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.
This commit is contained in:
Liav A 2022-06-10 23:02:35 +03:00 committed by Linus Groh
parent 20c9e4c05c
commit 1a641f9af7
Notes: sideshowbarker 2024-07-17 10:19:44 +09:00
2 changed files with 6 additions and 0 deletions

View file

@ -332,10 +332,13 @@ ErrorOr<void> Parser::parse()
}
u16 packed_id = read_be(&raw_edid().vendor.manufacturer_id);
if (packed_id == 0x0)
return {};
m_legacy_manufacturer_id[0] = (char)((u16)'A' + ((packed_id >> 10) & 0x1f) - 1);
m_legacy_manufacturer_id[1] = (char)((u16)'A' + ((packed_id >> 5) & 0x1f) - 1);
m_legacy_manufacturer_id[2] = (char)((u16)'A' + (packed_id & 0x1f) - 1);
m_legacy_manufacturer_id[3] = '\0';
m_legacy_manufacturer_id_valid = true;
return {};
}
@ -420,6 +423,8 @@ StringView Parser::legacy_manufacturer_id() const
#ifndef KERNEL
String Parser::manufacturer_name() const
{
if (!m_legacy_manufacturer_id_valid)
return "Unknown";
auto manufacturer_id = legacy_manufacturer_id();
# ifdef ENABLE_PNP_IDS_DATA
if (auto pnp_id_data = PnpIDs::find_by_manufacturer_id(manufacturer_id); pnp_id_data.has_value())

View file

@ -457,6 +457,7 @@ private:
String m_version;
#endif
char m_legacy_manufacturer_id[4] {};
bool m_legacy_manufacturer_id_valid { false };
};
}