2 * These routines are fully independent from the traditional zzip
3 * implementation. They assume a readonly seekable stdio handle
4 * representing a complete zip file. The functions show how to
5 * parse the structure, find files and return a decoded bytestream.
7 * These routines are a bit simple and really here for documenting
8 * the way to access a zip file. The complexity of zip access comes
9 * from staggered reading of bytes and reposition of a filepointer in
10 * a big archive with lots of files and long compressed datastreams.
11 * Plus varaints of drop-in stdio replacements, obfuscation routines,
12 * auto fileextensions, drop-in dirent replacements, and so on...
14 * btw, we can _not_ use fgetpos/fsetpos since an fpos_t has no asserted
15 * relation to a linear seek value as specified in zip info headers. In
16 * general it is not a problem if your system has no fseeko/ftello pair
17 * since we can fallback to fseek/ftell which limits the zip disk size
18 * to 2MiBs but the zip-storable seek values are 32bit limited anyway.
21 * Guido Draheim <guidod@gmx.de>
23 * Copyright (c) 2003,2004 Guido Draheim
24 * All rights reserved,
25 * use under the restrictions of the
26 * Lesser GNU General Public License
27 * or alternatively the restrictions
28 * of the Mozilla Public License 1.1
31 #define _LARGEFILE_SOURCE
33 #include <zzip/fseeko.h>
38 #ifdef ZZIP_HAVE_FNMATCH_H
42 #if defined ZZIP_HAVE_STRING_H
44 #elif defined ZZIP_HAVE_STRINGS_H
49 #include <zzip/format.h>
50 #include <zzip/fetch.h>
51 #include <zzip/__mmap.h>
53 #if __STDC_VERSION__+0 > 199900L
61 #ifndef ZZIP_HAVE_FSEEKO
66 /* note that the struct zzip_entry inherits the zzip_disk_entry values
67 * and usually carries a copy of its values (in disk format!). To make the
68 * following code more readable, we use a shorthand notation for the
69 * upcast needed in C (not needed in C++) as "disk_(entry)".
72 #define disk_(_entry_) _entry_
74 #define disk_(_entry_) (& (_entry_)->head)
78 struct zzip_entry : public struct zzip_disk_entry
80 char* _zzip_restrict tail;
81 zzip_off_t tailalloc; /* the allocated size of tail */
82 FILE* diskfile; /* a file reference */
83 zzip_off_t disksize; /* the size of the file */
84 zzip_off_t headseek; /* the offset within the file */
87 struct zzip_entry /* : struct zzip_disk_entry */
89 struct zzip_disk_entry head;
90 char* _zzip_restrict tail;
91 zzip_off_t tailalloc; /* the allocated size of tail */
92 FILE* diskfile; /* a file reference */
93 zzip_off_t disksize; /* the size of the file */
94 zzip_off_t headseek; /* the offset within the file */
98 /* we try to round all seeks to the pagesize - since we do not use
99 * the sys/mmap interface we have to guess a good value here: */
100 #define PAGESIZE 8192
102 /* ====================================================================== */
103 /* helper functions */
105 /** => zzip_entry_data_offset
106 * This functions read the correspoding struct zzip_file_header from
107 * the zip disk of the given "entry". The returned off_t points to the
108 * end of the file_header where the current fseek pointer has stopped.
109 * This is used to immediatly parse out any filename/extras block following
110 * the file_header. The return value is null on error.
113 zzip_entry_fread_file_header (ZZIP_ENTRY* entry,
114 struct zzip_file_header* file_header)
116 zzip_off_t offset = zzip_disk_entry_fileoffset (disk_(entry));
117 if (0 > offset || offset >= entry->disksize) return 0;
118 fseeko (entry->diskfile, offset, SEEK_SET);
119 return (fread (file_header, sizeof(*file_header), 1, entry->diskfile)
120 ? offset+sizeof(*file_header) : 0 );
123 /** helper functions for (fseeko) zip access api
125 * This functions returns the seekval offset of the data portion of the
126 * file referenced by the given zzip_entry. It requires an intermediate
127 * check of the file_header structure (i.e. it reads it from disk). After
128 * this call, the contained diskfile readposition is already set to the
129 * data_offset returned here. On error -1 is returned.
