Move file_util to base/files/ directory.

This updates the includes in base but leaves a forwarding header for the rest of the project for now.

R=yzshen@chromium.org

Review URL: https://codereview.chromium.org/468253002

Cr-Commit-Position: refs/heads/master@{#289360}
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@289360 0039d316-1c4b-4281-b951-d872f2087c98


CrOS-Libchrome-Original-Commit: e3177dd5063e419cb181cf6a45d3ff94cb0feebd
diff --git a/base/files/file_util_posix.cc b/base/files/file_util_posix.cc
new file mode 100644
index 0000000..07c21d1
--- /dev/null
+++ b/base/files/file_util_posix.cc
@@ -0,0 +1,912 @@
+// 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"
+
+#include <dirent.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <libgen.h>
+#include <limits.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/errno.h>
+#include <sys/mman.h>
+#include <sys/param.h>
+#include <sys/stat.h>
+#include <sys/time.h>
+#include <sys/types.h>
+#include <time.h>
+#include <unistd.h>
+
+#if defined(OS_MACOSX)
+#include <AvailabilityMacros.h>
+#include "base/mac/foundation_util.h"
+#elif !defined(OS_CHROMEOS) && defined(USE_GLIB)
+#include <glib.h>  // for g_get_home_dir()
+#endif
+
+#include <fstream>
+
+#include "base/basictypes.h"
+#include "base/files/file_enumerator.h"
+#include "base/files/file_path.h"
+#include "base/files/scoped_file.h"
+#include "base/logging.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/memory/singleton.h"
+#include "base/path_service.h"
+#include "base/posix/eintr_wrapper.h"
+#include "base/stl_util.h"
+#include "base/strings/string_util.h"
+#include "base/strings/stringprintf.h"
+#include "base/strings/sys_string_conversions.h"
+#include "base/strings/utf_string_conversions.h"
+#include "base/sys_info.h"
+#include "base/threading/thread_restrictions.h"
+#include "base/time/time.h"
+
+#if defined(OS_ANDROID)
+#include "base/android/content_uri_utils.h"
+#include "base/os_compat_android.h"
+#endif
+
+#if !defined(OS_IOS)
+#include <grp.h>
+#endif
+
+namespace base {
+
+namespace {
+
+#if defined(OS_BSD) || defined(OS_MACOSX) || defined(OS_NACL)
+static int CallStat(const char *path, stat_wrapper_t *sb) {
+  ThreadRestrictions::AssertIOAllowed();
+  return stat(path, sb);
+}
+static int CallLstat(const char *path, stat_wrapper_t *sb) {
+  ThreadRestrictions::AssertIOAllowed();
+  return lstat(path, sb);
+}
+#else  //  defined(OS_BSD) || defined(OS_MACOSX) || defined(OS_NACL)
+static int CallStat(const char *path, stat_wrapper_t *sb) {
+  ThreadRestrictions::AssertIOAllowed();
+  return stat64(path, sb);
+}
+static int CallLstat(const char *path, stat_wrapper_t *sb) {
+  ThreadRestrictions::AssertIOAllowed();
+  return lstat64(path, sb);
+}
+#endif  // !(defined(OS_BSD) || defined(OS_MACOSX) || defined(OS_NACL))
+
+// Helper for NormalizeFilePath(), defined below.
+bool RealPath(const FilePath& path, FilePath* real_path) {
+  ThreadRestrictions::AssertIOAllowed();  // For realpath().
+  FilePath::CharType buf[PATH_MAX];
+  if (!realpath(path.value().c_str(), buf))
+    return false;
+
+  *real_path = FilePath(buf);
+  return true;
+}
+
+// Helper for VerifyPathControlledByUser.
