481 lines
12 KiB
C++
481 lines
12 KiB
C++
/*
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* \brief TAR file system
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* \author Norman Feske
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* \date 2011-02-17
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*/
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/*
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* Copyright (C) 2011-2012 Genode Labs GmbH
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*
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* This file is part of the Genode OS framework, which is distributed
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* under the terms of the GNU General Public License version 2.
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*/
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#ifndef _NOUX__TAR_FILE_SYSTEM_H_
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#define _NOUX__TAR_FILE_SYSTEM_H_
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/* Genode includes */
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#include <base/printf.h>
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#include <base/lock.h>
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#include <rom_session/connection.h>
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#include <dataspace/client.h>
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/* Noux includes */
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#include <noux_session/sysio.h>
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#include <file_system.h>
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#include <vfs_handle.h>
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namespace Noux {
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class Tar_file_system : public File_system
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{
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enum { verbose = false };
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Lock _lock;
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struct Rom_name
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{
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enum { ROM_NAME_MAX_LEN = 64 };
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char name[ROM_NAME_MAX_LEN];
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Rom_name(Xml_node config) {
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config.attribute("name").value(name, sizeof(name));
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}
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} _rom_name;
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Rom_connection _rom;
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char *_tar_base;
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size_t _tar_size;
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class Record
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{
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private:
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char _name[100];
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char _mode[8];
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char _uid[8];
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char _gid[8];
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char _size[12];
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char _mtime[12];
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char _checksum[8];
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char _type[1];
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char _linked_name[100];
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/**
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* Convert ASCII-encoded octal number to unsigned value
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*/
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template <typename T>
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unsigned long _read(T const &field) const
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{
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/*
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* Copy-out ASCII string to temporary buffer that is
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* large enough to host an additional zero.
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*/
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char buf[sizeof(field) + 1];
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strncpy(buf, field, sizeof(buf));
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unsigned long value = 0;
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ascii_to(buf, &value, 8);
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return value;
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}
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public:
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/* length of on data block in tar */
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enum { BLOCK_LEN = 512 };
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/* record type values */
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enum { TYPE_FILE = 0, TYPE_HARDLINK = 1,
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TYPE_SYMLINK = 2, TYPE_DIR = 5 };
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size_t size() const { return _read(_size); }
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unsigned uid() const { return _read(_uid); }
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unsigned gid() const { return _read(_gid); }
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unsigned mode() const { return _read(_mode); }
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unsigned type() const { return _read(_type); }
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char const *name() const { return _name; }
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char const *linked_name() const { return _linked_name; }
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void *data() const { return (char *)this + BLOCK_LEN; }
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};
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class Tar_vfs_handle : public Vfs_handle
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{
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private:
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Record const *_record;
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public:
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Tar_vfs_handle(File_system *fs, int status_flags, Record *record)
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: Vfs_handle(fs, fs, status_flags), _record(record)
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{ }
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Record const *record() const { return _record; }
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};
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struct Lookup_criterion { virtual bool match(char const *path) = 0; };
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/**
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* Return portion of 'path' without leading slashes and dots
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*/
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static char const *_skip_leading_slashes_dots(char const *path)
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{
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while (*path == '.' || *path == '/')
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path++;
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return path;
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}
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static void _remove_trailing_slashes(char *str)
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{
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size_t len = 0;
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while ((len = strlen(str)) && (str[len - 1] == '/'))
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str[len - 1] = 0;
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}
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struct Lookup_exact : public Lookup_criterion
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{
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Absolute_path _match_path;
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Lookup_exact(char const *match_path)
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: _match_path(match_path)
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{
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_match_path.remove_trailing('/');
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}
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bool match(char const *path)
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{
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Absolute_path test_path(path);
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test_path.remove_trailing('/');
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return _match_path.equals(test_path);
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}
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};
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/**
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* Lookup the Nth record in the specified path
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*/
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struct Lookup_member_of_path : public Lookup_criterion
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{
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Absolute_path _dir_path;
