Add a fiin parser

Don't know what this file format is actually used for, but it was fun
to reverse engineer, and I don't think anyone has done it for this
format yet!

CMakeLists.txt

@@ -32,7 +32,9 @@ set(SRC
         src/launcherwindow.cpp
         include/launcherwindow.h
         src/gamescopesettingswindow.cpp
-        include/gamescopesettingswindow.h)
+        include/gamescopesettingswindow.h
+        src/fiinparser.cpp
+        include/fiinparser.h)
 
 include(FetchContent)
 

include/fiinparser.h

@@ -0,0 +1,40 @@
+#pragma once
+
+#include <cstdint>
+#include <vector>
+#include <string_view>
+
+// this is methods dedicated to parsing "fiin" files, commonly shown as "fileinfo.fiin"
+
+// header is 1024 bytes
+// for some reason, they store unknown1 and unknown 2 in this weird format,
+// unknown1 is capped at 256 (in decimal) and will overflow into unknown 2
+// for example, 1 is equal to unknown1 = 96 and unknown2 = 0
+// 96 / 1 == 1
+// if you have say, 14 entries, then unknown1 = 64 and unknown2 = 5
+// 5 (unknown2) * 256 = 1280 + 64 (unknown1) = 1344
+// 1344 / 96 = 14
+// i could've made a mistake and this is actually really common but i don't know
+struct FileInfoHeader {
+    char magic[9];
+    uint8_t dummy1[16];
+    uint8_t unknown; // version? always seems to be 4
+    uint8_t dummy2[2];
+    uint8_t unknown1;
+    uint8_t unknown2;
+    uint8_t dummy[994];
+};
+
+// each entry is 96 bytes
+struct FileInfoEntry {
+    uint8_t dummy[8]; // length of file name in some format
+    char str[64]; // simple \0 encoded string
+    uint8_t dummy2[24]; // sha1
+};
+
+struct FileInfo {
+    FileInfoHeader header;
+    std::vector<FileInfoEntry> entries;
+};
+
+FileInfo readFileInfo(const std::string_view path);

src/fiinparser.cpp

@@ -0,0 +1,47 @@
+#include "fiinparser.h"
+
+#include <cstdio>
+#include <QDebug>
+
+FileInfo readFileInfo(const std::string_view path) {
+    FILE* file = fopen(path.data(), "rb");
+    if(!file) {
+        qInfo() << "Failed to read file info " << path.data();
+        return {};
+    }
+
+    FileInfo info;
+    fread(&info.header, sizeof info.header, 1, file);
+
+    char magic[9] = "FileInfo";
+    if(strcmp(info.header.magic, magic) != 0)
+        qInfo() << "Invalid magic for fileinfo.";
+    else
+        qInfo() << "Got matching magic:" << info.header.magic;
+
+    qInfo() << "unknown (version?) = " << info.header.unknown;
+    qInfo() << "unknown1 = " << info.header.unknown1;
+    qInfo() << "unknown2 = " << info.header.unknown2;
+
+    int overflow = info.header.unknown2;
+    int extra = overflow * 256;
+    int first = info.header.unknown1 / 96;
+    int first2 = extra / 96;
+    int actualEntries = first + first2 + 1; // is this 1 really needed? lol
+
+    qInfo() << "Guessed number of entries: " << actualEntries;
+
+    int numEntries = actualEntries;
+    for(int i = 0; i < numEntries; i++) {
+        FileInfoEntry entry;
+        fread(&entry, sizeof entry, 1, file);
+
+        info.entries.push_back(entry);
+
+        qDebug() << entry.str;
+    }
+
+    fclose(file);
+
+    return info;
+}