WinOldAp interface.  WinOldAp
  21    (WINOLDAP.MOD) is a Microsoft Windows extension supporting
  22    "old" (character-mode) application access to Dynamic Data Exchange,
  23    menus, and the Windows clipboard.  */
  24
  25 /* Written by Dale P. Smith <dpsm@en.com>  */
  26 /* Adapted to DJGPP v1 by Eli Zaretskii <eliz@is.elta.co.il>  */
  27
  28 #ifdef MSDOS
  29
  30 #include <config.h>
  31 #include <string.h>
  32 #include <dpmi.h>
  33 #include <go32.h>
  34 #include <sys/farptr.h>
  35 #include "lisp.h"
  36 #include "dispextern.h" /* frame.h seems to want this */
  37 #include "frame.h"      /* Need this to get the X window of selected_frame */
  38 #include "blockinput.h"
  39 #include "buffer.h"
  40 #include "character.h"
  41 #include "coding.h"
  42 #include "composite.h"
  43
  44 /* If ever some function outside this file will need to call any
  45    clipboard-related function, the following prototypes and constants
  46    should be put on a header file.  Right now, nobody else uses them.  */
  47
  48 #define CF_TEXT      0x01
  49 #define CF_BITMAP    0x02
  50 #define CF_METAFILE  0x03
  51 #define CF_SYLK      0x04
  52 #define CF_DIF       0x05
  53 #define CF_TIFF      0x06
  54 #define CF_OEMTEXT   0x07
  55 #define CF_DIBBITMAP 0x08
  56 #define CF_WINWRITE  0x80
  57 #define CF_DSPTEXT   0x81
  58 #define CF_DSPBITMAP 0x82
  59
  60 unsigned identify_winoldap_version (void);
  61 unsigned open_clipboard (void);
  62 unsigned empty_clipboard (void);
  63 unsigned set_clipboard_data (unsigned, void *, unsigned, int);
  64 unsigned get_clipboard_data_size (unsigned);
  65 unsigned get_clipboard_data (unsigned, void *, unsigned, int);
  66 unsigned close_clipboard (void);
  67 unsigned clipboard_compact (unsigned);
  68
  69 Lisp_Object QCLIPBOARD, QPRIMARY;
  70
  71 /* Coding system for communicating with other Windows programs via the
  72    clipboard.  */
  73 static Lisp_Object Vselection_coding_system;
  74
  75 /* Coding system for the next communicating with other Windows programs.  */
  76 static Lisp_Object Vnext_selection_coding_system;
  77
  78 /* The segment address and the size of the buffer in low
  79    memory used to move data between us and WinOldAp module.  */
  80 static struct {
  81   unsigned long size;
  82   unsigned short rm_segment;
  83 } clipboard_xfer_buf_info;
  84
  85 /* The last text we put into the clipboard.  This is used to prevent
  86    passing back our own text from the clipboard, instead of using the
  87    kill ring.  The former is undesirable because the clipboard data
  88    could be MULEtilated by inappropriately chosen
  89    (next-)selection-coding-system.  For this reason, we must store the
  90    text *after* it was encoded/Unix-to-DOS-converted.  */
  91 static unsigned char *last_clipboard_text;
  92
  93 /* The size of allocated storage for storing the clipboard data.  */
  94 static size_t clipboard_storage_size;
  95 \f
  96 /* Emulation of `__dpmi_int' and friends for DJGPP v1.x  */
  97
  98 #if __DJGPP__ < 2
  99
 100 typedef _go32_dpmi_registers __dpmi_regs;
 101 #define __tb      _go32_info_block.linear_address_of_transfer_buffer
 102 #define _dos_ds   _go32_info_block.selector_for_linear_memory
 103
 104 static int
 105 __dpmi_int (intno, regs)
 106      int intno;
 107      __dpmi_regs *regs;
 108 {
 109   regs->x.ss = regs->x.sp = regs->x.flags = 0;
 110   return _go32_dpmi_simulate_int (intno, regs);
 111 }
 112
 113 #endif /* __DJGPP__ < 2 */
 114 \f
 115 /* C functions to access the Windows 3.1x clipboard from DOS apps.
