blob: 150ddf6606283f7b299ff1dcb8f4478b5dc7398c [file] [log] [blame]
// 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"
// windows.h includes winsock.h which isn't compatible with winsock2.h. To use
// winsock2.h you have to include it first.
// clang-format off
#include <winsock2.h>
#include <windows.h>
// clang-format on
#include <io.h>
#include <psapi.h>
#include <share.h>
#include <shellapi.h>
#include <shlobj.h>
#include <stddef.h>
#include <stdint.h>
#include <time.h>
#include <algorithm>
#include <iterator>
#include <limits>
#include <string>
#include <string_view>
#include "base/files/file_enumerator.h"
#include "base/files/file_path.h"
#include "base/logging.h"
#include "base/strings/string_number_conversions.h"
#include "base/strings/string_util.h"
#include "base/strings/stringprintf.h"
#include "base/strings/utf_string_conversions.h"
#include "base/win/scoped_handle.h"
#include "base/win/win_util.h"
// #define needed to link in RtlGenRandom(), a.k.a. SystemFunction036. See the
// "Community Additions" comment on MSDN here:
// http://msdn.microsoft.com/en-us/library/windows/desktop/aa387694.aspx
#define SystemFunction036 NTAPI SystemFunction036
#include <ntsecapi.h>
#undef SystemFunction036
namespace base {
namespace {
const DWORD kFileShareAll =
FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE;
// Deletes all files and directories in a path.
// Returns ERROR_SUCCESS on success or the Windows error code corresponding to
// the first error encountered.
DWORD DeleteFileRecursive(const FilePath& path,
const FilePath::StringType& pattern,
bool recursive) {
FileEnumerator traversal(path, false,
FileEnumerator::FILES | FileEnumerator::DIRECTORIES,
pattern);
DWORD result = ERROR_SUCCESS;
for (FilePath current = traversal.Next(); !current.empty();
current = traversal.Next()) {
// Try to clear the read-only bit if we find it.
FileEnumerator::FileInfo info = traversal.GetInfo();
if ((info.find_data().dwFileAttributes & FILE_ATTRIBUTE_READONLY) &&
(recursive || !info.IsDirectory())) {
::SetFileAttributes(
ToWCharT(&current.value()),
info.find_data().dwFileAttributes & ~FILE_ATTRIBUTE_READONLY);
}
DWORD this_result = ERROR_SUCCESS;
if (info.IsDirectory()) {
if (recursive) {
this_result = DeleteFileRecursive(current, pattern, true);
if (this_result == ERROR_SUCCESS &&
!::RemoveDirectory(ToWCharT(&current.value()))) {
this_result = ::GetLastError();
}
}
} else if (!::DeleteFile(ToWCharT(&current.value()))) {
this_result = ::GetLastError();
}
if (result == ERROR_SUCCESS)
result = this_result;
}
return result;
}
// Appends |mode_char| to |mode| before the optional character set encoding; see
// https://msdn.microsoft.com/library/yeby3zcb.aspx for details.
void AppendModeCharacter(char16_t mode_char, std::u16string* mode) {
size_t comma_pos = mode->find(L',');
mode->insert(comma_pos == std::u16string::npos ? mode->length() : comma_pos,
1, mode_char);
}
// Returns ERROR_SUCCESS on success, or a Windows error code on failure.
DWORD DoDeleteFile(const FilePath& path, bool recursive) {
if (path.empty())
return ERROR_SUCCESS;
if (path.value().length() >= MAX_PATH)
return ERROR_BAD_PATHNAME;
// Handle any path with wildcards.
if (path.BaseName().value().find_first_of(u"*?") !=
FilePath::StringType::npos) {
return DeleteFileRecursive(path.DirName(), path.BaseName().value(),
recursive);
}
// Report success if the file or path does not exist.
const DWORD attr = ::GetFileAttributes(ToWCharT(&path.value()));
if (attr == INVALID_FILE_ATTRIBUTES) {
const DWORD error_code = ::GetLastError();
return (error_code == ERROR_FILE_NOT_FOUND ||
error_code == ERROR_PATH_NOT_FOUND)
? ERROR_SUCCESS
: error_code;
}
// Clear the read-only bit if it is set.
