genode/repos/os/include/vfs/fs_file_system.h

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/*
* \brief Adapter from Genode 'File_system' session to VFS
* \author Norman Feske
* \date 2011-02-17
*/
/*
* Copyright (C) 2012-2014 Genode Labs GmbH
*
* This file is part of the Genode OS framework, which is distributed
* under the terms of the GNU General Public License version 2.
*/
#ifndef _INCLUDE__VFS__FS_FILE_SYSTEM_H_
#define _INCLUDE__VFS__FS_FILE_SYSTEM_H_
/* Genode includes */
#include <base/allocator_avl.h>
#include <file_system_session/connection.h>
namespace Vfs { class Fs_file_system; }
class Vfs::Fs_file_system : public File_system
{
enum { verbose = false };
private:
/*
* Lock used to serialize the interaction with the packet stream of the
* file-system session.
*
* XXX Once, we change the VFS file-system interface to use
* asynchronous read/write operations, we can possibly remove it.
*/
Lock _lock;
Genode::Allocator_avl _fs_packet_alloc;
typedef Genode::String<64> Label_string;
Label_string _label;
typedef Genode::String<::File_system::MAX_NAME_LEN> Root_string;
Root_string _root;
::File_system::Connection _fs;
class Fs_vfs_handle : public Vfs_handle
{
private:
::File_system::File_handle const _handle;
public:
Fs_vfs_handle(File_system &fs, int status_flags,
::File_system::File_handle handle)
: Vfs_handle(fs, fs, status_flags), _handle(handle)
{ }
~Fs_vfs_handle()
{
Fs_file_system &fs = static_cast<Fs_file_system &>(ds());
fs._fs.close(_handle);
}
::File_system::File_handle file_handle() const { return _handle; }
};
/**
* Helper for managing the lifetime of temporary open node handles
*/
struct Fs_handle_guard
{
::File_system::Session &_fs;
::File_system::Node_handle _handle;
Fs_handle_guard(::File_system::Session &fs,
::File_system::Node_handle handle)
: _fs(fs), _handle(handle) { }
~Fs_handle_guard() { _fs.close(_handle); }
};
file_size _read(::File_system::Node_handle node_handle, void *buf,
file_size const count, file_size const seek_offset)
{
::File_system::Session::Tx::Source &source = *_fs.tx();
file_size const max_packet_size = source.bulk_buffer_size() / 2;
file_size const clipped_count = min(max_packet_size, count);
::File_system::Packet_descriptor const
packet_in(source.alloc_packet(clipped_count),
node_handle,
::File_system::Packet_descriptor::READ,
clipped_count,
seek_offset);
/* pass packet to server side */
source.submit_packet(packet_in);
/* obtain result packet descriptor with updated status info */
::File_system::Packet_descriptor const
packet_out = source.get_acked_packet();
file_size const read_num_bytes = min(packet_out.length(), count);
memcpy(buf, source.packet_content(packet_out), read_num_bytes);
/*
* XXX check if acked packet belongs to request,
* needed for thread safety
*/
source.release_packet(packet_out);
return read_num_bytes;
}
file_size _write(::File_system::Node_handle node_handle,
const char *buf, file_size count, file_size seek_offset)
{
::File_system::Session::Tx::Source &source = *_fs.tx();
file_size const max_packet_size = source.bulk_buffer_size() / 2;
count = min(max_packet_size, count);
::File_system::Packet_descriptor
packet(source.alloc_packet(count),
node_handle,
::File_system::Packet_descriptor::WRITE,
count,
seek_offset);
memcpy(source.packet_content(packet), buf, count);
/* pass packet to server side */
source.submit_packet(packet);
source.get_acked_packet();
/*
* XXX check if acked packet belongs to request,
* needed for thread safety
*/
source.release_packet(packet);
return count;
}
public:
Fs_file_system(Xml_node config)
:
_fs_packet_alloc(env()->heap()),
_label(config.attribute_value("label", Label_string())),
