src/base/files/file_util.cc

// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "base/files/file_util.h"

#if defined(OS_WIN)
#include <io.h>
#endif
#include <stdio.h>

#include <fstream>
#include <limits>
#include <string_view>

#include "base/files/file_enumerator.h"
#include "base/files/file_path.h"
#include "base/logging.h"
#include "base/strings/string_util.h"
#include "base/strings/stringprintf.h"
#include "base/strings/utf_string_conversions.h"
#include "util/build_config.h"

namespace base {

namespace {

// The maximum number of 'uniquified' files we will try to create.
// This is used when the filename we're trying to download is already in use,
// so we create a new unique filename by appending " (nnn)" before the
// extension, where 1 <= nnn <= kMaxUniqueFiles.
// Also used by code that cleans up said files.
static const int kMaxUniqueFiles = 100;

}  // namespace

int64_t ComputeDirectorySize(const FilePath& root_path) {
  int64_t running_size = 0;
  FileEnumerator file_iter(root_path, true, FileEnumerator::FILES);
  while (!file_iter.Next().empty())
    running_size += file_iter.GetInfo().GetSize();
  return running_size;
}

bool ContentsEqual(const FilePath& filename1, const FilePath& filename2) {
  // We open the file in binary format even if they are text files because
  // we are just comparing that bytes are exactly same in both files and not
  // doing anything smart with text formatting.
  std::ifstream file1(filename1.As8Bit().c_str(),
                      std::ios::in | std::ios::binary);
  std::ifstream file2(filename2.As8Bit().c_str(),
                      std::ios::in | std::ios::binary);

  // Even if both files aren't openable (and thus, in some sense, "equal"),
  // any unusable file yields a result of "false".
  if (!file1.is_open() || !file2.is_open())
    return false;

  const int BUFFER_SIZE = 2056;
  char buffer1[BUFFER_SIZE], buffer2[BUFFER_SIZE];
  do {
    file1.read(buffer1, BUFFER_SIZE);
    file2.read(buffer2, BUFFER_SIZE);

    if ((file1.eof() != file2.eof()) || (file1.gcount() != file2.gcount()) ||
        (memcmp(buffer1, buffer2, static_cast<size_t>(file1.gcount())))) {
      file1.close();
      file2.close();
      return false;
    }
  } while (!file1.eof() || !file2.eof());

  file1.close();
  file2.close();
  return true;
}

bool TextContentsEqual(const FilePath& filename1, const FilePath& filename2) {
  std::ifstream file1(filename1.As8Bit().c_str(), std::ios::in);
  std::ifstream file2(filename2.As8Bit().c_str(), std::ios::in);

  // Even if both files aren't openable (and thus, in some sense, "equal"),
  // any unusable file yields a result of "false".
  if (!file1.is_open() || !file2.is_open())
    return false;

  do {
    std::string line1, line2;
    getline(file1, line1);
    getline(file2, line2);

    // Check for mismatched EOF states, or any error state.
    if ((file1.eof() != file2.eof()) || file1.bad() || file2.bad()) {
      return false;
    }

    // Trim all '\r' and '\n' characters from the end of the line.
    std::string::size_type end1 = line1.find_last_not_of("\r\n");
    if (end1 == std::string::npos)
      line1.clear();
    else if (end1 + 1 < line1.length())
      line1.erase(end1 + 1);

    std::string::size_type end2 = line2.find_last_not_of("\r\n");
    if (end2 == std::string::npos)
      line2.clear();
    else if (end2 + 1 < line2.length())
      line2.erase(end2 + 1);

    if (line1 != line2)
      return false;
  } while (!file1.eof() || !file2.eof());

  return true;
}

bool ReadFileToStringWithMaxSize(const FilePath& path,
                                 std::string* contents,
                                 size_t max_size) {
  if (contents)
    contents->clear();
  if (path.ReferencesParent())
    return false;
  FILE* file = OpenFile(path, "rb");
  if (!file) {
    return false;
  }

  // Many files supplied in |path| have incorrect size (proc files etc).
  // Hence, the file is read sequentially as opposed to a one-shot read, using
  // file size as a hint for chunk size if available.
  constexpr int64_t kDefaultChunkSize = 1 << 16;
  int64_t chunk_size;
  if (!GetFileSize(path, &chunk_size) || chunk_size <= 0)
    chunk_size = kDefaultChunkSize - 1;
  // We need to attempt to read at EOF for feof flag to be set so here we
  // use |chunk_size| + 1.
  chunk_size = std::min<uint64_t>(chunk_size, max_size) + 1;
  size_t bytes_read_this_pass;
  size_t bytes_read_so_far = 0;
  bool read_status = true;
  std::string local_contents;
  local_contents.resize(chunk_size);

  while ((bytes_read_this_pass = fread(&local_contents[bytes_read_so_far], 1,
                                       chunk_size, file)) > 0) {
    if ((max_size - bytes_read_so_far) < bytes_read_this_pass) {
      // Read more than max_size bytes, bail out.
      bytes_read_so_far = max_size;
      read_status = false;
      break;
    }
    // In case EOF was not reached, iterate again but revert to the default
    // chunk size.
    if (bytes_read_so_far == 0)
      chunk_size = kDefaultChunkSize;

    bytes_read_so_far += bytes_read_this_pass;
    // Last fread syscall (after EOF) can be avoided via feof, which is just a
    // flag check.
    if (feof(file))
      break;
    local_contents.resize(bytes_read_so_far + chunk_size);
  }
  read_status = read_status && !ferror(file);
  CloseFile(file);
  if (contents) {
    contents->swap(local_contents);
    contents->resize(bytes_read_so_far);
  }

  return read_status;
}

bool ReadFileToString(const FilePath& path, std::string* contents) {
  return ReadFileToStringWithMaxSize(path, contents,
                                     std::numeric_limits<size_t>::max());
}

bool IsDirectoryEmpty(const FilePath& dir_path) {
  FileEnumerator files(dir_path, false,
                       FileEnumerator::FILES | FileEnumerator::DIRECTORIES);
  if (files.Next().empty())
    return true;
  return false;
}

bool CreateDirectory(const FilePath& full_path) {
  return CreateDirectoryAndGetError(full_path, nullptr);
}

bool GetFileSize(const FilePath& file_path, int64_t* file_size) {
  File::Info info;
  if (!GetFileInfo(file_path, &info))
    return false;
  *file_size = info.size;
  return true;
}

bool CloseFile(FILE* file) {
  if (file == nullptr)
    return true;
  return fclose(file) == 0;
}

bool TruncateFile(FILE* file) {
  if (file == nullptr)
    return false;
  long current_offset = ftell(file);
  if (current_offset == -1)
    return false;
#if defined(OS_WIN)
  int fd = _fileno(file);
  if (_chsize(fd, current_offset) != 0)
    return false;
#else
  int fd = fileno(file);
  if (ftruncate(fd, current_offset) != 0)
    return false;
#endif
  return true;
}

int GetUniquePathNumber(const FilePath& path,
                        const FilePath::StringType& suffix) {
  bool have_suffix = !suffix.empty();
  if (!PathExists(path) &&
      (!have_suffix || !PathExists(FilePath(path.value() + suffix)))) {
    return 0;
  }

  FilePath new_path;
  for (int count = 1; count <= kMaxUniqueFiles; ++count) {
    new_path = path.InsertBeforeExtensionASCII(StringPrintf(" (%d)", count));
    if (!PathExists(new_path) &&
        (!have_suffix || !PathExists(FilePath(new_path.value() + suffix)))) {
      return count;
    }
  }

  return -1;
}

}  // namespace base