Fixed a few bugs preventing basic functions

Worked on extraction, including creating DataReader
Added proper access to id, fragment, and export tables

src/util/data.zig

@@ -0,0 +1,130 @@
+const std = @import("std");
+const Reader = std.Io.Reader;
+const Writer = std.Io.Writer;
+const Limit = std.Io.Limit;
+
+const Archive = @import("../archive.zig");
+const FragEntry = Archive.FragEntry;
+const DecompMgr = @import("../decomp.zig");
+const BlockSize = @import("../inode_data/file.zig").BlockSize;
+const OffsetFile = @import("offset_file.zig");
+
+const DataReader = @This();
+
+alloc: std.mem.Allocator,
+fil: OffsetFile,
+decomp: *DecompMgr,
+block_size: u32,
+
+blocks: []BlockSize,
+
+frag: ?FragEntry, // TODO: do something better?
+frag_offset: u32 = 0,
+size: u64,
+
+interface: Reader,
+
+cur_offset: u64,
+block_idx: u32 = 0,
+
+pub fn init(archive: *Archive, blocks: []BlockSize, start: u64, size: u64) DataReader {
+    return .{
+        .alloc = archive.allocator(),
+        .fil = archive.fil,
+        .decomp = &archive.decomp,
+        .block_size = archive.super.block_size,
+        .blocks = blocks,
+        .size = size,
+        .cur_offset = start,
+        .interface = .{
+            .end = 0,
+            .seek = 0,
+            .buffer = &[0]u8{},
+            .vtable = &.{
+                .stream = stream,
+                .discard = discard,
+                .readVec = readVec,
+            },
+        },
+    };
+}
+pub fn deinit(self: *DataReader) void {
+    self.alloc.free(self.inteface.buffer);
+}
+
+pub fn addFragment(self: *DataReader, entry: FragEntry, frag_offset: u32) void {
+    self.frag = entry;
+    self.frag_offset = frag_offset;
+}
+
+fn blockNum(self: DataReader) u32 {
+    var res = self.blocks.len;
+    if (self.frag != null) res += 1;
+    return res;
+}
+
+fn advance(self: *DataReader) !void {
+    if (self.block_idx > self.blocks.len) return Reader.Error.EndOfStream;
+    defer self.block_idx += 1;
+    self.interface.seek = 0;
+    self.alloc.free(self.interface.buffer);
+    const cur_block_size = if (self.block_idx == self.blockNum() - 1) self.size % self.block_size else self.block_size;
+    if (self.block_idx == self.blocks.len) {
+        if (self.frag == null) return Reader.Error.EndOfStream;
+        // TODO: Fragment
+        return error.TODO;
+    }
+    const block = self.blocks[self.block_idx];
+    if (block.uncompressed) {
+        var rdr = try self.fil.readerAt(self.cur_offset, &[0]u8);
+        self.interface.buffer = try rdr.interface.readAlloc(self.alloc, cur_block_size);
+        self.interface.end = self.interface.buffer.len;
+        return;
+    }
+    return error.TODO;
+}
+
+fn stream(rdr: *Reader, wrt: *Writer, limit: Limit) Reader.StreamError!usize {
+    var self: *DataReader = @fieldParentPtr("interface", rdr);
+    if (rdr.seek >= rdr.end) self.advance() catch |err| {
+        if (err == .EndOfStream) return err;
+        std.log.err("Error advancing data reader: {}\n", .{err});
+        return Reader.Error.ReadFailed;
+    };
+    if (limit == .nothing) return 0;
+    const to_read = @min(rdr.end - rdr.seek, @intFromEnum(limit));
+    const res = try wrt.write(rdr.buffer[rdr.seek .. rdr.seek + to_read]);
+    rdr.seek += res;
+    return res;
+}
+
+fn discard(rdr: *Reader, limit: Limit) Reader.Error!usize {
+    var self: *DataReader = @fieldParentPtr("interface", rdr);
+    if (rdr.seek >= rdr.end) self.advance() catch |err| {
+        if (err == .EndOfStream) return err;
+        std.log.err("Error advancing data reader: {}\n", .{err});
+        return Reader.Error.ReadFailed;
+    };
+    if (limit == .nothing) return 0;
+    const to_adv = @min(rdr.end - rdr.seek, @intFromEnum(limit));
+    rdr.seek += to_adv;
+    return to_adv;
+}
+
+fn readVec(rdr: *Reader, vec: [][]u8) Reader.Error!usize {
+    var self: *DataReader = @fieldParentPtr("interface", rdr);
+    if (rdr.seek >= rdr.end) self.advance() catch |err| {
+        if (err == .EndOfStream) return err;
+        std.log.err("Error advancing data reader: {}\n", .{err});
+        return Reader.Error.ReadFailed;
+    };
+    var cur_red: usize = 0;
+    for (vec) |s| {
+        const to_copy: usize = @min(rdr.end - rdr.seek, s.len);
+        @memcpy(s[0..to_copy], self.buf[rdr.seek .. rdr.seek + to_copy]);
+        rdr.seek += to_copy;
+        cur_red += to_copy;
+        if (rdr.end == rdr.seek) break;
+    }
+    return cur_red;
+}