From 3dfb012a1adb86e1ec2be03a9c29df39e18ed86c Mon Sep 17 00:00:00 2001
From: Nico Weber <thakis@chromium.org>
Date: Sat, 21 Jan 2023 20:50:20 -0500
Subject: [PATCH] LibGfx: Add ICCProfile support for textType

This is used in v2 profiles for the required 'cprt' tag.
---
 Userland/Libraries/LibGfx/ICCProfile.cpp | 50 ++++++++++++++++++++++--
 Userland/Libraries/LibGfx/ICCProfile.h   | 25 +++++++++++-
 2 files changed, 70 insertions(+), 5 deletions(-)

diff --git a/Userland/Libraries/LibGfx/ICCProfile.cpp b/Userland/Libraries/LibGfx/ICCProfile.cpp
index 2d9f6757e1..20c991fd78 100644
--- a/Userland/Libraries/LibGfx/ICCProfile.cpp
+++ b/Userland/Libraries/LibGfx/ICCProfile.cpp
@@ -532,6 +532,48 @@ DeviceAttributes::DeviceAttributes(u64 bits)
 {
 }
 
+static TagTypeSignature tag_type(ReadonlyBytes tag_bytes)
+{
+    VERIFY(tag_bytes.size() >= sizeof(u32));
+    return *bit_cast<BigEndian<TagTypeSignature> const*>(tag_bytes.data());
+}
+
+static ErrorOr<void> check_reserved(ReadonlyBytes tag_bytes)
+{
+    if (tag_bytes.size() < 2 * sizeof(u32))
+        return Error::from_string_literal("ICC::Profile: Not enough data for tag reserved field");
+
+    if (*bit_cast<BigEndian<u32> const*>(tag_bytes.data() + sizeof(u32)) != 0)
+        return Error::from_string_literal("ICC::Profile: tag reserved field not 0");
+
+    return {};
+}
+
+ErrorOr<NonnullRefPtr<TextTagData>> TextTagData::from_bytes(ReadonlyBytes bytes, u32 offset, u32 size)
+{
+    // ICC v4, 10.24 textType
+    VERIFY(tag_type(bytes) == TextTagData::Type);
+    TRY(check_reserved(bytes));
+
+    // "The textType is a simple text structure that contains a 7-bit ASCII text string. The length of the string is obtained
+    //  by subtracting 8 from the element size portion of the tag itself. This string shall be terminated with a 00h byte."
+    u32 length = bytes.size() - 8;
+
+    u8 const* text_data = bytes.data() + 8;
+    for (u32 i = 0; i < length; ++i) {
+        if (text_data[i] >= 128)
+            return Error::from_string_literal("ICC::Profile: textType data not 7-byte ASCII");
+    }
+
+    if (length == 0)
+        return Error::from_string_literal("ICC::Profile: textType too short for \\0 byte");
+
+    if (text_data[length - 1] != '\0')
+        return Error::from_string_literal("ICC::Profile: textType data not \\0-terminated");
+
+    return adopt_ref(*new TextTagData(offset, size, TRY(String::from_utf8(StringView(text_data, length - 1)))));
+}
+
 ErrorOr<void> Profile::read_header(ReadonlyBytes bytes)
 {
     if (bytes.size() < sizeof(ICCHeader))
@@ -574,12 +616,14 @@ ErrorOr<NonnullRefPtr<TagData>> Profile::read_tag(ReadonlyBytes bytes, Detail::T
     //  what kind of data is contained within a tag."
     if (tag_bytes.size() < sizeof(u32))
         return Error::from_string_literal("ICC::Profile: Not enough data for tag type");
-    auto tag_type = *bit_cast<BigEndian<TagTypeSignature> const*>(tag_bytes.data());
 
-    switch ((u32)(TagTypeSignature)tag_type) {
+    auto type = tag_type(tag_bytes);
+    switch (type) {
+    case TextTagData::Type:
+        return TextTagData::from_bytes(tag_bytes, entry.offset_to_beginning_of_tag_data_element, entry.size_of_tag_data_element);
     default:
         // FIXME: optionally ignore tags of unknown type
-        return adopt_ref(*new UnknownTagData(entry.offset_to_beginning_of_tag_data_element, entry.size_of_tag_data_element, tag_type));
+        return adopt_ref(*new UnknownTagData(entry.offset_to_beginning_of_tag_data_element, entry.size_of_tag_data_element, type));
     }
 }
 
diff --git a/Userland/Libraries/LibGfx/ICCProfile.h b/Userland/Libraries/LibGfx/ICCProfile.h
index 062b93b711..66a91c6da9 100644
--- a/Userland/Libraries/LibGfx/ICCProfile.h
+++ b/Userland/Libraries/LibGfx/ICCProfile.h
@@ -12,6 +12,7 @@
 #include <AK/NonnullRefPtr.h>
 #include <AK/RefCounted.h>
 #include <AK/Span.h>
+#include <AK/String.h>
 #include <AK/URL.h>
 #include <LibCrypto/Hash/MD5.h>
 
@@ -31,11 +32,11 @@ enum class FourCCType {
 
 template<FourCCType type>
 struct [[gnu::packed]] DistinctFourCC {
-    explicit DistinctFourCC(u32 value)
+    constexpr explicit DistinctFourCC(u32 value)
         : value(value)
     {
     }
-    explicit operator u32() const { return value; }
+    constexpr operator u32() const { return value; }
 
     char c0() const { return value >> 24; }
     char c1() const { return (value >> 16) & 0xff; }
@@ -256,6 +257,26 @@ public:
     }
 };
 
+// ICC v4, 10.24 textType
+class TextTagData : public TagData {
+public:
+    static constexpr TagTypeSignature Type { 0x74657874 }; // 'text'
+
+    static ErrorOr<NonnullRefPtr<TextTagData>> from_bytes(ReadonlyBytes, u32 offset, u32 size);
+
+    TextTagData(u32 offset, u32 size, String text)
+        : TagData(offset, size, Type)
+        , m_text(move(text))
+    {
+    }
+
+    // Guaranteed to be 7-bit ASCII.
+    String const& text() const { return m_text; }
+
+private:
+    String m_text;
+};
+
 namespace Detail {
 struct TagTableEntry;
 }