 116
 117    The information was obtained from the Microsoft Knowledge Base,
 118    article Q67675 and can be found at:
 119    http://www.microsoft.com/kb/developr/win_dk/q67675.htm  */
 120
 121 /* See also Ralf Brown's Interrupt List.
 122
 123    I also seem to remember reading about this in Dr. Dobbs Journal a
 124    while ago, but if you knew my memory...  :-)
 125
 126    Dale P. Smith <dpsm@en.com> */
 127
 128 /* Return the WinOldAp support version, or 0x1700 if not supported.  */
 129 unsigned
 130 identify_winoldap_version ()
 131 {
 132   __dpmi_regs regs;
 133
 134   /* Calls Int 2Fh/AX=1700h
 135      Return Values   AX == 1700H: Clipboard functions not available
 136                         <> 1700H: AL = Major version number
 137                                   AH = Minor version number */
 138   regs.x.ax = 0x1700;
 139   __dpmi_int(0x2f, &regs);
 140   return regs.x.ax;
 141 }
 142
 143 /* Open the clipboard, return non-zero if successfull.  */
 144 unsigned
 145 open_clipboard ()
 146 {
 147   __dpmi_regs regs;
 148
 149   /* Is WINOLDAP supported?  */
 150   /* Kludge alert!!  If WinOldAp is not supported, we return a 0,
 151      which is the same as ``Clipboard already open''.  Currently,
 152      this is taken as an error by all the functions that use
 153      `open_clipboard', but if somebody someday will use that ``open''
 154      clipboard, they will have interesting time debugging it...  */
 155   if (identify_winoldap_version () == 0x1700)
 156     return 0;
 157
 158   /* Calls Int 2Fh/AX=1701h
 159      Return Values   AX == 0: Clipboard already open
 160                         <> 0: Clipboard opened */
 161   regs.x.ax = 0x1701;
 162   __dpmi_int(0x2f, &regs);
 163   return regs.x.ax;
 164 }
 165
 166 /* Empty clipboard, return non-zero if successfull.  */
 167 unsigned
 168 empty_clipboard ()
 169 {
 170   __dpmi_regs regs;
 171
 172   /* Calls Int 2Fh/AX=1702h
 173      Return Values   AX == 0: Error occurred
 174                         <> 0: OK, Clipboard emptied */
 175   regs.x.ax = 0x1702;
 176   __dpmi_int(0x2f, &regs);
 177   return regs.x.ax;
 178 }
 179
 180 /* Ensure we have a buffer in low memory with enough memory for data
 181    of size WANT_SIZE.  Return the linear address of the buffer.  */
 182 static unsigned long
 183 alloc_xfer_buf (want_size)
 184      unsigned want_size;
 185 {
 186   __dpmi_regs regs;
 187
 188   /* If the usual DJGPP transfer buffer is large enough, use that.  */
 189   if (want_size <= _go32_info_block.size_of_transfer_buffer)
 190     return __tb & 0xfffff;
 191
 192   /* Don't even try to allocate more than 1MB of memory: DOS cannot
 193      possibly handle that (it will overflow the BX register below).  */
 194   if (want_size > 0xfffff)
 195     return 0;
 196
 197   /* Need size rounded up to the nearest paragraph, and in
 198      paragraph units (1 paragraph = 16 bytes).  */
 199   clipboard_xfer_buf_info.size = (want_size + 15) >> 4;
 200
 201   /* The NT DPMI host crashes us if we free DOS memory via the
 202      DPMI service.  Work around by calling DOS allocate/free block.  */
 203   regs.h.ah = 0x48;
 204   regs.x.bx = clipboard_xfer_buf_info.size;
 205   __dpmi_int (0x21, &regs);
 206   if (regs.x.flags & 1)
 207     {
 208       clipboard_xfer_buf_info.size = 0;
 209       return 0;
 210     }
 211
 212   clipboard_xfer_buf_info.rm_segment = regs.x.ax;
 213   return (((int)clipboard_xfer_buf_info.rm_segment) << 4) & 0xfffff;
 214 }
 215
 216 /* Free our clipboard buffer.  We always free it after use, because
 217    keeping it leaves less free conventional memory for subprocesses.
