215 lines
7.2 KiB
C++
215 lines
7.2 KiB
C++
/**
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* =========================================================================
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* File : archive.h
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* Project : 0 A.D.
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* Description : provide access to archive "resources". allows
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* : opening, reading from, and creating them.
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* =========================================================================
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*/
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// license: GPL; see lib/license.txt
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#ifndef INCLUDED_ARCHIVE
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#define INCLUDED_ARCHIVE
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#include "lib/res/handle.h"
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#include "../file.h" // FileCB for afile_enum
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#include "compression.h" // CompressionMethod
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namespace ERR
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{
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const LibError IS_COMPRESSED = -110400;
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}
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// note: filenames are case-insensitive.
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//
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// archive
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//
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// open and return a handle to the archive indicated by <fn>.
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// somewhat slow - each file is added to an internal index.
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extern Handle archive_open(const char* fn);
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// close the archive <ha> and set ha to 0
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extern LibError archive_close(Handle& ha);
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// successively call <cb> for each valid file in the archive <ha>,
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// passing the complete path and <user>.
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// if it returns a nonzero value, abort and return that, otherwise 0.
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//
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// FileCB's name parameter will be the full path and unique
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// (i.e. returned by file_make_unique_fn_copy).
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extern LibError archive_enum(const Handle ha, const FileCB cb, const uintptr_t user);
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//
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// file
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//
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// get file status (size, mtime). output param is zeroed on error.
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extern LibError afile_stat(Handle ha, const char* fn, struct stat* s);
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// open file, and fill *f with information about it.
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// return < 0 on error (output param zeroed).
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extern LibError afile_open(Handle ha, const char* fn, uintptr_t memento, uint flags, File* f);
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// close file.
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extern LibError afile_close(File* f);
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extern LibError afile_validate(const File* f);
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extern LibError afile_open_vfs(const char* fn, uint flags, File* f, TFile* tf);
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//
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// asynchronous read
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//
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// begin transferring <size> bytes, starting at <ofs>. get result
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// with afile_io_wait; when no longer needed, free via afile_io_discard.
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extern LibError afile_io_issue(File* f, off_t ofs, size_t size, u8* buf, FileIo* io);
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// indicates if the IO referenced by <io> has completed.
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// return value: 0 if pending, 1 if complete, < 0 on error.
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extern int afile_io_has_completed(FileIo* io);
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// wait until the transfer <io> completes, and return its buffer.
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// output parameters are zeroed on error.
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extern LibError afile_io_wait(FileIo* io, u8*& p, size_t& size);
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// finished with transfer <io> - free its buffer (returned by afile_io_wait)
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extern LibError afile_io_discard(FileIo* io);
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extern LibError afile_io_validate(const FileIo* io);
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//
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// synchronous read
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//
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// read from the (possibly compressed) file <zf> as if it were a normal file.
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// starting at the beginning of the logical (decompressed) file,
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// skip <ofs> bytes of data; read the next <size> bytes into <buf>.
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//
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// if non-NULL, <cb> is called for each block read, passing <ctx>.
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// if it returns a negative error code,
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// the read is aborted and that value is returned.
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// the callback mechanism is useful for user progress notification or
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// processing data while waiting for the next I/O to complete
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// (quasi-parallel, without the complexity of threads).
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//
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// return bytes read, or a negative error code.
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extern ssize_t afile_read(File* f, off_t ofs, size_t size, FileIOBuf* pbuf, FileIOCB cb = 0, uintptr_t ctx = 0);
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//
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// memory mapping
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//
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// useful for files that are too large to be loaded into memory,
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// or if only (non-sequential) portions of a file are needed at a time.
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//
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// this is of course only possible for uncompressed files - compressed files
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// would have to be inflated sequentially, which defeats the point of mapping.
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// map the entire file <f> into memory. mapping compressed files
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// isn't allowed, since the compression algorithm is unspecified.
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// output parameters are zeroed on failure.
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//
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// the mapping will be removed (if still open) when its archive is closed.
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// however, map/unmap calls should still be paired so that the archive mapping
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// may be removed when no longer needed.
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extern LibError afile_map(File* f, u8*& p, size_t& size);
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// remove the mapping of file <f>; fail if not mapped.
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//
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// the mapping will be removed (if still open) when its archive is closed.
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// however, map/unmap calls should be paired so that the archive mapping
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// may be removed when no longer needed.
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extern LibError afile_unmap(File* f);
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//
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// interface for backends
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//
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// the archive-specific backends call back here for each file;
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// this module provides storage for the file table.
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enum ArchiveFileFlags
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{
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// indicates ArchiveEntry.ofs points to a "local file header"
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// instead of the file data. a fixup routine is called upon
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// file open; it skips past LFH and clears this flag.
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// this is somewhat of a hack, but vital to archive open
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// performance. without it, we'd have to scan through the
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// entire Zip file, which can take *seconds*.
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// (we cannot use the information in CDFH, because its 'extra' field
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// has been observed to differ from that of the LFH)
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// by reading LFH when a file in archive is opened, the block cache
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// absorbs the IO cost because the file will likely be read anyway.
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ZIP_LFH_FIXUP_NEEDED = 1
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};
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// holds all per-file information extracted from the header.
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// this is intended to work for all archive types.
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//
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// note: File* (state of a currently open file) is separate because
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// some of its fields need not be stored here; we'd like to minimize
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// size of the file table.
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struct ArchiveEntry
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{
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// these are returned by afile_stat:
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off_t usize;
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time_t mtime;
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// used in IO
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off_t ofs;
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off_t csize;
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CompressionMethod method;
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u32 checksum;
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uint flags; // ArchiveFileFlags
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const char* atom_fn;
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// why csize?
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// file I/O may be N-buffered, so it's good to know when the raw data
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// stops, or else we potentially overshoot by N-1 blocks.
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// if we do read too much though, nothing breaks - inflate would just
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// ignore it, since Zip files are compressed individually.
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//
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// we also need a way to check if a file is compressed (e.g. to fail
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// mmap requests if the file is compressed). packing a bit in ofs or
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// usize is error prone and ugly (1 bit less won't hurt though).
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// any other way will mess up the nice 2^n byte size anyway, so
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// might as well store csize.
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};
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// successively called for each valid file in the archive,
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// passing the complete path and <user>.
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// return INFO::CB_CONTINUE to continue calling; anything else will cause
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// the caller to abort and immediately return that value.
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//
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// HACK: call back with negative index the first time; its abs. value is
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// the number of entries in the archive. lookup needs to know this so it can
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// preallocate memory. having lookup_init call z_get_num_files and then
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// za_enum_files would require passing around a ZipInfo struct, or searching
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// for the ECDR twice - both ways aren't nice. nor is expanding on demand -
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// we try to minimize allocations (faster, less fragmentation).
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// fn (filename) is not necessarily 0-terminated!
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// loc is only valid during the callback! must be copied or saved.
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typedef LibError (*CDFH_CB)(uintptr_t user, i32 i, const ArchiveEntry* loc, size_t fn_len);
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struct Archive;
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extern LibError archive_allocate_entries(Archive* a, size_t num_entries);
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extern LibError archive_add_file(Archive* a, const ArchiveEntry* ent);
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#endif // #ifndef INCLUDED_ARCHIVE
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