zziplib Library Functions

Version 0.13.60

#include <zzip/fseeko.h>

Documentation

zzip_entry_fopen(ZZIP_ENTRY * entry, int takeover) : zzip__new__ ZZIP_ENTRY_FILE *

zzip_entry_ffile(FILE * disk, char *filename) : zzip__new__ ZZIP_ENTRY_FILE *

zzip_entry_fread(void *ptr, zzip_size_t sized, zzip_size_t nmemb, ZZIP_ENTRY_FILE * file) : zzip_size_t

zzip_entry_fclose(ZZIP_ENTRY_FILE * file) : int

zzip_entry_feof(ZZIP_ENTRY_FILE * file) : int

open a file within a zip disk for reading zzip/fseeko.c The zzip_entry_fopen function does take an "entry" argument and copies it (or just takes it over as owner) to a new ZZIP_ENTRY_FILE handle structure. That structure contains also a zlib buffer for decoding. The zzip_entry_fopen function does seek to the file_header of the given "entry" and validates it for the data buffer following it. We do also prefetch some data from the data buffer thereby trying to match the disk pagesize for faster access later. The zzip_entry_fread will then read in chunks of pagesizes which is the size of the internal readahead buffer. If an error occurs then null is returned.

The zzip_entry_ffile function opens a file found by name, so it does a search into the zip central directory with zzip_entry_findfile and whatever is found first is given to zzip_entry_fopen

The zzip_entry_fread function reads more bytes into the output buffer specified as arguments. The return value is null on eof or error, the stdio-like interface can not distinguish between these so you need to check with zzip_entry_feof for the difference.

The zzip_entry_fclose function releases any zlib decoder info needed for decompression and dumps the ZZIP_ENTRY_FILE struct then.

The zzip_entry_feof function allows to distinguish an error from an eof condition. Actually, if we found an error but we did already reach eof then we just keep on saying that it was an eof, so the app can just continue.

zzip_entry_data_offset(ZZIP_ENTRY * entry) : zzip_off_t

zzip_entry_fread_file_header(ZZIP_ENTRY * entry, struct zzip_file_header *file_header) : static zzip_off_t

zzip_entry_strdup_name(ZZIP_ENTRY * entry) : zzip__new__ char *

helper functions for (fseeko) zip access api zzip/fseeko.c The zzip_entry_data_offset functions returns the seekval offset of the data portion of the file referenced by the given zzip_entry. It requires an intermediate check of the file_header structure (i.e. it reads it from disk). After this call, the contained diskfile readposition is already set to the data_offset returned here. On error -1 is returned.

The zzip_entry_fread_file_header functions read the correspoding struct zzip_file_header from the zip disk of the given "entry". The returned off_t points to the end of the file_header where the current fseek pointer has stopped. This is used to immediatly parse out any filename/extras block following the file_header. The return value is null on error.

The zzip_entry_strdup_name function is a big helper despite its little name: in a zip file the encoded filenames are usually NOT zero-terminated but for common usage with libc we need it that way. Secondly, the filename SHOULD be present in the zip central directory but if not then we fallback to the filename given in the file_header of each compressed data portion.

zzip_entry_findfile(FILE * disk, char *filename, ZZIP_ENTRY * _zzip_restrict entry, zzip_strcmp_fn_t compare) : zzip__new__ ZZIP_ENTRY *

zzip_entry_findfirst(FILE * disk) : zzip__new__ ZZIP_ENTRY *

zzip_entry_findnext(ZZIP_ENTRY * _zzip_restrict entry) : zzip__new__ ZZIP_ENTRY *

zzip_entry_free(ZZIP_ENTRY * entry) : int

zzip_entry_findmatch(FILE * disk, char *filespec, ZZIP_ENTRY * _zzip_restrict entry, zzip_fnmatch_fn_t compare, int flags) : zzip__new__ ZZIP_ENTRY *

search for files in the (fseeko) zip central directory zzip/fseeko.c The zzip_entry_findfile function is given a filename as an additional argument, to find the disk_entry matching a given filename. The compare-function is usually strcmp or strcasecmp or perhaps strcoll, if null then strcmp is used. - use null as argument for "old"-entry when searching the first matching entry, otherwise the last returned value if you look for other entries with a special "compare" function (if null then a doubled search is rather useless with this variant of _findfile). If no further entry is found then null is returned and any "old"-entry gets already free()d.

The zzip_entry_findfirst function is the first call of all the zip access functions here. It contains the code to find the first entry of the zip central directory. Here we require the stdio handle to represent a real zip file where the disk_trailer is _last_ in the file area, so that its position would be at a fixed offset from the end of the file area if not for the comment field allowed to be of variable length (which needs us to do a little search for the disk_tailer). However, in this simple implementation we disregard any disk_trailer info telling about multidisk archives, so we just return a pointer to the first entry in the zip central directory of that file. For an actual means, we are going to search backwards from the end of the mmaped block looking for the PK-magic signature of a disk_trailer. If we see one then we check the rootseek value to find the first disk_entry of the root central directory. If we find the correct PK-magic signature of a disk_entry over there then we assume we are done and we are going to return a pointer to that label. The return value is a pointer to the first zzip_disk_entry being checked to be within the bounds of the file area specified by the arguments. If no disk_trailer was found then null is returned, and likewise we only accept a disk_trailer with a seekvalue that points to a disk_entry and both parts have valid PK-magic parts. Beyond some sanity check we try to catch a common brokeness with zip archives that still allows us to find the start of the zip central directory.

The zzip_entry_findnext function takes an existing "entry" in the central root directory (e.g. from zzip_entry_findfirst) and moves it to point to the next entry. On error it returns 0, otherwise the old entry. If no further match is found then null is returned and the entry already free()d. If you want to stop searching for matches before that case then please call zzip_entry_free on the cursor struct ZZIP_ENTRY.

the zzip_entry_free function releases the malloc()ed areas needed for zzip_entry, the pointer is invalid afterwards. The zzip_entry_free function has #define synonyms of zzip_entry_findlast(), zzip_entry_findlastfile(), zzip_entry_findlastmatch()

The zzip_entry_findmatch function uses a compare-function with an additional argument and it is called just like fnmatch(3) from POSIX.2 AD:1993), i.e. the argument filespec first and the ziplocal filename second with the integer-flags put in as third to the indirect call. If the platform has fnmatch available then null-compare will use that one and otherwise we fall back to mere strcmp, so if you need fnmatch searching then please provide an implementation somewhere else. - use null as argument for "after"-entry when searching the first matching entry, or the last disk_entry return-value to find the next entry matching the given filespec. If no further entry is found then null is returned and any "old"-entry gets already free()d.