| // Copyright 2016 The Bazel 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 <stdint.h> // uint8_t |
| #include <windows.h> |
| |
| #include <memory> |
| #include <sstream> |
| #include <string> |
| |
| #include "src/main/native/windows/file.h" |
| #include "src/main/native/windows/util.h" |
| |
| namespace bazel { |
| namespace windows { |
| |
| using std::unique_ptr; |
| using std::wstring; |
| |
| wstring AddUncPrefixMaybe(const wstring& path) { |
| return path.empty() || IsDevNull(path.c_str()) || HasUncPrefix(path.c_str()) |
| ? path |
| : (wstring(L"\\\\?\\") + path); |
| } |
| |
| wstring RemoveUncPrefixMaybe(const wstring& path) { |
| return bazel::windows::HasUncPrefix(path.c_str()) ? path.substr(4) : path; |
| } |
| |
| bool HasDriveSpecifierPrefix(const wstring& p) { |
| if (HasUncPrefix(p.c_str())) { |
| return p.size() >= 7 && iswalpha(p[4]) && p[5] == ':' && p[6] == '\\'; |
| } else { |
| return p.size() >= 3 && iswalpha(p[0]) && p[1] == ':' && p[2] == '\\'; |
| } |
| } |
| |
| bool IsAbsoluteNormalizedWindowsPath(const wstring& p) { |
| if (p.empty()) { |
| return false; |
| } |
| if (IsDevNull(p.c_str())) { |
| return true; |
| } |
| if (p.find_first_of('/') != wstring::npos) { |
| return false; |
| } |
| |
| return HasDriveSpecifierPrefix(p) && p.find(L".\\") != 0 && |
| p.find(L"\\.\\") == wstring::npos && p.find(L"\\.") != p.size() - 2 && |
| p.find(L"..\\") != 0 && p.find(L"\\..\\") == wstring::npos && |
| p.find(L"\\..") != p.size() - 3; |
| } |
| |
| static wstring uint32asHexString(uint32_t value) { |
| WCHAR attr_str[8]; |
| for (int i = 0; i < 8; ++i) { |
| attr_str[7 - i] = L"0123456789abcdef"[value & 0xF]; |
| value >>= 4; |
| } |
| return wstring(attr_str, 8); |
| } |
| |
| int IsJunctionOrDirectorySymlink(const WCHAR* path, wstring* error) { |
| if (!IsAbsoluteNormalizedWindowsPath(path)) { |
| if (error) { |
| *error = MakeErrorMessage(WSTR(__FILE__), __LINE__, |
| L"IsJunctionOrDirectorySymlink", path, |
| L"expected an absolute Windows path"); |
| } |
| return IS_JUNCTION_ERROR; |
| } |
| |
| DWORD attrs = ::GetFileAttributesW(path); |
| if (attrs == INVALID_FILE_ATTRIBUTES) { |
| DWORD err = GetLastError(); |
| if (error) { |
| *error = MakeErrorMessage(WSTR(__FILE__), __LINE__, |
| L"IsJunctionOrDirectorySymlink", path, err); |
| } |
| return IS_JUNCTION_ERROR; |
| } else { |
| if ((attrs & FILE_ATTRIBUTE_DIRECTORY) && |
| (attrs & FILE_ATTRIBUTE_REPARSE_POINT)) { |
| return IS_JUNCTION_YES; |
| } else { |
| return IS_JUNCTION_NO; |
| } |
| } |
| } |
| |
| wstring GetLongPath(const WCHAR* path, unique_ptr<WCHAR[]>* result) { |
| if (!IsAbsoluteNormalizedWindowsPath(path)) { |
| return MakeErrorMessage(WSTR(__FILE__), __LINE__, L"GetLongPath", path, |
| L"expected an absolute Windows path"); |
| } |
| |
| std::wstring wpath(AddUncPrefixMaybe(path)); |
| DWORD size = ::GetLongPathNameW(wpath.c_str(), NULL, 0); |
| if (size == 0) { |
| DWORD err_code = GetLastError(); |
| return MakeErrorMessage(WSTR(__FILE__), __LINE__, L"GetLongPathNameW", path, |
| err_code); |
| } |
| result->reset(new WCHAR[size]); |
| ::GetLongPathNameW(wpath.c_str(), result->get(), size); |
| return L""; |
| } |
| |
| #pragma pack(push, 4) |
| typedef struct _JunctionDescription { |
| typedef struct _Header { |
| DWORD ReparseTag; |
| WORD ReparseDataLength; |
| WORD Reserved; |
| } Header; |
| |
| typedef struct _WriteDesc { |
| WORD SubstituteNameOffset; |
| WORD SubstituteNameLength; |
| WORD PrintNameOffset; |
| WORD PrintNameLength; |
| } Descriptor; |
| |
| Header header; |
| Descriptor descriptor; |
| WCHAR PathBuffer[ANYSIZE_ARRAY]; |
| } JunctionDescription; |
| #pragma pack(pop) |
| |
| int CreateJunction(const wstring& junction_name, const wstring& junction_target, |