 218    The clipboard buffer tends to be large in size, because for small
 219    clipboard data sizes we use the DJGPP transfer buffer.  */
 220 static void
 221 free_xfer_buf ()
 222 {
 223   /* If the size is 0, we used DJGPP transfer buffer, so don't free.  */
 224   if (clipboard_xfer_buf_info.size)
 225     {
 226       __dpmi_regs regs;
 227
 228       /* The NT DPMI host crashes us if we free DOS memory via
 229          the DPMI service.  Work around by calling DOS free block.  */
 230       regs.h.ah = 0x49;
 231       regs.x.es = clipboard_xfer_buf_info.rm_segment;
 232       __dpmi_int (0x21, &regs);
 233       clipboard_xfer_buf_info.size = 0;
 234     }
 235 }
 236
 237 /* Copy data into the clipboard, return zero if successfull.  */
 238 unsigned
 239 set_clipboard_data (Format, Data, Size, Raw)
 240      unsigned Format;
 241      void *Data;
 242      unsigned Size;
 243      int Raw;
 244 {
 245   __dpmi_regs regs;
 246   unsigned truelen;
 247   unsigned long xbuf_addr, buf_offset;
 248   unsigned char *dp = Data, *dstart = dp;
 249
 250   if (Format != CF_OEMTEXT)
 251     return 3;
 252
 253   /* need to know final size after '\r' chars are inserted (the
 254      standard CF_OEMTEXT clipboard format uses CRLF line endings,
 255      while Emacs uses just LF internally).  */
 256   truelen = Size + 1;           /* +1 for the terminating null */
 257
 258   if (!Raw)
 259     {
 260       /* avoid using strchr because it recomputes the length everytime */
 261       while ((dp = memchr (dp, '\n', Size - (dp - dstart))) != 0)
 262         {
 263           truelen++;
 264           dp++;
 265         }
 266     }
 267
 268   if (clipboard_compact (truelen) < truelen)
 269     return 1;
 270
 271   if ((xbuf_addr = alloc_xfer_buf (truelen)) == 0)
 272     return 1;
 273
 274   /* Move the buffer into the low memory, convert LF into CR-LF if needed.  */
 275   if (Raw)
 276     {
 277       dosmemput (Data, Size, xbuf_addr);
 278
 279       /* Terminate with a null, otherwise Windows does strange things
 280          when the text size is an integral multiple of 32 bytes. */
 281       _farpokeb (_dos_ds, xbuf_addr + Size, '\0');
 282     }
 283   else
 284     {
 285       dp = Data;
 286       buf_offset = xbuf_addr;
 287       _farsetsel (_dos_ds);
 288       while (Size--)
 289         {
 290           /* Don't allow them to put binary data into the clipboard, since
 291              it will cause yanked data to be truncated at the first null.  */
 292           if (*dp == '\0')
 293             return 2;
 294           if (*dp == '\n')
 295             _farnspokeb (buf_offset++, '\r');
 296           _farnspokeb (buf_offset++, *dp++);
 297         }
 298
 299       /* Terminate with a null, otherwise Windows does strange things
 300          when the text size is an integral multiple of 32 bytes. */
 301       _farnspokeb (buf_offset, '\0');
 302     }
 303
 304   /* Stash away the data we are about to put into the clipboard, so we
 305      could later check inside get_clipboard_data whether the clipboard
 306      still holds our data.  */
 307   if (clipboard_storage_size < truelen)
 308     {
 309       clipboard_storage_size = truelen + 100;
 310       last_clipboard_text =
 311         (char *) xrealloc (last_clipboard_text, clipboard_storage_size);
 312     }
 313   if (last_clipboard_text)
 314     dosmemget (xbuf_addr, truelen, last_clipboard_text);
 315
 316   /* Calls Int 2Fh/AX=1703h with:
 317                      DX = WinOldAp-Supported Clipboard format
 318                      ES:BX = Pointer to data
 319                      SI:CX = Size of data in bytes
 320      Return Values   AX == 0: Error occurred
 321                         <> 0: OK.  Data copied into the Clipboard.  */
 322   regs.x.ax = 0x1703;
 323   regs.x.dx = Format;
 324   regs.x.si = truelen >> 16;
 325   regs.x.cx = truelen & 0xffff;
 326   regs.x.es = xbuf_addr >> 4;
 327   regs.x.bx = xbuf_addr & 15;
 328   __dpmi_int(0x2f, &regs);
 329
 330   free_xfer_buf ();
 331
 332   /* If the above failed, invalidate the local copy of the clipboard.  */
 333   if (regs.x.ax == 0)
 334     *last_clipboard_text = '\0';
 335
 336   /* Zero means success, otherwise (1, 2, or 3) it's an error.  */
 337   return regs.x.ax > 0 ? 0 : 3;
 338 }
 339
 340 /* Return the size of the clipboard data of format FORMAT.  */
 341 unsigned
 342 get_clipboard_data_size (Format)
 343      unsigned Format;
 344 {
 345   __dpmi_regs regs;
 346
 347   /* Calls Int 2Fh/AX=1704h with:
 348                      DX = WinOldAp-Supported Clipboard format
 349      Return Values   DX:AX == Size of the data in bytes, including any
 350                               headers.