+bool VerifySpecificPathControlledByUser(const FilePath& path,
+                                        uid_t owner_uid,
+                                        const std::set<gid_t>& group_gids) {
+  stat_wrapper_t stat_info;
+  if (CallLstat(path.value().c_str(), &stat_info) != 0) {
+    DPLOG(ERROR) << "Failed to get information on path "
+                 << path.value();
+    return false;
+  }
+
+  if (S_ISLNK(stat_info.st_mode)) {
+    DLOG(ERROR) << "Path " << path.value()
+               << " is a symbolic link.";
+    return false;
+  }
+
+  if (stat_info.st_uid != owner_uid) {
+    DLOG(ERROR) << "Path " << path.value()
+                << " is owned by the wrong user.";
+    return false;
+  }
+
+  if ((stat_info.st_mode & S_IWGRP) &&
+      !ContainsKey(group_gids, stat_info.st_gid)) {
+    DLOG(ERROR) << "Path " << path.value()
+                << " is writable by an unprivileged group.";
+    return false;
+  }
+
+  if (stat_info.st_mode & S_IWOTH) {
+    DLOG(ERROR) << "Path " << path.value()
+                << " is writable by any user.";
+    return false;
+  }
+
+  return true;
+}
+
+std::string TempFileName() {
+#if defined(OS_MACOSX)
+  return StringPrintf(".%s.XXXXXX", base::mac::BaseBundleID());
+#endif
+
+#if defined(GOOGLE_CHROME_BUILD)
+  return std::string(".com.google.Chrome.XXXXXX");
+#else
+  return std::string(".org.chromium.Chromium.XXXXXX");
+#endif
+}
+
+// Creates and opens a temporary file in |directory|, returning the
+// file descriptor. |path| is set to the temporary file path.
+// This function does NOT unlink() the file.
+int CreateAndOpenFdForTemporaryFile(FilePath directory, FilePath* path) {
+  ThreadRestrictions::AssertIOAllowed();  // For call to mkstemp().
+  *path = directory.Append(base::TempFileName());
+  const std::string& tmpdir_string = path->value();
+  // this should be OK since mkstemp just replaces characters in place
+  char* buffer = const_cast<char*>(tmpdir_string.c_str());
+
+  return HANDLE_EINTR(mkstemp(buffer));
+}
+
+#if defined(OS_LINUX)
+// Determine if /dev/shm files can be mapped and then mprotect'd PROT_EXEC.
+// This depends on the mount options used for /dev/shm, which vary among
+// different Linux distributions and possibly local configuration.  It also
+// depends on details of kernel--ChromeOS uses the noexec option for /dev/shm
+// but its kernel allows mprotect with PROT_EXEC anyway.
+bool DetermineDevShmExecutable() {
+  bool result = false;
+  FilePath path;
+
+  ScopedFD fd(CreateAndOpenFdForTemporaryFile(FilePath("/dev/shm"), &path));
+  if (fd.is_valid()) {
+    DeleteFile(path, false);
+    long sysconf_result = sysconf(_SC_PAGESIZE);
+    CHECK_GE(sysconf_result, 0);
+    size_t pagesize = static_cast<size_t>(sysconf_result);
+    CHECK_GE(sizeof(pagesize), sizeof(sysconf_result));
+    void* mapping = mmap(NULL, pagesize, PROT_READ, MAP_SHARED, fd.get(), 0);
+    if (mapping != MAP_FAILED) {
+      if (mprotect(mapping, pagesize, PROT_READ | PROT_EXEC) == 0)
+        result = true;
+      munmap(mapping, pagesize);
+    }
+  }
+  return result;
+}
+#endif  // defined(OS_LINUX)
+
+}  // namespace
+
+FilePath MakeAbsoluteFilePath(const FilePath& input) {
+  ThreadRestrictions::AssertIOAllowed();
+  char full_path[PATH_MAX];
+  if (realpath(input.value().c_str(), full_path) == NULL)
+    return FilePath();
+  return FilePath(full_path);
+}
+
+// TODO(erikkay): The Windows version of this accepts paths like "foo/bar/*"
+// which works both with and without the recursive flag.  I'm not sure we need
+// that functionality. If not, remove from file_util_win.cc, otherwise add it
+// here.
+bool DeleteFile(const FilePath& path, bool recursive) {
+  ThreadRestrictions::AssertIOAllowed();
+  const char* path_str = path.value().c_str();
+  stat_wrapper_t file_info;
+  int test = CallLstat(path_str, &file_info);
+  if (test != 0) {
+    // The Windows version defines this condition as success.