132 zzip_entry_data_offset(ZZIP_ENTRY* entry)
134 struct zzip_file_header file_header;
135 if (! entry) return -1;
136 ___ zzip_off_t offset =
137 zzip_entry_fread_file_header (entry, & file_header);
138 if (! offset) return -1;
139 offset += zzip_file_header_sizeof_tails (& file_header);
140 fseeko (entry->diskfile, offset, SEEK_SET);
144 /** => zzip_entry_data_offset
145 * This function is a big helper despite its little name: in a zip file the
146 * encoded filenames are usually NOT zero-terminated but for common usage
147 * with libc we need it that way. Secondly, the filename SHOULD be present
148 * in the zip central directory but if not then we fallback to the filename
149 * given in the file_header of each compressed data portion.
152 zzip_entry_strdup_name(ZZIP_ENTRY* entry)
154 if (! entry) return 0;
157 if ((len = zzip_disk_entry_namlen (disk_(entry))))
159 char* name = malloc (len+1);
160 if (! name) return 0;
161 memcpy (name, entry->tail, len);
165 ___ auto struct zzip_file_header header;
166 if (zzip_entry_fread_file_header (entry, &header) &&
167 (( len = zzip_file_header_namlen(&header) )))
169 char* name = malloc (len+1);
170 if (! name) return 0;
171 fread (name, 1, len, entry->diskfile);
179 /* ====================================================================== */
181 /** => zzip_entry_findfile
183 * This function is the first call of all the zip access functions here.
184 * It contains the code to find the first entry of the zip central directory.
185 * Here we require the stdio handle to represent a real zip file where the
186 * disk_trailer is _last_ in the file area, so that its position would be at
187 * a fixed offset from the end of the file area if not for the comment field
188 * allowed to be of variable length (which needs us to do a little search
189 * for the disk_tailer). However, in this simple implementation we disregard
190 * any disk_trailer info telling about multidisk archives, so we just return
191 * a pointer to the first entry in the zip central directory of that file.
193 * For an actual means, we are going to search backwards from the end
194 * of the mmaped block looking for the PK-magic signature of a
195 * disk_trailer. If we see one then we check the rootseek value to
196 * find the first disk_entry of the root central directory. If we find
197 * the correct PK-magic signature of a disk_entry over there then we
198 * assume we are done and we are going to return a pointer to that label.
200 * The return value is a pointer to the first zzip_disk_entry being checked
201 * to be within the bounds of the file area specified by the arguments. If
202 * no disk_trailer was found then null is returned, and likewise we only
203 * accept a disk_trailer with a seekvalue that points to a disk_entry and
204 * both parts have valid PK-magic parts. Beyond some sanity check we try to
205 * catch a common brokeness with zip archives that still allows us to find
206 * the start of the zip central directory.
208 ZZIP_ENTRY* _zzip_restrict
209 zzip_entry_findfirst(FILE* disk)
211 if (! disk) return 0;
212 fseeko (disk, 0, SEEK_END);
213 ___ zzip_off_t disksize = ftello (disk);
214 if (disksize < (zzip_off_t) sizeof(struct zzip_disk_trailer)) return 0;
215 /* we read out chunks of 8 KiB in the hope to match disk granularity */
216 ___ zzip_off_t pagesize = PAGESIZE; /* getpagesize() */
217 ___ ZZIP_ENTRY* entry = malloc (sizeof(*entry)); if (! entry) return 0;
218 ___ char* buffer = malloc (pagesize); if (! buffer) goto nomem;
220 assert (pagesize/2 > (zzip_off_t) sizeof (struct zzip_disk_trailer));
221 /* at each step, we will fread a pagesize block which overlaps with the
222 * previous read by means of pagesize/2 step at the end of the while(1) */
223 ___ zzip_off_t mapoffs = disksize &~ (pagesize-1);
