// Copyright 2014 The Crashpad Authors. All rights reserved.
//
// 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 "util/file/file_io.h"

#include <fcntl.h>
#include <sys/file.h>
#include <sys/stat.h>
#include <unistd.h>

#include "base/files/file_path.h"
#include "base/logging.h"
#include "base/numerics/safe_conversions.h"
#include "base/posix/eintr_wrapper.h"

namespace {

struct ReadTraits {
  using VoidBufferType = void*;
  using CharBufferType = char*;
  static crashpad::FileOperationResult Operate(int fd,
                                               CharBufferType buffer,
                                               size_t size) {
    return read(fd, buffer, size);
  }
};

struct WriteTraits {
  using VoidBufferType = const void*;
  using CharBufferType = const char*;
  static crashpad::FileOperationResult Operate(int fd,
                                               CharBufferType buffer,
                                               size_t size) {
    return write(fd, buffer, size);
  }
};

template <typename Traits>
crashpad::FileOperationResult
ReadOrWrite(int fd, typename Traits::VoidBufferType buffer, size_t size) {
  typename Traits::CharBufferType buffer_c =
      reinterpret_cast<typename Traits::CharBufferType>(buffer);

  crashpad::FileOperationResult total_bytes = 0;
  while (size > 0) {
    crashpad::FileOperationResult bytes =
        HANDLE_EINTR(Traits::Operate(fd, buffer_c, size));
    if (bytes < 0) {
      return bytes;
    } else if (bytes == 0) {
      break;
    }

    buffer_c += bytes;
    size -= bytes;
    total_bytes += bytes;
  }

  return total_bytes;
}

}  // namespace

namespace crashpad {

namespace {

FileHandle OpenFileForOutput(int rdwr_or_wronly,
                             const base::FilePath& path,
                             FileWriteMode mode,
                             FilePermissions permissions) {
  DCHECK(rdwr_or_wronly & (O_RDWR | O_WRONLY));
  DCHECK_EQ(rdwr_or_wronly & ~(O_RDWR | O_WRONLY), 0);

  int flags = rdwr_or_wronly;

  switch (mode) {
    case FileWriteMode::kReuseOrFail:
      break;
    case FileWriteMode::kReuseOrCreate:
      flags |= O_CREAT;
      break;
    case FileWriteMode::kTruncateOrCreate:
      flags |= O_CREAT | O_TRUNC;
      break;
    case FileWriteMode::kCreateOrFail:
      flags |= O_CREAT | O_EXCL;
      break;
  }

  return HANDLE_EINTR(
      open(path.value().c_str(),
           flags,
           permissions == FilePermissions::kWorldReadable ? 0644 : 0600));
}

}  // namespace

FileOperationResult ReadFile(FileHandle file, void* buffer, size_t size) {
  return ReadOrWrite<ReadTraits>(file, buffer, size);
}

FileOperationResult WriteFile(FileHandle file,
                              const void* buffer,
                              size_t size) {
  return ReadOrWrite<WriteTraits>(file, buffer, size);
}

FileHandle OpenFileForRead(const base::FilePath& path) {
  return HANDLE_EINTR(open(path.value().c_str(), O_RDONLY));
}

FileHandle OpenFileForWrite(const base::FilePath& path,
                            FileWriteMode mode,
                            FilePermissions permissions) {
  return OpenFileForOutput(O_WRONLY, path, mode, permissions);
}

FileHandle OpenFileForReadAndWrite(const base::FilePath& path,
                                   FileWriteMode mode,
                                   FilePermissions permissions) {
  return OpenFileForOutput(O_RDWR, path, mode, permissions);
}

FileHandle LoggingOpenFileForRead(const base::FilePath& path) {
  FileHandle fd = OpenFileForRead(path);
  PLOG_IF(ERROR, fd < 0) << "open " << path.value();
  return fd;
}

FileHandle LoggingOpenFileForWrite(const base::FilePath& path,
                                   FileWriteMode mode,
                                   FilePermissions permissions) {
  FileHandle fd = OpenFileForWrite(path, mode, permissions);
  PLOG_IF(ERROR, fd < 0) << "open " << path.value();
  return fd;
}

FileHandle LoggingOpenFileForReadAndWrite(const base::FilePath& path,
                                          FileWriteMode mode,
                                          FilePermissions permissions) {
  FileHandle fd = OpenFileForReadAndWrite(path, mode, permissions);
  PLOG_IF(ERROR, fd < 0) << "open " << path.value();
  return fd;
}

bool LoggingLockFile(FileHandle file, FileLocking locking) {
  int operation = (locking == FileLocking::kShared) ? LOCK_SH : LOCK_EX;
  int rv = HANDLE_EINTR(flock(file, operation));
  PLOG_IF(ERROR, rv != 0) << "flock";
  return rv == 0;
}

bool LoggingUnlockFile(FileHandle file) {
  int rv = flock(file, LOCK_UN);
  PLOG_IF(ERROR, rv != 0) << "flock";
  return rv == 0;
}

FileOffset LoggingSeekFile(FileHandle file, FileOffset offset, int whence) {
  off_t rv = lseek(file, offset, whence);
  PLOG_IF(ERROR, rv < 0) << "lseek";
  return rv;
}

bool LoggingTruncateFile(FileHandle file) {
  if (HANDLE_EINTR(ftruncate(file, 0)) != 0) {
    PLOG(ERROR) << "ftruncate";
    return false;
  }
  return true;
}

bool LoggingCloseFile(FileHandle file) {
  int rv = IGNORE_EINTR(close(file));
  PLOG_IF(ERROR, rv != 0) << "close";
  return rv == 0;
}

FileOffset LoggingFileSizeByHandle(FileHandle file) {
  struct stat st;
  if (fstat(file, &st) != 0) {
    PLOG(ERROR) << "fstat";
    return -1;
  }
  return st.st_size;
}

}  // namespace crashpad