More work on extraction, especially for regular files

src/file.zig

@@ -8,7 +8,9 @@ const DirEntry = @import("directory.zig");
 const ExtractionOptions = @import("options.zig");
 const Inode = @import("inode.zig");
 const DataExtractor = @import("util/data_extractor.zig");
+const Decompressor = @import("util/decompressor.zig");
 const MetadataReader = @import("util/metadata.zig");
+const SharedCache = @import("util/shared_cache.zig");
 
 const File = @This();
 
@@ -83,16 +85,36 @@ pub fn open(self: File, alloc: std.mem.Allocator, io: Io, filepath: []const u8)
 }
 
 pub fn extract(self: File, alloc: std.mem.Allocator, io: Io, filepath: []const u8, options: ExtractionOptions) !void {
+    var cache: SharedCache = try .init(alloc, 10); // TODO: calculate a good initial cache size.
+    defer cache.deinit();
+    var decomp = switch (self.archive.super.compression) {
+        .gzip => {},
+        .lzma => {},
+        .xz => {},
+        .zstd => {},
+        else => unreachable,
+    };
+    return self.extractReal(alloc, io, &cache, &decomp.interface, filepath, options);
+}
+fn extractReal(self: File, alloc: std.mem.Allocator, io: Io, cache: *SharedCache, decomp: *const Decompressor, filepath: []const u8, options: ExtractionOptions) !void {
+    _ = options;
     switch (self.inode.hdr.inode_type) {
         .file, .ext_file => {
+            var ext = try self.inode.dataExtractor(
+                self.archive.file,
+                cache,
+                decomp,
+                self.archive.super.block_size,
+            );
+
             var atomic_file = try Io.Dir.cwd().createFileAtomic(io, filepath, .{});
             defer atomic_file.deinit(io);
+
+            try ext.extract(alloc, io, atomic_file.file);
+            try atomic_file.link(io);
         },
         else => return error.TODO,
     }
-    _ = alloc;
-    _ = options;
-    return error.TODO;
 }
 
 // Types