xref: /reactos/dll/win32/itss/chm_lib.c (revision 12e94103)
1 /***************************************************************************
2  *             chm_lib.c - CHM archive manipulation routines               *
3  *                           -------------------                           *
4  *                                                                         *
5  *  author:     Jed Wing <jedwin@ugcs.caltech.edu>                         *
6  *  version:    0.3                                                        *
7  *  notes:      These routines are meant for the manipulation of microsoft *
8  *              .chm (compiled html help) files, but may likely be used    *
9  *              for the manipulation of any ITSS archive, if ever ITSS     *
10  *              archives are used for any other purpose.                   *
11  *                                                                         *
12  *              Note also that the section names are statically handled.   *
13  *              To be entirely correct, the section names should be read   *
14  *              from the section names meta-file, and then the various     *
15  *              content sections and the "transforms" to apply to the data *
16  *              they contain should be inferred from the section name and  *
17  *              the meta-files referenced using that name; however, all of *
18  *              the files I've been able to get my hands on appear to have *
19  *              only two sections: Uncompressed and MSCompressed.          *
20  *              Additionally, the ITSS.DLL file included with Windows does *
21  *              not appear to handle any different transforms than the     *
22  *              simple LZX-transform.  Furthermore, the list of transforms *
23  *              to apply is broken, in that only half the required space   *
24  *              is allocated for the list.  (It appears as though the      *
25  *              space is allocated for ASCII strings, but the strings are  *
26  *              written as unicode.  As a result, only the first half of   *
27  *              the string appears.)  So this is probably not too big of   *
28  *              a deal, at least until CHM v4 (MS .lit files), which also  *
29  *              incorporate encryption, of some description.               *
30  *                                                                         *
31  ***************************************************************************/
32 
33 /***************************************************************************
34  *
35  * This library is free software; you can redistribute it and/or
36  * modify it under the terms of the GNU Lesser General Public
37  * License as published by the Free Software Foundation; either
38  * version 2.1 of the License, or (at your option) any later version.
39  *
40  * This library is distributed in the hope that it will be useful,
41  * but WITHOUT ANY WARRANTY; without even the implied warranty of
42  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
43  * Lesser General Public License for more details.
44  *
45  * You should have received a copy of the GNU Lesser General Public
46  * License along with this library; if not, write to the Free Software
47  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
48  *
49  ***************************************************************************/
50 
51 /***************************************************************************
52  *                                                                         *
53  * Adapted for Wine by Mike McCormack                                      *
54  *                                                                         *
55  ***************************************************************************/
56 
57 #include "config.h"
58 #include "wine/port.h"
59 
60 #include <stdarg.h>
61 #include <stdio.h>
62 #include <stdlib.h>
63 #include <string.h>
64 
65 #include "windef.h"
66 #include "winbase.h"
67 #include "wine/unicode.h"
68 
69 #include "chm_lib.h"
70 #include "lzx.h"
71 
72 #define CHM_ACQUIRE_LOCK(a) do {                        \
73         EnterCriticalSection(&(a));                     \
74     } while(0)
75 #define CHM_RELEASE_LOCK(a) do {                        \
76         LeaveCriticalSection(&(a));                     \
77     } while(0)
78 
79 #define CHM_NULL_FD (INVALID_HANDLE_VALUE)
80 #define CHM_CLOSE_FILE(fd) CloseHandle((fd))
81 
82 /*
83  * defines related to tuning
84  */
85 #ifndef CHM_MAX_BLOCKS_CACHED
86 #define CHM_MAX_BLOCKS_CACHED 5
87 #endif
88 #define CHM_PARAM_MAX_BLOCKS_CACHED 0
89 
90 /*
91  * architecture specific defines
92  *
93  * Note: as soon as C99 is more widespread, the below defines should
94  * probably just use the C99 sized-int types.
95  *
96  * The following settings will probably work for many platforms.  The sizes
97  * don't have to be exactly correct, but the types must accommodate at least as
98  * many bits as they specify.
99  */
100 
101 /* i386, 32-bit, Windows */
102 typedef BYTE   UChar;
103 typedef SHORT  Int16;
104 typedef USHORT UInt16;
105 typedef LONG   Int32;
106 typedef DWORD      UInt32;
107 typedef LONGLONG   Int64;
108 typedef ULONGLONG  UInt64;
109 
110 /* utilities for unmarshalling data */
111 static BOOL _unmarshal_char_array(unsigned char **pData,
112                                   unsigned int *pLenRemain,
113                                   char *dest,
114                                   int count)
115 {
116     if (count <= 0  ||  (unsigned int)count > *pLenRemain)
117         return FALSE;
118     memcpy(dest, (*pData), count);
119     *pData += count;
120     *pLenRemain -= count;
121     return TRUE;
122 }
123 
124 static BOOL _unmarshal_uchar_array(unsigned char **pData,
125                                    unsigned int *pLenRemain,
126                                    unsigned char *dest,
127                                    int count)
128 {
129     if (count <= 0  || (unsigned int)count > *pLenRemain)
130         return FALSE;
131     memcpy(dest, (*pData), count);
132     *pData += count;
133     *pLenRemain -= count;
134     return TRUE;
135 }
136 
137 static BOOL _unmarshal_int32(unsigned char **pData,
138                              unsigned int *pLenRemain,
139                              Int32 *dest)
140 {
141     if (4 > *pLenRemain)
142         return FALSE;
143     *dest = (*pData)[0] | (*pData)[1]<<8 | (*pData)[2]<<16 | (*pData)[3]<<24;
144     *pData += 4;
145     *pLenRemain -= 4;
146     return TRUE;
147 }
148 
149 static BOOL _unmarshal_uint32(unsigned char **pData,
150                               unsigned int *pLenRemain,
151                               UInt32 *dest)
152 {
153     if (4 > *pLenRemain)
154         return FALSE;
155     *dest = (*pData)[0] | (*pData)[1]<<8 | (*pData)[2]<<16 | (*pData)[3]<<24;
156     *pData += 4;
157     *pLenRemain -= 4;
158     return TRUE;
159 }
160 
161 static BOOL _unmarshal_int64(unsigned char **pData,
162                              unsigned int *pLenRemain,
163                              Int64 *dest)
164 {
165     Int64 temp;
166     int i;
167     if (8 > *pLenRemain)
168         return FALSE;
169     temp=0;
170     for(i=8; i>0; i--)
171     {
172         temp <<= 8;
173         temp |= (*pData)[i-1];
174     }
175     *dest = temp;
176     *pData += 8;
177     *pLenRemain -= 8;
178     return TRUE;
179 }
180 
181 static BOOL _unmarshal_uint64(unsigned char **pData,
182                               unsigned int *pLenRemain,
183                               UInt64 *dest)
184 {
185     UInt64 temp;
186     int i;
187     if (8 > *pLenRemain)
188         return FALSE;
189     temp=0;
190     for(i=8; i>0; i--)
191     {
192         temp <<= 8;
193         temp |= (*pData)[i-1];
194     }
195     *dest = temp;
