janwas
c0ef326340
2) ERR_PATH_LENGTH (instead of ERR_VFS_): now used by file.cpp also 3) better document file_enum and FileCB This was SVN commit r1433.
190 lines
6.1 KiB
C
Executable File
190 lines
6.1 KiB
C
Executable File
// file layer on top of POSIX.
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// provides streaming support and caching.
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//
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// Copyright (c) 2004 Jan Wassenberg
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//
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// This file is free software; you can redistribute it and/or
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// modify it under the terms of the GNU General Public License as
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// published by the Free Software Foundation; either version 2 of the
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// License, or (at your option) any later version.
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//
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// This file is distributed in the hope that it will be useful, but
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// WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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// General Public License for more details.
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//
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// Contact info:
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// Jan.Wassenberg@stud.uni-karlsruhe.de
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// http://www.stud.uni-karlsruhe.de/~urkt/
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#ifndef FILE_H
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#define FILE_H
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struct File
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{
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#ifdef PARANOIA
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u32 magic;
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#endif
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// keep offset of flags and size members in sync with struct ZFile!
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// it is accessed by VFS and must be the same for both (union).
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// dirty, but necessary because VFile is pushing the HDATA size limit.
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uint flags;
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off_t size;
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u32 fn_hash;
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void* mapping;
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uint map_refs;
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int fd;
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};
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enum
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{
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// write-only access; otherwise, read only
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FILE_WRITE = 0x01,
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// the file's contents aren't cached at a higher level; do so here.
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// we keep the file open (until the cache is "full enough"). if it
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// is loaded, we keep the buffer there to satisfy later loads.
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FILE_CACHE = 0x04,
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// random access hint
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// FILE_RANDOM = 0x08,
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FILE_NO_AIO = 0x10,
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FILE_CACHE_BLOCK = 0x20
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};
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//
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// path conversion functions (native <--> portable),
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// for external libraries that require the real filename.
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//
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// replaces '/' with platform's directory separator and vice versa.
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// verifies path length < PATH_MAX (otherwise return ERR_PATH_LENGTH).
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//
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// relative paths (relative to root, established with file_rel_chdir)
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extern int file_make_native_path(const char* const path, char* const n_path);
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extern int file_make_portable_path(const char* const n_path, char* const path);
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// as above, but with full native paths (portable paths are always relative).
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// prepends current directory, resp. makes sure it matches the given path.
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extern int file_make_full_native_path(const char* const path, char* const n_full_path);
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extern int file_make_full_portable_path(const char* const n_full_path, char* const path);
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// set current directory to rel_path, relative to the path to the executable,
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// which is taken from argv0.
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//
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// example: executable in "$install_dir/system"; desired root dir is
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// "$install_dir/data" => rel_path = "../data".
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//
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// this is necessary because the current directory is unknown at startup
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// (e.g. it isn't set when invoked via batch file), and this is the
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// easiest portable way to find our install directory.
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//
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// can only be called once, by design (see source). rel_path is trusted.
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extern int file_rel_chdir(const char* argv0, const char* rel_path);
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// called by file_enum for each entry in the directory.
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// name doesn't include path! it's a directory <==> size < 0.
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// return non-zero to immediately abort; file_enum will return that value.
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typedef int(*FileCB)(const char* const name, const ssize_t size, const uintptr_t user);
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// call <cb> for each file and subdirectory in <dir> (alphabetical order),
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// passing <user> and the entry name (not full path!).
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//
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// first builds a list of entries (sorted) and remembers if an error occurred.
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// if <cb> returns non-zero, abort immediately and return that; otherwise,
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// return first error encountered while listing files, or 0 on success.
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extern int file_enum(const char* dir, FileCB cb, uintptr_t user);
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// get file status. output param is zeroed on error.
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extern int file_stat(const char* path, struct stat*);
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extern int file_open(const char* fn, uint flags, File* f);
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extern int file_close(File* f);
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//
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// asynchronous IO
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//
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struct FileIO
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{
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void* cb;
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};
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extern int file_start_io(File* f, off_t ofs, size_t size, void* buf, FileIO* io);
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// indicates if the given IO has completed.
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// return value: 0 if pending, 1 if complete, < 0 on error.
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extern int file_io_complete(FileIO* io);
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extern int file_wait_io(FileIO* io, void*& p, size_t& size);
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extern int file_discard_io(FileIO* io);
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//
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// synchronous IO
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//
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// return value:
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// < 0: failed; abort transfer.
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// >= 0: bytes output; continue.
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typedef ssize_t(*FileIOCB)(uintptr_t ctx, void* p, size_t size);
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// transfer <size> bytes, starting at <ofs>, to/from the given file.
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// (read or write access was chosen at file-open time).
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//
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// if non-NULL, <cb> is called for each block transferred, passing <ctx>.
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// it returns how much data was actually transferred, or a negative error
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// code (in which case we abort the transfer and return that value).
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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 number of bytes transferred (see above), or a negative error code.
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extern ssize_t file_io(File* f, off_t ofs, size_t size, void* buf, 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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// map the entire file <f> into memory. if already currently mapped,
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// return the previous mapping (reference-counted).
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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 file is closed.
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// however, map/unmap calls should still be paired so that the mapping
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// may be removed when no longer needed.
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//
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// rationale: reference counting is required for zip_map: several
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// Zip "mappings" each reference one ZArchive's actual file mapping.
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// implement it here so that we also get refcounting for normal files.
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extern int file_map(File* f, void*& p, size_t& size);
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// decrement the reference count for the mapping belonging to file <f>.
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// fail if there are no references; remove the mapping if the count reaches 0.
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//
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// the mapping will be removed (if still open) when its file is closed.
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// however, map/unmap calls should still be paired so that the mapping
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// may be removed when no longer needed.
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extern int file_unmap(File* f);
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#endif // #ifndef FILE_H
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