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int const index;
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int cnt;
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Lookup_member_of_path(char const *dir_path, int index)
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: _dir_path(dir_path), index(index), cnt(0)
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{
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_dir_path.remove_trailing('/');
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}
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bool match(char const *path)
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{
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Absolute_path test_path(path);
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if (!test_path.strip_prefix(_dir_path.base()))
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return false;
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if (!test_path.has_single_element())
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return false;
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cnt++;
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/* match only if index is reached */
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if (cnt - 1 != index)
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return false;
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return true;
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}
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};
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Record *_lookup(Lookup_criterion *criterion)
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{
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/* measure size of archive in blocks */
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unsigned block_id = 0, block_cnt = _tar_size/Record::BLOCK_LEN;
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/* scan metablocks of archive */
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while (block_id < block_cnt) {
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Record *record = (Record *)(_tar_base + block_id*Record::BLOCK_LEN);
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/* get infos about current file */
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if (criterion->match(record->name()))
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return record;
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size_t file_size = record->size();
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/* some datablocks */ /* one metablock */
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block_id = block_id + (file_size / Record::BLOCK_LEN) + 1;
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/* round up */
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if (file_size % Record::BLOCK_LEN != 0) block_id++;
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/* check for end of tar archive */
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if (block_id*Record::BLOCK_LEN >= _tar_size)
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break;
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/* lookout for empty eof-blocks */
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if (*(_tar_base + (block_id*Record::BLOCK_LEN)) == 0x00)
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if (*(_tar_base + (block_id*Record::BLOCK_LEN + 1)) == 0x00)
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break;
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}
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return 0;
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}
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struct Num_dirent_cache
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{
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Lock lock;
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Tar_file_system &tar_fs;
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bool valid; /* true after first lookup */
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char key[256]; /* key used for lookup */
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size_t cached_num_dirent; /* cached value */
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Num_dirent_cache(Tar_file_system &tar_fs)
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: tar_fs(tar_fs), valid(false), cached_num_dirent(0) { }
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size_t num_dirent(char const *path)
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{
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Lock::Guard guard(lock);
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/* check for cache miss */
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if (!valid || strcmp(path, key) != 0) {
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Lookup_member_of_path lookup_criterion(path, ~0);
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tar_fs._lookup(&lookup_criterion);
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strncpy(key, path, sizeof(key));
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cached_num_dirent = lookup_criterion.cnt;
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valid = true;
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}
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return cached_num_dirent;
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}
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} _cached_num_dirent;
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public:
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Tar_file_system(Xml_node config)
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:
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_rom_name(config), _rom(_rom_name.name),
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_tar_base(env()->rm_session()->attach(_rom.dataspace())),
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_tar_size(Dataspace_client(_rom.dataspace()).size()),
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_cached_num_dirent(*this)
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{
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PINF("tar archive '%s' local at %p, size is %zd",
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_rom_name.name, _tar_base, _tar_size);
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}
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/*********************************
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** Directory-service interface **
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*********************************/
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Dataspace_capability dataspace(char const *path)
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{
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/*
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* Walk hardlinks until we reach a file
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*/
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Record *record = 0;
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for (;;) {
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Lookup_exact lookup_criterion(path);
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record = _lookup(&lookup_criterion);
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if (!record)
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return Dataspace_capability();
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if (record->type() == Record::TYPE_HARDLINK) {
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path = record->linked_name();
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continue;
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}
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if (record->type() == Record::TYPE_FILE)
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break;
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PERR("TAR record \"%s\" has unsupported type %d",
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record->name(), record->type());
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return Dataspace_capability();
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}
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try {
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Ram_dataspace_capability ds_cap =
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env()->ram_session()->alloc(record->size());
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void *local_addr = env()->rm_session()->attach(ds_cap);
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memcpy(local_addr, record->data(), record->size());
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env()->rm_session()->detach(local_addr);
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return ds_cap;
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}
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catch (...) { PDBG("Could not create new dataspace"); }
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return Dataspace_capability();
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}
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void release(char const *, Dataspace_capability ds_cap)
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{
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env()->ram_session()->free(static_cap_cast<Ram_dataspace>(ds_cap));
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}
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bool stat(Sysio *sysio, char const *path)
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{
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Lookup_exact lookup_criterion(path);