 351                            == 0 If data in this format is not in
 352                            the clipboard.  */
 353   regs.x.ax = 0x1704;
 354   regs.x.dx = Format;
 355   __dpmi_int(0x2f, &regs);
 356   return ( (((unsigned)regs.x.dx) << 16) | regs.x.ax);
 357 }
 358
 359 /* Get clipboard data, return its length.
 360    Warning: this doesn't check whether DATA has enough space to hold
 361    SIZE bytes.  */
 362 unsigned
 363 get_clipboard_data (Format, Data, Size, Raw)
 364      unsigned Format;
 365      void *Data;
 366      unsigned Size;
 367      int Raw;
 368 {
 369   __dpmi_regs regs;
 370   unsigned long xbuf_addr;
 371   unsigned char *dp = Data;
 372
 373   if (Format != CF_OEMTEXT)
 374     return 0;
 375
 376   if (Size == 0)
 377     return 0;
 378
 379   if ((xbuf_addr = alloc_xfer_buf (Size)) == 0)
 380     return 0;
 381
 382   /* Calls Int 2Fh/AX=1705h with:
 383                      DX = WinOldAp-Supported Clipboard format
 384                      ES:BX = Pointer to data buffer to hold data
 385      Return Values   AX == 0: Error occurred (or data in this format is not
 386                               in the clipboard)
 387                         <> 0: OK  */
 388   regs.x.ax = 0x1705;
 389   regs.x.dx = Format;
 390   regs.x.es = xbuf_addr >> 4;
 391   regs.x.bx = xbuf_addr & 15;
 392   __dpmi_int(0x2f, &regs);
 393   if (regs.x.ax != 0)
 394     {
 395       unsigned char null_char = '\0';
 396       unsigned long xbuf_beg = xbuf_addr;
 397
 398       /* If last_clipboard_text is NULL, we don't want to slow down
 399          the next loop by an additional test.  */
 400       register unsigned char *lcdp =
 401         last_clipboard_text == NULL ? &null_char : last_clipboard_text;
 402
 403       /* Copy data from low memory, remove CR
 404          characters before LF if needed.  */
 405       _farsetsel (_dos_ds);
 406       while (Size--)
 407         {
 408           register unsigned char c = _farnspeekb (xbuf_addr++);
 409
 410           if (*lcdp == c)
 411             lcdp++;
 412
 413           if ((*dp++ = c) == '\r' && !Raw && _farnspeekb (xbuf_addr) == '\n')
 414             {
 415               dp--;
 416               *dp++ = '\n';
 417               xbuf_addr++;
 418               if (*lcdp == '\n')
 419                 lcdp++;
 420             }
 421           /* Windows reportedly rounds up the size of clipboard data
 422              (passed in SIZE) to a multiple of 32, and removes trailing
 423              spaces from each line without updating SIZE.  We therefore
 424              bail out when we see the first null character.  */
 425           else if (c == '\0')
 426             break;
 427         }
 428
 429       /* If the text in clipboard is identical to what we put there
 430          last time set_clipboard_data was called, pretend there's no
 431          data in the clipboard.  This is so we don't pass our own text
 432          from the clipboard (which might be troublesome if the killed
 433          text includes null characters).  */
 434       if (last_clipboard_text &&
 435           xbuf_addr - xbuf_beg == (long)(lcdp - last_clipboard_text))
 436         dp = (unsigned char *)Data + 1;
 437     }
 438
 439   free_xfer_buf ();
 440
 441   return (unsigned) (dp - (unsigned char *)Data - 1);
 442 }
 443
 444 /* Close clipboard, return non-zero if successfull.  */
 445 unsigned
 446 close_clipboard ()
 447 {
 448   __dpmi_regs regs;
 449
 450   /* Calls Int 2Fh/AX=1708h
 451      Return Values   AX == 0: Error occurred
 452                         <> 0: OK */
 453   regs.x.ax = 0x1708;
 454   __dpmi_int(0x2f, &regs);
 455   return regs.x.ax;
 456 }
 457
 458 /* Compact clipboard data so that at least SIZE bytes is available.  */
 459 unsigned
 460 clipboard_compact (Size)
 461      unsigned Size;
 462 {
 463   __dpmi_regs regs;
 464
 465   /* Calls Int 2Fh/AX=1709H with:
