LibArchive: Implement ZipOutputStream for zip archive creation

This output stream can be used to create zip archives, and will
be used in the implementation of the zip utility.

2 files changed, 89 insertions, 0 deletions

diff --git a/Userland/Libraries/LibArchive/Zip.cpp b/Userland/Libraries/LibArchive/Zip.cpp
index 4c54622085..69a70169f5 100644
--- a/Userland/Libraries/LibArchive/Zip.cpp
+++ b/Userland/Libraries/LibArchive/Zip.cpp
@@ -117,4 +117,79 @@ bool Zip::for_each_member(Function<IterationDecision(const ZipMember&)> callback
     return true;
 }
 
+ZipOutputStream::ZipOutputStream(OutputStream& stream)
+    : m_stream(stream)
+{
+}
+
+void ZipOutputStream::add_member(const ZipMember& member)
+{
+    VERIFY(!m_finished);
+    VERIFY(member.name.length() <= UINT16_MAX);
+    VERIFY(member.compressed_data.size() <= UINT32_MAX);
+    m_members.append(member);
+
+    LocalFileHeader local_file_header {};
+    local_file_header.minimum_version = member.compression_method == ZipCompressionMethod::Deflate ? 20 : 10; // Deflate was added in PKZip 2.0
+    local_file_header.general_purpose_flags = 0;
+    local_file_header.compression_method = static_cast<u16>(member.compression_method);
+    local_file_header.modification_time = 0; // TODO: support modification time
+    local_file_header.modification_date = 0;
+    local_file_header.crc32 = member.crc32;
+    local_file_header.compressed_size = member.compressed_data.size();
+    local_file_header.uncompressed_size = member.uncompressed_size;
+    local_file_header.name_length = member.name.length();
+    local_file_header.extra_data_length = 0;
+    local_file_header.name = (const u8*)(member.name.characters());
+    local_file_header.extra_data = nullptr;
+    local_file_header.compressed_data = member.compressed_data.data();
+    local_file_header.write(m_stream);
+}
+
+void ZipOutputStream::finish()
+{
+    VERIFY(!m_finished);
+    m_finished = true;
+
+    auto file_header_offset = 0;
+    auto central_directory_size = 0;
+    for (const ZipMember& member : m_members) {
+        CentralDirectoryRecord central_directory_record {};
+        auto zip_version = member.compression_method == ZipCompressionMethod::Deflate ? 20 : 10; // Deflate was added in PKZip 2.0
+        central_directory_record.made_by_version = zip_version;
+        central_directory_record.minimum_version = zip_version;
+        central_directory_record.general_purpose_flags = 0;
+        central_directory_record.compression_method = static_cast<u16>(member.compression_method);
+        central_directory_record.modification_time = 0; // TODO: support modification time
+        central_directory_record.modification_date = 0;
+        central_directory_record.crc32 = member.crc32;
+        central_directory_record.compressed_size = member.compressed_data.size();
+        central_directory_record.uncompressed_size = member.uncompressed_size;
+        central_directory_record.name_length = member.name.length();
+        central_directory_record.extra_data_length = 0;
+        central_directory_record.comment_length = 0;
+        central_directory_record.start_disk = 0;
+        central_directory_record.internal_attributes = 0;
+        central_directory_record.external_attributes = member.is_directory ? zip_directory_external_attribute : 0;
+        central_directory_record.local_file_header_offset = file_header_offset; // FIXME: we assume the wrapped output stream was never written to before us
+        file_header_offset += sizeof(local_file_header_signature) + (sizeof(LocalFileHeader) - (sizeof(u8*) * 3)) + member.name.length() + member.compressed_data.size();
+        central_directory_record.name = (const u8*)(member.name.characters());
+        central_directory_record.extra_data = nullptr;
+        central_directory_record.comment = nullptr;
+        central_directory_record.write(m_stream);
+        central_directory_size += central_directory_record.size();
+    }
+
+    EndOfCentralDirectory end_of_central_directory {};
+    end_of_central_directory.disk_number = 0;
+    end_of_central_directory.central_directory_start_disk = 0;
+    end_of_central_directory.disk_records_count = m_members.size();
+    end_of_central_directory.total_records_count = m_members.size();
+    end_of_central_directory.central_directory_size = central_directory_size;
+    end_of_central_directory.central_directory_offset = file_header_offset;
+    end_of_central_directory.comment_length = 0;
+    end_of_central_directory.comment = nullptr;
+    end_of_central_directory.write(m_stream);
+}
+
 }
diff --git a/Userland/Libraries/LibArchive/Zip.h b/Userland/Libraries/LibArchive/Zip.h
index dd8c632ec2..ac835b8bfa 100644
--- a/Userland/Libraries/LibArchive/Zip.h
+++ b/Userland/Libraries/LibArchive/Zip.h
@@ -31,6 +31,7 @@
 #include <AK/Span.h>
 #include <AK/Stream.h>
 #include <AK/String.h>
+#include <AK/Vector.h>
 #include <string.h>
 
 namespace Archive {
@@ -231,4 +232,17 @@ private:
     ReadonlyBytes m_input_data;
 };
 
+class ZipOutputStream {
+public:
+    ZipOutputStream(OutputStream&);
+    void add_member(const ZipMember&);
+    void finish();
+
+private:
+    OutputStream& m_stream;
+    Vector<ZipMember> m_members;
+
+    bool m_finished { false };
+};
+
 }