| wstring* error) { |
| if (!IsAbsoluteNormalizedWindowsPath(junction_name)) { |
| if (error) { |
| *error = MakeErrorMessage( |
| WSTR(__FILE__), __LINE__, L"CreateJunction", junction_name, |
| L"expected an absolute Windows path for junction_name"); |
| } |
| CreateJunctionResult::kError; |
| } |
| if (!IsAbsoluteNormalizedWindowsPath(junction_target)) { |
| if (error) { |
| *error = MakeErrorMessage( |
| WSTR(__FILE__), __LINE__, L"CreateJunction", junction_target, |
| L"expected an absolute Windows path for junction_target"); |
| } |
| CreateJunctionResult::kError; |
| } |
| |
| const wstring target = HasUncPrefix(junction_target.c_str()) |
| ? junction_target.substr(4) |
| : junction_target; |
| // The entire JunctionDescription cannot be larger than |
| // MAXIMUM_REPARSE_DATA_BUFFER_SIZE bytes. |
| // |
| // The structure's layout is: |
| // [JunctionDescription::Header] |
| // [JunctionDescription::Descriptor] |
| // ---- start of JunctionDescription::PathBuffer ---- |
| // [4 WCHARs] : "\??\" prefix |
| // [target.size() WCHARs] : junction target name |
| // [1 WCHAR] : null-terminator |
| // [target.size() WCHARs] : junction target displayed name |
| // [1 WCHAR] : null-terminator |
| // The sum of these must not exceed MAXIMUM_REPARSE_DATA_BUFFER_SIZE. |
| // We can rearrange this to get the limit for target.size(). |
| static const size_t kMaxJunctionTargetLen = |
| ((MAXIMUM_REPARSE_DATA_BUFFER_SIZE - sizeof(JunctionDescription::Header) - |
| sizeof(JunctionDescription::Descriptor) - |
| /* one "\??\" prefix */ sizeof(WCHAR) * 4 - |
| /* two null terminators */ sizeof(WCHAR) * 2) / |
| /* two copies of the string are stored */ 2) / |
| sizeof(WCHAR); |
| if (target.size() > kMaxJunctionTargetLen) { |
| if (error) { |
| *error = MakeErrorMessage(WSTR(__FILE__), __LINE__, L"CreateJunction", |
| target, L"target path is too long"); |
| } |
| return CreateJunctionResult::kTargetNameTooLong; |
| } |
| const wstring name = HasUncPrefix(junction_name.c_str()) |
| ? junction_name |
| : (wstring(L"\\\\?\\") + junction_name); |
| |
| // Junctions are directories, so create a directory. |
| // If CreateDirectoryW succeeds, we'll try to set the junction's target. |
| // If CreateDirectoryW fails, we don't care about the exact reason -- could be |
| // that the directory already exists, or we have no access to create a |
| // directory, or the path was invalid to begin with. Either way set `create` |
| // to false, meaning we'll just attempt to open the path for metadata-reading |
| // and check if it's a junction pointing to the desired target. |
| bool create = CreateDirectoryW(name.c_str(), NULL) != 0; |
| |
| AutoHandle handle; |
| if (create) { |
| handle = CreateFileW( |
| name.c_str(), GENERIC_READ | GENERIC_WRITE, FILE_SHARE_READ, NULL, |
| OPEN_EXISTING, |
| FILE_FLAG_OPEN_REPARSE_POINT | FILE_FLAG_BACKUP_SEMANTICS, NULL); |
| } |
| |
| if (!handle.IsValid()) { |
| // We can't open the directory for writing: either we didn't even try to |
| // (`create` was false), or the path disappeared, or it turned into a file, |
| // or another process holds it open without write-sharing. |
| // Either way, don't try to create the junction, just try opening it without |
| // any read or write access (we can still read its metadata) and maximum |
| // sharing, and check its target. |
| create = false; |
| handle = CreateFileW( |
| name.c_str(), 0, FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE, |
| NULL, OPEN_EXISTING, |
| FILE_FLAG_OPEN_REPARSE_POINT | FILE_FLAG_BACKUP_SEMANTICS, NULL); |
| if (!handle.IsValid()) { |
| // We can't open the directory at all: either it disappeared, or it turned |
