forked from 0ad/0ad
janwas
afe37d9fe2
- made file_io_wait buffer non-const (less const_casting around - buffers are really non-const. besides which, inadvertent use will be caught via MMU) - zip: disambiguate abs() param This was SVN commit r3426.
364 lines
13 KiB
C
Executable File
364 lines
13 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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#include "posix.h" // struct stat
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extern LibError file_init();
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// convenience "class" that simplifies successively appending a filename to
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// its parent directory. this avoids needing to allocate memory and calling
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// strlen/strcat. used by wdetect and dir_next_ent.
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// we want to maintain C compatibility, so this isn't a C++ class.
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struct PathPackage
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{
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char* end;
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size_t chars_left;
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char path[PATH_MAX];
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};
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// write the given directory path into our buffer and set end/chars_left
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// accordingly. <dir> need and should not end with a directory separator.
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//
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// note: <dir> and the filename set via pp_append_file are separated by
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// '/'. this is to allow use on portable paths; the function otherwise
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// does not care if paths are relative/portable/absolute.
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extern LibError pp_set_dir(PathPackage* pp, const char* dir);
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// append the given filename to the directory established by the last
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// pp_set_dir on this package. the whole path is accessible at pp->path.
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extern LibError pp_append_file(PathPackage* pp, const char* file);
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// is s2 a subpath of s1, or vice versa? used by VFS and wdir_watch.
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// works for portable and native paths.
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extern bool file_is_subpath(const char* s1, const char* s2);
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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 dir)
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extern LibError file_make_native_path(const char* path, char* n_path);
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extern LibError file_make_portable_path(const char* n_path, char* 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 LibError file_make_full_native_path(const char* path, char* n_full_path);
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extern LibError file_make_full_portable_path(const char* n_full_path, char* path);
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// establish the root directory from <rel_path>, which is treated as
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// relative to the executable's directory (determined via argv[0]).
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// all relative file paths passed to this module will be based from
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// this root dir.
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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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// argv[0] 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 below). rel_path is trusted.
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extern LibError file_set_root_dir(const char* argv0, const char* rel_path);
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// allocate a copy of P_fn in our string pool. strings are equal iff
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// their addresses are equal, thus allowing fast comparison.
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// fn_len can be 0 to indicate P_fn is a null-terminated C string
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// (normal case) or the string length [characters].
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extern const char* file_make_unique_fn_copy(const char* P_fn, size_t fn_len);
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//
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// dir_next_ent
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//
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// layer on top of POSIX opendir/readdir/closedir that handles
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// portable -> native path conversion, ignores non-file/directory entries,
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// and additionally returns the file status (size and mtime).
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// directory state initialized by dir_open.
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// rationale: some private storage apart from opendir's DIR* is required
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// to support stat(). we prefer having the caller reserve room (on the stack)
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// rather than allocating dynamically (less efficient or more complicated).
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//
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// this is an opaque struct to avoid exposing our internals and insulate
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// user code against changes; we verify at compile-time that the
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// public/private definitions match.
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// note: cannot just typedef to DirIterator_ because other modules
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// instantiate this.
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struct DirIterator
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{
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char opaque[PATH_MAX+32];
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};
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// information about a directory entry filled by dir_next_ent.
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struct DirEnt
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{
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// we want to keep this as small as possible because
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// file_enum allocates one copy for each file in the directory.
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// store only required stat fields (in VC's order of decl)
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off_t size;
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time_t mtime;
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// name (not including path!) of this entry.
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// valid until a subsequent dir_next_ent or dir_close call for the
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// current dir state.
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// rationale: we don't want to return a pointer to a copy because
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// users would have to free it (won't happen).
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const char* name;
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};
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// return [bool] indicating whether the given DirEnt* (filled by
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// dir_next_ent) represents a directory.
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#define DIRENT_IS_DIR(p_ent) ((p_ent)->size == -1)
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// prepare to iterate (once) over entries in the given directory.
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// returns a negative error code or 0 on success, in which case <d> is
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// ready for subsequent dir_next_ent calls and must be freed via dir_close.
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extern LibError dir_open(const char* P_path, DirIterator* d);
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// return ERR_DIR_END if all entries have already been returned once,
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// another negative error code, or 0 on success, in which case <ent>
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// describes the next (order is unspecified) directory entry.
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extern LibError dir_next_ent(DirIterator* d, DirEnt* ent);
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// indicate the directory iterator is no longer needed; all resources it
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// held are freed.
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extern LibError dir_close(DirIterator* d);
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// called by file_enum for each entry in the directory.
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// name doesn't include path!
