add ToHumanReadableSize, which formats data sizes into MiB, GiB, etc.

this is needed in order to display data sizes in upcoming changes
related to tracking statistics about the server's performance

include/Common.h

@@ -178,6 +178,7 @@ void RegisterThread(const std::string& str);
 #define KB 1024llu
 #define MB (KB * 1024llu)
 #define GB (MB * 1024llu)
+#define TB (GB * 1024llu)
 #define SSU_UNRAW SECRET_SENTRY_URL
 
 #define _file_basename std::filesystem::path(__FILE__).filename().string()
@@ -352,3 +353,5 @@ inline T DeComp(const T& Compressed) {
 
 std::string GetPlatformAgnosticErrorString();
 #define S_DSN SU_RAW
+
+std::string ToHumanReadableSize(size_t Size);

src/Common.cpp

@@ -427,3 +427,17 @@ std::string GetPlatformAgnosticErrorString() {
     return "(no human-readable errors on this platform)";
 #endif
 }
+
+std::string ToHumanReadableSize(size_t Size) {
+    if (Size > TB) {
+        return fmt::format("{:.2f} TiB", double(Size) / TB);
+    } else if (Size > GB) {
+        return fmt::format("{:.2f} GiB", double(Size) / GB);
+    } else if (Size > MB) {
+        return fmt::format("{:.2f} MiB", double(Size) / MB);
+    } else if (Size > KB) {
+        return fmt::format("{:.2f} KiB", double(Size) / KB);
+    } else {
+        return fmt::format("{} B", Size);
+    }
+}