1 files changed, 85 insertions, 0 deletions
diff --git a/src/posix_extras.cc b/src/posix_extras.cc
new file mode 100644
index 0000000..d06dc41
--- /dev/null
+++ b/src/posix_extras.cc
@@ -0,0 +1,85 @@
+// 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 _POSIX_C_SOURCE 201502L
+#undef _GNU_SOURCE
+
+#include "posix_extras.h"
+
+#include <cerrno>
+#include <stdexcept>
+#include <vector>
+
+#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(errno);
+  }
+}
+
+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(errno);
+  }
+  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(errno);
+  }
+  return result;
+}
+
+}  // scoville