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// Copyright (C) 2001-2007 Miklos Szeredi <miklos@szeredi.hu>
// Copyright (C) 2011 Sebastian Pipping <sebastian@pipping.org>
// Copyright (C) 2016 Benjamin Barenblat <benjamin@barenblat.name>
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful, but WITHOUT
// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
// FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
// details.
//
// You should have received a copy of the GNU General Public License along with
// this program. If not, see <http://www.gnu.org/licenses/>.
#include "operations.h"
#include <cerrno>
#include <cstdint>
#include <cstring>
#include <experimental/optional>
#include <memory>
#include <new>
#include <system_error>
#include <type_traits>
#include <dirent.h>
#include <glog/logging.h>
#include <sys/stat.h>
#include <sys/types.h>
#include "fuse.h"
#include "posix_extras.h"
namespace scoville {
namespace {
// Pointer to the directory underlying the mount point.
File* root_;
mode_t DirectoryTypeToFileType(const unsigned char type) noexcept {
return static_cast<mode_t>(DTTOIF(type));
}
void* Initialize(fuse_conn_info*) noexcept { return nullptr; }
void Destroy(void*) noexcept {}
int Getattr(const char* const path, struct stat* output) noexcept {
try {
if (path[0] == '\0') {
LOG(ERROR) << "getattr: called on path not starting with /";
return -ENOENT;
}
if (std::strcmp(path, "/") == 0) {
// They're asking for information about the mount point.
*output = root_->Stat();
return 0;
}
// Trim the leading slash so LinkStatAt will treat it relative to root_.
LOG(INFO) << "getattr: trimming leading slash";
*output = root_->LinkStatAt(path + 1);
return 0;
} catch (const std::system_error& e) {
return -e.code().value();
} catch (...) {
LOG(ERROR) << "getattr: caught unexpected value";
return -ENOTRECOVERABLE;
}
}
template <typename T>
int OpenResource(const char* const path, const int flags, const mode_t mode,
uint64_t* const handle) noexcept {
try {
std::unique_ptr<T> t(new T(
std::strcmp(path, "/") == 0
?
// They're asking to open the mount point.
*root_
:
// Trim the leading slash so OpenAt will treat it relative to root_.
root_->OpenAt(path + 1, flags, mode)));
static_assert(sizeof(*handle) == sizeof(std::uintptr_t),
"FUSE file handles are a different size than pointers");
*handle = reinterpret_cast<std::uintptr_t>(t.release());
return 0;
} catch (const std::bad_alloc&) {
return -ENOMEM;
} catch (const std::system_error& e) {
return -e.code().value();
} catch (...) {
LOG(ERROR) << "caught unexpected value";
return -ENOTRECOVERABLE;
}
}
template <typename T>
int ReleaseResource(const uint64_t handle) noexcept {
delete reinterpret_cast<T*>(handle);
return 0;
}
int Open(const char* const path, fuse_file_info* const file_info) noexcept {
return OpenResource<File>(path, file_info->flags, 0777, &file_info->fh);
}
int Create(const char* const path, const mode_t mode,
fuse_file_info* const file_info) noexcept {
try {
if (std::strcmp(path, "/") == 0) {
// They're asking to create the mount point. Huh?
return -EEXIST;
}
return OpenResource<File>(path,
file_info->flags | O_CREAT | O_WRONLY | O_EXCL,
mode, &file_info->fh);
} catch (const std::system_error& e) {
return -e.code().value();
} catch (...) {
LOG(ERROR) << "create: caught unexpected value";
return -ENOTRECOVERABLE;
}
}
int Release(const char*, fuse_file_info* const file_info) noexcept {
return ReleaseResource<File>(file_info->fh);
}
int Unlink(const char* c_path) noexcept {
try {
if (std::strcmp(path, "/") == 0) {
// Removing the root is probably a bad idea.
return -EPERM;
}
// Trim the leading slash so UnlinkAt will treat it relative to root_.
root_->UnlinkAt(path + 1);
return 0;
} catch (const std::system_error& e) {
return -e.code().value();
} catch (...) {
LOG(ERROR) << "unlink: caught unexpected value";
return -ENOTRECOVERABLE;
}
}
int Opendir(const char* const path, fuse_file_info* const file_info) noexcept {
return OpenResource<Directory>(path, O_DIRECTORY, 0777, &file_info->fh);
}
int Readdir(const char*, void* const buffer, fuse_fill_dir_t filler,
const off_t offset, fuse_file_info* const file_info) noexcept {
try {
auto* const directory = reinterpret_cast<Directory*>(file_info->fh);
static_assert(std::is_same<off_t, long>(),
"off_t is not convertible with long");
if (offset != directory->offset()) {
directory->Seek(offset);
}
for (std::experimental::optional<dirent> entry = directory->ReadOne();
entry; entry = directory->ReadOne()) {
struct stat stats;
std::memset(&stats, 0, sizeof(stats));
stats.st_ino = entry->d_ino;
stats.st_mode = DirectoryTypeToFileType(entry->d_type);
const off_t next_offset = directory->offset();
if (filler(buffer, entry->d_name, &stats, next_offset)) {
break;
}
}
} catch (const std::system_error& e) {
return -e.code().value();
} catch (...) {
LOG(ERROR) << "readdir: caught unexpected value";
return -ENOTRECOVERABLE;
}
return 0;
}
int Releasedir(const char*, fuse_file_info* const file_info) noexcept {
return ReleaseResource<Directory>(file_info->fh);
}
} // namespace
fuse_operations FuseOperations(File* const root) {
root_ = root;
fuse_operations result;
result.flag_nullpath_ok = true;
result.flag_nopath = true;
result.flag_utime_omit_ok = true;
result.init = &Initialize;
result.destroy = &Destroy;
result.getattr = &Getattr;
result.open = &Open;
result.create = &Create;
result.release = &Release;
result.unlink = &Unlink;
result.opendir = &Opendir;
result.readdir = &Readdir;
result.releasedir = &Releasedir;
return result;
}
} // namespace scoville
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