Refactor Android filesystem platform helpers (#6928)

* Use std::filesystem to implement Android platform helpers

* Add a note in the changelog

CHANGELOG.md

@@ -25,9 +25,7 @@ const realm = new Realm({
 * File format: generates Realms with format v24 (reads and upgrades file format v10).
 
 ### Internal
-<!-- * Either mention core version or upgrade -->
-<!-- * Using Realm Core vX.Y.Z -->
-<!-- * Upgraded Realm Core from vX.Y.Z to vA.B.C -->
+* Refactored Android filesystem platform helpers. ([#5296](https://github.com/realm/realm-js/issues/5296) and [realm/realm-js-private#507](https://github.com/realm/realm-js-private/issues/507))
 
 ## 20.0.0 (2024-09-09)
 

packages/realm/binding/android/src/main/cpp/platform.cpp

@@ -21,6 +21,8 @@
 #include <stdarg.h>
 #include <unistd.h>
 #include <cstdio>
+#include <vector>
+#include <filesystem>
 #include <android/asset_manager.h>
 #include <android/log.h>
 
@@ -29,6 +31,8 @@
 #define REALM_FILE_FILTER ".realm"
 #define REALM_FILE_FILTER_LEN 6
 
+namespace fs = std::filesystem;
+
 static inline bool is_realm_file(const char* str)
 {
     size_t lenstr = strlen(str);
@@ -57,7 +61,11 @@ std::string JsPlatformHelpers::default_realm_file_directory()
     return s_default_realm_directory;
 }
 
-void JsPlatformHelpers::ensure_directory_exists_for_file(const std::string& file) {}
+void JsPlatformHelpers::ensure_directory_exists_for_file(const std::string& file)
+{
+    auto parent_path = fs::path(file).parent_path();
+    fs::create_directories(parent_path);
+}
 
 void JsPlatformHelpers::copy_bundled_realm_files()
 {
@@ -88,23 +96,31 @@ void JsPlatformHelpers::copy_bundled_realm_files()
 
 void JsPlatformHelpers::remove_realm_files_from_directory(const std::string& directory)
 {
-    std::string cmd = "rm " + s_default_realm_directory + "/*.realm " + s_default_realm_directory + "/*.realm.lock";
-    system(cmd.c_str());
+    std::vector<fs::path> files_to_delete;
+    // Collect the files to delete (as deleting while iterating gives undefined behaviour)
+    for (const auto& entry : fs::directory_iterator(directory)) {
+        if (entry.is_regular_file()) {
+            const auto& path = entry.path();
+            if (path.extension() == ".realm" || path.extension() == ".realm.lock") {
+                files_to_delete.push_back(path);
+            }
+        }
+    }
+
+    // Delete the files
+    for (const auto& path : files_to_delete) {
+        fs::remove(path);
+    }
 }
 
 void JsPlatformHelpers::remove_directory(const std::string& path)
 {
-    std::string cmd_clear_dir = "rm " + path + "/*";
-    system(cmd_clear_dir.c_str());
-
-    std::string cmd_rmdir = "rmdir " + path;
-    system(cmd_rmdir.c_str());
+    fs::remove_all(path);
 }
 
 void JsPlatformHelpers::remove_file(const std::string& path)
 {
-    std::string cmd = "rm " + path;
-    system(cmd.c_str());
+    fs::remove(path);
 }
 
 void JsPlatformHelpers::print(const char* fmt, ...)