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<section> <date> 2005 </date>
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<H2> zzip/memdisk </H2> zip cache for mmapped views
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These routines are fully independent from the traditional zzip
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implementation. They build on top of
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<a href="mmapped.html">zzip/mmapped</a> that uses a readonly
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mmapped sharedmem block. These functions add additional hints
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how to parse extension blocks and how to cache the zip central
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directory entries which does furthermore allow to convert them
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to any host-local format as required.
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<H3> zzip disk handle </H3>
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Other than with the <a href="fseeko.html">fseeko</a> alternative
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interface there is no need to have an actual disk handle to the
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zip archive. Instead you can use a bytewise copy of a file or
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even use a mmapped view of a file. This is generally the fastest
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way to get to the data contained in a zipped file. All it requires
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is enough of virtual memory space but a desktop computer with a
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a modern operating system will easily take care of that.
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The zzipmmapped library provides a number of calls to create a
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disk handle representing a zip archive in virtual memory. Per
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default we use the sys/mmap.h (or MappedView) functionality
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of the operating system. See for more details in the
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<a href="mmapped.html">zzip/mmapped</a> descriptions.
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The zzip/memdisk extensions of zzip/mmapped are made to have a
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very similar call API - therefore you will find again open and
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close functions for filenames or filehandles. However the
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direct mmap interface is not re-exported under the zzip_mem_disk
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prefix (of the underlying zzip_disk prefix). The "_mem_" part
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hints that the central directory of the underlying zzip_disk
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is preparsed to a separate memory block.
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ZZIP_MEM_DISK* zzip_mem_disk_open(char* filename);
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ZZIP_MEM_DISK* zzip_mem_disk_fdopen(int fd);
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void zzip_mem_disk_close(ZZIP_MEM_DISK* disk);
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int zzip_mem_disk_load (ZZIP_MEM_DISK* dir, ZZIP_DISK* disk);
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void zzip_mem_disk_unload (ZZIP_MEM_DISK* dir);
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The last two functions export some parts of the underlying
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interface. It is possible to bind an existing ZZIP_MEM_DISK
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handle with an arbitrary ZZIP_DISK handle. Upon calling "load"
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the central directory will be loaded from the underlying zip
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disk content and parsed to an internal mem block. The corresponding
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"unload" function will trash that central directory cache but it
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leaves the handles intact.
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<H3> reading the central directory </H3>
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All other zzip_mem_disk functions are simply re-exporting the
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underlying zzip_disk functions. Note that the first field in
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the ZZIP_MEM_DISK is a "ZZIP_DISK* disk" - the header file
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zzip/memdisk.h will simply export inline functions where there
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is no special zzip_mem_disk function. Therefore, whenever a
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function call on a ZZIP_DISK handle is appropriate one can
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also use its cousin for a ZZIP_MEM_DISK handle without any
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penalties but future compatibility for extra functionality in
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zzip/memdisk layer of the zzip/mmapped library.
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<P><small>Note: by default the re-exports are done with the help
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of the C precompiler as precompiler macros. Using USE_INLINE
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will force to make them real inlines. In the future that may
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change in favor of a better autodetection for inline capabilities
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of the compiler and/or using a standard cpp-define that enables
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the C/C++ inline functions. The inline functions do have the
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added value of having strongtyped arguments provoking more
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readable warning messages in user application code.</small></P>
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inline ZZIP_DISK_ENTRY*
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zzip_mem_disk_findfirst(ZZIP_MEM_DISK* dir);
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inline ZZIP_DISK_ENTRY*
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zzip_mem_disk_findnext(ZZIP_MEM_DISK* dir, ZZIP_DISK_ENTRY* entry);
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inline char* _zzip_restrict
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zzip_mem_disk_entry_strdup_name(ZZIP_MEM_DISK* dir,
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ZZIP_DISK_ENTRY* entry);
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inline struct zzip_file_header*
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zzip_mem_disk_entry_to_file_header(ZZIP_MEM_DISK* dir,
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ZZIP_DISK_ENTRY* entry);
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zzip_mem_disk_entry_to_data(ZZIP_MEM_DISK* dir, ZZIP_DISK_ENTRY* entry);
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inline ZZIP_DISK_ENTRY*
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zzip_mem_disk_findfile(ZZIP_MEM_DISK* dir,
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char* filename, ZZIP_DISK_ENTRY* after,
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zzip_strcmp_fn_t compare);
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inline ZZIP_DISK_ENTRY*
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zzip_mem_disk_findmatch(ZZIP_MEM_DISK* dir,
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char* filespec, ZZIP_DISK_ENTRY* after,
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zzip_fnmatch_fn_t compare, int flags);
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inline ZZIP_DISK_FILE* _zzip_restrict
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zzip_mem_disk_entry_fopen (ZZIP_MEM_DISK* dir, ZZIP_DISK_ENTRY* entry);
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inline ZZIP_DISK_FILE* _zzip_restrict
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zzip_mem_disk_fopen (ZZIP_MEM_DISK* dir, char* filename);
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zzip_mem_disk_fread (void* ptr, _zzip_size_t size, _zzip_size_t nmemb,
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ZZIP_DISK_FILE* file);
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zzip_mem_disk_fclose (ZZIP_DISK_FILE* file);
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zzip_mem_disk_feof (ZZIP_DISK_FILE* file);
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src/libs/zziplib/docs/memdisk.htm