if ((attr & FILE_ATTRIBUTE_READONLY) &&
!::SetFileAttributes(ToWCharT(&path.value()),
attr & ~FILE_ATTRIBUTE_READONLY)) {
return ::GetLastError();
}
// Perform a simple delete on anything that isn't a directory.
if (!(attr & FILE_ATTRIBUTE_DIRECTORY)) {
return ::DeleteFile(ToWCharT(&path.value())) ? ERROR_SUCCESS
: ::GetLastError();
}
if (recursive) {
const DWORD error_code = DeleteFileRecursive(path, u"*", true);
if (error_code != ERROR_SUCCESS)
return error_code;
}
return ::RemoveDirectory(ToWCharT(&path.value())) ? ERROR_SUCCESS
: ::GetLastError();
}
std::string RandomDataToGUIDString(const uint64_t bytes[2]) {
return base::StringPrintf(
"%08x-%04x-%04x-%04x-%012llx", static_cast<unsigned int>(bytes[0] >> 32),
static_cast<unsigned int>((bytes[0] >> 16) & 0x0000ffff),
static_cast<unsigned int>(bytes[0] & 0x0000ffff),
static_cast<unsigned int>(bytes[1] >> 48),
bytes[1] & 0x0000ffff'ffffffffULL);
}
void RandBytes(void* output, size_t output_length) {
char* output_ptr = static_cast<char*>(output);
while (output_length > 0) {
const ULONG output_bytes_this_pass = static_cast<ULONG>(std::min(
output_length, static_cast<size_t>(std::numeric_limits<ULONG>::max())));
const bool success =
RtlGenRandom(output_ptr, output_bytes_this_pass) != FALSE;
CHECK(success);
output_length -= output_bytes_this_pass;
output_ptr += output_bytes_this_pass;
}
}
std::string GenerateGUID() {
uint64_t sixteen_bytes[2];
// Use base::RandBytes instead of crypto::RandBytes, because crypto calls the
// base version directly, and to prevent the dependency from base/ to crypto/.
RandBytes(&sixteen_bytes, sizeof(sixteen_bytes));
// Set the GUID to version 4 as described in RFC 4122, section 4.4.
// The format of GUID version 4 must be xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx,
// where y is one of [8, 9, A, B].
// Clear the version bits and set the version to 4:
sixteen_bytes[0] &= 0xffffffff'ffff0fffULL;
sixteen_bytes[0] |= 0x00000000'00004000ULL;
// Set the two most significant bits (bits 6 and 7) of the
// clock_seq_hi_and_reserved to zero and one, respectively:
sixteen_bytes[1] &= 0x3fffffff'ffffffffULL;
sixteen_bytes[1] |= 0x80000000'00000000ULL;
return RandomDataToGUIDString(sixteen_bytes);
}
} // namespace
FilePath MakeAbsoluteFilePath(const FilePath& input) {
char16_t file_path[MAX_PATH];
if (!_wfullpath(ToWCharT(file_path), ToWCharT(&input.value()), MAX_PATH))
return FilePath();
return FilePath(file_path);
}
bool DeleteFile(const FilePath& path, bool recursive) {
static constexpr char kRecursive[] = "DeleteFile.Recursive";
static constexpr char kNonRecursive[] = "DeleteFile.NonRecursive";
const std::string_view operation(recursive ? kRecursive : kNonRecursive);
// Metrics for delete failures tracked in https://crbug.com/599084. Delete may
// fail for a number of reasons. Log some metrics relating to failures in the
// current code so that any improvements or regressions resulting from
// subsequent code changes can be detected.
const DWORD error = DoDeleteFile(path, recursive);
return error == ERROR_SUCCESS;
}
bool DeleteFileAfterReboot(const FilePath& path) {
if (path.value().length() >= MAX_PATH)
return false;
return MoveFileEx(ToWCharT(&path.value()), NULL,
MOVEFILE_DELAY_UNTIL_REBOOT | MOVEFILE_REPLACE_EXISTING) !=
FALSE;
}
bool ReplaceFile(const FilePath& from_path,
const FilePath& to_path,
File::Error* error) {
// Try a simple move first. It will only succeed when |to_path| doesn't
// already exist.