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Record *record = _lookup(&lookup_criterion);
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if (!record) {
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sysio->error.stat = Sysio::STAT_ERR_NO_ENTRY;
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return false;
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}
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/* convert TAR record modes to stat modes */
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unsigned mode = record->mode();
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switch (record->type()) {
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case Record::TYPE_FILE: mode |= Sysio::STAT_MODE_FILE; break;
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case Record::TYPE_SYMLINK: mode |= Sysio::STAT_MODE_SYMLINK; break;
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case Record::TYPE_DIR: mode |= Sysio::STAT_MODE_DIRECTORY; break;
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default:
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if (verbose)
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PDBG("unhandled record type %d", record->type());
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}
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sysio->stat_out.st.mode = mode;
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sysio->stat_out.st.size = record->size();
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sysio->stat_out.st.uid = record->uid();
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sysio->stat_out.st.gid = record->gid();
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sysio->stat_out.st.inode = (unsigned long)record;
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return true;
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}
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bool dirent(Sysio *sysio, char const *path, off_t index)
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{
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Lock::Guard guard(_lock);
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Lookup_member_of_path lookup_criterion(path, index);
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Record *record = _lookup(&lookup_criterion);
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if (!record) {
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sysio->dirent_out.entry.type = Sysio::DIRENT_TYPE_END;
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return true;
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}
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sysio->dirent_out.entry.fileno = (unsigned long)record;
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switch (record->type()) {
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case 0: sysio->dirent_out.entry.type = Sysio::DIRENT_TYPE_FILE; break;
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case 2: sysio->dirent_out.entry.type = Sysio::DIRENT_TYPE_SYMLINK; break;
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case 5: sysio->dirent_out.entry.type = Sysio::DIRENT_TYPE_DIRECTORY; break;
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default:
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if (verbose)
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PDBG("unhandled record type %d", record->type());
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}
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Absolute_path absolute_path(record->name());
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absolute_path.keep_only_last_element();
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absolute_path.remove_trailing('/');
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strncpy(sysio->dirent_out.entry.name,
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absolute_path.base() + 1,
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sizeof(sysio->dirent_out.entry.name));
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return true;
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}
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bool unlink(Sysio *, char const *) { return false; }
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bool rename(Sysio *, char const *, char const *) { return false; }
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bool mkdir(Sysio *, char const *) { return false; }
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size_t num_dirent(char const *path)
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{
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return _cached_num_dirent.num_dirent(path);
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}
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bool is_directory(char const *path)
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{
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Lookup_exact lookup_criterion(path);
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Record const * record = _lookup(&lookup_criterion);
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return record && (record->type() == Record::TYPE_DIR);
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}
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char const *leaf_path(char const *path)
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{
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/*
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* Check if path exists within the file system. If this is the
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* case, return the whole path, which is relative to the root
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* of this file system.
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*/
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Lookup_exact lookup_criterion(path);
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Record const * record = _lookup(&lookup_criterion);
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return record ? path : 0;
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}
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Vfs_handle *open(Sysio *sysio, char const *path)
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{
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Lock::Guard guard(_lock);
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Lookup_exact lookup_criterion(path);
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Record *record = 0;
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if ((record = _lookup(&lookup_criterion)))
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return new (env()->heap())
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Tar_vfs_handle(this, 0, record);
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sysio->error.open = Sysio::OPEN_ERR_UNACCESSIBLE;
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return 0;
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}
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/***************************
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** File_system interface **
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***************************/
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char const *name() const { return "tar"; }
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/********************************
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** File I/O service interface **
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********************************/
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bool write(Sysio *sysio, Vfs_handle *handle)
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{
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PDBG("called\n");
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return false;
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}
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bool read(Sysio *sysio, Vfs_handle *vfs_handle)
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{
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Tar_vfs_handle const *handle = static_cast<Tar_vfs_handle *>(vfs_handle);
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size_t const record_size = handle->record()->size();
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size_t const record_bytes_left = record_size >= handle->seek()
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? record_size - handle->seek() : 0;
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size_t const count = min(record_bytes_left,
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min(sizeof(sysio->read_out.chunk),
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sysio->read_in.count));
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char const *data = (char *)handle->record()->data() + handle->seek();
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memcpy(sysio->read_out.chunk, data, count);
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sysio->read_out.count = count;
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return true;
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}
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bool ftruncate(Sysio *sysio, Vfs_handle *handle)
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{
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PDBG("called\n");
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return false;
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}
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};
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}
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#endif /* _NOUX__TAR_FILE_SYSTEM_H_ */
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