224 ___ zzip_off_t mapsize = disksize - mapoffs;
225 if (mapoffs && mapsize < pagesize/2) {
226 mapoffs -= pagesize/2; mapsize += pagesize/2; }
229 fseeko (disk, mapoffs, SEEK_SET);
230 fread (buffer, 1, mapsize, disk);
231 ___ char* p = buffer + mapsize - sizeof(struct zzip_disk_trailer);
232 for (; p >= buffer ; p--)
234 if (! zzip_disk_trailer_check_magic(p)) continue;
235 ___ zzip_off_t root =
236 zzip_disk_trailer_rootseek ((struct zzip_disk_trailer*)p);
237 if ((char*) root > p)
238 { /* the first disk_entry is after the disk_trailer? can't be! */
239 zzip_off_t rootsize =
240 zzip_disk_trailer_rootsize ((struct zzip_disk_trailer*)p);
241 if (rootsize > mapoffs) continue;
242 /* a common brokeness that can be fixed: we just assume that
243 * the central directory was written directly before : */
244 root = mapoffs - rootsize;
246 assert (0 <= root && root < mapsize);
247 fseeko (disk, root, SEEK_SET);
248 fread (disk_(entry), 1, sizeof(*disk_(entry)), disk);
249 if (zzip_disk_entry_check_magic(entry))
252 entry->headseek = root;
253 entry->diskfile = disk;
254 entry->disksize = disksize;
255 ___ zzip_size_t tailsize =
256 zzip_disk_entry_sizeof_tails (disk_(entry));
257 if (!( entry->tail = malloc (tailsize+1) )) goto nomem;
258 fread (entry->tail, 1, tailsize, disk);
259 entry->tailalloc = tailsize+1;
264 if (! mapoffs) break; assert (mapsize >= pagesize/2);
265 mapoffs -= pagesize/2; /* mapsize += pagesize/2; */
266 mapsize = pagesize; /* if (mapsize > pagesize) ... */
267 if (disksize - mapoffs > 64*1024) break;
271 free (entry); ____;____;____;____;____;____;
275 /** => zzip_entry_findfile
277 * This function takes an existing "entry" in the central root directory
278 * (e.g. from zzip_entry_findfirst) and moves it to point to the next entry.
279 * On error it returns 0, otherwise the old entry. If no further match is
280 * found then null is returned and the entry already free()d. If you want
281 * to stop searching for matches before that case then please call
282 * => zzip_entry_free on the cursor struct ZZIP_ENTRY.
284 ZZIP_ENTRY* _zzip_restrict
285 zzip_entry_findnext(ZZIP_ENTRY* _zzip_restrict entry)
287 if (! entry) return entry;
288 ___ zzip_off_t seek =
289 entry->headseek + zzip_disk_entry_sizeto_end (disk_(entry));
290 if (seek + (zzip_off_t) sizeof(*disk_(entry)) > entry->disksize) goto err;
291 fseeko (entry->diskfile, seek, SEEK_SET);
292 fread (disk_(entry), 1, sizeof(*disk_(entry)), entry->diskfile);
293 entry->headseek = seek;
294 ___ zzip_off_t tailsize = zzip_disk_entry_sizeof_tails (disk_(entry));
295 if (tailsize+1 > entry->tailalloc)
297 char* newtail = realloc (entry->tail, tailsize+1);
298 if (! newtail) goto err;
299 entry->tail = newtail;
300 entry->tailalloc = tailsize+1;
302 fread (entry->tail, 1, tailsize, entry->diskfile);
305 zzip_entry_free (entry);
309 /** => zzip_entry_findfile
310 * this function releases the malloc()ed areas needed for zzip_entry, the
311 * pointer is invalid afterwards. This function has #define synonyms of
312 * zzip_entry_findlast(), zzip_entry_findlastfile(), zzip_entry_findlastmatch()
315 zzip_entry_free(ZZIP_ENTRY* entry)
317 if (! entry) return 0;
323 /** search for files in the (fseeko) zip central directory
325 * This function is given a filename as an additional argument, to find the
326 * disk_entry matching a given filename. The compare-function is usually
327 * strcmp or strcasecmp or perhaps strcoll, if null then strcmp is used.
328 * - use null as argument for "old"-entry when searching the first
329 * matching entry, otherwise the last returned value if you look for other
330 * entries with a special "compare" function (if null then a doubled search
331 * is rather useless with this variant of _findfile). If no further entry is
332 * found then null is returned and any "old"-entry gets already free()d.
