Remove mksquashfs executable

.gitmodules

@@ -7,3 +7,9 @@
 [submodule "crun"]
 	path = crun
 	url = https://github.com/containers/crun.git
+[submodule "squashfs-tools"]
+	path = squashfs-tools
+	url = https://github.com/plougher/squashfs-tools.git
+[submodule "zstd"]
+	path = zstd
+	url = https://github.com/facebook/zstd.git

build.zig

@@ -114,6 +114,74 @@ pub fn build(b: *std.Build) void {
         .link_libc = true,
     });
 
+    dockerc.addIncludePath(b.path("zstd/lib"));
+    dockerc.addCSourceFiles(.{
+        .files = &[_][]const u8{
+            "zstd/lib/common/debug.c",
+            "zstd/lib/common/entropy_common.c",
+            "zstd/lib/common/error_private.c",
+            "zstd/lib/common/fse_decompress.c",
+            "zstd/lib/common/pool.c",
+            "zstd/lib/common/threading.c",
+            "zstd/lib/common/xxhash.c",
+            "zstd/lib/common/zstd_common.c",
+
+            "zstd/lib/compress/fse_compress.c",
+            "zstd/lib/compress/hist.c",
+            "zstd/lib/compress/huf_compress.c",
+            "zstd/lib/compress/zstd_compress.c",
+            "zstd/lib/compress/zstd_compress_literals.c",
+            "zstd/lib/compress/zstd_compress_sequences.c",
+            "zstd/lib/compress/zstd_compress_superblock.c",
+            "zstd/lib/compress/zstd_double_fast.c",
+            "zstd/lib/compress/zstd_fast.c",
+            "zstd/lib/compress/zstd_lazy.c",
+            "zstd/lib/compress/zstd_ldm.c",
+            "zstd/lib/compress/zstdmt_compress.c",
+            "zstd/lib/compress/zstd_opt.c",
+
+            "zstd/lib/decompress/huf_decompress.c",
+            "zstd/lib/decompress/zstd_ddict.c",
+            "zstd/lib/decompress/zstd_decompress_block.c",
+            "zstd/lib/decompress/zstd_decompress.c",
+
+            "squashfs-tools/squashfs-tools/mksquashfs.c",
+            "squashfs-tools/squashfs-tools/progressbar.c",
+            "squashfs-tools/squashfs-tools/caches-queues-lists.c",
+            "squashfs-tools/squashfs-tools/date.c",
+            "squashfs-tools/squashfs-tools/pseudo.c",
+            "squashfs-tools/squashfs-tools/action.c",
+            "squashfs-tools/squashfs-tools/sort.c",
+            "squashfs-tools/squashfs-tools/restore.c",
+            "squashfs-tools/squashfs-tools/info.c",
+            "squashfs-tools/squashfs-tools/mksquashfs_help.c",
+            "squashfs-tools/squashfs-tools/print_pager.c",
+            "squashfs-tools/squashfs-tools/compressor.c",
+            "squashfs-tools/squashfs-tools/tar.c",
+            "squashfs-tools/squashfs-tools/reader.c",
+            "squashfs-tools/squashfs-tools/read_fs.c",
+            "squashfs-tools/squashfs-tools/memory.c",
+            "squashfs-tools/squashfs-tools/process_fragments.c",
+            "squashfs-tools/squashfs-tools/zstd_wrapper.c",
+        },
+        .flags = &[_][]const u8{
+            // avoid collision of main function
+            "-Dmain=mksquashfs_main",
+            // zstd: asm is only used for decompression so it is fine to disable
+            "-DZSTD_DISABLE_ASM",
+            // squashfs defines
+            "-DZSTD_SUPPORT",
+            "-D_GNU_SOURCE",
+            "-DVERSION=\"dockerc\"",
+            "-DDATE=\"2024/07/21\"",
+            "-DYEAR=\"2024\"",
+            "-DCOMP_DEFAULT=\"zstd\"",
+            "-DCOMPRESSORS=\"zstd\"",
+            // There's UB in squashfs. This deals with it.
+            "-fno-sanitize=undefined",
+        },
+    });
+
     dockerc.root_module.addAnonymousImport(
         "runtime",
         .{ .root_source_file = runtime.getEmittedBin() },

