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// Copyright 2016 Benjamin Barenblat
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may not
// use this file except in compliance with the License. You may obtain a copy
// of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
// License for the specific language governing permissions and limitations under
// the License.
#include "posix_extras.h"
#include <array>
#include <cerrno>
#include <cstdint>
#include <experimental/optional>
#include <stdexcept>
#include <system_error>
#include <vector>
#include <dirent.h>
#include <fcntl.h>
#include <glog/logging.h>
#include <stdio.h>
#include <sys/stat.h>
#include <sys/statvfs.h>
#include <sys/types.h>
#include <unistd.h>
namespace scoville {
namespace {
std::system_error SystemError() {
return std::system_error(errno, std::system_category());
}
void ValidatePath(const char* const path) {
if (path[0] == '/') {
throw std::invalid_argument("absolute path");
}
}
template <typename T>
T CheckSyscall(const T result) {
if (result == -1) {
throw SystemError();
}
return result;
}
} // namespace
File::File(const char* const path, const int flags, const mode_t mode)
: path_(path) {
fd_ = CheckSyscall(open(path, flags, mode));
VLOG(1) << "opening file descriptor " << fd_;
}
File::File(const File& other) : path_(other.path_), fd_(other.Duplicate()) {
VLOG(1) << "opening file descriptor " << fd_;
}
File::~File() noexcept {
VLOG(1) << "closing file descriptor " << fd_;
try {
CheckSyscall(close(fd_));
} catch (...) {
LOG(ERROR) << "failed to close file descriptor " << fd_;
}
}
struct stat File::Stat() const {
struct stat result;
CheckSyscall(fstat(fd_, &result));
return result;
}
void File::ChModAt(const char* const path, const mode_t mode) const {
ValidatePath(path);
CheckSyscall(fchmodat(fd_, path, mode, 0));
}
struct stat File::LinkStatAt(const char* const path) const {
ValidatePath(path);
struct stat result;
CheckSyscall(fstatat(fd_, path, &result, AT_SYMLINK_NOFOLLOW));
return result;
}
void File::MkDir(const char* const path, const mode_t mode) const {
ValidatePath(path);
CheckSyscall(mkdirat(fd_, path, mode | S_IFDIR));
}
void File::MkNod(const char* const path, const mode_t mode,
const dev_t dev) const {
ValidatePath(path);
CheckSyscall(mknodat(fd_, path, mode, dev));
}
File File::OpenAt(const char* const path, const int flags,
const mode_t mode) const {
ValidatePath(path);
File result;
result.fd_ = CheckSyscall(openat(fd_, path, flags, mode));
result.path_ = path_ + "/" + path;
return result;
}
std::vector<std::uint8_t> File::Read(off_t offset, size_t bytes) const {
std::vector<std::uint8_t> result(bytes, 0);
size_t cursor = 0;
ssize_t bytes_read;
while (0 < (bytes_read = CheckSyscall(
pread(fd_, result.data() + cursor, bytes, offset)))) {
cursor += static_cast<size_t>(bytes_read);
offset += bytes_read;
bytes -= static_cast<size_t>(bytes_read);
}
result.resize(cursor);
return result;
}
std::string File::ReadLinkAt(const char* const path) const {
ValidatePath(path);
std::vector<char> result(64, '\0');
size_t bytes_read;
while ((bytes_read = static_cast<size_t>(CheckSyscall(readlinkat(
fd_, path, result.data(), result.size())))) == result.size()) {
// We filled the entire buffer. There may be more data we missed.
result.resize(result.size() * 2);
}
return std::string(result.data(), result.data() + bytes_read);
}
void File::RenameAt(const char* old_path, const char* new_path) const {
ValidatePath(old_path);
ValidatePath(new_path);
CheckSyscall(renameat(fd_, old_path, fd_, new_path));
}
void File::RmDirAt(const char* const path) const {
ValidatePath(path);
CheckSyscall(unlinkat(fd_, path, AT_REMOVEDIR));
}
struct statvfs File::StatVFs() const {
struct statvfs result;
CheckSyscall(fstatvfs(fd_, &result));
return result;
}
void File::SymLinkAt(const char* const target, const char* const source) const {
ValidatePath(source);
CheckSyscall(symlinkat(target, fd_, source));
}
void File::Truncate(const off_t size) { CheckSyscall(ftruncate(fd_, size)); }
void File::UnlinkAt(const char* const path) const {
ValidatePath(path);
CheckSyscall(unlinkat(fd_, path, 0));
}
void File::UTimeNs(const char* const path, const timespec& access,
const timespec& modification) const {
ValidatePath(path);
std::array<const timespec, 2> times{{access, modification}};
CheckSyscall(utimensat(fd_, path, times.data(), AT_SYMLINK_NOFOLLOW));
}
size_t File::Write(const off_t offset,
const std::vector<std::uint8_t>& to_write) {
size_t bytes_written = 0;
while (bytes_written < to_write.size()) {
bytes_written += static_cast<size_t>(CheckSyscall(pwrite(
fd_, to_write.data() + bytes_written, to_write.size() - bytes_written,
offset + static_cast<off_t>(bytes_written))));
}
return bytes_written;
}
int File::Duplicate() const { return CheckSyscall(dup(fd_)); }
Directory::Directory(const File& file) {
// "After a successful call to fdopendir(), fd is used internally by the
// implementation, and should not otherwise be used by the application." We
// therefore need to grab an unmanaged copy of the file descriptor from file.
if (!(stream_ = fdopendir(file.Duplicate()))) {
throw SystemError();
}
rewinddir(stream_);
}
Directory::~Directory() noexcept {
try {
CheckSyscall(closedir(stream_));
} catch (...) {
LOG(ERROR) << "failed to close directory stream";
}
}
long Directory::offset() const { return CheckSyscall(telldir(stream_)); }
void Directory::Seek(const long offset) noexcept { seekdir(stream_, offset); }
std::experimental::optional<dirent> Directory::ReadOne() {
dirent* result;
errno = 0;
if (!(result = readdir(stream_))) {
if (errno == 0) {
return std::experimental::nullopt;
} else {
throw SystemError();
}
}
return *result;
}
} // scoville
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