196     *pData += 8;
197     *pLenRemain -= 8;
198     return TRUE;
199 }
200 
201 static BOOL _unmarshal_uuid(unsigned char **pData,
202                             unsigned int *pDataLen,
203                             unsigned char *dest)
204 {
205     return _unmarshal_uchar_array(pData, pDataLen, dest, 16);
206 }
207 
208 /* names of sections essential to decompression */
209 static const WCHAR _CHMU_RESET_TABLE[] = {
210 ':',':','D','a','t','a','S','p','a','c','e','/',
211         'S','t','o','r','a','g','e','/',
212         'M','S','C','o','m','p','r','e','s','s','e','d','/',
213         'T','r','a','n','s','f','o','r','m','/',
214         '{','7','F','C','2','8','9','4','0','-','9','D','3','1',
215           '-','1','1','D','0','-','9','B','2','7','-',
216           '0','0','A','0','C','9','1','E','9','C','7','C','}','/',
217         'I','n','s','t','a','n','c','e','D','a','t','a','/',
218         'R','e','s','e','t','T','a','b','l','e',0
219 };
220 static const WCHAR _CHMU_LZXC_CONTROLDATA[] = {
221 ':',':','D','a','t','a','S','p','a','c','e','/',
222         'S','t','o','r','a','g','e','/',
223         'M','S','C','o','m','p','r','e','s','s','e','d','/',
224         'C','o','n','t','r','o','l','D','a','t','a',0
225 };
226 static const WCHAR _CHMU_CONTENT[] = {
227 ':',':','D','a','t','a','S','p','a','c','e','/',
228         'S','t','o','r','a','g','e','/',
229         'M','S','C','o','m','p','r','e','s','s','e','d','/',
230         'C','o','n','t','e','n','t',0
231 };
232 
233 /*
234  * structures local to this module
235  */
236 
237 /* structure of ITSF headers */
238 #define _CHM_ITSF_V2_LEN (0x58)
239 #define _CHM_ITSF_V3_LEN (0x60)
240 struct chmItsfHeader
241 {
242     char        signature[4];           /*  0 (ITSF) */
243     Int32       version;                /*  4 */
244     Int32       header_len;             /*  8 */
245     Int32       unknown_000c;           /*  c */
246     UInt32      last_modified;          /* 10 */
247     UInt32      lang_id;                /* 14 */
248     UChar       dir_uuid[16];           /* 18 */
249     UChar       stream_uuid[16];        /* 28 */
250     UInt64      unknown_offset;         /* 38 */
251     UInt64      unknown_len;            /* 40 */
252     UInt64      dir_offset;             /* 48 */
253     UInt64      dir_len;                /* 50 */
254     UInt64      data_offset;            /* 58 (Not present before V3) */
255 }; /* __attribute__ ((aligned (1))); */
256 
257 static BOOL _unmarshal_itsf_header(unsigned char **pData,
258                                    unsigned int *pDataLen,
259                                    struct chmItsfHeader *dest)
260 {
261     /* we only know how to deal with the 0x58 and 0x60 byte structures */
262     if (*pDataLen != _CHM_ITSF_V2_LEN  &&  *pDataLen != _CHM_ITSF_V3_LEN)
263         return FALSE;
264 
265     /* unmarshal common fields */
266     _unmarshal_char_array(pData, pDataLen,  dest->signature, 4);
267     _unmarshal_int32     (pData, pDataLen, &dest->version);
268     _unmarshal_int32     (pData, pDataLen, &dest->header_len);
269     _unmarshal_int32     (pData, pDataLen, &dest->unknown_000c);
270     _unmarshal_uint32    (pData, pDataLen, &dest->last_modified);
271     _unmarshal_uint32    (pData, pDataLen, &dest->lang_id);
272     _unmarshal_uuid      (pData, pDataLen,  dest->dir_uuid);
273     _unmarshal_uuid      (pData, pDataLen,  dest->stream_uuid);
274     _unmarshal_uint64    (pData, pDataLen, &dest->unknown_offset);
275     _unmarshal_uint64    (pData, pDataLen, &dest->unknown_len);
276     _unmarshal_uint64    (pData, pDataLen, &dest->dir_offset);
277     _unmarshal_uint64    (pData, pDataLen, &dest->dir_len);
278 
279     /* error check the data */
280     /* XXX: should also check UUIDs, probably, though with a version 3 file,
281      * current MS tools do not seem to use them.
282      */
283     if (memcmp(dest->signature, "ITSF", 4) != 0)
284         return FALSE;
285     if (dest->version == 2)
286     {
287         if (dest->header_len < _CHM_ITSF_V2_LEN)
288             return FALSE;
289     }
290     else if (dest->version == 3)
291     {
292         if (dest->header_len < _CHM_ITSF_V3_LEN)
293             return FALSE;
294     }
295     else
296         return FALSE;
297 
298     /* now, if we have a V3 structure, unmarshal the rest.
299      * otherwise, compute it
300      */
301     if (dest->version == 3)
302     {
303         if (*pDataLen != 0)
304             _unmarshal_uint64(pData, pDataLen, &dest->data_offset);
305         else
306             return FALSE;
307     }
308     else
309         dest->data_offset = dest->dir_offset + dest->dir_len;
310 
311     return TRUE;
312 }
313 
314 /* structure of ITSP headers */
315 #define _CHM_ITSP_V1_LEN (0x54)
316 struct chmItspHeader
317 {
318     char        signature[4];           /*  0 (ITSP) */
319     Int32       version;                /*  4 */
320     Int32       header_len;             /*  8 */
321     Int32       unknown_000c;           /*  c */
322     UInt32      block_len;              /* 10 */
323     Int32       blockidx_intvl;         /* 14 */
324     Int32       index_depth;            /* 18 */
325     Int32       index_root;             /* 1c */
326     Int32       index_head;             /* 20 */
327     Int32       unknown_0024;           /* 24 */
328     UInt32      num_blocks;             /* 28 */
329     Int32       unknown_002c;           /* 2c */
330     UInt32      lang_id;                /* 30 */
331     UChar       system_uuid[16];        /* 34 */
332     UChar       unknown_0044[16];       /* 44 */
333 }; /* __attribute__ ((aligned (1))); */
334 
335 static BOOL _unmarshal_itsp_header(unsigned char **pData,
336                                    unsigned int *pDataLen,
337                                    struct chmItspHeader *dest)
338 {
339     /* we only know how to deal with a 0x54 byte structures */
340     if (*pDataLen != _CHM_ITSP_V1_LEN)
341         return FALSE;
342 
343     /* unmarshal fields */
344     _unmarshal_char_array(pData, pDataLen,  dest->signature, 4);
345     _unmarshal_int32     (pData, pDataLen, &dest->version);
346     _unmarshal_int32     (pData, pDataLen, &dest->header_len);
347     _unmarshal_int32     (pData, pDataLen, &dest->unknown_000c);
348     _unmarshal_uint32    (pData, pDataLen, &dest->block_len);
349     _unmarshal_int32     (pData, pDataLen, &dest->blockidx_intvl);
350     _unmarshal_int32     (pData, pDataLen, &dest->index_depth);
351     _unmarshal_int32     (pData, pDataLen, &dest->index_root);
352     _unmarshal_int32     (pData, pDataLen, &dest->index_head);
353     _unmarshal_int32     (pData, pDataLen, &dest->unknown_0024);
354     _unmarshal_uint32    (pData, pDataLen, &dest->num_blocks);
355     _unmarshal_int32     (pData, pDataLen, &dest->unknown_002c);
356     _unmarshal_uint32    (pData, pDataLen, &dest->lang_id);
357     _unmarshal_uuid      (pData, pDataLen,  dest->system_uuid);
358     _unmarshal_uchar_array(pData, pDataLen, dest->unknown_0044, 16);
359 
360     /* error check the data */
361     if (memcmp(dest->signature, "ITSP", 4) != 0)
362         return FALSE;
363     if (dest->version != 1)
364         return FALSE;
365     if (dest->header_len != _CHM_ITSP_V1_LEN)
366         return FALSE;
367 
368     return TRUE;
369 }
370 
371 /* structure of PMGL headers */
372 static const char _chm_pmgl_marker[4] = "PMGL";
373 #define _CHM_PMGL_LEN (0x14)
374 struct chmPmglHeader
375 {
376     char        signature[4];           /*  0 (PMGL) */
377     UInt32      free_space;             /*  4 */
378     UInt32      unknown_0008;           /*  8 */
379     Int32       block_prev;             /*  c */
380     Int32       block_next;             /* 10 */
381 }; /* __attribute__ ((aligned (1))); */
382 
383 static BOOL _unmarshal_pmgl_header(unsigned char **pData,
