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

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/*
* \brief Symlink filesystem
* \author Norman Feske
* \date 2015-08-21
*
*/
/*
* Copyright (C) 2015 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__SYMLINK_FILE_SYSTEM_H_
#define _INCLUDE__VFS__SYMLINK_FILE_SYSTEM_H_
#include <vfs/file_system.h>
namespace Vfs { class Symlink_file_system; }
class Vfs::Symlink_file_system : public File_system
{
private:
enum { FILENAME_MAX_LEN = 64 };
char _target[MAX_PATH_LEN];
char _filename[FILENAME_MAX_LEN];
bool _is_root(const char *path)
{
return (strcmp(path, "") == 0) || (strcmp(path, "/") == 0);
}
bool _is_single_file(const char *path)
{
return (strlen(path) == (strlen(_filename) + 1)) &&
(strcmp(&path[1], _filename) == 0);
}
public:
Symlink_file_system(Xml_node config)
{
try {
config.attribute("name").value(_filename, sizeof(_filename));
config.attribute("target").value(_target, sizeof(_target));
} catch (...) { }
}
static char const *name() { return "symlink"; }
/*********************************
** Directory-service interface **
*********************************/
Symlink_result symlink(char const *from, char const *to) override {
return SYMLINK_ERR_EXISTS; }
Readlink_result readlink(char const *path,
char *buf,
file_size buf_size,
file_size &out_len) override
{
out_len = min(buf_size, file_size(sizeof(_target)));
strncpy(buf, _target, out_len);
return READLINK_OK;
}
Stat_result stat(char const *path, Stat &out) override
{
out = { 0, 0, 0, 0, 0, 0 };
if (_is_root(path)) {
out.mode = STAT_MODE_DIRECTORY;
} else if (_is_single_file(path)) {
out.mode = STAT_MODE_SYMLINK;
} else {
return STAT_ERR_NO_ENTRY;
}
return STAT_OK;
}
file_size num_dirent(char const *path) override
{
if (_is_root(path))
return 1;
else
return 0;
}
bool is_directory(char const *path) override
{
if (_is_root(path))
return true;
return false;
}
char const *leaf_path(char const *path) override
{
return path;
}
Dirent_result dirent(char const *path, file_offset index, Dirent &out) override
{
if (!_is_root(path))
return DIRENT_ERR_INVALID_PATH;
if (index == 0) {
out.type = DIRENT_TYPE_SYMLINK;
strncpy(out.name, _filename, sizeof(out.name));
} else {
out.type = DIRENT_TYPE_END;
}
return DIRENT_OK;
}
Dataspace_capability dataspace(char const *path) override {
return Dataspace_capability(); }
void release(char const *path, Dataspace_capability ds_cap) override { }
Open_result open(char const *path, unsigned,
Vfs_handle **out_handle) override {
return OPEN_ERR_UNACCESSIBLE; }
Unlink_result unlink(char const *) override {
return UNLINK_ERR_NO_PERM; }
Rename_result rename(char const *, char const *) override {
return RENAME_ERR_NO_PERM; }
Mkdir_result mkdir(char const *, unsigned) override {
return MKDIR_ERR_NO_PERM; }
/********************************
** File I/O service interface **
********************************/
Write_result write(Vfs_handle *handle, char const *, file_size,
file_size &) override
{
return WRITE_ERR_INVALID;
}
Read_result read(Vfs_handle *, char *, file_size, file_size &) override
{
return READ_ERR_INVALID;
}
Ftruncate_result ftruncate(Vfs_handle *, file_size) override
{
return FTRUNCATE_ERR_NO_PERM;
}
};
#endif /* _INCLUDE__VFS__SYMLINK_FILE_SYSTEM_H_ */