src/dockerc.zig

@@ -10,7 +10,6 @@ const debug = std.debug;
 const io = std.io;
 
 const skopeo_content = @embedFile("skopeo");
-const mksquashfs_content = @embedFile("tools/mksquashfs");
 const umoci_content = @embedFile("umoci");
 
 const policy_content = @embedFile("tools/policy.json");
@@ -23,6 +22,8 @@ const runtime_content_len_u64 = data: {
     break :data buf;
 };
 
+extern fn mksquashfs_main(argc: c_int, argv: [*:null]const ?[*:0]const u8) void;
+
 pub fn main() !void {
     var gpa = std.heap.GeneralPurposeAllocator(.{}){};
     defer _ = gpa.deinit();
@@ -37,9 +38,6 @@ pub fn main() !void {
     const umoci_path = try extract_file(&temp_dir_path, "umoci", umoci_content, allocator);
     defer allocator.free(umoci_path);
 
-    const mksquashfs_path = try extract_file(&temp_dir_path, "mksquashfs", mksquashfs_content, allocator);
-    defer allocator.free(mksquashfs_path);
-
     const policy_path = try extract_file(&temp_dir_path, "policy.json", policy_content, allocator);
     defer allocator.free(policy_path);
 
@@ -85,7 +83,8 @@ pub fn main() !void {
 
     // safe to assert because checked above
     const image = res.args.image.?;
-    const output_path = res.args.output.?;
+    const output_path = try allocator.dupeZ(u8, res.args.output.?);
+    defer allocator.free(output_path);
 
     const destination_arg = try std.fmt.allocPrint(allocator, "oci:{s}/image:latest", .{temp_dir_path});
     defer allocator.free(destination_arg);
@@ -96,7 +95,7 @@ pub fn main() !void {
     const umoci_image_layout_path = try std.fmt.allocPrint(allocator, "{s}/image:latest", .{temp_dir_path});
     defer allocator.free(umoci_image_layout_path);
 
-    const bundle_destination = try std.fmt.allocPrint(allocator, "{s}/bundle", .{temp_dir_path});
+    const bundle_destination = try std.fmt.allocPrintZ(allocator, "{s}/bundle", .{temp_dir_path});
     defer allocator.free(bundle_destination);
 
     const umoci_args = [_][]const u8{
@@ -110,11 +109,11 @@ pub fn main() !void {
     var umociProcess = std.process.Child.init(if (res.args.rootfull == 0) &umoci_args else umoci_args[0 .. umoci_args.len - 1], gpa.allocator());
     _ = try umociProcess.spawnAndWait();
 
-    const offset_arg = try std.fmt.allocPrint(allocator, "{}", .{runtime_content.len});
+    const offset_arg = try std.fmt.allocPrintZ(allocator, "{}", .{runtime_content.len});
     defer allocator.free(offset_arg);
 
-    var mksquashfsProcess = std.process.Child.init(&[_][]const u8{
-        mksquashfs_path,
+    const mksquashfs_args = [_:null]?[*:0]const u8{
+        "mksquashfs",
         bundle_destination,
         output_path,
         "-comp",
@@ -122,8 +121,12 @@ pub fn main() !void {
         "-offset",
         offset_arg,
         "-noappend",
-    }, gpa.allocator());
-    _ = try mksquashfsProcess.spawnAndWait();
+    };
+
+    mksquashfs_main(
+        mksquashfs_args.len,
+        &mksquashfs_args,
+    );
 
     const file = try std.fs.cwd().openFile(output_path, .{
         .mode = .write_only,