384                                    unsigned int *pDataLen,
385                                    struct chmPmglHeader *dest)
386 {
387     /* we only know how to deal with a 0x14 byte structures */
388     if (*pDataLen != _CHM_PMGL_LEN)
389         return FALSE;
390 
391     /* unmarshal fields */
392     _unmarshal_char_array(pData, pDataLen,  dest->signature, 4);
393     _unmarshal_uint32    (pData, pDataLen, &dest->free_space);
394     _unmarshal_uint32    (pData, pDataLen, &dest->unknown_0008);
395     _unmarshal_int32     (pData, pDataLen, &dest->block_prev);
396     _unmarshal_int32     (pData, pDataLen, &dest->block_next);
397 
398     /* check structure */
399     if (memcmp(dest->signature, _chm_pmgl_marker, 4) != 0)
400         return FALSE;
401 
402     return TRUE;
403 }
404 
405 /* structure of PMGI headers */
406 static const char _chm_pmgi_marker[4] = "PMGI";
407 #define _CHM_PMGI_LEN (0x08)
408 struct chmPmgiHeader
409 {
410     char        signature[4];           /*  0 (PMGI) */
411     UInt32      free_space;             /*  4 */
412 }; /* __attribute__ ((aligned (1))); */
413 
414 static BOOL _unmarshal_pmgi_header(unsigned char **pData,
415                                    unsigned int *pDataLen,
416                                    struct chmPmgiHeader *dest)
417 {
418     /* we only know how to deal with a 0x8 byte structures */
419     if (*pDataLen != _CHM_PMGI_LEN)
420         return FALSE;
421 
422     /* unmarshal fields */
423     _unmarshal_char_array(pData, pDataLen,  dest->signature, 4);
424     _unmarshal_uint32    (pData, pDataLen, &dest->free_space);
425 
426     /* check structure */
427     if (memcmp(dest->signature, _chm_pmgi_marker, 4) != 0)
428         return FALSE;
429 
430     return TRUE;
431 }
432 
433 /* structure of LZXC reset table */
434 #define _CHM_LZXC_RESETTABLE_V1_LEN (0x28)
435 struct chmLzxcResetTable
436 {
437     UInt32      version;
438     UInt32      block_count;
439     UInt32      unknown;
440     UInt32      table_offset;
441     UInt64      uncompressed_len;
442     UInt64      compressed_len;
443     UInt64      block_len;
444 }; /* __attribute__ ((aligned (1))); */
445 
446 static BOOL _unmarshal_lzxc_reset_table(unsigned char **pData,
447                                         unsigned int *pDataLen,
448                                         struct chmLzxcResetTable *dest)
449 {
450     /* we only know how to deal with a 0x28 byte structures */
451     if (*pDataLen != _CHM_LZXC_RESETTABLE_V1_LEN)
452         return FALSE;
453 
454     /* unmarshal fields */
455     _unmarshal_uint32    (pData, pDataLen, &dest->version);
456     _unmarshal_uint32    (pData, pDataLen, &dest->block_count);
457     _unmarshal_uint32    (pData, pDataLen, &dest->unknown);
458     _unmarshal_uint32    (pData, pDataLen, &dest->table_offset);
459     _unmarshal_uint64    (pData, pDataLen, &dest->uncompressed_len);
460     _unmarshal_uint64    (pData, pDataLen, &dest->compressed_len);
461     _unmarshal_uint64    (pData, pDataLen, &dest->block_len);
462 
463     /* check structure */
464     if (dest->version != 2)
465         return FALSE;
466 
467     return TRUE;
468 }
469 
470 /* structure of LZXC control data block */
471 #define _CHM_LZXC_MIN_LEN (0x18)
472 #define _CHM_LZXC_V2_LEN (0x1c)
473 struct chmLzxcControlData
474 {
475     UInt32      size;                   /*  0        */
476     char        signature[4];           /*  4 (LZXC) */
477     UInt32      version;                /*  8        */
478     UInt32      resetInterval;          /*  c        */
479     UInt32      windowSize;             /* 10        */
480     UInt32      windowsPerReset;        /* 14        */
481     UInt32      unknown_18;             /* 18        */
482 };
483 
484 static BOOL _unmarshal_lzxc_control_data(unsigned char **pData,
485                                          unsigned int *pDataLen,
486                                          struct chmLzxcControlData *dest)
487 {
488     /* we want at least 0x18 bytes */
489     if (*pDataLen < _CHM_LZXC_MIN_LEN)
490         return FALSE;
491 
492     /* unmarshal fields */
493     _unmarshal_uint32    (pData, pDataLen, &dest->size);
494     _unmarshal_char_array(pData, pDataLen,  dest->signature, 4);
495     _unmarshal_uint32    (pData, pDataLen, &dest->version);
496     _unmarshal_uint32    (pData, pDataLen, &dest->resetInterval);
497     _unmarshal_uint32    (pData, pDataLen, &dest->windowSize);
498     _unmarshal_uint32    (pData, pDataLen, &dest->windowsPerReset);
499 
500     if (*pDataLen >= _CHM_LZXC_V2_LEN)
501         _unmarshal_uint32    (pData, pDataLen, &dest->unknown_18);
502     else
503         dest->unknown_18 = 0;
504 
505     if (dest->version == 2)
506     {
507         dest->resetInterval *= 0x8000;
508         dest->windowSize *= 0x8000;
509     }
510     if (dest->windowSize == 0  ||  dest->resetInterval == 0)
511         return FALSE;
512 
513     /* for now, only support resetInterval a multiple of windowSize/2 */
514     if (dest->windowSize == 1)
515         return FALSE;
516     if ((dest->resetInterval % (dest->windowSize/2)) != 0)
517         return FALSE;
518 
519     /* check structure */
520     if (memcmp(dest->signature, "LZXC", 4) != 0)
521         return FALSE;
522 
523     return TRUE;
524 }
525 
526 /* the structure used for chm file handles */
527 struct chmFile
528 {
529     HANDLE              fd;
530 
531     CRITICAL_SECTION    mutex;
532     CRITICAL_SECTION    lzx_mutex;
533     CRITICAL_SECTION    cache_mutex;
534 
535     UInt64              dir_offset;
536     UInt64              dir_len;
537     UInt64              data_offset;
538     Int32               index_root;
539     Int32               index_head;
540     UInt32              block_len;
541 
542     UInt64              span;
543     struct chmUnitInfo  rt_unit;
544     struct chmUnitInfo  cn_unit;
545     struct chmLzxcResetTable reset_table;
546 
547     /* LZX control data */
548     int                 compression_enabled;
549     UInt32              window_size;
550     UInt32              reset_interval;
551     UInt32              reset_blkcount;
552 
553     /* decompressor state */
554     struct LZXstate    *lzx_state;
555     int                 lzx_last_block;
556 
557     /* cache for decompressed blocks */
558     UChar             **cache_blocks;
559     Int64              *cache_block_indices;
560     Int32               cache_num_blocks;
561 };
562 
563 /*
564  * utility functions local to this module
565  */
566 
567 /* utility function to handle differences between {pread,read}(64)? */
568 static Int64 _chm_fetch_bytes(struct chmFile *h,
569                               UChar *buf,
570                               UInt64 os,
571                               Int64 len)
572 {
573     Int64 readLen=0;
574     if (h->fd  ==  CHM_NULL_FD)
575         return readLen;
576 
577     CHM_ACQUIRE_LOCK(h->mutex);
578     /* NOTE: this might be better done with CreateFileMapping, et cetera... */
579     {
580         LARGE_INTEGER old_pos, new_pos;
581         DWORD actualLen=0;
582 
583         /* awkward Win32 Seek/Tell */
584         new_pos.QuadPart = 0;
585         SetFilePointerEx( h->fd, new_pos, &old_pos, FILE_CURRENT );
586         new_pos.QuadPart = os;
587         SetFilePointerEx( h->fd, new_pos, NULL, FILE_BEGIN );
588 
589         /* read the data */
590         if (ReadFile(h->fd,
591                      buf,
592                      (DWORD)len,
593                      &actualLen,
594                      NULL))
595             readLen = actualLen;
596         else
597             readLen = 0;
598 
599         /* restore original position */
600         SetFilePointerEx( h->fd, old_pos, NULL, FILE_BEGIN );
601     }
602     CHM_RELEASE_LOCK(h->mutex);
603     return readLen;
604 }
605 
606 /*
607  * set a parameter on the file handle.
