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src/directory.zig

@@ -1,5 +1,62 @@
-pub const DirHeader = packed struct {};
+const std = @import("std");
+const io = std.io;
 
-pub const RawDirEntry = struct {};
+const InodeType = @import("inode/inode.zig").InodeType;
 
-pub const DirEntry = struct {};
+const DirHeader = packed struct {
+    count: u32,
+    inode_block_start: u32,
+    inode_num: u32,
+};
+
+const RawDirEntryStart = packed struct {
+    inode_block_offset: u16,
+    /// Difference from the current DirHeader inode_num
+    inode_num_difference: i16,
+    /// Extended inodes will be their basic type.
+    inode_type: InodeType,
+    name_size: u16,
+};
+
+pub const DirEntry = struct {
+    block_start: u32,
+    offset: u16,
+    inode_num: u32,
+    name: []const u8,
+
+    fn init(alloc: std.mem.Allocator, hdr: DirHeader, rdr: io.AnyReader) !DirEntry {
+        const raw = try rdr.readStruct(RawDirEntryStart);
+        const name = try alloc.alloc(u8, raw.name_size + 1);
+        _ = try rdr.read(name);
+        return .{
+            .block_start = hdr.inode_block_start,
+            .offset = raw.inode_block_offset,
+            .inode_num = if (raw.inode_num_difference > 0)
+                hdr.inode_num + @abs(raw.inode_num_difference)
+            else
+                hdr.inode_num - @abs(raw.inode_num_difference),
+            .name = name,
+        };
+    }
+
+    pub fn deinit(self: DirEntry, alloc: std.mem.Allocator) void {
+        alloc.free(self.name);
+    }
+};
+
+pub fn readDirectory(alloc: std.mem.Allocator, rdr: io.AnyReader, size: u64) !std.StringHashMap(DirEntry) {
+    var out: std.StringHashMap(DirEntry) = .init(alloc);
+    errdefer out.deinit();
+    var red_size: u64 = 3;
+    var hdr: DirHeader = try rdr.readStruct(DirHeader);
+    while (red_size < size) : (hdr = try rdr.readStruct(DirHeader)) {
+        var i: u32 = 0;
+        while (i <= hdr.count) : (i += 1) {
+            var tmp: DirEntry = try .init(alloc, hdr, rdr);
+            errdefer tmp.deinit(alloc);
+            try out.put(tmp.name, tmp);
+            red_size += 8 + tmp.name.len;
+        }
+    }
+    return out;
+}