uid mapping

build.zig

@@ -247,6 +247,35 @@ pub fn build(b: *std.Build) void {
         },
     });
 
+    runtime.addIncludePath(b.dependency("shadow", .{}).path("libsubid"));
+    runtime.addIncludePath(b.dependency("shadow", .{}).path("lib"));
+    runtime.addIncludePath(b.dependency("shadow", .{}).path(""));
+
+    runtime.addCSourceFiles(.{
+        .root = b.dependency("shadow", .{}).path(""),
+        .files = &[_][]const u8{
+            "libsubid/api.c",
+            "lib/shadowlog.c",
+            "lib/subordinateio.c",
+            "lib/commonio.c",
+            "lib/write_full.c",
+            "lib/nss.c",
+            "lib/get_pid.c",
+            "lib/memzero.c",
+            "lib/alloc.c",
+            "lib/atoi/str2i.c",
+            "lib/atoi/a2i.c",
+            "lib/atoi/strtou_noneg.c",
+            "lib/atoi/strtoi.c",
+            "lib/string/sprintf.c",
+        },
+        .flags = &[_][]const u8{
+            "-DENABLE_SUBIDS",
+            // duplicate symbol with crun
+            "-Dxasprintf=shadow_xasprintf",
+        },
+    });
+
     const aarch64_target = b.resolveTargetQuery(.{
         .cpu_arch = .aarch64,
         .abi = .musl,

build.zig.zon

@@ -19,6 +19,10 @@
             .url = "https://github.com/Hejsil/zig-clap/archive/60cd46aacff4960104703da9ba683077b1e3c76c.tar.gz",
             .hash = "12205eb22c644df2469045083efe9c92189d56494ebe8901b36ef1218c3717e6eb78",
         },
+        .shadow = .{
+            .url = "https://github.com/shadow-maint/shadow/releases/download/4.15.3/shadow-4.15.3.tar.gz",
+            .hash = "12202972bc830245199eb4c5b10f853f1be094eb8c86d431299a69b1c01fa5781a7e",
+        },
     },
     .paths = .{
         // This makes *all* files, recursively, included in this package. It is generally

src/dockerc.zig

@@ -178,13 +178,12 @@ pub fn main() !void {
         "0",
     };
 
-    // in rootfull, do not force uid/gid to 0,0
-    if (res.args.rootfull != 0) {
-        mksquashfs_args[mksquashfs_args.len - 4] = null;
-    }
-
     mksquashfs_main(
-        mksquashfs_args.len,
+        // in rootfull, do not force uid/gid to 0,0
+        if (res.args.rootfull != 0)
+            mksquashfs_args.len - 4
+        else
+            mksquashfs_args.len,
         &mksquashfs_args,
     );