if (::MoveFile(ToWCharT(&from_path.value()), ToWCharT(&to_path.value())))
return true;
File::Error move_error = File::OSErrorToFileError(GetLastError());
// Try the full-blown replace if the move fails, as ReplaceFile will only
// succeed when |to_path| does exist. When writing to a network share, we may
// not be able to change the ACLs. Ignore ACL errors then
// (REPLACEFILE_IGNORE_MERGE_ERRORS).
if (::ReplaceFile(ToWCharT(&to_path.value()), ToWCharT(&from_path.value()),
NULL, REPLACEFILE_IGNORE_MERGE_ERRORS, NULL, NULL)) {
return true;
}
// In the case of FILE_ERROR_NOT_FOUND from ReplaceFile, it is likely that
// |to_path| does not exist. In this case, the more relevant error comes
// from the call to MoveFile.
if (error) {
File::Error replace_error = File::OSErrorToFileError(GetLastError());
*error = replace_error == File::FILE_ERROR_NOT_FOUND ? move_error
: replace_error;
}
return false;
}
bool PathExists(const FilePath& path) {
return (GetFileAttributes(ToWCharT(&path.value())) !=
INVALID_FILE_ATTRIBUTES);
}
bool PathIsWritable(const FilePath& path) {
HANDLE dir =
CreateFile(ToWCharT(&path.value()), FILE_ADD_FILE, kFileShareAll, NULL,
OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS, NULL);
if (dir == INVALID_HANDLE_VALUE)
return false;
CloseHandle(dir);
return true;
}
bool DirectoryExists(const FilePath& path) {
DWORD fileattr = GetFileAttributes(ToWCharT(&path.value()));
if (fileattr != INVALID_FILE_ATTRIBUTES)
return (fileattr & FILE_ATTRIBUTE_DIRECTORY) != 0;
return false;
}
bool GetTempDir(FilePath* path) {
char16_t temp_path[MAX_PATH + 1];
DWORD path_len = ::GetTempPath(MAX_PATH, ToWCharT(temp_path));
if (path_len >= MAX_PATH || path_len <= 0)
return false;
// TODO(evanm): the old behavior of this function was to always strip the
// trailing slash. We duplicate this here, but it shouldn't be necessary
// when everyone is using the appropriate FilePath APIs.
*path = FilePath(temp_path).StripTrailingSeparators();
return true;
}
File CreateAndOpenTemporaryFileInDir(const FilePath& dir, FilePath* temp_file) {
constexpr uint32_t kFlags =
File::FLAG_CREATE | File::FLAG_READ | File::FLAG_WRITE;
// Use GUID instead of ::GetTempFileName() to generate unique file names.
// "Due to the algorithm used to generate file names, GetTempFileName can
// perform poorly when creating a large number of files with the same prefix.
// In such cases, it is recommended that you construct unique file names based
// on GUIDs."
// https://msdn.microsoft.com/library/windows/desktop/aa364991.aspx
FilePath temp_name;
File file;
// Although it is nearly impossible to get a duplicate name with GUID, we
// still use a loop here in case it happens.
for (int i = 0; i < 100; ++i) {
temp_name = dir.Append(FormatTemporaryFileName(UTF8ToWide(GenerateGUID())));
file.Initialize(temp_name, kFlags);
if (file.IsValid())
break;
}
if (!file.IsValid()) {
DPLOG(WARNING) << "Failed to get temporary file name in " << dir.value();
return file;
}
wchar_t long_temp_name[MAX_PATH + 1];
const DWORD long_name_len =
GetLongPathName(temp_name.value().c_str(), long_temp_name, MAX_PATH);
if (long_name_len != 0 && long_name_len <= MAX_PATH) {
*temp_file =
FilePath(FilePath::StringPieceType(long_temp_name, long_name_len));
} else {
// GetLongPathName() failed, but we still have a temporary file.