334 ZZIP_ENTRY* _zzip_restrict
335 zzip_entry_findfile(FILE* disk, char* filename,
336 ZZIP_ENTRY* _zzip_restrict entry,
337 zzip_strcmp_fn_t compare)
339 if (! filename || ! disk) return 0;
340 entry = ! entry ? zzip_entry_findfirst (disk)
341 : zzip_entry_findnext (entry);
343 if (! compare) compare = (zzip_strcmp_fn_t)(strcmp);
344 for (; entry ; entry = zzip_entry_findnext (entry))
346 /* filenames within zip files are often not null-terminated! */
347 char* realname = zzip_entry_strdup_name (entry);
348 if (realname && ! compare(filename, realname))
358 #ifdef ZZIP_HAVE_FNMATCH_H
359 #define _zzip_fnmatch fnmatch
361 # define _zzip_fnmatch_CASEFOLD FNM_CASEFOLD
363 # define _zzip_fnmatch_CASEFOLD 0
366 # define _zzip_fnmatch_CASEFOLD 0
367 /* if your system does not have fnmatch, we fall back to strcmp: */
368 static int _zzip_fnmatch(char* pattern, char* string, int flags)
370 puts ("<zzip:strcmp>");
371 return strcmp (pattern, string);
375 /** => zzip_entry_findfile
377 * This function uses a compare-function with an additional argument
378 * and it is called just like fnmatch(3) from POSIX.2 AD:1993), i.e.
379 * the argument filespec first and the ziplocal filename second with
380 * the integer-flags put in as third to the indirect call. If the
381 * platform has fnmatch available then null-compare will use that one
382 * and otherwise we fall back to mere strcmp, so if you need fnmatch
383 * searching then please provide an implementation somewhere else.
384 * - use null as argument for "after"-entry when searching the first
385 * matching entry, or the last disk_entry return-value to find the
386 * next entry matching the given filespec. If no further entry is
387 * found then null is returned and any "old"-entry gets already free()d.
389 ZZIP_ENTRY* _zzip_restrict
390 zzip_entry_findmatch(FILE* disk, char* filespec,
391 ZZIP_ENTRY* _zzip_restrict entry,
392 zzip_fnmatch_fn_t compare, int flags)
394 if (! filespec || ! disk) return 0;
395 entry = ! entry ? zzip_entry_findfirst (disk)
396 : zzip_entry_findnext (entry);
398 if (! compare) compare = (zzip_fnmatch_fn_t) _zzip_fnmatch;
399 for (; entry ; entry = zzip_entry_findnext (entry))
401 /* filenames within zip files are often not null-terminated! */
402 char* realname = zzip_entry_strdup_name(entry);
403 if (realname && ! compare(filespec, realname, flags))
413 /* ====================================================================== */
416 * typedef struct zzip_disk_file ZZIP_ENTRY_FILE;
418 struct zzip_entry_file /* : zzip_file_header */
420 struct zzip_file_header header; /* fopen detected header */
421 ZZIP_ENTRY* entry; /* fopen entry */
422 zzip_off_t data; /* for stored blocks */
423 zzip_size_t avail; /* memorized for checks on EOF */
424 zzip_size_t compressed; /* compressed flag and datasize */
425 zzip_size_t dataoff; /* offset from data start */
426 z_stream zlib; /* for inflated blocks */
427 char buffer[PAGESIZE]; /* work buffer for inflate algorithm */
430 /** open a file within a zip disk for reading
432 * This function does take an "entry" argument and copies it (or just takes
433 * it over as owner) to a new ZZIP_ENTRY_FILE handle structure. That
434 * structure contains also a zlib buffer for decoding. This function does
435 * seek to the file_header of the given "entry" and validates it for the
436 * data buffer following it. We do also prefetch some data from the data
437 * buffer thereby trying to match the disk pagesize for faster access later.
