partition_filesystem: Ensure all class members of PartitionFilesystem are initialized

Previously is_hfs and pfs_header members wouldn't be initialized in the
constructor, as they were stored in locals instead. This would result in
things like GetName() and PrintDebugInfo() behaving incorrectly.

While we're at it, initialize the members to deterministic values as
well, in case loading ever fails.

src/core/file_sys/partition_filesystem.cpp

@@ -11,6 +11,11 @@
 
 namespace FileSys {
 
+bool PartitionFilesystem::Header::HasValidMagicValue() const {
+    return magic == Common::MakeMagic('H', 'F', 'S', '0') ||
+           magic == Common::MakeMagic('P', 'F', 'S', '0');
+}
+
 PartitionFilesystem::PartitionFilesystem(std::shared_ptr<VfsFile> file) {
     // At least be as large as the header
     if (file->GetSize() < sizeof(Header)) {
@@ -20,19 +25,17 @@ PartitionFilesystem::PartitionFilesystem(std::shared_ptr<VfsFile> file) {
 
     // For cartridges, HFSs can get very large, so we need to calculate the size up to
     // the actual content itself instead of just blindly reading in the entire file.
-    Header pfs_header;
     if (sizeof(Header) != file->ReadObject(&pfs_header)) {
         status = Loader::ResultStatus::Error;
         return;
     }
 
-    if (pfs_header.magic != Common::MakeMagic('H', 'F', 'S', '0') &&
-        pfs_header.magic != Common::MakeMagic('P', 'F', 'S', '0')) {
+    if (!pfs_header.HasValidMagicValue()) {
         status = Loader::ResultStatus::ErrorInvalidFormat;
         return;
     }
 
-    bool is_hfs = pfs_header.magic == Common::MakeMagic('H', 'F', 'S', '0');
+    is_hfs = pfs_header.magic == Common::MakeMagic('H', 'F', 'S', '0');
 
     size_t entry_size = is_hfs ? sizeof(HFSEntry) : sizeof(PFSEntry);
     size_t metadata_size =
@@ -40,27 +43,13 @@ PartitionFilesystem::PartitionFilesystem(std::shared_ptr<VfsFile> file) {
 
     // Actually read in now...
     std::vector<u8> file_data = file->ReadBytes(metadata_size);
+    const size_t total_size = file_data.size();
 
-    if (file_data.size() != metadata_size) {
-        status = Loader::ResultStatus::Error;
-        return;
-    }
-
-    size_t total_size = file_data.size();
-    if (total_size < sizeof(Header)) {
+    if (total_size != metadata_size) {
         status = Loader::ResultStatus::Error;
         return;
     }
 
-    memcpy(&pfs_header, file_data.data(), sizeof(Header));
-    if (pfs_header.magic != Common::MakeMagic('H', 'F', 'S', '0') &&
-        pfs_header.magic != Common::MakeMagic('P', 'F', 'S', '0')) {
-        status = Loader::ResultStatus::ErrorInvalidFormat;
-        return;
-    }
-
-    is_hfs = pfs_header.magic == Common::MakeMagic('H', 'F', 'S', '0');
-
     size_t entries_offset = sizeof(Header);
     size_t strtab_offset = entries_offset + (pfs_header.num_entries * entry_size);
     content_offset = strtab_offset + pfs_header.strtab_size;

src/core/file_sys/partition_filesystem.h

@@ -42,6 +42,8 @@ private:
         u32_le num_entries;
         u32_le strtab_size;
         INSERT_PADDING_BYTES(0x4);
+
+        bool HasValidMagicValue() const;
     };
 
     static_assert(sizeof(Header) == 0x10, "PFS/HFS header structure size is wrong");
@@ -73,11 +75,11 @@ private:
 
 #pragma pack(pop)
 
-    Loader::ResultStatus status;
+    Loader::ResultStatus status{};
 
-    Header pfs_header;
-    bool is_hfs;
-    size_t content_offset;
+    Header pfs_header{};
+    bool is_hfs = false;
+    size_t content_offset = 0;
 
     std::vector<VirtualFile> pfs_files;
     std::vector<VirtualDir> pfs_dirs;