*temp_file = std::move(temp_name);
}
return file;
}
bool CreateTemporaryDirInDir(const FilePath& base_dir,
const FilePath::StringType& prefix,
FilePath* new_dir) {
FilePath path_to_create;
for (int count = 0; count < 50; ++count) {
// Try create a new temporary directory with random generated name. If
// the one exists, keep trying another path name until we reach some limit.
std::u16string new_dir_name;
new_dir_name.assign(prefix);
new_dir_name.append(IntToString16(::GetCurrentProcessId()));
new_dir_name.push_back('_');
new_dir_name.append(UTF8ToUTF16(GenerateGUID()));
path_to_create = base_dir.Append(new_dir_name);
if (::CreateDirectory(ToWCharT(&path_to_create.value()), NULL)) {
*new_dir = path_to_create;
return true;
}
}
return false;
}
bool CreateNewTempDirectory(const FilePath::StringType& prefix,
FilePath* new_temp_path) {
FilePath system_temp_dir;
if (!GetTempDir(&system_temp_dir))
return false;
return CreateTemporaryDirInDir(system_temp_dir, prefix, new_temp_path);
}
bool CreateDirectoryAndGetError(const FilePath& full_path, File::Error* error) {
// If the path exists, we've succeeded if it's a directory, failed otherwise.
DWORD fileattr = ::GetFileAttributes(ToWCharT(&full_path.value()));
if (fileattr != INVALID_FILE_ATTRIBUTES) {
if ((fileattr & FILE_ATTRIBUTE_DIRECTORY) != 0) {
return true;
}
DLOG(WARNING) << "CreateDirectory(" << UTF16ToUTF8(full_path.value())
<< "), "
<< "conflicts with existing file.";
if (error) {
*error = File::FILE_ERROR_NOT_A_DIRECTORY;
}
return false;
}
// Invariant: Path does not exist as file or directory.
// Attempt to create the parent recursively. This will immediately return
// true if it already exists, otherwise will create all required parent
// directories starting with the highest-level missing parent.
FilePath parent_path(full_path.DirName());
if (parent_path.value() == full_path.value()) {
if (error) {
*error = File::FILE_ERROR_NOT_FOUND;
}
return false;
}
if (!CreateDirectoryAndGetError(parent_path, error)) {
DLOG(WARNING) << "Failed to create one of the parent directories.";
if (error) {
DCHECK(*error != File::FILE_OK);
}
return false;
}
if (!::CreateDirectory(ToWCharT(&full_path.value()), NULL)) {
DWORD error_code = ::GetLastError();
if (error_code == ERROR_ALREADY_EXISTS && DirectoryExists(full_path)) {
// This error code ERROR_ALREADY_EXISTS doesn't indicate whether we
// were racing with someone creating the same directory, or a file
// with the same path. If DirectoryExists() returns true, we lost the
// race to create the same directory.
return true;
} else {
if (error)
*error = File::OSErrorToFileError(error_code);
DLOG(WARNING) << "Failed to create directory "
<< UTF16ToUTF8(full_path.value()) << ", last error is "
<< error_code << ".";
return false;
}
} else {
return true;
}
}
bool NormalizeFilePath(const FilePath& path, FilePath* real_path) {
FilePath mapped_file;
if (!NormalizeToNativeFilePath(path, &mapped_file))
return false;
// NormalizeToNativeFilePath() will return a path that starts with
// "\Device\Harddisk...". Helper DevicePathToDriveLetterPath()
// will find a drive letter which maps to the path's device, so
// that we return a path starting with a drive letter.
return DevicePathToDriveLetterPath(mapped_file, real_path);
}
bool DevicePathToDriveLetterPath(const FilePath& nt_device_path,
FilePath* out_drive_letter_path) {
// Get the mapping of drive letters to device paths.
const int kDriveMappingSize = 1024;
char16_t drive_mapping[kDriveMappingSize] = {'\0'};
if (!::GetLogicalDriveStrings(kDriveMappingSize - 1,
ToWCharT(drive_mapping))) {
DLOG(ERROR) << "Failed to get drive mapping.";
return false;
}
// The drive mapping is a sequence of null terminated strings.