+    bool ret = (errno == ENOENT || errno == ENOTDIR);
+    return ret;
+  }
+  if (!S_ISDIR(file_info.st_mode))
+    return (unlink(path_str) == 0);
+  if (!recursive)
+    return (rmdir(path_str) == 0);
+
+  bool success = true;
+  std::stack<std::string> directories;
+  directories.push(path.value());
+  FileEnumerator traversal(path, true,
+      FileEnumerator::FILES | FileEnumerator::DIRECTORIES |
+      FileEnumerator::SHOW_SYM_LINKS);
+  for (FilePath current = traversal.Next(); success && !current.empty();
+       current = traversal.Next()) {
+    if (traversal.GetInfo().IsDirectory())
+      directories.push(current.value());
+    else
+      success = (unlink(current.value().c_str()) == 0);
+  }
+
+  while (success && !directories.empty()) {
+    FilePath dir = FilePath(directories.top());
+    directories.pop();
+    success = (rmdir(dir.value().c_str()) == 0);
+  }
+  return success;
+}
+
+bool ReplaceFile(const FilePath& from_path,
+                 const FilePath& to_path,
+                 File::Error* error) {
+  ThreadRestrictions::AssertIOAllowed();
+  if (rename(from_path.value().c_str(), to_path.value().c_str()) == 0)
+    return true;
+  if (error)
+    *error = File::OSErrorToFileError(errno);
+  return false;
+}
+
+bool CopyDirectory(const FilePath& from_path,
+                   const FilePath& to_path,
+                   bool recursive) {
+  ThreadRestrictions::AssertIOAllowed();
+  // Some old callers of CopyDirectory want it to support wildcards.
+  // After some discussion, we decided to fix those callers.
+  // Break loudly here if anyone tries to do this.
+  DCHECK(to_path.value().find('*') == std::string::npos);
+  DCHECK(from_path.value().find('*') == std::string::npos);
+
+  if (from_path.value().size() >= PATH_MAX) {
+    return false;
+  }
+
+  // This function does not properly handle destinations within the source
+  FilePath real_to_path = to_path;
+  if (PathExists(real_to_path)) {
+    real_to_path = MakeAbsoluteFilePath(real_to_path);
+    if (real_to_path.empty())
+      return false;
+  } else {
+    real_to_path = MakeAbsoluteFilePath(real_to_path.DirName());
+    if (real_to_path.empty())
+      return false;
+  }
+  FilePath real_from_path = MakeAbsoluteFilePath(from_path);
+  if (real_from_path.empty())
+    return false;
+  if (real_to_path.value().size() >= real_from_path.value().size() &&
+      real_to_path.value().compare(0, real_from_path.value().size(),
+                                   real_from_path.value()) == 0) {
+    return false;
+  }
+
+  int traverse_type = FileEnumerator::FILES | FileEnumerator::SHOW_SYM_LINKS;
+  if (recursive)
+    traverse_type |= FileEnumerator::DIRECTORIES;
+  FileEnumerator traversal(from_path, recursive, traverse_type);
+
+  // We have to mimic windows behavior here. |to_path| may not exist yet,
+  // start the loop with |to_path|.
+  struct stat from_stat;
+  FilePath current = from_path;
+  if (stat(from_path.value().c_str(), &from_stat) < 0) {
+    DLOG(ERROR) << "CopyDirectory() couldn't stat source directory: "
+                << from_path.value() << " errno = " << errno;
+    return false;
+  }
+  struct stat to_path_stat;
+  FilePath from_path_base = from_path;
+  if (recursive && stat(to_path.value().c_str(), &to_path_stat) == 0 &&
+      S_ISDIR(to_path_stat.st_mode)) {
+    // If the destination already exists and is a directory, then the
+    // top level of source needs to be copied.
+    from_path_base = from_path.DirName();
+  }
+
+  // The Windows version of this function assumes that non-recursive calls
+  // will always have a directory for from_path.
+  // TODO(maruel): This is not necessary anymore.
+  DCHECK(recursive || S_ISDIR(from_stat.st_mode));
+
+  bool success = true;
+  while (success && !current.empty()) {
+    // current is the source path, including from_path, so append
+    // the suffix after from_path to to_path to create the target_path.
