642 lines
15 KiB
C++
642 lines
15 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) 2011-2014 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 _INCLUDE__VFS__TAR_FILE_SYSTEM_H_
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#define _INCLUDE__VFS__TAR_FILE_SYSTEM_H_
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#include <rom_session/connection.h>
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#include <vfs/file_system.h>
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#include <vfs/vfs_handle.h>
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namespace Vfs { class Tar_file_system; }
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class Vfs::Tar_file_system : public File_system
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{
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enum { verbose = false };
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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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Genode::Rom_connection _rom;
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Genode::Dataspace_capability _tar_ds;
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char *_tar_base;
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file_size _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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Genode::ascii_to_unsigned_long(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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file_size 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 const *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 Scanner_policy_path_element
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{
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static bool identifier_char(char c, unsigned /* i */)
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{
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return (c != '/') && (c != 0);
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}
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};
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typedef Genode::Token<Scanner_policy_path_element> Path_element_token;
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struct Node : List<Node>, List<Node>::Element
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{
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char const *name;
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Record const *record;
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Node(char const *name, Record const *record) : name(name), record(record) { }
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Node *lookup(char const *name)
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{
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Absolute_path lookup_path(name);
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if (verbose)
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PDBG("lookup_path = %s", lookup_path.base());
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Node *parent_node = this;
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Node *child_node;
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Path_element_token t(lookup_path.base());
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while (t) {
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if (t.type() != Path_element_token::IDENT) {
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t = t.next();
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continue;
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}
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char path_element[MAX_PATH_LEN];
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t.string(path_element, sizeof(path_element));
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if (verbose)
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PDBG("path_element = %s", path_element);
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for (child_node = parent_node->first(); child_node; child_node = child_node->next()) {
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if (verbose)
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PDBG("comparing with node %s", child_node->name);
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if (strcmp(child_node->name, path_element) == 0) {
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if (verbose)
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PDBG("found matching child node");
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parent_node = child_node;
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break;
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}
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}
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if (!child_node)
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return 0;
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t = t.next();
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}
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return parent_node;
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}
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Node *lookup_child(int index)
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{
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for (Node *child_node = first(); child_node; child_node = child_node->next(), index--) {
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if (index == 0)
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return child_node;
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}
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return 0;
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}
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file_size num_dirent()
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{
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file_size count = 0;
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for (Node *child_node = first(); child_node; child_node = child_node->next(), count++) ;
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return count;
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}
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} _root_node;
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/*
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* Create a Node for a tar record and insert it into the node list
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*/
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class Add_node_action
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{
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private:
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Node &_root_node;
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public:
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Add_node_action(Node &root_node) : _root_node(root_node) { }
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void operator()(Record const *record)
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{
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Absolute_path current_path(record->name());
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if (verbose)
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PDBG("current_path = %s", current_path.base());
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char path_element[MAX_PATH_LEN];
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Path_element_token t(current_path.base());
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Node *parent_node = &_root_node;
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Node *child_node;
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while(t) {
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if (t.type() != Path_element_token::IDENT) {
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t = t.next();
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continue;
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}
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Absolute_path remaining_path(t.start());
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t.string(path_element, sizeof(path_element));
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for (child_node = parent_node->first(); child_node; child_node = child_node->next()) {
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if (strcmp(child_node->name, path_element) == 0)
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break;
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}
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if (child_node) {
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if (verbose)
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PDBG("found node for %s", path_element);
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if (remaining_path.has_single_element()) {
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/* Found a node for the record to be inserted.
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* This is usually a directory node without
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* record. */
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child_node->record = record;
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}
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} else {
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if (remaining_path.has_single_element()) {
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if (verbose)
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PDBG("creating node for %s", path_element);
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/*
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* TODO: find 'path_element' in 'record->name'
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* and use the location in the record as name
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* pointer to save some memory
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*/
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Genode::size_t name_size = strlen(path_element) + 1;
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char *name = (char*)env()->heap()->alloc(name_size);
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strncpy(name, path_element, name_size);
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child_node = new (env()->heap()) Node(name, record);
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} else {
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if (verbose)
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PDBG("creating node without record for %s", path_element);
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/* create a directory node without record */
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Genode::size_t name_size = strlen(path_element) + 1;
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char *name = (char*)env()->heap()->alloc(name_size);
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strncpy(name, path_element, name_size);
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child_node = new (env()->heap()) Node(name, 0);
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}
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parent_node->insert(child_node);
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}
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parent_node = child_node;
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t = t.next();
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}
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}
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};
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template <typename Tar_record_action>
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void _for_each_tar_record_do(Tar_record_action tar_record_action)
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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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tar_record_action(record);
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file_size size = record->size();
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/* some datablocks */ /* one metablock */
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block_id = block_id + (size / Record::BLOCK_LEN) + 1;
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/* round up */
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if (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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}
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struct Num_dirent_cache
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{
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Lock lock;
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Node &root_node;
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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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file_size cached_num_dirent; /* cached value */
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Num_dirent_cache(Node &root_node)
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: root_node(root_node), valid(false), cached_num_dirent(0) { }
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file_size 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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Node *node = root_node.lookup(path);
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if (!node)
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return 0;
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strncpy(key, path, sizeof(key));