| // into a file, or the path is invalid, or another process holds it open |
| // without any sharing. Give up. |
| DWORD err = GetLastError(); |
| if (err == ERROR_SHARING_VIOLATION) { |
| // The junction is held open by another process. |
| return CreateJunctionResult::kAccessDenied; |
| } else if (err == ERROR_FILE_NOT_FOUND || err == ERROR_PATH_NOT_FOUND) { |
| // Meanwhile the directory disappeared or one of its parent directories |
| // disappeared. |
| return CreateJunctionResult::kDisappeared; |
| } |
| |
| // The path seems to exist yet we cannot open it for metadata-reading. |
| // Report as much information as we have, then give up. |
| if (error) { |
| *error = MakeErrorMessage(WSTR(__FILE__), __LINE__, L"CreateFileW", |
| name, err); |
| } |
| return CreateJunctionResult::kError; |
| } |
| } |
| |
| // We have an open handle to the file! It may still be other than a junction, |
| // so check its attributes. |
| BY_HANDLE_FILE_INFORMATION info; |
| if (!GetFileInformationByHandle(handle, &info)) { |
| DWORD err = GetLastError(); |
| // Some unknown error occurred. |
| if (error) { |
| *error = MakeErrorMessage(WSTR(__FILE__), __LINE__, |
| L"GetFileInformationByHandle", name, err); |
| } |
| return CreateJunctionResult::kError; |
| } |
| |
| if (info.dwFileAttributes == INVALID_FILE_ATTRIBUTES) { |
| DWORD err = GetLastError(); |
| // Some unknown error occurred. |
| if (error) { |
| *error = MakeErrorMessage(WSTR(__FILE__), __LINE__, |
| L"GetFileInformationByHandle", name, err); |
| } |
| return CreateJunctionResult::kError; |
| } |
| |
| if (info.dwFileAttributes & FILE_ATTRIBUTE_REPARSE_POINT) { |
| // The path already exists and it's a junction. Do not overwrite, just check |
| // its target. |
| create = false; |
| } |
| |
| if (create) { |
| if (!(info.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY)) { |
| // Even though we managed to create the directory and it didn't exist |
| // before, another process changed it in the meantime so it's no longer a |
| // directory. |
| create = false; |
| if (!(info.dwFileAttributes & FILE_ATTRIBUTE_REPARSE_POINT)) { |
| // The path is no longer a directory, and it's not a junction either. |
| // Though this is a case for kAlreadyExistsButNotJunction, let's instead |
| // print the attributes and return kError, to give more information to |
| // the user. |
| if (error) { |
| *error = MakeErrorMessage( |
| WSTR(__FILE__), __LINE__, L"GetFileInformationByHandle", name, |
| wstring(L"attrs=0x") + uint32asHexString(info.dwFileAttributes)); |
| } |
| return CreateJunctionResult::kError; |
| } |
| } |
| } |
| |
| if (!create) { |
| // The path already exists. Check if it's a junction. |
| if (!(info.dwFileAttributes & FILE_ATTRIBUTE_REPARSE_POINT)) { |
| return CreateJunctionResult::kAlreadyExistsButNotJunction; |
| } |
| } |
| |
| uint8_t reparse_buffer_bytes[MAXIMUM_REPARSE_DATA_BUFFER_SIZE]; |
| JunctionDescription* reparse_buffer = |
| reinterpret_cast<JunctionDescription*>(reparse_buffer_bytes); |
| if (create) { |
| // The junction doesn't exist yet, and we have an open handle to the |
| // candidate directory with write access and no sharing. Proceed to turn the |
| // directory into a junction. |
| |
| memset(reparse_buffer_bytes, 0, MAXIMUM_REPARSE_DATA_BUFFER_SIZE); |
| |
| // "\??\" is meaningful to the kernel, it's a synomym for the "\DosDevices\" |
| // object path. (NOT to be confused with "\\?\" which is meaningful for the |
| // Win32 API.) We need to use this prefix to tell the kernel where the |
| // reparse point is pointing to. |
| memcpy(reparse_buffer->PathBuffer, L"\\??\\", 4 * sizeof(WCHAR)); |
| memcpy(reparse_buffer->PathBuffer + 4, target.c_str(), |
| target.size() * sizeof(WCHAR)); |
