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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.
#define _XOPEN_SOURCE 700
#undef _GNU_SOURCE
#include "posix_extras.h"
#include <cerrno>
#include <experimental/optional>
#include <stdexcept>
#include <string>
#include <vector>
#include <dirent.h>
#include <fcntl.h>
#include <glog/logging.h>
#include <string.h> // a POSIX header, not a libc one
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
namespace scoville {
std::string IoError::Message(const int number) noexcept {
try {
std::vector<char> text(64);
int strerror_result;
while ((strerror_result = strerror_r(number, text.data(), text.size())) ==
ERANGE) {
VLOG(1) << "IoError::Message: doubling message size from " << text.size();
text.resize(text.size() * 2);
}
if (strerror_result == 0) {
return std::string(text.begin(), text.end());
}
} catch (...) {
}
return "(could not generate error message)";
}
File::File(const char* const path, const int flags) : path_(path) {
if ((fd_ = open(path, flags)) == -1) {
throw IoError();
}
VLOG(1) << "opening file descriptor " << fd_;
}
File::File(const char* const path, const int flags, const mode_t mode)
: path_(path) {
if ((fd_ = open(path, flags, mode)) == -1) {
throw IoError();
}
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_;
if (close(fd_) == -1) {
LOG(ERROR) << "failed to close file descriptor " << fd_ << ": "
<< IoError::Message(errno);
}
}
struct stat File::Stat() const {
struct stat result;
if (fstat(fd_, &result) == -1) {
throw IoError();
}
return result;
}
struct stat File::LinkStatAt(const char* const path) const {
if (path[0] == '/') {
throw std::invalid_argument("absolute path");
}
struct stat result;
if (fstatat(fd_, path, &result, AT_SYMLINK_NOFOLLOW) == -1) {
throw IoError();
}
return result;
}
File File::OpenAt(const char* const path, const int flags) const {
if (path[0] == '/') {
throw std::invalid_argument("absolute path");
}
File result;
if ((result.fd_ = openat(fd_, path, flags)) == -1) {
throw IoError();
}
result.path_ = path_ + "/" + path;
return result;
}
File File::OpenAt(const char* const path, const int flags,
const mode_t mode) const {
if (path[0] == '/') {
throw std::invalid_argument("absolute path");
}
File result;
if ((result.fd_ = openat(fd_, path, flags, mode)) == -1) {
throw IoError();
}
result.path_ = path_ + "/" + path;
return result;
}
int File::Duplicate() const {
int result;
if ((result = dup(fd_)) == -1) {
throw IoError();
}
return result;
}
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 IoError();
}
rewinddir(stream_);
}
Directory::~Directory() noexcept {
if (closedir(stream_) == -1) {
LOG(ERROR) << "failed to close directory stream: "
<< IoError::Message(errno);
}
}
long Directory::offset() const {
long result;
if ((result = telldir(stream_)) == -1) {
throw IoError();
}
return result;
}
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 IoError();
}
}
return *result;
}
} // scoville
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