 466                      SI:CX = Desired memory size in bytes.
 467      Return Values   DX:AX == Number of bytes of largest block of free memory.
 468                            == 0 if error or no memory  */
 469   regs.x.ax = 0x1709;
 470   regs.x.si = Size >> 16;
 471   regs.x.cx = Size & 0xffff;
 472   __dpmi_int(0x2f, &regs);
 473   return ((unsigned)regs.x.dx << 16) | regs.x.ax;
 474 }
 475 \f
 476 static char no_mem_msg[] =
 477   "(Not enough DOS memory to put saved text into clipboard.)";
 478 static char binary_msg[] =
 479   "(Binary characters in saved text; clipboard data not set.)";
 480 static char system_error_msg[] =
 481   "(Clipboard interface failure; clipboard data not set.)";
 482
 483 DEFUN ("w16-set-clipboard-data", Fw16_set_clipboard_data, Sw16_set_clipboard_data, 1, 2, 0,
 484        doc: /* This sets the clipboard data to the given text.  */)
 485      (string, frame)
 486      Lisp_Object string, frame;
 487 {
 488   unsigned ok = 1, put_status = 0;
 489   int nbytes, charset_info, no_crlf_conversion;
 490   unsigned char *src, *dst = NULL;
 491
 492   CHECK_STRING (string);
 493
 494   if (NILP (frame))
 495     frame = Fselected_frame ();
 496
 497   CHECK_LIVE_FRAME (frame);
 498   if ( !FRAME_MSDOS_P (XFRAME (frame)))
 499     goto done;
 500
 501   BLOCK_INPUT;
 502
 503   if (!open_clipboard ())
 504     goto error;
 505
 506   nbytes = SBYTES (string);
 507   src = SDATA (string);
 508
 509   /* Do we need to encode this text?  */
 510   for (dst = src; dst < src + nbytes; dst++)
 511     {
 512       if (*dst == '\0' || *dst >= 0x80)
 513         break;
 514     }
 515   if (dst >= src + nbytes)
 516     {
 517       /* No multibyte characters in text.  We need not encode it, but we
 518          will have to convert it to DOS CR-LF style.  */
 519       no_crlf_conversion = 0;
 520       Vlast_coding_system_used = Qraw_text;
 521       dst = NULL;       /* so we don't try to free a random pointer */
 522     }
 523   else
 524     {
 525       /* We must encode contents of STRING according to what
 526          clipboard-coding-system specifies.  */
 527       int bufsize;
 528       struct coding_system coding;
 529       unsigned char *htext2;
