WIP node module bundles

Former-commit-id: 797b2ff557

src/node_module_bundle.zig

@@ -0,0 +1,69 @@
+const Api = @import("./api/schema.zig").Api;
+const std = @import("std");
+usingnamespace @import("global.zig");
+
+pub const NodeModuleBundle = struct {
+    container: *Api.JavascriptBundleContainer,
+    bundle: *Api.JavascriptBundle,
+    allocator: *std.mem.Allocator,
+    fd: FileDescriptorType = 0,
+
+    pub const magic_bytes = "#!/usr/bin/env speedy\n\n";
+    threadlocal var jsbundle_prefix: [magic_bytes.len + 5]u8 = undefined;
+
+    pub fn getCodeEndPosition(stream: anytype, comptime needs_seek: bool) !u32 {
+        if (needs_seek) try stream.seekTo(0);
+
+        const read_bytes = try stream.read(&jsbundle_prefix);
+        if (read_bytes != jsbundle_prefix.len) {
+            return error.JSBundleBadHeaderTooShort;
+        }
+
+        return std.mem.readIntNative(u32, jsbundle_prefix[magic_bytes.len .. magic_bytes.len + 4]);
+    }
+
+    pub fn loadBundle(allocator: *std.mem.Allocator, stream: anytype) !NodeModuleBundle {
+        const end = try getCodeEndPosition(stream);
+        try stream.seekTo(end + 1);
+        var reader = stream.reader();
+        var container = try Api.JavascriptBundleContainer.decode(allocator, reader);
+        return NodeModuleBundle{
+            .allocator = allocator,
+            .container = container,
+            .bundle = container.bundle,
+            .fd = if (std.meta.trait.hasField("handle")(stream)) stream.handle else 0,
+        };
+    }
+
+    pub fn printBundle(
+        comptime StreamType: type,
+        input: StreamType,
+        comptime DestinationStreamType: type,
+        output: DestinationStreamType,
+    ) !void {
+        const BufferStreamContext = struct {
+            pub fn run(in: StreamType, out: DestinationStreamType, end_at: u32) !void {
+                var buf: [4096]u8 = undefined;
+                var remain = @intCast(i64, end_at);
+                var read_amount: i64 = @intCast(i64, in.read(&buf) catch 0);
+                while (remain > 0 and read_amount > 0) {
+                    remain -= @intCast(i64, try out.write(buf[0..@intCast(usize, std.math.min(read_amount, remain))]));
+                    read_amount = @intCast(i64, in.read(&buf) catch 0);
+                }
+
+                _ = try out.write(buf[0..@intCast(usize, remain + 1)]);
+            }
+        };
+        if (isMac) {
+            // darwin only allows reading ahead on/off, not specific amount
+            _ = std.os.fcntl(input.handle, std.os.F_RDAHEAD, 1) catch 0;
+        }
+        const end = try getCodeEndPosition(input, false);
+
+        try BufferStreamContext.run(
+            input,
+            output,
+            end,
+        );
+    }
+};