438 * The => zzip_entry_fread will then read in chunks of pagesizes which is
439 * the size of the internal readahead buffer. If an error occurs then null
442 ZZIP_ENTRY_FILE* _zzip_restrict
443 zzip_entry_fopen (ZZIP_ENTRY* entry, int takeover)
445 if (! entry) return 0;
448 ZZIP_ENTRY* found = malloc (sizeof(*entry));
449 if (! found) return 0;
450 memcpy (found, entry, sizeof(*entry));
451 found->tail = malloc (found->tailalloc);
452 if (! found->tail) { free (found); return 0; }
453 memcpy (found->tail, entry->tail, entry->tailalloc);
456 ___ ZZIP_ENTRY_FILE* file = malloc(sizeof(*file));
457 if (! file) goto fail1;
459 if (! zzip_entry_fread_file_header (entry, &file->header))
461 file->avail = zzip_file_header_usize (&file->header);
462 file->data = zzip_entry_data_offset (entry);
465 if (! file->avail || zzip_file_header_data_stored (&file->header))
466 { file->compressed = 0; return file; }
468 file->compressed = zzip_file_header_csize (&file->header);
469 file->zlib.opaque = 0;
470 file->zlib.zalloc = Z_NULL;
471 file->zlib.zfree = Z_NULL;
473 ___ zzip_off_t seek = file->data;
474 seek += sizeof(file->buffer); seek -= seek & (sizeof(file->buffer)-1);
475 assert (file->data < seek); /* pre-read to next PAGESIZE boundary... */
476 fseeko (file->entry->diskfile, file->data + file->dataoff, SEEK_SET);
477 file->zlib.next_in = file->buffer;
478 file->zlib.avail_in = fread (file->buffer, 1, seek - file->data,
479 file->entry->diskfile);
480 file->dataoff += file->zlib.avail_in; ____;
482 if (! zzip_file_header_data_deflated (&file->header) ||
483 inflateInit2 (& file->zlib, -MAX_WBITS) != Z_OK) goto fail2;
489 zzip_entry_free (entry);
493 /** => zzip_entry_fopen
495 * This function opens a file found by name, so it does a search into
496 * the zip central directory with => zzip_entry_findfile and whatever
497 * is found first is given to => zzip_entry_fopen
499 ZZIP_ENTRY_FILE* _zzip_restrict
500 zzip_entry_ffile (FILE* disk, char* filename)
502 ZZIP_ENTRY* entry = zzip_entry_findfile (disk, filename, 0, 0);
503 if (! entry) return 0; else return zzip_entry_fopen (entry, 1);
507 /** => zzip_entry_fopen
509 * This function reads more bytes into the output buffer specified as
510 * arguments. The return value is null on eof or error, the stdio-like
511 * interface can not distinguish between these so you need to check
512 * with => zzip_entry_feof for the difference.
515 zzip_entry_fread (void* ptr, zzip_size_t sized, zzip_size_t nmemb,
516 ZZIP_ENTRY_FILE* file)
518 zzip_size_t size = sized*nmemb;
519 if (! file->compressed)
521 if (size > file->avail) size = file->avail;
522 fread (ptr, 1, size, file->entry->diskfile);
523 file->dataoff += size;
528 file->zlib.avail_out = size;
529 file->zlib.next_out = ptr;
530 ___ zzip_size_t total_old = file->zlib.total_out;
533 if (! file->zlib.avail_in)
535 size = file->compressed - file->dataoff;
536 if (size > sizeof(file->buffer)) size = sizeof(file->buffer);
537 /* fseek (file->data + file->dataoff, file->entry->diskfile); */
538 file->zlib.avail_in = fread (file->buffer, 1, size,
539 file->entry->diskfile);
540 file->zlib.next_in = file->buffer;
541 file->dataoff += file->zlib.avail_in;
543 if (! file->zlib.avail_in) return 0;
545 ___ int err = inflate (& file->zlib, Z_NO_FLUSH);
546 if (err == Z_STREAM_END)
548 else if (err == Z_OK)
549 file->avail -= file->zlib.total_out - total_old;
553 if (file->zlib.avail_out && ! file->zlib.avail_in) continue;
554 return file->zlib.total_out - total_old;
558 /** => zzip_entry_fopen
559 * This function releases any zlib decoder info needed for decompression
560 * and dumps the ZZIP_ENTRY_FILE struct then.
563 zzip_entry_fclose (ZZIP_ENTRY_FILE* file)
565 if (file->compressed)
566 inflateEnd (& file->zlib);
567 zzip_entry_free (file->entry);
572 /** => zzip_entry_fopen
574 * This function allows to distinguish an error from an eof condition.
575 * Actually, if we found an error but we did already reach eof then we
576 * just keep on saying that it was an eof, so the app can just continue.
579 zzip_entry_feof (ZZIP_ENTRY_FILE* file)
581 return ! file || ! file->avail;