608  * valid parameter types:
609  *          CHM_PARAM_MAX_BLOCKS_CACHED:
610  *                 how many decompressed blocks should be cached?  A simple
611  *                 caching scheme is used, wherein the index of the block is
612  *                 used as a hash value, and hash collision results in the
613  *                 invalidation of the previously cached block.
614  */
615 static void chm_set_param(struct chmFile *h,
616                           int paramType,
617                           int paramVal)
618 {
619     switch (paramType)
620     {
621         case CHM_PARAM_MAX_BLOCKS_CACHED:
622             CHM_ACQUIRE_LOCK(h->cache_mutex);
623             if (paramVal != h->cache_num_blocks)
624             {
625                 UChar **newBlocks;
626                 Int64 *newIndices;
627                 int     i;
628 
629                 /* allocate new cached blocks */
630                 newBlocks = HeapAlloc(GetProcessHeap(), 0, paramVal * sizeof (UChar *));
631                 newIndices = HeapAlloc(GetProcessHeap(), 0, paramVal * sizeof (UInt64));
632                 for (i=0; i<paramVal; i++)
633                 {
634                     newBlocks[i] = NULL;
635                     newIndices[i] = 0;
636                 }
637 
638                 /* re-distribute old cached blocks */
639                 if (h->cache_blocks)
640                 {
641                     for (i=0; i<h->cache_num_blocks; i++)
642                     {
643                         int newSlot = (int)(h->cache_block_indices[i] % paramVal);
644 
645                         if (h->cache_blocks[i])
646                         {
647                             /* in case of collision, destroy newcomer */
648                             if (newBlocks[newSlot])
649                             {
650                                 HeapFree(GetProcessHeap(), 0, h->cache_blocks[i]);
651                                 h->cache_blocks[i] = NULL;
652                             }
653                             else
654                             {
655                                 newBlocks[newSlot] = h->cache_blocks[i];
656                                 newIndices[newSlot] =
657                                             h->cache_block_indices[i];
658                             }
659                         }
660                     }
661 
662                     HeapFree(GetProcessHeap(), 0, h->cache_blocks);
663                     HeapFree(GetProcessHeap(), 0, h->cache_block_indices);
664                 }
665 
666                 /* now, set new values */
667                 h->cache_blocks = newBlocks;
668                 h->cache_block_indices = newIndices;
669                 h->cache_num_blocks = paramVal;
670             }
671             CHM_RELEASE_LOCK(h->cache_mutex);
672             break;
673 
674         default:
675             break;
676     }
677 }
678 
679 /* open an ITS archive */
680 struct chmFile *chm_openW(const WCHAR *filename)
681 {
682     unsigned char               sbuffer[256];
683     unsigned int                sremain;
684     unsigned char              *sbufpos;
685     struct chmFile             *newHandle=NULL;
686     struct chmItsfHeader        itsfHeader;
687     struct chmItspHeader        itspHeader;
688 #if 0
689     struct chmUnitInfo          uiSpan;
690 #endif
691     struct chmUnitInfo          uiLzxc;
692     struct chmLzxcControlData   ctlData;
693 
694     /* allocate handle */
695     newHandle = HeapAlloc(GetProcessHeap(), 0, sizeof(struct chmFile));
696     newHandle->fd = CHM_NULL_FD;
697     newHandle->lzx_state = NULL;
698     newHandle->cache_blocks = NULL;
699     newHandle->cache_block_indices = NULL;
700     newHandle->cache_num_blocks = 0;
701 
702     /* open file */
703     if ((newHandle->fd=CreateFileW(filename,
704                                    GENERIC_READ,
705                                    FILE_SHARE_READ,
706                                    NULL,
707                                    OPEN_EXISTING,
708                                    FILE_ATTRIBUTE_NORMAL,
709                                    NULL)) == CHM_NULL_FD)
710     {
711         HeapFree(GetProcessHeap(), 0, newHandle);
712         return NULL;
713     }
714 
715     /* initialize mutexes, if needed */
716     InitializeCriticalSection(&newHandle->mutex);
717     newHandle->mutex.DebugInfo->Spare[0] = (DWORD_PTR)(__FILE__ ": chmFile.mutex");
718     InitializeCriticalSection(&newHandle->lzx_mutex);
719     newHandle->lzx_mutex.DebugInfo->Spare[0] = (DWORD_PTR)(__FILE__ ": chmFile.lzx_mutex");
720     InitializeCriticalSection(&newHandle->cache_mutex);
721     newHandle->cache_mutex.DebugInfo->Spare[0] = (DWORD_PTR)(__FILE__ ": chmFile.cache_mutex");
722 
723     /* read and verify header */
724     sremain = _CHM_ITSF_V3_LEN;
725     sbufpos = sbuffer;
726     if (_chm_fetch_bytes(newHandle, sbuffer, 0, sremain) != sremain    ||
727         !_unmarshal_itsf_header(&sbufpos, &sremain, &itsfHeader))
728     {
729         chm_close(newHandle);
730         return NULL;
731     }
732 
733     /* stash important values from header */
734     newHandle->dir_offset  = itsfHeader.dir_offset;
735     newHandle->dir_len     = itsfHeader.dir_len;
736     newHandle->data_offset = itsfHeader.data_offset;
737 
738     /* now, read and verify the directory header chunk */
739     sremain = _CHM_ITSP_V1_LEN;
740     sbufpos = sbuffer;
741     if (_chm_fetch_bytes(newHandle, sbuffer,
742                          itsfHeader.dir_offset, sremain) != sremain    ||
743         !_unmarshal_itsp_header(&sbufpos, &sremain, &itspHeader))
744     {
745         chm_close(newHandle);
746         return NULL;
747     }
748 
749     /* grab essential information from ITSP header */
750     newHandle->dir_offset += itspHeader.header_len;
751     newHandle->dir_len    -= itspHeader.header_len;
752     newHandle->index_root  = itspHeader.index_root;
753     newHandle->index_head  = itspHeader.index_head;
754     newHandle->block_len   = itspHeader.block_len;
755 
756     /* if the index root is -1, this means we don't have any PMGI blocks.