 530       Lisp_Object coding_system =
 531         NILP (Vnext_selection_coding_system) ?
 532         Vselection_coding_system : Vnext_selection_coding_system;
 533
 534       setup_coding_system (Fcheck_coding_system (coding_system), &coding);
 535       coding.dst_bytes = nbytes * 4;
 536       coding.destination = (unsigned char *) xmalloc (coding.dst_bytes);
 537       Vnext_selection_coding_system = Qnil;
 538       coding.mode |= CODING_MODE_LAST_BLOCK;
 539       dst = coding.destination;
 540       encode_coding_object (&coding, string, 0, 0,
 541                             SCHARS (string), nbytes, Qnil);
 542       no_crlf_conversion = 1;
 543       nbytes = coding.produced;
 544       Vlast_coding_system_used = CODING_ID_NAME (coding.id);
 545       src = dst;
 546     }
 547
 548   ok = empty_clipboard ()
 549     && ((put_status
 550          = set_clipboard_data (CF_OEMTEXT, src, nbytes, no_crlf_conversion))
 551         == 0);
 552
 553   if (!no_crlf_conversion)
 554   close_clipboard ();
 555
 556   if (ok) goto unblock;
 557
 558  error:
 559
 560   ok = 0;
 561
 562  unblock:
 563   xfree (dst);
 564   UNBLOCK_INPUT;
 565
 566   /* Notify user if the text is too large to fit into DOS memory.
 567      (This will happen somewhere after 600K bytes (470K in DJGPP v1.x),
 568      depending on user system configuration.)  If we just silently
 569      fail the function, people might wonder why their text sometimes
 570      doesn't make it to the clipboard.  */
 571   if (put_status)
 572     {
 573       switch (put_status)
 574         {
 575           case 1:
 576             message2 (no_mem_msg, sizeof (no_mem_msg) - 1, 0);
 577             break;
 578           case 2:
 579             message2 (binary_msg, sizeof (binary_msg) - 1, 0);
 580             break;
 581           case 3:
 582             message2 (system_error_msg, sizeof (system_error_msg) - 1, 0);
 583             break;
 584         }
 585       sit_for (make_number (2), 0, 2);
 586     }
 587
 588  done:
 589
 590   return (ok && put_status == 0 ? string : Qnil);
 591 }
 592
 593 DEFUN ("w16-get-clipboard-data", Fw16_get_clipboard_data, Sw16_get_clipboard_data, 0, 1, 0,
 594        doc: /* This gets the clipboard data in text format.  */)
 595      (frame)
 596      Lisp_Object frame;
 597 {
 598   unsigned data_size, truelen;
 599   unsigned char *htext = NULL;
 600   Lisp_Object ret = Qnil;
 601   int no_crlf_conversion, require_decoding = 0;
 602
 603   if (NILP (frame))
 604     frame = Fselected_frame ();
 605
 606   CHECK_LIVE_FRAME (frame);
 607   if ( !FRAME_MSDOS_P (XFRAME (frame)))
 608     goto done;
 609
 610   BLOCK_INPUT;
 611
 612   if (!open_clipboard ())
 613     goto unblock;
 614
 615   if ((data_size = get_clipboard_data_size (CF_OEMTEXT)) == 0 ||
 616       (htext = (unsigned char *)xmalloc (data_size)) == 0)
 617     goto closeclip;
 618
 619   /* need to know final size after '\r' chars are removed because
 620      we can't change the string size manually, and doing an extra
 621      copy is silly */
 622   if ((truelen = get_clipboard_data (CF_OEMTEXT, htext, data_size, 0)) == 0)
 623     goto closeclip;
 624
 625   /* Do we need to decode it?  */
 626   {
 627     /* If the clipboard data contains any 8-bit Latin-1 code, we
 628        need to decode it.  */
 629     int i;
 630
 631     for (i = 0; i < truelen; i++)
 632       {
 633         if (htext[i] >= 0x80)
 634           {
 635             require_decoding = 1;
 636             break;
 637           }
 638       }
 639   }
 640   if (require_decoding)
 641     {
 642       int bufsize;
 643       unsigned char *buf;
 644       struct coding_system coding;
 645       Lisp_Object coding_system = Vnext_selection_coding_system;
 646
 647       truelen = get_clipboard_data (CF_OEMTEXT, htext, data_size, 1);
 648       if (NILP (coding_system))
 649         coding_system = Vselection_coding_system;
 650       setup_coding_system (Fcheck_coding_system (coding_system), &coding);
 651       coding.source = htext;
 652       coding.mode |= CODING_MODE_LAST_BLOCK;
 653       /* We explicitly disable composition handling because selection
 654          data should not contain any composition sequence.  */
 655       coding.mode &= CODING_ANNOTATION_MASK;
 656       decode_coding_object (&coding, Qnil, 0, 0, truelen, truelen, Qt);
 657       ret = coding.dst_object;
 658       Vlast_coding_system_used = CODING_ID_NAME (coding.id);
 659     }
 660   else
 661     {
 662       ret = make_unibyte_string ((char *) htext, truelen);
 663       Vlast_coding_system_used = Qraw_text;
 664     }
 665
 666   xfree (htext);
 667   Vnext_selection_coding_system = Qnil;
 668
 669  closeclip:
 670   close_clipboard ();
 671
 672  unblock:
 673   UNBLOCK_INPUT;
 674
 675  done:
 676
 677   return (ret);
 678 }
 679
 680 /* Support checking for a clipboard selection. */
 681
 682 DEFUN ("x-selection-exists-p", Fx_selection_exists_p, Sx_selection_exists_p,
 683        0, 1, 0,
 684        doc: /* Whether there is an owner for the given X Selection.