_root( config.attribute_value("root", Root_string())),
_fs(_fs_packet_alloc,
::File_system::DEFAULT_TX_BUF_SIZE,
_label.string(), _root.string(),
config.attribute_value("writeable", true))
{ }
/*********************************
** Directory-service interface **
*********************************/
Dataspace_capability dataspace(char const *path) override
{
Lock::Guard guard(_lock);
Absolute_path dir_path(path);
dir_path.strip_last_element();
dir_path.remove_trailing('/');
Absolute_path file_name(path);
file_name.keep_only_last_element();
Ram_dataspace_capability ds_cap;
char *local_addr = 0;
try {
::File_system::Dir_handle dir = _fs.dir(dir_path.base(),
false);
Fs_handle_guard dir_guard(_fs, dir);
::File_system::File_handle file =
_fs.file(dir, file_name.base() + 1,
::File_system::READ_ONLY, false);
Fs_handle_guard file_guard(_fs, file);
::File_system::Status status = _fs.status(file);
Ram_dataspace_capability ds_cap =
env()->ram_session()->alloc(status.size);
local_addr = env()->rm_session()->attach(ds_cap);
::File_system::Session::Tx::Source &source = *_fs.tx();
file_size const max_packet_size = source.bulk_buffer_size() / 2;
for (file_size seek_offset = 0; seek_offset < status.size;
seek_offset += max_packet_size) {
file_size const count = min(max_packet_size, status.size -
seek_offset);
::File_system::Packet_descriptor
packet(source.alloc_packet(count),
file,
::File_system::Packet_descriptor::READ,
count,
seek_offset);
/* pass packet to server side */
source.submit_packet(packet);
source.get_acked_packet();
memcpy(local_addr + seek_offset, source.packet_content(packet), count);
/*
* XXX check if acked packet belongs to request,
* needed for thread safety
*/
source.release_packet(packet);
}
env()->rm_session()->detach(local_addr);
return ds_cap;
} catch(...) {
env()->rm_session()->detach(local_addr);
env()->ram_session()->free(ds_cap);
return Dataspace_capability();
}
}
void release(char const *path, Dataspace_capability ds_cap) override
{
if (ds_cap.valid())
env()->ram_session()->free(static_cap_cast<Genode::Ram_dataspace>(ds_cap));
}
Stat_result stat(char const *path, Stat &out) override
{
::File_system::Status status;
try {
::File_system::Node_handle node = _fs.node(path);
Fs_handle_guard node_guard(_fs, node);
status = _fs.status(node);
} catch (...) {
if (verbose)
PDBG("stat failed for path '%s'", path);
return STAT_ERR_NO_ENTRY;
}
memset(&out, 0, sizeof(out));
out.size = status.size;
out.mode = STAT_MODE_FILE | 0777;
if (status.is_symlink())
out.mode = STAT_MODE_SYMLINK | 0777;
if (status.is_directory())
out.mode = STAT_MODE_DIRECTORY | 0777;
out.uid = 0;
out.gid = 0;
return STAT_OK;
}
Dirent_result dirent(char const *path, file_offset index, Dirent &out) override
{
Lock::Guard guard(_lock);
::File_system::Session::Tx::Source &source = *_fs.tx();
if (strcmp(path, "") == 0)
path = "/";
::File_system::Dir_handle dir_handle = _fs.dir(path, false);
Fs_handle_guard dir_guard(_fs, dir_handle);
enum { DIRENT_SIZE = sizeof(::File_system::Directory_entry) };
::File_system::Packet_descriptor
packet(source.alloc_packet(DIRENT_SIZE),
dir_handle,
::File_system::Packet_descriptor::READ,
DIRENT_SIZE,
index*DIRENT_SIZE);
/* pass packet to server side */
source.submit_packet(packet);
source.get_acked_packet();
/*
* XXX check if acked packet belongs to request,
* needed for thread safety
*/
typedef ::File_system::Directory_entry Directory_entry;
/* copy-out payload into destination buffer */
Directory_entry const *entry =
(Directory_entry *)source.packet_content(packet);
/*
* The default value has no meaning because the switch below
* assigns a value in each possible branch. But it is needed to
* keep the compiler happy.
