Fixed the file implementations, they weren't using a mode, and the base path was always set to /tmp/.

We now get the systems idea of where the users download folder is and use that as the base path when receiving a file.

PiperOrigin-RevId: 406406731

cpp/platform/impl/windows/test_utils.cc

@@ -14,6 +14,8 @@
 
 #include "platform/impl/windows/test_utils.h"
 
+#include <shlobj.h>
+
 #include "absl/strings/str_cat.h"
 
 namespace test_utils {
@@ -29,8 +31,27 @@ std::wstring StringToWideString(const std::string& s) {
 }
 
 std::string GetPayloadPath(location::nearby::PayloadId payload_id) {
-  auto returnString = absl::StrCat("/tmp/", payload_id);
+  PWSTR basePath;
 
-  return returnString;
+  // Retrieves the full path of a known folder identified by the folder's
+  // KNOWNFOLDERID.
+  // https://docs.microsoft.com/en-us/windows/win32/api/shlobj_core/nf-shlobj_core-shgetknownfolderpath
+  SHGetKnownFolderPath(
+      FOLDERID_Downloads,  //  rfid: A reference to the KNOWNFOLDERID that
+                           //  identifies the folder.
+      0,           // dwFlags: Flags that specify special retrieval options.
+      NULL,        // hToken: An access token that represents a particular user.
+      &basePath);  // ppszPath: When this method returns, contains the address
+                   // of a pointer to a null-terminated Unicode string that
+                   // specifies the path of the known folder. The calling
+                   // process is responsible for freeing this resource once it
+                   // is no longer needed by calling CoTaskMemFree, whether
+                   // SHGetKnownFolderPath succeeds or not.
+
+  char* fullpathUTF8 = new char((wcslen(basePath) + 1) * sizeof(char));
+  wcstombs(fullpathUTF8, basePath, (wcslen(basePath) + 1) * sizeof(char));
+  std::string fullPath = std::string(fullpathUTF8);
+  auto retval = absl::StrCat(fullPath += "/", payload_id);
+  return retval;
 }
 }  // namespace test_utils