+    FilePath target_path(to_path);
+    if (from_path_base != current) {
+      if (!from_path_base.AppendRelativePath(current, &target_path)) {
+        success = false;
+        break;
+      }
+    }
+
+    if (S_ISDIR(from_stat.st_mode)) {
+      if (mkdir(target_path.value().c_str(), from_stat.st_mode & 01777) != 0 &&
+          errno != EEXIST) {
+        DLOG(ERROR) << "CopyDirectory() couldn't create directory: "
+                    << target_path.value() << " errno = " << errno;
+        success = false;
+      }
+    } else if (S_ISREG(from_stat.st_mode)) {
+      if (!CopyFile(current, target_path)) {
+        DLOG(ERROR) << "CopyDirectory() couldn't create file: "
+                    << target_path.value();
+        success = false;
+      }
+    } else {
+      DLOG(WARNING) << "CopyDirectory() skipping non-regular file: "
+                    << current.value();
+    }
+
+    current = traversal.Next();
+    if (!current.empty())
+      from_stat = traversal.GetInfo().stat();
+  }
+
+  return success;
+}
+
+bool PathExists(const FilePath& path) {
+  ThreadRestrictions::AssertIOAllowed();
+#if defined(OS_ANDROID)
+  if (path.IsContentUri()) {
+    return ContentUriExists(path);
+  }
+#endif
+  return access(path.value().c_str(), F_OK) == 0;
+}
+
+bool PathIsWritable(const FilePath& path) {
+  ThreadRestrictions::AssertIOAllowed();
+  return access(path.value().c_str(), W_OK) == 0;
+}
+
+bool DirectoryExists(const FilePath& path) {
+  ThreadRestrictions::AssertIOAllowed();
+  stat_wrapper_t file_info;
+  if (CallStat(path.value().c_str(), &file_info) == 0)
+    return S_ISDIR(file_info.st_mode);
+  return false;
+}
+
+bool ReadFromFD(int fd, char* buffer, size_t bytes) {
+  size_t total_read = 0;
+  while (total_read < bytes) {
+    ssize_t bytes_read =
+        HANDLE_EINTR(read(fd, buffer + total_read, bytes - total_read));
+    if (bytes_read <= 0)
+      break;
+    total_read += bytes_read;
+  }
+  return total_read == bytes;
+}
+
+bool CreateSymbolicLink(const FilePath& target_path,
+                        const FilePath& symlink_path) {
+  DCHECK(!symlink_path.empty());
+  DCHECK(!target_path.empty());
+  return ::symlink(target_path.value().c_str(),
+                   symlink_path.value().c_str()) != -1;
+}
+
+bool ReadSymbolicLink(const FilePath& symlink_path, FilePath* target_path) {
+  DCHECK(!symlink_path.empty());
+  DCHECK(target_path);
+  char buf[PATH_MAX];
+  ssize_t count = ::readlink(symlink_path.value().c_str(), buf, arraysize(buf));
+
+  if (count <= 0) {
+    target_path->clear();
+    return false;
+  }
+
+  *target_path = FilePath(FilePath::StringType(buf, count));
+  return true;
+}
+
+bool GetPosixFilePermissions(const FilePath& path, int* mode) {
+  ThreadRestrictions::AssertIOAllowed();
+  DCHECK(mode);
+
+  stat_wrapper_t file_info;
+  // Uses stat(), because on symbolic link, lstat() does not return valid
+  // permission bits in st_mode
+  if (CallStat(path.value().c_str(), &file_info) != 0)
+    return false;
+
+  *mode = file_info.st_mode & FILE_PERMISSION_MASK;
+  return true;
+}
+
+bool SetPosixFilePermissions(const FilePath& path,
+                             int mode) {
+  ThreadRestrictions::AssertIOAllowed();
+  DCHECK((mode & ~FILE_PERMISSION_MASK) == 0);
+
+  // Calls stat() so that we can preserve the higher bits like S_ISGID.
+  stat_wrapper_t stat_buf;
+  if (CallStat(path.value().c_str(), &stat_buf) != 0)
+    return false;
+
+  // Clears the existing permission bits, and adds the new ones.
+  mode_t updated_mode_bits = stat_buf.st_mode & ~FILE_PERMISSION_MASK;
+  updated_mode_bits |= mode & FILE_PERMISSION_MASK;
+
+  if (HANDLE_EINTR(chmod(path.value().c_str(), updated_mode_bits)) != 0)
+    return false;
+
+  return true;
+}
+
+#if !defined(OS_MACOSX)
+// This is implemented in file_util_mac.mm for Mac.
