Add file read function

src/chunks/chunks.odin

@@ -12,6 +12,7 @@ VERSION :: 1
 COMPRESSION :: 0
 SIZE_PER_CHUNK :: 2 * (1 << 30) // 2GiB
 PATH_SIZE :: 512
+CHUNK :: "CHUNK"
 
 // -----------------------------------------
 
@@ -44,6 +45,7 @@ Writer :: struct {
 }
 
 Error :: union #shared_nil {
+	runtime.Allocator_Error,
 	io.Error,
 	os.Error,
 	Read_Error,
@@ -86,7 +88,7 @@ compute_chunk_path :: proc(
 	@(static) buf: [20]u8
 
 	chunk_index_str := strconv.write_int(buf[:], cast(i64)chunk_index, 10)
-	chunk_name := strings.concatenate({"CHUNK", chunk_index_str}, allocator)
+	chunk_name := strings.concatenate({CHUNK, chunk_index_str}, allocator)
 	defer delete(chunk_name, allocator)
 
 	chunk_path, c_err := os.join_path({output_path, chunk_name}, allocator)

src/chunks/read_metadata.odin

@@ -1,9 +1,11 @@
 package chunks
 
 import "base:runtime"
+import "core:fmt"
 import "core:io"
 import "core:mem"
 import "core:os"
+import "core:strings"
 
 // -----------------------------------------
 
@@ -12,16 +14,13 @@ Reader :: struct {}
 Read_Error :: enum u8 {
 	None             = 0,
 	File_Not_A_Chunk = 1,
+	File_Not_Exist   = 2,
 	Unimplemented    = 127,
 	Okay             = None,
 }
 
 // -----------------------------------------
 
-// read header
-// file_exists() func
-// read_file() -> check chunks -> check fs -> fail
-
 read_header :: proc(
 	chunk1: ^os.File,
 	allocator := context.allocator,
@@ -40,6 +39,7 @@ read_header_by_path :: proc(
 	err: Error,
 ) {
 	chunk1_file := os.open(chunk1, {.Read}) or_return
+	defer os.close(chunk1_file)
 
 	return read_header_impl(chunk1_file, allocator)
 }
@@ -67,3 +67,118 @@ read_header_impl :: proc(
 
 	return header, nil
 }
+
+// Returning `[]Asset_Index` is owned by the caller.
+read_asset_index :: proc(
+	chunk1: ^os.File,
+	header: Header,
+	allocator := context.allocator,
+) -> (
+	indices: []Asset_Index,
+	err: Error,
+) {
+	chunk1_stream := os.to_stream(chunk1)
+
+	indices = make([]Asset_Index, header.number_of_assets, allocator) or_return
+	index_bytes := mem.slice_to_bytes(indices)
+	io.read_at(chunk1_stream, index_bytes, size_of(Header)) or_return
+
+	return indices, nil
+}
+
+file_exists :: proc(
+	header: Header,
+	indices: []Asset_Index,
+	path: string,
+) -> (
+	bool,
+	u32,
+) {
+	for i in 0 ..< header.number_of_assets {
+		str := string(indices[i].relpath[:])
+		relpath := strings.trim_right_null(str)
+		if path == relpath do return true, i
+	}
+
+	return false, 0
+}
+
+// Returning `[]u8` is owned by the caller.
+read_file :: proc(
+	header: Header,
+	indices: []Asset_Index,
+	output: ^os.File,
+	path: string,
+	allocator := context.allocator,
+) -> (
+	bytes: []u8,
+	err: Error,
+) {
+
+	// Check filesystem first, so chunks can be overriden
+	if os.exists(path) {
+		// Open file
+		fmt.println("searching:", path)
+		file := os.open(path, {.Read}) or_return
+		defer os.close(file)
+
+		// Read
+		file_size := os.file_size(file) or_return
+		bytes = make([]u8, file_size, allocator)
+		os.read(file, bytes) or_return
+
+		return bytes, nil
+	}
+
+	// Check chunk
+	if found, i := file_exists(header, indices, path); found {
+		output_path := os.name(output)
+		entry := indices[i]
+
+		// Find correct chunk
+		chunk_index := entry.offset / header.size_per_chunk
+
+		// Find offset within this chunk
+		chunk_offset := entry.offset % header.size_per_chunk
+
+		bytes = make([]u8, entry.size, allocator)
+		n_left: u64
+		n_read: u64
+
+		for entry.size > n_read {
+			// Chunk path
+			chunk_path := compute_chunk_path(
+				output_path,
+				cast(int)chunk_index,
+				allocator,
+			)
+			defer delete(chunk_path, allocator)
+
+			// Open chunk
+			file := os.open(chunk_path, {.Read}) or_return
+			defer os.close(file)
+
+			// Calculate how much of the current chunk should be read
+			if entry.size > n_read + header.size_per_chunk - chunk_offset {
+				n_left = header.size_per_chunk - chunk_offset
+			} else {
+				n_left = entry.size - n_read
+			}
+
+			// Read
+			n_read += cast(u64)os.read_at(
+				file,
+				bytes[n_read:n_read + n_left],
+				cast(i64)chunk_offset,
+			) or_return
+
+			// Overflow to next chunk
+			chunk_index += 1
+			chunk_offset = 0
+		}
+
+		return bytes, nil
+	}
+
+	return nil, .File_Not_Exist
+}