// The last string is empty.
char16_t* drive_map_ptr = drive_mapping;
char16_t device_path_as_string[MAX_PATH];
char16_t drive[] = u" :";
// For each string in the drive mapping, get the junction that links
// to it. If that junction is a prefix of |device_path|, then we
// know that |drive| is the real path prefix.
while (*drive_map_ptr) {
drive[0] = drive_map_ptr[0]; // Copy the drive letter.
if (QueryDosDevice(ToWCharT(drive), ToWCharT(device_path_as_string),
MAX_PATH)) {
FilePath device_path(device_path_as_string);
if (device_path == nt_device_path ||
device_path.IsParent(nt_device_path)) {
*out_drive_letter_path =
FilePath(drive + nt_device_path.value().substr(
wcslen(ToWCharT(device_path_as_string))));
return true;
}
}
// Move to the next drive letter string, which starts one
// increment after the '\0' that terminates the current string.
while (*drive_map_ptr++) {
}
}
// No drive matched. The path does not start with a device junction
// that is mounted as a drive letter. This means there is no drive
// letter path to the volume that holds |device_path|, so fail.
return false;
}
bool NormalizeToNativeFilePath(const FilePath& path, FilePath* nt_path) {
// In Vista, GetFinalPathNameByHandle() would give us the real path
// from a file handle. If we ever deprecate XP, consider changing the
// code below to a call to GetFinalPathNameByHandle(). The method this
// function uses is explained in the following msdn article:
// http://msdn.microsoft.com/en-us/library/aa366789(VS.85).aspx
win::ScopedHandle file_handle(
::CreateFile(ToWCharT(&path.value()), GENERIC_READ, kFileShareAll, NULL,
OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL));
if (!file_handle.IsValid())
return false;
// Create a file mapping object. Can't easily use MemoryMappedFile, because
// we only map the first byte, and need direct access to the handle. You can
// not map an empty file, this call fails in that case.
win::ScopedHandle file_map_handle(
::CreateFileMapping(file_handle.Get(), NULL, PAGE_READONLY, 0,
1, // Just one byte. No need to look at the data.
NULL));
if (!file_map_handle.IsValid())
return false;
// Use a view of the file to get the path to the file.
void* file_view =
MapViewOfFile(file_map_handle.Get(), FILE_MAP_READ, 0, 0, 1);
if (!file_view)
return false;
// The expansion of |path| into a full path may make it longer.
// GetMappedFileName() will fail if the result is longer than MAX_PATH.
// Pad a bit to be safe. If kMaxPathLength is ever changed to be less
// than MAX_PATH, it would be nessisary to test that GetMappedFileName()
// not return kMaxPathLength. This would mean that only part of the
// path fit in |mapped_file_path|.
const int kMaxPathLength = MAX_PATH + 10;
char16_t mapped_file_path[kMaxPathLength];
bool success = false;
HANDLE cp = GetCurrentProcess();
if (::GetMappedFileNameW(cp, file_view, ToWCharT(mapped_file_path),
kMaxPathLength)) {
*nt_path = FilePath(mapped_file_path);
success = true;
}
::UnmapViewOfFile(file_view);
return success;
}
// TODO(rkc): Work out if we want to handle NTFS junctions here or not, handle
// them if we do decide to.
bool IsLink(const FilePath& file_path) {
return false;
}
bool GetFileInfo(const FilePath& file_path, File::Info* results) {
WIN32_FILE_ATTRIBUTE_DATA attr;
if (!GetFileAttributesEx(ToWCharT(&file_path.value()), GetFileExInfoStandard,
&attr)) {
return false;
}
ULARGE_INTEGER size;
size.HighPart = attr.nFileSizeHigh;
size.LowPart = attr.nFileSizeLow;
results->size = size.QuadPart;
results->is_directory =
(attr.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) != 0;
results->last_modified = *reinterpret_cast<uint64_t*>(&attr.ftLastWriteTime);
results->last_accessed = *reinterpret_cast<uint64_t*>(&attr.ftLastAccessTime);
results->creation_time = *reinterpret_cast<uint64_t*>(&attr.ftCreationTime);
return true;
}
FILE* OpenFile(const FilePath& filename, const char* mode) {
// 'N' is unconditionally added below, so be sure there is not one already
// present before a comma in |mode|.