757      * as a result, we must use the sole PMGL block as the index root
758      */
759     if (newHandle->index_root == -1)
760         newHandle->index_root = newHandle->index_head;
761 
762     /* initialize cache */
763     chm_set_param(newHandle, CHM_PARAM_MAX_BLOCKS_CACHED,
764                   CHM_MAX_BLOCKS_CACHED);
765 
766     /* By default, compression is enabled. */
767     newHandle->compression_enabled = 1;
768 
769     /* prefetch most commonly needed unit infos */
770     if (CHM_RESOLVE_SUCCESS != chm_resolve_object(newHandle,
771                                                   _CHMU_RESET_TABLE,
772                                                   &newHandle->rt_unit)    ||
773         newHandle->rt_unit.space == CHM_COMPRESSED                        ||
774         CHM_RESOLVE_SUCCESS != chm_resolve_object(newHandle,
775                                                   _CHMU_CONTENT,
776                                                   &newHandle->cn_unit)    ||
777         newHandle->cn_unit.space == CHM_COMPRESSED                        ||
778         CHM_RESOLVE_SUCCESS != chm_resolve_object(newHandle,
779                                                   _CHMU_LZXC_CONTROLDATA,
780                                                   &uiLzxc)                ||
781         uiLzxc.space == CHM_COMPRESSED)
782     {
783         newHandle->compression_enabled = 0;
784     }
785 
786     /* read reset table info */
787     if (newHandle->compression_enabled)
788     {
789         sremain = _CHM_LZXC_RESETTABLE_V1_LEN;
790         sbufpos = sbuffer;
791         if (chm_retrieve_object(newHandle, &newHandle->rt_unit, sbuffer,
792                                 0, sremain) != sremain                        ||
793             !_unmarshal_lzxc_reset_table(&sbufpos, &sremain,
794                                          &newHandle->reset_table))
795         {
796             newHandle->compression_enabled = 0;
797         }
798     }
799 
800     /* read control data */
801     if (newHandle->compression_enabled)
802     {
803         sremain = (unsigned long)uiLzxc.length;
804         sbufpos = sbuffer;
805         if (chm_retrieve_object(newHandle, &uiLzxc, sbuffer,
806                                 0, sremain) != sremain                       ||
807             !_unmarshal_lzxc_control_data(&sbufpos, &sremain,
808                                           &ctlData))
809         {
810             newHandle->compression_enabled = 0;
811         }
812 
813         newHandle->window_size = ctlData.windowSize;
814         newHandle->reset_interval = ctlData.resetInterval;
815 
816 /* Jed, Mon Jun 28: Experimentally, it appears that the reset block count */
817 /*       must be multiplied by this formerly unknown ctrl data field in   */
818 /*       order to decompress some files.                                  */
819 #if 0
820         newHandle->reset_blkcount = newHandle->reset_interval /
821                     (newHandle->window_size / 2);
822 #else
823         newHandle->reset_blkcount = newHandle->reset_interval    /
824                                     (newHandle->window_size / 2) *
825                                     ctlData.windowsPerReset;
826 #endif
827     }
828 
829     return newHandle;
830 }
831 
832 /* Duplicate an ITS archive handle */
833 struct chmFile *chm_dup(struct chmFile *oldHandle)
834 {
835     struct chmFile *newHandle=NULL;
836 
837     newHandle = HeapAlloc(GetProcessHeap(), 0, sizeof(struct chmFile));
838     *newHandle = *oldHandle;
839 
840     /* duplicate fd handle */
841     DuplicateHandle(GetCurrentProcess(), oldHandle->fd,
842                     GetCurrentProcess(), &(newHandle->fd),
843                     0, FALSE, DUPLICATE_SAME_ACCESS);
844     newHandle->lzx_state = NULL;
845     newHandle->cache_blocks = NULL;
846     newHandle->cache_block_indices = NULL;
847     newHandle->cache_num_blocks = 0;
848 
849     /* initialize mutexes, if needed */
850     InitializeCriticalSection(&newHandle->mutex);
851     newHandle->mutex.DebugInfo->Spare[0] = (DWORD_PTR)(__FILE__ ": chmFile.mutex");
852     InitializeCriticalSection(&newHandle->lzx_mutex);
853     newHandle->lzx_mutex.DebugInfo->Spare[0] = (DWORD_PTR)(__FILE__ ": chmFile.lzx_mutex");
854     InitializeCriticalSection(&newHandle->cache_mutex);
855     newHandle->cache_mutex.DebugInfo->Spare[0] = (DWORD_PTR)(__FILE__ ": chmFile.cache_mutex");
856 
857     /* initialize cache */
858     chm_set_param(newHandle, CHM_PARAM_MAX_BLOCKS_CACHED,
859                   CHM_MAX_BLOCKS_CACHED);
860 
861     return newHandle;
862 }
863 
864 /* close an ITS archive */
865 void chm_close(struct chmFile *h)
866 {
867     if (h != NULL)
868     {
869         if (h->fd != CHM_NULL_FD)
870             CHM_CLOSE_FILE(h->fd);
871         h->fd = CHM_NULL_FD;
872 
873         h->mutex.DebugInfo->Spare[0] = 0;
874         DeleteCriticalSection(&h->mutex);
875         h->lzx_mutex.DebugInfo->Spare[0] = 0;
876         DeleteCriticalSection(&h->lzx_mutex);
877         h->cache_mutex.DebugInfo->Spare[0] = 0;
878         DeleteCriticalSection(&h->cache_mutex);
879 
880         if (h->lzx_state)
881             LZXteardown(h->lzx_state);
882         h->lzx_state = NULL;
883 
884         if (h->cache_blocks)
885         {
886             int i;
887             for (i=0; i<h->cache_num_blocks; i++)
888             {
889                 HeapFree(GetProcessHeap(), 0, h->cache_blocks[i]);
890             }
891             HeapFree(GetProcessHeap(), 0, h->cache_blocks);
892             h->cache_blocks = NULL;
893         }
894 
895         HeapFree(GetProcessHeap(), 0, h->cache_block_indices);
896         h->cache_block_indices = NULL;
897 
898         HeapFree(GetProcessHeap(), 0, h);
899     }
900 }
901 
902 /*
903  * helper methods for chm_resolve_object
904  */
905 
906 /* skip a compressed dword */
907 static void _chm_skip_cword(UChar **pEntry)
908 {
909     while (*(*pEntry)++ >= 0x80)
910         ;
911 }
912 
913 /* skip the data from a PMGL entry */
914 static void _chm_skip_PMGL_entry_data(UChar **pEntry)
915 {
916     _chm_skip_cword(pEntry);
917     _chm_skip_cword(pEntry);
918     _chm_skip_cword(pEntry);
919 }
920 
921 /* parse a compressed dword */
922 static UInt64 _chm_parse_cword(UChar **pEntry)
923 {
924     UInt64 accum = 0;
925     UChar temp;
926     while ((temp=*(*pEntry)++) >= 0x80)
927     {
928         accum <<= 7;
929         accum += temp & 0x7f;
930     }
931 
932     return (accum << 7) + temp;
933 }
934 
935 /* parse a utf-8 string into an ASCII char buffer */
936 static BOOL _chm_parse_UTF8(UChar **pEntry, UInt64 count, WCHAR *path)
937 {
938     DWORD length = MultiByteToWideChar(CP_UTF8, 0, (char *)*pEntry, count, path, CHM_MAX_PATHLEN);
939     path[length] = '\0';
940     *pEntry += count;
941     return !!length;
942 }
943 
944 /* parse a PMGL entry into a chmUnitInfo struct; return 1 on success. */
945 static BOOL _chm_parse_PMGL_entry(UChar **pEntry, struct chmUnitInfo *ui)
946 {
947     UInt64 strLen;
948 
949     /* parse str len */
950     strLen = _chm_parse_cword(pEntry);
951     if (strLen > CHM_MAX_PATHLEN)
952         return FALSE;
953 
954     /* parse path */
955     if (! _chm_parse_UTF8(pEntry, strLen, ui->path))
956         return FALSE;
957 
958     /* parse info */
959     ui->space  = (int)_chm_parse_cword(pEntry);
960     ui->start  = _chm_parse_cword(pEntry);
961     ui->length = _chm_parse_cword(pEntry);
962     return TRUE;
963 }
964 
965 /* find an exact entry in PMGL; return NULL if we fail */
966 static UChar *_chm_find_in_PMGL(UChar *page_buf,
967                          UInt32 block_len,
968                          const WCHAR *objPath)
969 {
970     /* XXX: modify this to do a binary search using the nice index structure
971      *      that is provided for us.
