LibArchive: Use named members for ZIP general purpose flags

This fixes the faulty bit check that misclassified ZIPs as having
data descriptors.

Userland/Libraries/LibArchive/Zip.cpp

@@ -51,9 +51,9 @@ Optional<Zip> Zip::try_create(ReadonlyBytes buffer)
             return {};
         if (!central_directory_record.read(buffer.slice(member_offset)))
             return {};
-        if (central_directory_record.general_purpose_flags & 1)
+        if (central_directory_record.general_purpose_flags.encrypted)
             return {}; // TODO: support encrypted zip members
-        if (central_directory_record.general_purpose_flags & 3)
+        if (central_directory_record.general_purpose_flags.data_descriptor)
             return {}; // TODO: support zip data descriptors
         if (central_directory_record.compression_method != ZipCompressionMethod::Store && central_directory_record.compression_method != ZipCompressionMethod::Deflate)
             return {}; // TODO: support obsolete zip compression methods
@@ -128,7 +128,7 @@ void ZipOutputStream::add_member(ZipMember const& member)
 
     LocalFileHeader local_file_header {
         .minimum_version = minimum_version_needed(member.compression_method),
-        .general_purpose_flags = 0,
+        .general_purpose_flags = { .flags = 0 },
         .compression_method = static_cast<u16>(member.compression_method),
         .modification_time = 0, // TODO: support modification time
         .modification_date = 0,
@@ -156,7 +156,7 @@ void ZipOutputStream::finish()
         CentralDirectoryRecord central_directory_record {
             .made_by_version = zip_version,
             .minimum_version = zip_version,
-            .general_purpose_flags = 0,
+            .general_purpose_flags = { .flags = 0 },
             .compression_method = member.compression_method,
             .modification_time = 0, // TODO: support modification time
             .modification_date = 0,

Userland/Libraries/LibArchive/Zip.h

@@ -82,6 +82,24 @@ enum class ZipCompressionMethod : u16 {
     Deflate = 8
 };
 
+union ZipGeneralPurposeFlags {
+    u16 flags;
+    struct {
+        u16 encrypted : 1;
+        u16 compression_options : 2;
+        u16 data_descriptor : 1;
+        u16 enhanced_deflation : 1;
+        u16 compressed_patched_data : 1;
+        u16 strong_encryption : 1;
+        u16 : 4;
+        u16 language_encoding : 1;
+        u16 : 1;
+        u16 masked_data_values : 1;
+        u16 : 2;
+    };
+};
+static_assert(sizeof(ZipGeneralPurposeFlags) == sizeof(u16));
+
 OutputStream& operator<<(OutputStream& stream, ZipCompressionMethod method);
 
 struct [[gnu::packed]] CentralDirectoryRecord {
@@ -89,7 +107,7 @@ struct [[gnu::packed]] CentralDirectoryRecord {
 
     u16 made_by_version;
     u16 minimum_version;
-    u16 general_purpose_flags;
+    ZipGeneralPurposeFlags general_purpose_flags;
     ZipCompressionMethod compression_method;
     u16 modification_time;
     u16 modification_date;
@@ -125,7 +143,7 @@ struct [[gnu::packed]] CentralDirectoryRecord {
         stream.write_or_error(signature);
         stream << made_by_version;
         stream << minimum_version;
-        stream << general_purpose_flags;
+        stream << general_purpose_flags.flags;
         stream << compression_method;
         stream << modification_time;
         stream << modification_date;
@@ -158,7 +176,7 @@ struct [[gnu::packed]] LocalFileHeader {
     static constexpr Array<u8, signature_length> signature = { 0x50, 0x4b, 0x03, 0x04 }; // 'PK\x03\x04'
 
     u16 minimum_version;
-    u16 general_purpose_flags;
+    ZipGeneralPurposeFlags general_purpose_flags;
     u16 compression_method;
     u16 modification_time;
     u16 modification_date;
@@ -188,7 +206,7 @@ struct [[gnu::packed]] LocalFileHeader {
     {
         stream.write_or_error(signature);
         stream << minimum_version;
-        stream << general_purpose_flags;
+        stream << general_purpose_flags.flags;
         stream << compression_method;
         stream << modification_time;
         stream << modification_date;