+bool GetTempDir(FilePath* path) {
+  const char* tmp = getenv("TMPDIR");
+  if (tmp) {
+    *path = FilePath(tmp);
+  } else {
+#if defined(OS_ANDROID)
+    return PathService::Get(base::DIR_CACHE, path);
+#else
+    *path = FilePath("/tmp");
+#endif
+  }
+  return true;
+}
+#endif  // !defined(OS_MACOSX)
+
+#if !defined(OS_MACOSX)  // Mac implementation is in file_util_mac.mm.
+FilePath GetHomeDir() {
+#if defined(OS_CHROMEOS)
+  if (SysInfo::IsRunningOnChromeOS()) {
+    // On Chrome OS chrome::DIR_USER_DATA is overridden with a primary user
+    // homedir once it becomes available. Return / as the safe option.
+    return FilePath("/");
+  }
+#endif
+
+  const char* home_dir = getenv("HOME");
+  if (home_dir && home_dir[0])
+    return FilePath(home_dir);
+
+#if defined(OS_ANDROID)
+  DLOG(WARNING) << "OS_ANDROID: Home directory lookup not yet implemented.";
+#elif defined(USE_GLIB) && !defined(OS_CHROMEOS)
+  // g_get_home_dir calls getpwent, which can fall through to LDAP calls so
+  // this may do I/O. However, it should be rare that $HOME is not defined and
+  // this is typically called from the path service which has no threading
+  // restrictions. The path service will cache the result which limits the
+  // badness of blocking on I/O. As a result, we don't have a thread
+  // restriction here.
+  home_dir = g_get_home_dir();
+  if (home_dir && home_dir[0])
+    return FilePath(home_dir);
+#endif
+
+  FilePath rv;
+  if (GetTempDir(&rv))
+    return rv;
+
+  // Last resort.
+  return FilePath("/tmp");
+}
+#endif  // !defined(OS_MACOSX)
+
+bool CreateTemporaryFile(FilePath* path) {
+  ThreadRestrictions::AssertIOAllowed();  // For call to close().
+  FilePath directory;
+  if (!GetTempDir(&directory))
+    return false;
+  int fd = CreateAndOpenFdForTemporaryFile(directory, path);
+  if (fd < 0)
+    return false;
+  close(fd);
+  return true;
+}
+
+FILE* CreateAndOpenTemporaryFileInDir(const FilePath& dir, FilePath* path) {
+  int fd = CreateAndOpenFdForTemporaryFile(dir, path);
+  if (fd < 0)
+    return NULL;
+
+  FILE* file = fdopen(fd, "a+");
+  if (!file)
+    close(fd);
+  return file;
+}
+
+bool CreateTemporaryFileInDir(const FilePath& dir, FilePath* temp_file) {
+  ThreadRestrictions::AssertIOAllowed();  // For call to close().
+  int fd = CreateAndOpenFdForTemporaryFile(dir, temp_file);
+  return ((fd >= 0) && !IGNORE_EINTR(close(fd)));
+}
+
+static bool CreateTemporaryDirInDirImpl(const FilePath& base_dir,
+                                        const FilePath::StringType& name_tmpl,
+                                        FilePath* new_dir) {
+  ThreadRestrictions::AssertIOAllowed();  // For call to mkdtemp().
+  DCHECK(name_tmpl.find("XXXXXX") != FilePath::StringType::npos)
+      << "Directory name template must contain \"XXXXXX\".";
+
+  FilePath sub_dir = base_dir.Append(name_tmpl);
+  std::string sub_dir_string = sub_dir.value();
+
+  // this should be OK since mkdtemp just replaces characters in place
+  char* buffer = const_cast<char*>(sub_dir_string.c_str());
+  char* dtemp = mkdtemp(buffer);
+  if (!dtemp) {
+    DPLOG(ERROR) << "mkdtemp";
+    return false;
+  }
+  *new_dir = FilePath(dtemp);
+  return true;
+}
+
+bool CreateTemporaryDirInDir(const FilePath& base_dir,
+                             const FilePath::StringType& prefix,
+                             FilePath* new_dir) {
+  FilePath::StringType mkdtemp_template = prefix;
+  mkdtemp_template.append(FILE_PATH_LITERAL("XXXXXX"));
+  return CreateTemporaryDirInDirImpl(base_dir, mkdtemp_template, new_dir);
+}
+
+bool CreateNewTempDirectory(const FilePath::StringType& prefix,
+                            FilePath* new_temp_path) {
+  FilePath tmpdir;
+  if (!GetTempDir(&tmpdir))
+    return false;
+
+  return CreateTemporaryDirInDirImpl(tmpdir, TempFileName(), new_temp_path);
+}
+
+bool CreateDirectoryAndGetError(const FilePath& full_path,
+                                File::Error* error) {
+  ThreadRestrictions::AssertIOAllowed();  // For call to mkdir().