DCHECK(
strchr(mode, 'N') == nullptr ||
(strchr(mode, ',') != nullptr && strchr(mode, 'N') > strchr(mode, ',')));
std::u16string w_mode = ASCIIToUTF16(mode);
AppendModeCharacter(L'N', &w_mode);
return _wfsopen(ToWCharT(&filename.value()), ToWCharT(&w_mode), _SH_DENYNO);
}
FILE* FileToFILE(File file, const char* mode) {
if (!file.IsValid())
return NULL;
int fd =
_open_osfhandle(reinterpret_cast<intptr_t>(file.GetPlatformFile()), 0);
if (fd < 0)
return NULL;
file.TakePlatformFile();
FILE* stream = _fdopen(fd, mode);
if (!stream)
_close(fd);
return stream;
}
int ReadFile(const FilePath& filename, char* data, int max_size) {
win::ScopedHandle file(CreateFile(ToWCharT(&filename.value()), GENERIC_READ,
FILE_SHARE_READ | FILE_SHARE_WRITE, NULL,
OPEN_EXISTING, FILE_FLAG_SEQUENTIAL_SCAN,
NULL));
if (!file.IsValid())
return -1;
DWORD read;
if (::ReadFile(file.Get(), data, max_size, &read, NULL))
return read;
return -1;
}
int WriteFile(const FilePath& filename, const char* data, int size) {
win::ScopedHandle file(CreateFile(ToWCharT(&filename.value()), GENERIC_WRITE,
0, NULL, CREATE_ALWAYS,
FILE_ATTRIBUTE_NORMAL, NULL));
if (!file.IsValid()) {
DPLOG(WARNING) << "CreateFile failed for path "
<< UTF16ToUTF8(filename.value());
return -1;
}
DWORD written;
BOOL result = ::WriteFile(file.Get(), data, size, &written, NULL);
if (result && static_cast<int>(written) == size)
return written;
if (!result) {
// WriteFile failed.
DPLOG(WARNING) << "writing file " << UTF16ToUTF8(filename.value())
<< " failed";
} else {
// Didn't write all the bytes.
DLOG(WARNING) << "wrote" << written << " bytes to "
<< UTF16ToUTF8(filename.value()) << " expected " << size;
}
return -1;
}
bool AppendToFile(const FilePath& filename, const char* data, int size) {
win::ScopedHandle file(CreateFile(ToWCharT(&filename.value()),
FILE_APPEND_DATA, 0, NULL, OPEN_EXISTING, 0,
NULL));
if (!file.IsValid()) {
return false;
}
DWORD written;
BOOL result = ::WriteFile(file.Get(), data, size, &written, NULL);
if (result && static_cast<int>(written) == size)
return true;
return false;
}
bool GetCurrentDirectory(FilePath* dir) {
char16_t system_buffer[MAX_PATH];
system_buffer[0] = 0;
DWORD len = ::GetCurrentDirectory(MAX_PATH, ToWCharT(system_buffer));
if (len == 0 || len > MAX_PATH)
return false;
// TODO(evanm): the old behavior of this function was to always strip the
// trailing slash. We duplicate this here, but it shouldn't be necessary
// when everyone is using the appropriate FilePath APIs.
std::u16string dir_str(system_buffer);
*dir = FilePath(dir_str).StripTrailingSeparators();
return true;
}
bool SetCurrentDirectory(const FilePath& directory) {
return ::SetCurrentDirectory(ToWCharT(&directory.value())) != 0;
}
int GetMaximumPathComponentLength(const FilePath& path) {
char16_t volume_path[MAX_PATH];
if (!GetVolumePathNameW(ToWCharT(&path.NormalizePathSeparators().value()),
ToWCharT(volume_path), std::size(volume_path))) {
return -1;
}
DWORD max_length = 0;
if (!GetVolumeInformationW(ToWCharT(volume_path), NULL, 0, NULL, &max_length,
NULL, NULL, 0)) {
return -1;
}
// Length of |path| with path separator appended.
size_t prefix = path.StripTrailingSeparators().value().size() + 1;
// The whole path string must be shorter than MAX_PATH. That is, it must be
// prefix + component_length < MAX_PATH (or equivalently, <= MAX_PATH - 1).
int whole_path_limit = std::max(0, MAX_PATH - 1 - static_cast<int>(prefix));
return std::min(whole_path_limit, static_cast<int>(max_length));
}
bool SetNonBlocking(int fd) {
unsigned long nonblocking = 1;
if (ioctlsocket(fd, FIONBIO, &nonblocking) == 0)
return true;
return false;
}
} // namespace base