972      */
973     struct chmPmglHeader header;
974     UInt32 hremain;
975     UChar *end;
976     UChar *cur;
977     UChar *temp;
978     UInt64 strLen;
979     WCHAR buffer[CHM_MAX_PATHLEN+1];
980 
981     /* figure out where to start and end */
982     cur = page_buf;
983     hremain = _CHM_PMGL_LEN;
984     if (! _unmarshal_pmgl_header(&cur, &hremain, &header))
985         return NULL;
986     end = page_buf + block_len - (header.free_space);
987 
988     /* now, scan progressively */
989     while (cur < end)
990     {
991         /* grab the name */
992         temp = cur;
993         strLen = _chm_parse_cword(&cur);
994         if (! _chm_parse_UTF8(&cur, strLen, buffer))
995             return NULL;
996 
997         /* check if it is the right name */
998         if (! strcmpiW(buffer, objPath))
999             return temp;
1000 
1001         _chm_skip_PMGL_entry_data(&cur);
1002     }
1003 
1004     return NULL;
1005 }
1006 
1007 /* find which block should be searched next for the entry; -1 if no block */
1008 static Int32 _chm_find_in_PMGI(UChar *page_buf,
1009                         UInt32 block_len,
1010                         const WCHAR *objPath)
1011 {
1012     /* XXX: modify this to do a binary search using the nice index structure
1013      *      that is provided for us
1014      */
1015     struct chmPmgiHeader header;
1016     UInt32 hremain;
1017     int page=-1;
1018     UChar *end;
1019     UChar *cur;
1020     UInt64 strLen;
1021     WCHAR buffer[CHM_MAX_PATHLEN+1];
1022 
1023     /* figure out where to start and end */
1024     cur = page_buf;
1025     hremain = _CHM_PMGI_LEN;
1026     if (! _unmarshal_pmgi_header(&cur, &hremain, &header))
1027         return -1;
1028     end = page_buf + block_len - (header.free_space);
1029 
1030     /* now, scan progressively */
1031     while (cur < end)
1032     {
1033         /* grab the name */
1034         strLen = _chm_parse_cword(&cur);
1035         if (! _chm_parse_UTF8(&cur, strLen, buffer))
1036             return -1;
1037 
1038         /* check if it is the right name */
1039         if (strcmpiW(buffer, objPath) > 0)
1040             return page;
1041 
1042         /* load next value for path */
1043         page = (int)_chm_parse_cword(&cur);
1044     }
1045 
1046     return page;
1047 }
1048 
1049 /* resolve a particular object from the archive */
1050 int chm_resolve_object(struct chmFile *h,
1051                        const WCHAR *objPath,
1052                        struct chmUnitInfo *ui)
1053 {
1054     /*
1055      * XXX: implement caching scheme for dir pages
1056      */
1057 
1058     Int32 curPage;
1059 
1060     /* buffer to hold whatever page we're looking at */
1061     UChar *page_buf = HeapAlloc(GetProcessHeap(), 0, h->block_len);
1062 
1063     /* starting page */
1064     curPage = h->index_root;
1065 
1066     /* until we have either returned or given up */
1067     while (curPage != -1)
1068     {
1069 
1070         /* try to fetch the index page */
1071         if (_chm_fetch_bytes(h, page_buf,
1072                              h->dir_offset + (UInt64)curPage*h->block_len,
1073                              h->block_len) != h->block_len)
1074 	{
1075 	    HeapFree(GetProcessHeap(), 0, page_buf);
1076             return CHM_RESOLVE_FAILURE;
1077 	}
1078 
1079         /* now, if it is a leaf node: */
1080         if (memcmp(page_buf, _chm_pmgl_marker, 4) == 0)
1081         {
1082             /* scan block */
1083             UChar *pEntry = _chm_find_in_PMGL(page_buf,
1084                                               h->block_len,
1085                                               objPath);
1086             if (pEntry == NULL)
1087             {
1088 	        HeapFree(GetProcessHeap(), 0, page_buf);
1089                 return CHM_RESOLVE_FAILURE;
1090             }
1091 
1092             /* parse entry and return */
1093             _chm_parse_PMGL_entry(&pEntry, ui);
1094 	    HeapFree(GetProcessHeap(), 0, page_buf);
1095             return CHM_RESOLVE_SUCCESS;
1096         }
1097 
1098         /* else, if it is a branch node: */
1099         else if (memcmp(page_buf, _chm_pmgi_marker, 4) == 0)
1100             curPage = _chm_find_in_PMGI(page_buf, h->block_len, objPath);
1101 
1102         /* else, we are confused.  give up. */
1103         else
1104         {
1105 	    HeapFree(GetProcessHeap(), 0, page_buf);
1106             return CHM_RESOLVE_FAILURE;
1107         }
1108     }
1109 
1110     /* didn't find anything.  fail. */
1111     HeapFree(GetProcessHeap(), 0, page_buf);
1112     return CHM_RESOLVE_FAILURE;
1113 }
1114 
1115 /*
1116  * utility methods for dealing with compressed data
1117  */
1118 
1119 /* get the bounds of a compressed block. Returns FALSE on failure */
1120 static BOOL _chm_get_cmpblock_bounds(struct chmFile *h,
1121                                      UInt64 block,
1122                                      UInt64 *start,
1123                                      Int64 *len)
1124 {
1125     UChar buffer[8], *dummy;
1126     UInt32 remain;
1127 
1128     /* for all but the last block, use the reset table */
1129     if (block < h->reset_table.block_count-1)
1130     {
1131         /* unpack the start address */
1132         dummy = buffer;
1133         remain = 8;
1134         if (_chm_fetch_bytes(h, buffer,
1135                              h->data_offset
1136                                 + h->rt_unit.start
1137                                 + h->reset_table.table_offset
1138                                 + block*8,
1139                              remain) != remain                            ||
1140             !_unmarshal_uint64(&dummy, &remain, start))
1141             return FALSE;
1142 
1143         /* unpack the end address */
1144         dummy = buffer;
1145         remain = 8;
1146         if (_chm_fetch_bytes(h, buffer,
1147                              h->data_offset