+  std::vector<FilePath> subpaths;
+
+  // Collect a list of all parent directories.
+  FilePath last_path = full_path;
+  subpaths.push_back(full_path);
+  for (FilePath path = full_path.DirName();
+       path.value() != last_path.value(); path = path.DirName()) {
+    subpaths.push_back(path);
+    last_path = path;
+  }
+
+  // Iterate through the parents and create the missing ones.
+  for (std::vector<FilePath>::reverse_iterator i = subpaths.rbegin();
+       i != subpaths.rend(); ++i) {
+    if (DirectoryExists(*i))
+      continue;
+    if (mkdir(i->value().c_str(), 0700) == 0)
+      continue;
+    // Mkdir failed, but it might have failed with EEXIST, or some other error
+    // due to the the directory appearing out of thin air. This can occur if
+    // two processes are trying to create the same file system tree at the same
+    // time. Check to see if it exists and make sure it is a directory.
+    int saved_errno = errno;
+    if (!DirectoryExists(*i)) {
+      if (error)
+        *error = File::OSErrorToFileError(saved_errno);
+      return false;
+    }
+  }
+  return true;
+}
+
+bool NormalizeFilePath(const FilePath& path, FilePath* normalized_path) {
+  FilePath real_path_result;
+  if (!RealPath(path, &real_path_result))
+    return false;
+
+  // To be consistant with windows, fail if |real_path_result| is a
+  // directory.
+  stat_wrapper_t file_info;
+  if (CallStat(real_path_result.value().c_str(), &file_info) != 0 ||
+      S_ISDIR(file_info.st_mode))
+    return false;
+
+  *normalized_path = real_path_result;
+  return true;
+}
+
+// TODO(rkc): Refactor GetFileInfo and FileEnumerator to handle symlinks
+// correctly. http://code.google.com/p/chromium-os/issues/detail?id=15948
+bool IsLink(const FilePath& file_path) {
+  stat_wrapper_t st;
+  // If we can't lstat the file, it's safe to assume that the file won't at
+  // least be a 'followable' link.
+  if (CallLstat(file_path.value().c_str(), &st) != 0)
+    return false;
+
+  if (S_ISLNK(st.st_mode))
+    return true;
+  else
+    return false;
+}
+
+bool GetFileInfo(const FilePath& file_path, File::Info* results) {
+  stat_wrapper_t file_info;
+#if defined(OS_ANDROID)
+  if (file_path.IsContentUri()) {
+    File file = OpenContentUriForRead(file_path);
+    if (!file.IsValid())
+      return false;
+    return file.GetInfo(results);
+  } else {
+#endif  // defined(OS_ANDROID)
+    if (CallStat(file_path.value().c_str(), &file_info) != 0)
+      return false;
+#if defined(OS_ANDROID)
+  }
+#endif  // defined(OS_ANDROID)
+
+  results->FromStat(file_info);
+  return true;
+}
+
+FILE* OpenFile(const FilePath& filename, const char* mode) {
+  ThreadRestrictions::AssertIOAllowed();
+  FILE* result = NULL;
+  do {
+    result = fopen(filename.value().c_str(), mode);
+  } while (!result && errno == EINTR);
+  return result;
+}
+
+// NaCl doesn't implement system calls to open files directly.