| |
| // In addition to their target, junctions also have another string which is |
| // a user-visible name of where the junction points, as listed by "dir". |
| // This can be any string and won't affect the usability of the junction. |
| // MKLINK uses the target path without the "\??\" prefix as the display |
| // name, so let's do that here too. This is also in line with how UNIX |
| // behaves. Using a dummy or fake display name would be misleading, it would |
| // make the output of `dir` look like: |
| // 2017-01-18 01:37 PM <JUNCTION> juncname [dummy string] |
| memcpy(reparse_buffer->PathBuffer + 4 + target.size() + 1, target.c_str(), |
| target.size() * sizeof(WCHAR)); |
| |
| reparse_buffer->descriptor.SubstituteNameOffset = 0; |
| reparse_buffer->descriptor.SubstituteNameLength = |
| (4 + target.size()) * sizeof(WCHAR); |
| reparse_buffer->descriptor.PrintNameOffset = |
| reparse_buffer->descriptor.SubstituteNameLength + |
| /* null-terminator */ sizeof(WCHAR); |
| reparse_buffer->descriptor.PrintNameLength = target.size() * sizeof(WCHAR); |
| |
| reparse_buffer->header.ReparseTag = IO_REPARSE_TAG_MOUNT_POINT; |
| reparse_buffer->header.ReparseDataLength = |
| sizeof(JunctionDescription::Descriptor) + |
| reparse_buffer->descriptor.SubstituteNameLength + |
| reparse_buffer->descriptor.PrintNameLength + |
| /* 2 null-terminators */ (2 * sizeof(WCHAR)); |
| reparse_buffer->header.Reserved = 0; |
| |
| DWORD bytes_returned; |
| if (!::DeviceIoControl(handle, FSCTL_SET_REPARSE_POINT, reparse_buffer, |
| reparse_buffer->header.ReparseDataLength + |
| sizeof(JunctionDescription::Header), |
| NULL, 0, &bytes_returned, NULL)) { |
| DWORD err = GetLastError(); |
| if (err == ERROR_DIR_NOT_EMPTY) { |
| return CreateJunctionResult::kAlreadyExistsButNotJunction; |
| } |
| // Some unknown error occurred. |
| if (error) { |
| *error = MakeErrorMessage(WSTR(__FILE__), __LINE__, L"DeviceIoControl", |
| name, err); |
| } |
| return CreateJunctionResult::kError; |
| } |
| } else { |
| // The junction already exists. Check if it points to the right target. |
| |
| DWORD bytes_returned; |
| if (!::DeviceIoControl(handle, FSCTL_GET_REPARSE_POINT, NULL, 0, |
| reparse_buffer, MAXIMUM_REPARSE_DATA_BUFFER_SIZE, |
| &bytes_returned, NULL)) { |
| DWORD err = GetLastError(); |
| // Some unknown error occurred. |
| if (error) { |
| *error = MakeErrorMessage(WSTR(__FILE__), __LINE__, L"DeviceIoControl", |
| name, err); |
| } |
| return CreateJunctionResult::kError; |
| } |
| |
| WCHAR* actual_target = reparse_buffer->PathBuffer + |
| reparse_buffer->descriptor.SubstituteNameOffset + |
| /* "\??\" prefix */ 4; |
| if (reparse_buffer->descriptor.SubstituteNameLength != |
| (/* "\??\" prefix */ 4 + target.size()) * sizeof(WCHAR) || |
| _wcsnicmp(actual_target, target.c_str(), target.size()) != 0) { |
| return CreateJunctionResult::kAlreadyExistsWithDifferentTarget; |
| } |
| } |
| |
| return CreateJunctionResult::kSuccess; |
| } |
| |
| int DeletePath(const wstring& path, wstring* error) { |
| if (!IsAbsoluteNormalizedWindowsPath(path)) { |
| if (error) { |
| *error = MakeErrorMessage(WSTR(__FILE__), __LINE__, L"DeletePath", path, |
| L"expected an absolute Windows path"); |
| } |
| return DeletePathResult::kError; |
| } |
| |
| const std::wstring winpath(AddUncPrefixMaybe(path)); |
| const wchar_t* wpath = winpath.c_str(); |
| |
| if (!DeleteFileW(wpath)) { |
| DWORD err = GetLastError(); |
| if (err == ERROR_SHARING_VIOLATION) { |
| // The file or directory is in use by some process or we have no |
| // permission to delete it. |
| return DeletePathResult::kAccessDenied; |
| } else if (err == ERROR_FILE_NOT_FOUND || err == ERROR_PATH_NOT_FOUND) { |