1148                                 + h->rt_unit.start
1149                                 + h->reset_table.table_offset
1150                                 + block*8 + 8,
1151                          remain) != remain                                ||
1152             !_unmarshal_int64(&dummy, &remain, len))
1153             return FALSE;
1154     }
1155 
1156     /* for the last block, use the span in addition to the reset table */
1157     else
1158     {
1159         /* unpack the start address */
1160         dummy = buffer;
1161         remain = 8;
1162         if (_chm_fetch_bytes(h, buffer,
1163                              h->data_offset
1164                                 + h->rt_unit.start
1165                                 + h->reset_table.table_offset
1166                                 + block*8,
1167                              remain) != remain                            ||
1168             !_unmarshal_uint64(&dummy, &remain, start))
1169             return FALSE;
1170 
1171         *len = h->reset_table.compressed_len;
1172     }
1173 
1174     /* compute the length and absolute start address */
1175     *len -= *start;
1176     *start += h->data_offset + h->cn_unit.start;
1177 
1178     return TRUE;
1179 }
1180 
1181 /* decompress the block.  must have lzx_mutex. */
1182 static Int64 _chm_decompress_block(struct chmFile *h,
1183                                    UInt64 block,
1184                                    UChar **ubuffer)
1185 {
1186     UChar *cbuffer = HeapAlloc( GetProcessHeap(), 0,
1187                               ((unsigned int)h->reset_table.block_len + 6144));
1188     UInt64 cmpStart;                                    /* compressed start  */
1189     Int64 cmpLen;                                       /* compressed len    */
1190     int indexSlot;                                      /* cache index slot  */
1191     UChar *lbuffer;                                     /* local buffer ptr  */
1192     UInt32 blockAlign = (UInt32)(block % h->reset_blkcount); /* reset interval align */
1193     UInt32 i;                                           /* local loop index  */
1194 
1195     /* let the caching system pull its weight! */
1196     if (block - blockAlign <= h->lzx_last_block  &&
1197         block              >= h->lzx_last_block)
1198         blockAlign = (block - h->lzx_last_block);
1199 
1200     /* check if we need previous blocks */
1201     if (blockAlign != 0)
1202     {
1203         /* fetch all required previous blocks since last reset */
1204         for (i = blockAlign; i > 0; i--)
1205         {
1206             UInt32 curBlockIdx = block - i;
1207 
1208             /* check if we most recently decompressed the previous block */
1209             if (h->lzx_last_block != curBlockIdx)
1210             {
1211                 if ((curBlockIdx % h->reset_blkcount) == 0)
1212                 {
1213 #ifdef CHM_DEBUG
1214                     fprintf(stderr, "***RESET (1)***\n");
1215 #endif
1216                     LZXreset(h->lzx_state);
1217                 }
1218 
1219                 indexSlot = (int)((curBlockIdx) % h->cache_num_blocks);
1220                 h->cache_block_indices[indexSlot] = curBlockIdx;
1221                 if (! h->cache_blocks[indexSlot])
1222                     h->cache_blocks[indexSlot] =
1223                       HeapAlloc(GetProcessHeap(), 0,
1224                                 (unsigned int)(h->reset_table.block_len));
1225                 lbuffer = h->cache_blocks[indexSlot];
1226 
1227                 /* decompress the previous block */
1228 #ifdef CHM_DEBUG
1229                 fprintf(stderr, "Decompressing block #%4d (EXTRA)\n", curBlockIdx);
1230 #endif
1231                 if (!_chm_get_cmpblock_bounds(h, curBlockIdx, &cmpStart, &cmpLen) ||
1232                     _chm_fetch_bytes(h, cbuffer, cmpStart, cmpLen) != cmpLen      ||
1233                     LZXdecompress(h->lzx_state, cbuffer, lbuffer, (int)cmpLen,
1234                                   (int)h->reset_table.block_len) != DECR_OK)
1235                 {
1236 #ifdef CHM_DEBUG
1237                     fprintf(stderr, "   (DECOMPRESS FAILED!)\n");
1238 #endif
1239                     HeapFree(GetProcessHeap(), 0, cbuffer);
1240                     return 0;
1241                 }
1242 
1243                 h->lzx_last_block = (int)curBlockIdx;
1244             }
1245         }
1246     }
1247     else
1248     {
1249         if ((block % h->reset_blkcount) == 0)
1250         {
1251 #ifdef CHM_DEBUG
1252             fprintf(stderr, "***RESET (2)***\n");
1253 #endif
1254             LZXreset(h->lzx_state);
1255         }
1256     }
1257 
1258     /* allocate slot in cache */
1259     indexSlot = (int)(block % h->cache_num_blocks);
1260     h->cache_block_indices[indexSlot] = block;
1261     if (! h->cache_blocks[indexSlot])
1262         h->cache_blocks[indexSlot] =
1263           HeapAlloc(GetProcessHeap(), 0, ((unsigned int)h->reset_table.block_len));
1264     lbuffer = h->cache_blocks[indexSlot];
1265     *ubuffer = lbuffer;
1266 
1267     /* decompress the block we actually want */
1268 #ifdef CHM_DEBUG
1269     fprintf(stderr, "Decompressing block #%4d (REAL )\n", block);
1270 #endif
1271     if (! _chm_get_cmpblock_bounds(h, block, &cmpStart, &cmpLen)          ||
1272         _chm_fetch_bytes(h, cbuffer, cmpStart, cmpLen) != cmpLen          ||
1273         LZXdecompress(h->lzx_state, cbuffer, lbuffer, (int)cmpLen,
1274                       (int)h->reset_table.block_len) != DECR_OK)
1275     {
1276 #ifdef CHM_DEBUG
1277         fprintf(stderr, "   (DECOMPRESS FAILED!)\n");
1278 #endif
1279         HeapFree(GetProcessHeap(), 0, cbuffer);
1280         return 0;
1281     }
1282     h->lzx_last_block = (int)block;
1283 
1284     /* XXX: modify LZX routines to return the length of the data they
1285      * decompressed and return that instead, for an extra sanity check.
