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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include <optional>
#include <rpc.h>
#include <string>
#include <windows.h>
static const size_t BUFFER_LEN = MAX_PATH + 1;
/**
* Create a unique tempfile name in a temp directory appropriate
* for this user.
* @return The temp filename, or std::nullopt on failure
*/
std::optional<std::wstring> get_tempfile_name() {
wchar_t pathBuffer[BUFFER_LEN];
wchar_t filenameBuffer[BUFFER_LEN];
UUID uuid;
DWORD pathLen = GetTempPath2W(BUFFER_LEN, pathBuffer);
if (pathLen > BUFFER_LEN || pathLen == 0) {
// Error getting path
return std::nullopt;
}
// Use a UUID as a convenient source of random bits
RPC_STATUS uuidStatus = UuidCreate(&uuid);
if (uuidStatus != RPC_S_OK && uuidStatus != RPC_S_UUID_LOCAL_ONLY) {
// Error creating a unique UUID for the filename
return std::nullopt;
}
// Since we're only using the UUID data structure as a source of random bits,
// rather than as something that we need to serialize and deserialize as a
// UUID, it's best not to leak the internal implementation details out of the
// abstraction of the filename.
// With that in mind, the following code converts the UUID data structure into
// a sequence of hexadecimal digits.
ULONG data4msb =
*((ULONG*)uuid.Data4); // First 4 bytes of the 8-byte Data4 char array
ULONG data4lsb =
*((ULONG*)(uuid.Data4 +
4)); // Second 4 bytes of the 8-byte Data4 char array
if (swprintf_s(filenameBuffer, BUFFER_LEN, L"%sfx%X%X%X%X%X.exe", pathBuffer,
uuid.Data1, uuid.Data2, uuid.Data3, data4msb, data4lsb) < 0) {
return std::nullopt;
}
return std::wstring(filenameBuffer);
}
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