 685 The arg should be the name of the selection in question, typically one of
 686 the symbols `PRIMARY', `SECONDARY', or `CLIPBOARD'.
 687 \(Those are literal upper-case symbol names, since that's what X expects.)
 688 For convenience, the symbol nil is the same as `PRIMARY',
 689 and t is the same as `SECONDARY'.  */)
 690      (selection)
 691      Lisp_Object selection;
 692 {
 693   CHECK_SYMBOL (selection);
 694
 695   /* Return nil for SECONDARY selection.  For PRIMARY (or nil)
 696      selection, check if there is some text on the kill-ring;
 697      for CLIPBOARD, check if the clipboard currently has valid
 698      text format contents.
 699
 700      The test for killed text on the kill-ring emulates the Emacs
 701      behavior on X, where killed text is also put into X selection
 702      by the X interface code.  (On MSDOS, killed text is only put
 703      into the clipboard if we run under Windows, so we cannot check
 704      the clipboard alone.)  */
 705   if ((EQ (selection, Qnil) || EQ (selection, QPRIMARY))
 706       && ! NILP (SYMBOL_VALUE (Fintern_soft (build_string ("kill-ring"),
 707                                              Qnil))))
 708     return Qt;
 709
 710   if (EQ (selection, QCLIPBOARD))
 711     {
 712       Lisp_Object val = Qnil;
 713
 714       if (open_clipboard ())
 715         {
 716           if (get_clipboard_data_size (CF_OEMTEXT))
 717             val = Qt;
 718           close_clipboard ();
 719         }
 720       return val;
 721     }
 722   return Qnil;
 723 }
 724
 725 void
 726 syms_of_win16select ()
 727 {
 728   defsubr (&Sw16_set_clipboard_data);
 729   defsubr (&Sw16_get_clipboard_data);
 730   defsubr (&Sx_selection_exists_p);
 731
 732   DEFVAR_LISP ("selection-coding-system", &Vselection_coding_system,
 733                doc: /* Coding system for communicating with other X clients.
 734 When sending or receiving text via cut_buffer, selection, and clipboard,
 735 the text is encoded or decoded by this coding system.
 736 The default value is `iso-latin-1-dos'.  */);
 737   Vselection_coding_system = intern ("iso-latin-1-dos");
 738
 739   DEFVAR_LISP ("next-selection-coding-system", &Vnext_selection_coding_system,
 740                doc: /* Coding system for the next communication with other X clients.
 741 Usually, `selection-coding-system' is used for communicating with
 742 other X clients.  But, if this variable is set, it is used for the
 743 next communication only.  After the communication, this variable is
 744 set to nil.  */);
 745   Vnext_selection_coding_system = Qnil;
 746
 747   QPRIMARY   = intern ("PRIMARY");      staticpro (&QPRIMARY);
 748   QCLIPBOARD = intern ("CLIPBOARD");    staticpro (&QCLIPBOARD);
 749 }
 750
 751 #endif /* MSDOS */
 752
 753 /* arch-tag: 085a22c8-7324-436e-a6da-102464ce95d8
 754    (do not change this comment) */