LibEDID: Return "Unknown" string if failed to determine the manufacturer

Before of this patch, It happened that the return string could be "@@@", as a result of doing mathematical addition of ASCII '@' with bits when decoding the packed manufacturer ID bytes from the EDID. To avoid this, consider m_legacy_manufacturer_id to be invalid until we successfully decode the packed bytes.
Author: https://github.com/supercomputer7 Commit: 1a641f9af7 Pull-request: https://github.com/SerenityOS/serenity/pull/14249 Issue: https://github.com/SerenityOS/serenity/issues/14139 Reviewed-by: https://github.com/linusg ✅
2025-08-01 21:59:07 +00:00 · 2022-06-10 23:02:35 +03:00 · 2022-06-10 23:02:35 +03:00 · 1a641f9af7 · 2024-07-17 10:19:44 +09:00
commit 1a641f9af7
parent 20c9e4c05c
2 changed files with 6 additions and 0 deletions
--- a/Userland/Libraries/LibEDID/EDID.h
+++ b/Userland/Libraries/LibEDID/EDID.h
@ -457,6 +457,7 @@ private:
    String m_version;
 #endif
    char m_legacy_manufacturer_id[4] {};
+    bool m_legacy_manufacturer_id_valid { false };
 };

 }