*/
Dirent_type type = DIRENT_TYPE_END;
switch (entry->type) {
case Directory_entry::TYPE_DIRECTORY: type = DIRENT_TYPE_DIRECTORY; break;
case Directory_entry::TYPE_FILE: type = DIRENT_TYPE_FILE; break;
case Directory_entry::TYPE_SYMLINK: type = DIRENT_TYPE_SYMLINK; break;
}
out.type = type;
out.fileno = index + 1;
strncpy(out.name, entry->name, sizeof(out.name));
source.release_packet(packet);
return DIRENT_OK;
}
Unlink_result unlink(char const *path) override
{
Absolute_path dir_path(path);
dir_path.strip_last_element();
dir_path.remove_trailing('/');
Absolute_path file_name(path);
file_name.keep_only_last_element();
try {
::File_system::Dir_handle dir = _fs.dir(dir_path.base(), false);
Fs_handle_guard dir_guard(_fs, dir);
_fs.unlink(dir, file_name.base() + 1);
}
catch (::File_system::Permission_denied) { return UNLINK_ERR_NO_PERM; }
catch (...) { return UNLINK_ERR_NO_ENTRY; }
return UNLINK_OK;
}
Readlink_result readlink(char const *path, char *buf, file_size buf_size,
file_size &out_len) override
{
/*
* Canonicalize path (i.e., path must start with '/')
*/
Absolute_path abs_path(path);
abs_path.strip_last_element();
abs_path.remove_trailing('/');
Absolute_path symlink_name(path);
symlink_name.keep_only_last_element();
try {
::File_system::Dir_handle dir_handle = _fs.dir(abs_path.base(), false);
Fs_handle_guard from_dir_guard(_fs, dir_handle);
::File_system::Symlink_handle symlink_handle =
_fs.symlink(dir_handle, symlink_name.base() + 1, false);
Fs_handle_guard symlink_guard(_fs, symlink_handle);
out_len = _read(symlink_handle, buf, buf_size, 0);
return READLINK_OK;
} catch (...) { }
return READLINK_ERR_NO_ENTRY;
}
Rename_result rename(char const *from_path, char const *to_path) override
{
Absolute_path from_dir_path(from_path);
from_dir_path.strip_last_element();
from_dir_path.remove_trailing('/');
Absolute_path from_file_name(from_path);
from_file_name.keep_only_last_element();
Absolute_path to_dir_path(to_path);
to_dir_path.strip_last_element();
to_dir_path.remove_trailing('/');
Absolute_path to_file_name(to_path);
to_file_name.keep_only_last_element();
try {
::File_system::Dir_handle from_dir = _fs.dir(from_dir_path.base(), false);
Fs_handle_guard from_dir_guard(_fs, from_dir);
::File_system::Dir_handle to_dir = _fs.dir(to_dir_path.base(), false);
Fs_handle_guard to_dir_guard(_fs, to_dir);
_fs.move(from_dir, from_file_name.base() + 1,
to_dir, to_file_name.base() + 1);
}
catch (::File_system::Lookup_failed) { return RENAME_ERR_NO_ENTRY; }
catch (...) { return RENAME_ERR_NO_PERM; }
return RENAME_OK;
}
Mkdir_result mkdir(char const *path, unsigned mode) override
{
/*
* Canonicalize path (i.e., path must start with '/')
*/
Absolute_path abs_path(path);
try {
_fs.close(_fs.dir(abs_path.base(), true));
}
catch (::File_system::Permission_denied) { return MKDIR_ERR_NO_PERM; }
catch (::File_system::Node_already_exists) { return MKDIR_ERR_EXISTS; }
catch (::File_system::Lookup_failed) { return MKDIR_ERR_NO_ENTRY; }
catch (::File_system::Name_too_long) { return MKDIR_ERR_NAME_TOO_LONG; }
catch (::File_system::No_space) { return MKDIR_ERR_NO_SPACE; }
catch (::File_system::Out_of_node_handles) { return MKDIR_ERR_NO_ENTRY; }
return MKDIR_OK;
}
Symlink_result symlink(char const *from, char const *to) override
{
/*
* We write to the symlink via the packet stream. Hence we need
* to serialize with other packet-stream operations.
*/
Lock::Guard guard(_lock);
/*
* Canonicalize path (i.e., path must start with '/')
*/
Absolute_path abs_path(to);
abs_path.strip_last_element();
abs_path.remove_trailing('/');
Absolute_path symlink_name(to);
symlink_name.keep_only_last_element();
try {
::File_system::Dir_handle dir_handle = _fs.dir(abs_path.base(), false);
Fs_handle_guard from_dir_guard(_fs, dir_handle);
::File_system::Symlink_handle symlink_handle =
_fs.symlink(dir_handle, symlink_name.base() + 1, true);
Fs_handle_guard symlink_guard(_fs, symlink_handle);
_write(symlink_handle, from, strlen(from) + 1, 0);
}
catch (::File_system::Invalid_handle) { return SYMLINK_ERR_NO_ENTRY; }
catch (::File_system::Node_already_exists) { return SYMLINK_ERR_EXISTS; }
catch (::File_system::Invalid_name) { return SYMLINK_ERR_NAME_TOO_LONG; }
catch (::File_system::Lookup_failed) { return SYMLINK_ERR_NO_ENTRY; }