| // The file or directory does not exist, or a parent directory does not |
| // exist, or a parent directory is actually a file. |
| return DeletePathResult::kDoesNotExist; |
| } else if (err != ERROR_ACCESS_DENIED) { |
| // Some unknown error occurred. |
| if (error) { |
| *error = MakeErrorMessage(WSTR(__FILE__), __LINE__, L"DeleteFileW", |
| path, err); |
| } |
| return DeletePathResult::kError; |
| } |
| |
| // DeleteFileW failed with access denied, because the file is read-only or |
| // it is a directory. |
| DWORD attr = GetFileAttributesW(wpath); |
| if (attr == INVALID_FILE_ATTRIBUTES) { |
| err = GetLastError(); |
| if (err == ERROR_FILE_NOT_FOUND || err == ERROR_PATH_NOT_FOUND) { |
| // The file disappeared, or one of its parent directories disappeared, |
| // or one of its parent directories is no longer a directory. |
| return DeletePathResult::kDoesNotExist; |
| } else { |
| // Some unknown error occurred. |
| if (error) { |
| *error = MakeErrorMessage(WSTR(__FILE__), __LINE__, |
| L"GetFileAttributesW", path, err); |
| } |
| return DeletePathResult::kError; |
| } |
| } |
| |
| // DeleteFileW failed with access denied, but the path exists. |
| if (attr & FILE_ATTRIBUTE_DIRECTORY) { |
| // It's a directory or a junction. |
| if (!RemoveDirectoryW(wpath)) { |
| // Failed to delete the directory. |
| err = GetLastError(); |
| if (err == ERROR_SHARING_VIOLATION || err == ERROR_ACCESS_DENIED) { |
| // The junction or directory is in use by another process, or we have |
| // no permission to delete it. |
| return DeletePathResult::kAccessDenied; |
| } else if (err == ERROR_DIR_NOT_EMPTY) { |
| // The directory is not empty. |
| return DeletePathResult::kDirectoryNotEmpty; |
| } else if (err == ERROR_FILE_NOT_FOUND || err == ERROR_PATH_NOT_FOUND) { |
| // The directory or one of its directories disappeared or is no longer |
| // a directory. |
| return DeletePathResult::kDoesNotExist; |
| } |
| |
| // Some unknown error occurred. |
| if (error) { |
| *error = MakeErrorMessage(WSTR(__FILE__), __LINE__, |
| L"RemoveDirectoryW", path, err); |
| } |
| return DeletePathResult::kError; |
| } |
| } else if (attr & FILE_ATTRIBUTE_READONLY) { |
| // It's a file and it's probably read-only. |
| // Make it writable then try deleting it again. |
| attr &= ~FILE_ATTRIBUTE_READONLY; |
| if (!SetFileAttributesW(wpath, attr)) { |
| err = GetLastError(); |
| if (err == ERROR_FILE_NOT_FOUND || err == ERROR_PATH_NOT_FOUND) { |
| // The file disappeared, or one of its parent directories disappeared, |
| // or one of its parent directories is no longer a directory. |
| return DeletePathResult::kDoesNotExist; |
| } |
| // Some unknown error occurred. |
| if (error) { |
| *error = MakeErrorMessage(WSTR(__FILE__), __LINE__, |
| L"SetFileAttributesW", path, err); |
| } |
| return DeletePathResult::kError; |
| } |
| |
| if (!DeleteFileW(wpath)) { |
| // Failed to delete the file again. |
| err = GetLastError(); |
| if (err == ERROR_FILE_NOT_FOUND || err == ERROR_PATH_NOT_FOUND) { |
| // The file disappeared, or one of its parent directories disappeared, |
| // or one of its parent directories is no longer a directory. |
| return DeletePathResult::kDoesNotExist; |
| } |
| |
| // Some unknown error occurred. |
| if (error) { |
| *error = MakeErrorMessage(WSTR(__FILE__), __LINE__, L"DeleteFileW", |
| path, err); |
| } |
| return DeletePathResult::kError; |
| } |
| } else { |
| if (error) { |
| *error = MakeErrorMessage( |
| WSTR(__FILE__), __LINE__, |
| (std::wstring(L"Unknown error, winpath=[") + winpath + L"]") |
| .c_str(), |
| path, err); |
| } |
| return DeletePathResult::kError; |
| } |
| } |
| return DeletePathResult::kSuccess; |
| } |
| |
| } // namespace windows |
| } // namespace bazel |