+#if !defined(OS_NACL)
+FILE* FileToFILE(File file, const char* mode) {
+  FILE* stream = fdopen(file.GetPlatformFile(), mode);
+  if (stream)
+    file.TakePlatformFile();
+  return stream;
+}
+#endif  // !defined(OS_NACL)
+
+int ReadFile(const FilePath& filename, char* data, int max_size) {
+  ThreadRestrictions::AssertIOAllowed();
+  int fd = HANDLE_EINTR(open(filename.value().c_str(), O_RDONLY));
+  if (fd < 0)
+    return -1;
+
+  ssize_t bytes_read = HANDLE_EINTR(read(fd, data, max_size));
+  if (IGNORE_EINTR(close(fd)) < 0)
+    return -1;
+  return bytes_read;
+}
+
+int WriteFile(const FilePath& filename, const char* data, int size) {
+  ThreadRestrictions::AssertIOAllowed();
+  int fd = HANDLE_EINTR(creat(filename.value().c_str(), 0640));
+  if (fd < 0)
+    return -1;
+
+  int bytes_written = WriteFileDescriptor(fd, data, size);
+  if (IGNORE_EINTR(close(fd)) < 0)
+    return -1;
+  return bytes_written;
+}
+
+int WriteFileDescriptor(const int fd, const char* data, int size) {
+  // Allow for partial writes.
+  ssize_t bytes_written_total = 0;
+  for (ssize_t bytes_written_partial = 0; bytes_written_total < size;
+       bytes_written_total += bytes_written_partial) {
+    bytes_written_partial =
+        HANDLE_EINTR(write(fd, data + bytes_written_total,
+                           size - bytes_written_total));
+    if (bytes_written_partial < 0)
+      return -1;
+  }
+
+  return bytes_written_total;
+}
+
+int AppendToFile(const FilePath& filename, const char* data, int size) {
+  ThreadRestrictions::AssertIOAllowed();
+  int fd = HANDLE_EINTR(open(filename.value().c_str(), O_WRONLY | O_APPEND));
+  if (fd < 0)
+    return -1;
+
+  int bytes_written = WriteFileDescriptor(fd, data, size);
+  if (IGNORE_EINTR(close(fd)) < 0)
+    return -1;
+  return bytes_written;
+}
+
+// Gets the current working directory for the process.
+bool GetCurrentDirectory(FilePath* dir) {
+  // getcwd can return ENOENT, which implies it checks against the disk.
+  ThreadRestrictions::AssertIOAllowed();
+
+  char system_buffer[PATH_MAX] = "";
+  if (!getcwd(system_buffer, sizeof(system_buffer))) {
+    NOTREACHED();
+    return false;
+  }
+  *dir = FilePath(system_buffer);
+  return true;
+}
+
+// Sets the current working directory for the process.
+bool SetCurrentDirectory(const FilePath& path) {
+  ThreadRestrictions::AssertIOAllowed();
+  int ret = chdir(path.value().c_str());
+  return !ret;
+}
+
+bool VerifyPathControlledByUser(const FilePath& base,
+                                const FilePath& path,
+                                uid_t owner_uid,
+                                const std::set<gid_t>& group_gids) {
+  if (base != path && !base.IsParent(path)) {
+     DLOG(ERROR) << "|base| must be a subdirectory of |path|.  base = \""
+                 << base.value() << "\", path = \"" << path.value() << "\"";
+     return false;
+  }
+
+  std::vector<FilePath::StringType> base_components;
+  std::vector<FilePath::StringType> path_components;
+
+  base.GetComponents(&base_components);
+  path.GetComponents(&path_components);
+
+  std::vector<FilePath::StringType>::const_iterator ib, ip;
+  for (ib = base_components.begin(), ip = path_components.begin();
+       ib != base_components.end(); ++ib, ++ip) {
+    // |base| must be a subpath of |path|, so all components should match.
+    // If these CHECKs fail, look at the test that base is a parent of
+    // path at the top of this function.
+    DCHECK(ip != path_components.end());
+    DCHECK(*ip == *ib);
+  }
+
+  FilePath current_path = base;
+  if (!VerifySpecificPathControlledByUser(current_path, owner_uid, group_gids))
+    return false;
+
+  for (; ip != path_components.end(); ++ip) {
+    current_path = current_path.Append(*ip);
+    if (!VerifySpecificPathControlledByUser(
+            current_path, owner_uid, group_gids))
+      return false;
+  }
+  return true;
+}
+
+#if defined(OS_MACOSX) && !defined(OS_IOS)
+bool VerifyPathControlledByAdmin(const FilePath& path) {
+  const unsigned kRootUid = 0;
+  const FilePath kFileSystemRoot("/");
+
+  // The name of the administrator group on mac os.
+  const char* const kAdminGroupNames[] = {
+    "admin",
+    "wheel"
+  };
+
+  // Reading the groups database may touch the file system.