catch (::File_system::Permission_denied) { return SYMLINK_ERR_NO_PERM; }
catch (::File_system::No_space) { return SYMLINK_ERR_NO_SPACE; }
catch (::File_system::Out_of_node_handles) { return SYMLINK_ERR_NO_ENTRY; }
return SYMLINK_OK;
}
file_size num_dirent(char const *path) override
{
if (strcmp(path, "") == 0)
path = "/";
/*
* XXX handle more exceptions
*/
::File_system::Node_handle node;
try { node = _fs.node(path); } catch (::File_system::Lookup_failed) { return 0; }
Fs_handle_guard node_guard(_fs, node);
::File_system::Status status = _fs.status(node);
return status.size / sizeof(::File_system::Directory_entry);
}
bool is_directory(char const *path) override
{
try {
::File_system::Node_handle node = _fs.node(path);
Fs_handle_guard node_guard(_fs, node);
::File_system::Status status = _fs.status(node);
return status.is_directory();
}
catch (...) { return false; }
}
char const *leaf_path(char const *path) override
{
/* check if node at path exists within file system */
try {
::File_system::Node_handle node = _fs.node(path);
_fs.close(node);
}
catch (...) { return 0; }
return path;
}
Open_result open(char const *path, unsigned vfs_mode, Vfs_handle **out_handle) override
{
Lock::Guard guard(_lock);
Absolute_path dir_path(path);
dir_path.strip_last_element();
dir_path.remove_trailing('/');
Absolute_path file_name(path);
file_name.keep_only_last_element();
::File_system::Mode mode;
switch (vfs_mode & OPEN_MODE_ACCMODE) {
default: mode = ::File_system::STAT_ONLY; break;
case OPEN_MODE_RDONLY: mode = ::File_system::READ_ONLY; break;
case OPEN_MODE_WRONLY: mode = ::File_system::WRITE_ONLY; break;
case OPEN_MODE_RDWR: mode = ::File_system::READ_WRITE; break;
}
bool const create = vfs_mode & OPEN_MODE_CREATE;
if (create)
if (verbose)
PDBG("creation of file %s requested", file_name.base() + 1);
try {
::File_system::Dir_handle dir = _fs.dir(dir_path.base(), false);
Fs_handle_guard dir_guard(_fs, dir);
::File_system::File_handle file = _fs.file(dir, file_name.base() + 1,
mode, create);
*out_handle = new (env()->heap()) Fs_vfs_handle(*this, vfs_mode, file);
}
catch (::File_system::Permission_denied) { return OPEN_ERR_NO_PERM; }
catch (::File_system::Invalid_handle) { return OPEN_ERR_NO_PERM; }
catch (::File_system::Lookup_failed) { return OPEN_ERR_UNACCESSIBLE; }
catch (::File_system::Node_already_exists) { return OPEN_ERR_EXISTS; }
catch (::File_system::Invalid_name) { return OPEN_ERR_NAME_TOO_LONG; }
catch (::File_system::No_space) { return OPEN_ERR_NO_SPACE; }
catch (::File_system::Out_of_node_handles) { return OPEN_ERR_UNACCESSIBLE; }
return OPEN_OK;
}
/***************************
** File_system interface **
***************************/
static char const *name() { return "fs"; }
void sync(char const *path) override
{
try {
::File_system::Node_handle node = _fs.node(path);
Fs_handle_guard node_guard(_fs, node);
_fs.sync(node);
} catch (...) { }
}
/********************************
** File I/O service interface **
********************************/
Write_result write(Vfs_handle *vfs_handle, char const *buf,
file_size buf_size, file_size &out_count) override
{
Lock::Guard guard(_lock);
Fs_vfs_handle const *handle = static_cast<Fs_vfs_handle *>(vfs_handle);
out_count = _write(handle->file_handle(), buf, buf_size, handle->seek());
return WRITE_OK;
}
Read_result read(Vfs_handle *vfs_handle, char *dst, file_size count,
file_size &out_count) override
{
Lock::Guard guard(_lock);
Fs_vfs_handle const *handle = static_cast<Fs_vfs_handle *>(vfs_handle);
::File_system::Status status = _fs.status(handle->file_handle());
file_size const size_of_file = status.size;
file_size const file_bytes_left = size_of_file >= handle->seek()
? size_of_file - handle->seek() : 0;
count = min(count, file_bytes_left);
out_count = _read(handle->file_handle(), dst, count, handle->seek());
return READ_OK;
}
Ftruncate_result ftruncate(Vfs_handle *vfs_handle, file_size len) override
{
Fs_vfs_handle const *handle = static_cast<Fs_vfs_handle *>(vfs_handle);
try {
_fs.truncate(handle->file_handle(), len);
}
catch (::File_system::Invalid_handle) { return FTRUNCATE_ERR_NO_PERM; }
catch (::File_system::Permission_denied) { return FTRUNCATE_ERR_NO_PERM; }
catch (::File_system::No_space) { return FTRUNCATE_ERR_NO_SPACE; }
return FTRUNCATE_OK;
}
};
#endif /* _INCLUDE__VFS__FS_FILE_SYSTEM_H_ */