genode/repos/os/src/lib/vfs/symlink_file_system.h

103 lines
2.6 KiB
C++

/*
* \brief Symlink filesystem
* \author Norman Feske
* \date 2015-08-21
*
*/
/*
* Copyright (C) 2015-2017 Genode Labs GmbH
*
* This file is part of the Genode OS framework, which is distributed
* under the terms of the GNU Affero General Public License version 3.
*/
#ifndef _INCLUDE__VFS__SYMLINK_FILE_SYSTEM_H_
#define _INCLUDE__VFS__SYMLINK_FILE_SYSTEM_H_
#include <vfs/single_file_system.h>
namespace Vfs { class Symlink_file_system; }
class Vfs::Symlink_file_system : public Single_file_system
{
private:
enum { FILENAME_MAX_LEN = 64 };
typedef Genode::String<MAX_PATH_LEN> Target;
Target const _target;
public:
Symlink_file_system(Genode::Env &, Genode::Allocator &,
Genode::Xml_node config,
Io_response_handler &, File_system &)
:
Single_file_system(NODE_TYPE_SYMLINK, "symlink", config),
_target(config.attribute_value("target", Target()))
{ }
static char const *name() { return "symlink"; }
char const *type() override { return "symlink"; }
/*********************************
** Directory-service interface **
*********************************/
Open_result open(char const *, unsigned, Vfs_handle **, Allocator&) override {
return OPEN_ERR_UNACCESSIBLE; }
Openlink_result openlink(char const *path, bool create,
Vfs_handle **out_handle, Allocator &alloc) override
{
if (!_single_file(path))
return OPENLINK_ERR_LOOKUP_FAILED;
if (create)
return OPENLINK_ERR_NODE_ALREADY_EXISTS;
try {
*out_handle = new (alloc) Vfs_handle(*this, *this, alloc, 0);
return OPENLINK_OK;
}
catch (Genode::Out_of_ram) { return OPENLINK_ERR_OUT_OF_RAM; }
catch (Genode::Out_of_caps) { return OPENLINK_ERR_OUT_OF_CAPS; }
}
void close(Vfs_handle *vfs_handle) override
{
if (!vfs_handle)
return;
destroy(vfs_handle->alloc(), vfs_handle);
}
/********************************
** File I/O service interface **
********************************/
Write_result write(Vfs_handle *, char const *,
file_size, file_size &) override {
return WRITE_ERR_INVALID; }
Read_result complete_read(Vfs_handle *, char *buf, file_size buf_len,
file_size &out_len) override
{
out_len = min(buf_len, (file_size)_target.length()-1);
memcpy(buf, _target.string(), out_len);
if (out_len < buf_len)
buf[out_len] = '\0';
return READ_OK;
}
bool read_ready(Vfs_handle *) override { return false; }
Ftruncate_result ftruncate(Vfs_handle *, file_size) override {
return FTRUNCATE_ERR_NO_PERM; }
};
#endif /* _INCLUDE__VFS__SYMLINK_FILE_SYSTEM_H_ */