+  ThreadRestrictions::AssertIOAllowed();
+
+  std::set<gid_t> allowed_group_ids;
+  for (int i = 0, ie = arraysize(kAdminGroupNames); i < ie; ++i) {
+    struct group *group_record = getgrnam(kAdminGroupNames[i]);
+    if (!group_record) {
+      DPLOG(ERROR) << "Could not get the group ID of group \""
+                   << kAdminGroupNames[i] << "\".";
+      continue;
+    }
+
+    allowed_group_ids.insert(group_record->gr_gid);
+  }
+
+  return VerifyPathControlledByUser(
+      kFileSystemRoot, path, kRootUid, allowed_group_ids);
+}
+#endif  // defined(OS_MACOSX) && !defined(OS_IOS)
+
+int GetMaximumPathComponentLength(const FilePath& path) {
+  ThreadRestrictions::AssertIOAllowed();
+  return pathconf(path.value().c_str(), _PC_NAME_MAX);
+}
+
+#if !defined(OS_ANDROID)
+// This is implemented in file_util_android.cc for that platform.
+bool GetShmemTempDir(bool executable, FilePath* path) {
+#if defined(OS_LINUX)
+  bool use_dev_shm = true;
+  if (executable) {
+    static const bool s_dev_shm_executable = DetermineDevShmExecutable();
+    use_dev_shm = s_dev_shm_executable;
+  }
+  if (use_dev_shm) {
+    *path = FilePath("/dev/shm");
+    return true;
+  }
+#endif
+  return GetTempDir(path);
+}
+#endif  // !defined(OS_ANDROID)
+
+// -----------------------------------------------------------------------------
+
+namespace internal {
+
+bool MoveUnsafe(const FilePath& from_path, const FilePath& to_path) {
+  ThreadRestrictions::AssertIOAllowed();
+  // Windows compatibility: if to_path exists, from_path and to_path
+  // must be the same type, either both files, or both directories.
+  stat_wrapper_t to_file_info;
+  if (CallStat(to_path.value().c_str(), &to_file_info) == 0) {
+    stat_wrapper_t from_file_info;
+    if (CallStat(from_path.value().c_str(), &from_file_info) == 0) {
+      if (S_ISDIR(to_file_info.st_mode) != S_ISDIR(from_file_info.st_mode))
+        return false;
+    } else {
+      return false;
+    }
+  }
+
+  if (rename(from_path.value().c_str(), to_path.value().c_str()) == 0)
+    return true;
+
+  if (!CopyDirectory(from_path, to_path, true))
+    return false;
+
+  DeleteFile(from_path, true);
+  return true;
+}
+
+#if !defined(OS_MACOSX)
+// Mac has its own implementation, this is for all other Posix systems.
+bool CopyFileUnsafe(const FilePath& from_path, const FilePath& to_path) {
+  ThreadRestrictions::AssertIOAllowed();
+  int infile = HANDLE_EINTR(open(from_path.value().c_str(), O_RDONLY));
+  if (infile < 0)
+    return false;
+
+  int outfile = HANDLE_EINTR(creat(to_path.value().c_str(), 0666));
+  if (outfile < 0) {
+    close(infile);
+    return false;
+  }
+
+  const size_t kBufferSize = 32768;
+  std::vector<char> buffer(kBufferSize);
+  bool result = true;
+
+  while (result) {
+    ssize_t bytes_read = HANDLE_EINTR(read(infile, &buffer[0], buffer.size()));
+    if (bytes_read < 0) {
+      result = false;
+      break;
+    }
+    if (bytes_read == 0)
+      break;
+    // Allow for partial writes
+    ssize_t bytes_written_per_read = 0;
+    do {
+      ssize_t bytes_written_partial = HANDLE_EINTR(write(
+          outfile,
+          &buffer[bytes_written_per_read],
+          bytes_read - bytes_written_per_read));
+      if (bytes_written_partial < 0) {
+        result = false;
+        break;
+      }
+      bytes_written_per_read += bytes_written_partial;
+    } while (bytes_written_per_read < bytes_read);
+  }
+
+  if (IGNORE_EINTR(close(infile)) < 0)
+    result = false;
+  if (IGNORE_EINTR(close(outfile)) < 0)
+    result = false;
+
+  return result;
+}
+#endif  // !defined(OS_MACOSX)
+
+}  // namespace internal
+}  // namespace base