1286      */
1287     HeapFree(GetProcessHeap(), 0, cbuffer);
1288     return h->reset_table.block_len;
1289 }
1290 
1291 /* grab a region from a compressed block */
1292 static Int64 _chm_decompress_region(struct chmFile *h,
1293                                     UChar *buf,
1294                                     UInt64 start,
1295                                     Int64 len)
1296 {
1297     UInt64 nBlock, nOffset;
1298     UInt64 nLen;
1299     UInt64 gotLen;
1300     UChar *ubuffer = NULL;
1301 
1302         if (len <= 0)
1303                 return 0;
1304 
1305     /* figure out what we need to read */
1306     nBlock = start / h->reset_table.block_len;
1307     nOffset = start % h->reset_table.block_len;
1308     nLen = len;
1309     if (nLen > (h->reset_table.block_len - nOffset))
1310         nLen = h->reset_table.block_len - nOffset;
1311 
1312     /* if block is cached, return data from it. */
1313     CHM_ACQUIRE_LOCK(h->lzx_mutex);
1314     CHM_ACQUIRE_LOCK(h->cache_mutex);
1315     if (h->cache_block_indices[nBlock % h->cache_num_blocks] == nBlock    &&
1316         h->cache_blocks[nBlock % h->cache_num_blocks] != NULL)
1317     {
1318         memcpy(buf,
1319                h->cache_blocks[nBlock % h->cache_num_blocks] + nOffset,
1320                (unsigned int)nLen);
1321         CHM_RELEASE_LOCK(h->cache_mutex);
1322         CHM_RELEASE_LOCK(h->lzx_mutex);
1323         return nLen;
1324     }
1325     CHM_RELEASE_LOCK(h->cache_mutex);
1326 
1327     /* data request not satisfied, so... start up the decompressor machine */
1328     if (! h->lzx_state)
1329     {
1330         int window_size = ffs(h->window_size) - 1;
1331         h->lzx_last_block = -1;
1332         h->lzx_state = LZXinit(window_size);
1333     }
1334 
1335     /* decompress some data */
1336     gotLen = _chm_decompress_block(h, nBlock, &ubuffer);
1337     if (gotLen < nLen)
1338         nLen = gotLen;
1339     memcpy(buf, ubuffer+nOffset, (unsigned int)nLen);
1340     CHM_RELEASE_LOCK(h->lzx_mutex);
1341     return nLen;
1342 }
1343 
1344 /* retrieve (part of) an object */
1345 LONGINT64 chm_retrieve_object(struct chmFile *h,
1346                                struct chmUnitInfo *ui,
1347                                unsigned char *buf,
1348                                LONGUINT64 addr,
1349                                LONGINT64 len)
1350 {
1351     /* must be valid file handle */
1352     if (h == NULL)
1353         return 0;
1354 
1355     /* starting address must be in correct range */
1356     if (addr >= ui->length)
1357         return 0;
1358 
1359     /* clip length */
1360     if (addr + len > ui->length)
1361         len = ui->length - addr;
1362 
1363     /* if the file is uncompressed, it's simple */
1364     if (ui->space == CHM_UNCOMPRESSED)
1365     {
1366         /* read data */
1367         return _chm_fetch_bytes(h,
1368                                 buf,
1369                                 h->data_offset + ui->start + addr,
1370                                 len);
1371     }
1372 
1373     /* else if the file is compressed, it's a little trickier */
1374     else /* ui->space == CHM_COMPRESSED */
1375     {
1376         Int64 swath=0, total=0;
1377 
1378         /* if compression is not enabled for this file... */
1379         if (! h->compression_enabled)
1380             return total;
1381 
1382         do {
1383 
1384             /* swill another mouthful */
1385             swath = _chm_decompress_region(h, buf, ui->start + addr, len);
1386 
1387             /* if we didn't get any... */
1388             if (swath == 0)
1389                 return total;
1390 
1391             /* update stats */
1392             total += swath;
1393             len -= swath;
1394             addr += swath;
1395             buf += swath;
1396 
1397         } while (len != 0);
1398 
1399         return total;
1400     }
1401 }
1402 
1403 BOOL chm_enumerate_dir(struct chmFile *h,
1404                        const WCHAR *prefix,
1405                        int what,
1406                        CHM_ENUMERATOR e,
1407                        void *context)
1408 {
1409     /*
1410      * XXX: do this efficiently (i.e. using the tree index)
1411      */
1412 
1413     Int32 curPage;
1414 
1415     /* buffer to hold whatever page we're looking at */
1416     UChar *page_buf = HeapAlloc(GetProcessHeap(), 0, h->block_len);
1417     struct chmPmglHeader header;
1418     UChar *end;
1419     UChar *cur;
1420     unsigned int lenRemain;
1421 
1422     /* set to TRUE once we've started */
1423     BOOL it_has_begun = FALSE;
1424 
1425     /* the current ui */
1426     struct chmUnitInfo ui;
1427     int flag;
1428     UInt64 ui_path_len;
1429 
1430     /* the length of the prefix */
1431     WCHAR prefixRectified[CHM_MAX_PATHLEN+1];
1432     int prefixLen;
1433     WCHAR lastPath[CHM_MAX_PATHLEN];
1434     int lastPathLen;
1435 
1436     /* starting page */
1437     curPage = h->index_head;
1438 
1439     /* initialize pathname state */
1440     lstrcpynW(prefixRectified, prefix, CHM_MAX_PATHLEN);
1441     prefixLen = strlenW(prefixRectified);
1442     if (prefixLen != 0)
1443     {
1444         if (prefixRectified[prefixLen-1] != '/')
1445         {
1446             prefixRectified[prefixLen] = '/';
1447             prefixRectified[prefixLen+1] = '\0';
1448             ++prefixLen;
1449         }
1450     }
1451     lastPath[0] = '\0';
1452     lastPathLen = -1;
1453 
1454     /* until we have either returned or given up */
1455     while (curPage != -1)
1456     {
1457 
1458         /* try to fetch the index page */
1459         if (_chm_fetch_bytes(h,
1460                              page_buf,
1461                              h->dir_offset + (UInt64)curPage*h->block_len,
1462                              h->block_len) != h->block_len)
1463         {
1464             HeapFree(GetProcessHeap(), 0, page_buf);
1465             return FALSE;
1466         }
1467 
1468         /* figure out start and end for this page */
1469         cur = page_buf;
1470         lenRemain = _CHM_PMGL_LEN;
1471         if (! _unmarshal_pmgl_header(&cur, &lenRemain, &header))
1472         {
1473             HeapFree(GetProcessHeap(), 0, page_buf);
1474             return FALSE;
1475         }
1476         end = page_buf + h->block_len - (header.free_space);
1477 
1478         /* loop over this page */
1479         while (cur < end)
1480         {
1481             if (! _chm_parse_PMGL_entry(&cur, &ui))
1482             {
1483                 HeapFree(GetProcessHeap(), 0, page_buf);
1484                 return FALSE;
1485             }
1486 
1487             /* check if we should start */
1488             if (! it_has_begun)
1489             {
1490                 if (ui.length == 0  &&  strncmpiW(ui.path, prefixRectified, prefixLen) == 0)
1491                     it_has_begun = TRUE;
1492                 else
1493                     continue;
1494 
1495                 if (ui.path[prefixLen] == '\0')
1496                     continue;
1497             }
1498 
1499             /* check if we should stop */
1500             else
1501             {
1502                 if (strncmpiW(ui.path, prefixRectified, prefixLen) != 0)
1503                 {
1504                     HeapFree(GetProcessHeap(), 0, page_buf);
1505                     return TRUE;
1506                 }
1507             }
1508 
1509             /* check if we should include this path */
1510             if (lastPathLen != -1)
1511             {
1512                 if (strncmpiW(ui.path, lastPath, lastPathLen) == 0)
1513                     continue;
1514             }
1515             strcpyW(lastPath, ui.path);
1516             lastPathLen = strlenW(lastPath);
1517 
1518             /* get the length of the path */
1519             ui_path_len = strlenW(ui.path)-1;
1520 
1521             /* check for DIRS */
1522             if (ui.path[ui_path_len] == '/'  &&  !(what & CHM_ENUMERATE_DIRS))
1523                 continue;
1524 
1525             /* check for FILES */
1526             if (ui.path[ui_path_len] != '/'  &&  !(what & CHM_ENUMERATE_FILES))
1527                 continue;
1528 
1529             /* check for NORMAL vs. META */
1530             if (ui.path[0] == '/')
1531             {
1532 
1533                 /* check for NORMAL vs. SPECIAL */
1534                 if (ui.path[1] == '#'  ||  ui.path[1] == '$')
1535                     flag = CHM_ENUMERATE_SPECIAL;
1536                 else
1537                     flag = CHM_ENUMERATE_NORMAL;
1538             }
1539             else
1540                 flag = CHM_ENUMERATE_META;
1541             if (! (what & flag))
1542                 continue;
1543 
1544             /* call the enumerator */
1545             {
1546                 int status = (*e)(h, &ui, context);
1547                 switch (status)
1548                 {
1549                     case CHM_ENUMERATOR_FAILURE:
1550                         HeapFree(GetProcessHeap(), 0, page_buf);
1551                         return FALSE;
1552                     case CHM_ENUMERATOR_CONTINUE:
1553                         break;
1554                     case CHM_ENUMERATOR_SUCCESS:
1555                         HeapFree(GetProcessHeap(), 0, page_buf);
1556                         return TRUE;
1557                     default:
1558                         break;
1559                 }
1560             }
1561         }
1562 
1563         /* advance to next page */
1564         curPage = header.block_next;
1565     }
1566 
1567     HeapFree(GetProcessHeap(), 0, page_buf);
1568     return TRUE;
1569 }
1570