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// return INFO_CB_CONTINUE to continue calling; anything else will cause
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// file_enum to abort and immediately return that value.
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typedef LibError (*FileCB)(const char* name, const struct stat* s, uintptr_t memento, const uintptr_t user);
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// call <cb> for each file and subdirectory in <dir> (alphabetical order),
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// passing the entry name (not full path!), stat info, and <user>.
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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 LibError file_enum(const char* dir, FileCB cb, uintptr_t user);
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struct FileCommon
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{
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// keep offset of flags and size members in sync with struct AFile!
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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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// copy of the filename that was passed to file_open;
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// its address uniquely identifies it. used as key for file cache.
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const char* atom_fn;
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};
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struct File
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{
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FileCommon fc;
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int fd;
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// for reference counted memory-mapping
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void* mapping;
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uint map_refs;
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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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//
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// note: only allowing either reads or writes simplifies file cache
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// coherency (need only invalidate when closing a FILE_WRITE file).
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FILE_WRITE = 0x01,
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// translate newlines: convert from/to native representation when
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// reading/writing. this is useful if files we create need to be
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// edited externally - e.g. Notepad requires \r\n.
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// caveats:
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// - FILE_NO_AIO must be set; translation is done by OS read()/write().
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// - not supported by POSIX, so this currently only has meaning on Win32.
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FILE_TEXT = 0x02,
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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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// sum of all flags above. used when validating flag parameters and
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// by zip.cpp because its flags live alongside these.
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FILE_FLAG_MAX = 0x3F
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};
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// get file information. output param is zeroed on error.
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extern LibError file_stat(const char* path, struct stat*);
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extern LibError file_open(const char* fn, uint flags, File* f);
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// note: final file size is calculated and returned in f->size.
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// see implementation for rationale.
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extern LibError file_close(File* f);
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extern LibError file_validate(const File* f);
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#define CHECK_FILE(f) CHECK_ERR(file_validate(f))
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// remove all blocks loaded from the file <fn>. used when reloading the file.
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extern LibError file_cache_invalidate(const char* fn);
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//
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// asynchronous IO
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//
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// this is a thin wrapper on top of the system AIO calls.
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// IOs are carried out exactly as requested - there is no caching or
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// alignment done here. rationale: see source.
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struct FileIo
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{
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void* cb;
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};
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// queue the IO; it begins after the previous ones (if any) complete.
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//
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// rationale: this interface is more convenient than implicitly advancing a
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// file pointer because archive.cpp often accesses random offsets.
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extern LibError file_io_issue(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_has_completed(FileIo* io);
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// wait for the given IO to complete. passes back its buffer and size.
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extern LibError file_io_wait(FileIo* io, void*& p, size_t& size);
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// indicates the IO's buffer is no longer needed and frees that memory.
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extern LibError file_io_discard(FileIo* io);
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extern LibError file_io_validate(const FileIo* io);
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//
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// synchronous IO
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//
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// block := power-of-two sized chunk of a file.
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// all transfers are expanded to naturally aligned, whole blocks
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// (this makes caching parts of files feasible; it is also much faster
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// for some aio implementations, e.g. wposix).
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const size_t FILE_BLOCK_SIZE = 16*KiB;
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typedef const u8* FileIOBuf;
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FileIOBuf* const FILE_BUF_TEMP = (FileIOBuf*)1;
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const FileIOBuf FILE_BUF_ALLOC = (FileIOBuf)2;
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extern FileIOBuf file_buf_alloc(size_t size, const char* atom_fn);
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extern LibError file_buf_free(FileIOBuf buf);
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// called by file_io after a block IO has completed.
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// *bytes_processed must be set; file_io will return the sum of these values.
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// example: when reading compressed data and decompressing in the callback,
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// indicate #bytes decompressed.
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// return value: INFO_CB_CONTINUE to continue calling; anything else:
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// abort immediately and return that.
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// note: in situations where the entire IO is not split into blocks
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// (e.g. when reading from cache or not using AIO), this is still called but
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// for the entire IO. we do not split into fake blocks because it is
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// advantageous (e.g. for decompressors) to have all data at once, if available
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// anyway.
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typedef LibError (*FileIOCB)(uintptr_t ctx, const void* block, size_t size, size_t* bytes_processed);
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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, FileIOBuf* pbuf, FileIOCB cb = 0, uintptr_t ctx = 0);
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extern ssize_t file_read_from_cache(const char* atom_fn, off_t ofs, size_t size,
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FileIOBuf* pbuf, FileIOCB cb, uintptr_t ctx);
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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 LibError 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 LibError file_unmap(File* f);
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extern LibError file_shutdown();
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#endif // #ifndef FILE_H
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