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

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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
2 changed files with 6 additions and 0 deletions
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5
Userland/Libraries/LibEDID/EDID.cpp
View file

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

1
Userland/Libraries/LibEDID/EDID.h
View file

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