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cached_num_dirent = node->num_dirent();
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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_ds(_rom.dataspace()),
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_tar_base(env()->rm_session()->attach(_tar_ds)),
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_tar_size(Dataspace_client(_tar_ds).size()),
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_root_node("", 0),
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_cached_num_dirent(_root_node)
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{
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PINF("tar archive '%s' local at %p, size is %llu",
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_rom_name.name, _tar_base, _tar_size);
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_for_each_tar_record_do(Add_node_action(_root_node));
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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) override
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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 const *record = 0;
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for (;;) {
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Node *node = _root_node.lookup(path);
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if (!node)
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return Dataspace_capability();
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record = node->record;
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if (record) {
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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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}
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PERR("TAR record \"%s\" has unsupported type %d",
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path, Record::TYPE_DIR);
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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) override
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{
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env()->ram_session()->free(static_cap_cast<Genode::Ram_dataspace>(ds_cap));
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}
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Stat_result stat(char const *path, Stat &out) override
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{
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if (verbose)
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PDBG("path = %s", path);
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Node const *node = 0;
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Record const *record = 0;
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/*
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* Walk hardlinks until we reach a file
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*/
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for (;;) {
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node = _root_node.lookup(path);
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if (!node)
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return STAT_ERR_NO_ENTRY;
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record = node->record;
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if (record) {
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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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} else
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break;
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} else {
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if (verbose)
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PDBG("found a virtual directoty node");
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memset(&out, 0, sizeof(out));
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out.mode = STAT_MODE_DIRECTORY;
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return STAT_OK;
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}
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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 |= STAT_MODE_FILE; break;
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case Record::TYPE_SYMLINK: mode |= STAT_MODE_SYMLINK; break;
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case Record::TYPE_DIR: mode |= 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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memset(&out, 0, sizeof(out));
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out.mode = mode;
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out.size = record->size();
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out.uid = record->uid();
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out.gid = record->gid();
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out.inode = (unsigned long)node;
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return STAT_OK;
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}
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Dirent_result dirent(char const *path, file_offset index, Dirent &out) override
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{
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Node *node = _root_node.lookup(path);
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if (!node)
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return DIRENT_ERR_INVALID_PATH;
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node = node->lookup_child(index);
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if (!node) {
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out.type = DIRENT_TYPE_END;
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return DIRENT_OK;
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}
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out.fileno = (unsigned long)node;
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Record const *record = node->record;
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if (record) {
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switch (record->type()) {
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case 0: out.type = DIRENT_TYPE_FILE; break;
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case 2: out.type = DIRENT_TYPE_SYMLINK; break;
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case 5: out.type = 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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}
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strncpy(out.name, node->name, sizeof(out.name));
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return DIRENT_OK;
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}
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Unlink_result unlink(char const *) override { return UNLINK_ERR_NO_PERM; }
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Readlink_result readlink(char const *path, char *buf, file_size buf_size,
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file_size &out_len) override
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{
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Node *node = _root_node.lookup(path);
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Record const *record = node ? node->record : 0;
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if (!record || (record->type() != Record::TYPE_SYMLINK))
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return READLINK_ERR_NO_ENTRY;
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file_size const count = min(buf_size, 100ULL);
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memcpy(buf, record->linked_name(), count);
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out_len = count;
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return READLINK_OK;
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}
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Rename_result rename(char const *, char const *) override
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{
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return RENAME_ERR_NO_PERM;
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}
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Mkdir_result mkdir(char const *, unsigned) override
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{
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return MKDIR_ERR_NO_PERM;
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}
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Symlink_result symlink(char const *, char const *) override
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{
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return SYMLINK_ERR_NO_ENTRY;
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}
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file_size num_dirent(char const *path) override
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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) override
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{
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Node *node = _root_node.lookup(path);
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if (!node)
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return false;
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Record const *record = node->record;
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return record ? (record->type() == Record::TYPE_DIR) : true;
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}
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char const *leaf_path(char const *path) override
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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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Node *node = _root_node.lookup(path);
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return node ? path : 0;
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}
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Open_result open(char const *path, unsigned, Vfs_handle **out_handle) override
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{
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Node *node = _root_node.lookup(path);
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if (!node)
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return OPEN_ERR_UNACCESSIBLE;
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*out_handle = new (env()->heap())
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Tar_vfs_handle(*this, 0, node->record);
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return OPEN_OK;
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}
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/***************************
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** File_system interface **
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***************************/
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static char const *name() { return "tar"; }
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/********************************
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** File I/O service interface **
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********************************/
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Write_result write(Vfs_handle *, char const *, file_size,
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file_size &) override
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{
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PDBG("called\n");
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return WRITE_ERR_INVALID;
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}
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Read_result read(Vfs_handle *vfs_handle, char *dst, file_size count,
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file_size &out_count) override
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{
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Tar_vfs_handle const *handle = static_cast<Tar_vfs_handle *>(vfs_handle);
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file_size const record_size = handle->record()->size();
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file_size const record_bytes_left = record_size >= handle->seek()
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? record_size - handle->seek() : 0;
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count = min(record_bytes_left, count);
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char const *data = (char *)handle->record()->data() + handle->seek();
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memcpy(dst, data, count);
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out_count = count;
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return READ_OK;
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}
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Ftruncate_result ftruncate(Vfs_handle *handle, file_size) override
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{
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PDBG("called\n");
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return FTRUNCATE_ERR_NO_PERM;
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}
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};
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#endif /* _INCLUDE__VFS__TAR_FILE_SYSTEM_H_ */
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