src/chunks/write_assets.odin

@@ -136,7 +136,7 @@ create_new_chunk :: proc(
 ) -> io.Stream {
 	// Remove old chunk
 	chunk_path := compute_chunk_path(output_path, chunk_index, allocator)
-	defer delete(chunk_path)
+	defer delete(chunk_path, allocator)
 	if os.exists(chunk_path) {
 		rm_err := os.remove(chunk_path)
 		if rm_err != nil {

src/chunks/write_metadata.odin

@@ -23,7 +23,7 @@ write_metadata :: proc(
 	// ----------------------------------------
 
 	chunk_path := compute_chunk_path(output_path, 0, allocator)
-	defer delete(chunk_path)
+	defer delete(chunk_path, allocator)
 	chunk_file, err := os.open(chunk_path, {.Read, .Write})
 	if err != nil {
 		fmt.eprintln("error: open chunk failed: ", err)

src/file/list_dir.odin

@@ -14,7 +14,7 @@ File_Entry :: struct #all_or_none {
 
 // -----------------------------------------
 
-// Returning `[dynamic]DirectoryEntry` and each relpath `string` inside it are owned by the caller.
+// Returning `[dynamic]File_Entry` and each relpath `string` inside it are owned by the caller.
 list_dir_recursive :: proc(
 	f: ^os.File,
 	working_dir: string,
@@ -24,7 +24,7 @@ list_dir_recursive :: proc(
 	return list_dir_recursive_by_path_impl(path, working_dir, allocator)
 }
 
-// Returning `[dynamic]DirectoryEntry` and each relpath `string` inside it are owned by the caller.
+// Returning `[dynamic]File_Entry` and each relpath `string` inside it are owned by the caller.
 list_dir_recursive_by_path :: proc(
 	path: string,
 	working_dir: string,

src/main.odin

@@ -1,5 +1,6 @@
 package main
 
+import "core:fmt"
 import "core:os"
 
 import "src:chunks"
@@ -24,21 +25,38 @@ main :: proc() {
 	w := chunks.writer_init(cast(u64)len(entries))
 	defer chunks.writer_destroy(&w)
 
-	chunks.write_assets(
-		&w,
-		opts.output,
-		entries[:],
-		opts.size,
-		opts.compression,
+	// chunks.write_assets(
+	// 	&w,
+	// 	opts.output,
+	// 	entries[:],
+	// 	opts.size,
+	// 	opts.compression,
+	// )
+	//
+	// chunks.write_metadata(
+	// 	&w,
+	// 	opts.output,
+	// 	entries[:],
+	// 	opts.size,
+	// 	opts.compression,
+	// )
+
+	header, err := chunks.read_header_by_path("./build/CHUNK0")
+	chunk0, o_err := os.open("./build/CHUNK0")
+	asset_index, a_err := chunks.read_asset_index(chunk0, header)
+	fmt.println(
+		"found: ",
+		chunks.file_exists(header, asset_index, "not_exists"),
+	)
+	fmt.println(
+		"found: ",
+		chunks.file_exists(header, asset_index, "./toby/engage"),
 	)
 
-	chunks.write_metadata(
-		&w,
-		opts.output,
-		entries[:],
-		opts.size,
-		opts.compression,
+	fmt.printf(
+		"file: %c\n",
+		chunks.read_file(header, asset_index, opts.output, "./toby/engage"),
 	)
-
-	chunks.read_header_by_path("./build/CHUNK0")
 }
+
+// TODO: .chunkignore