link-tests: test pagezero_size option for macho

lib/std/build.zig

@@ -1582,6 +1582,9 @@ pub const LibExeObjStep = struct {
     /// (Darwin) Path to entitlements file
     entitlements: ?[]const u8 = null,
 
+    /// (Darwin) Size of the pagezero segment.
+    pagezero_size: ?u64 = null,
+
     /// Position Independent Code
     force_pic: ?bool = null,
 
@@ -2638,6 +2641,10 @@ pub const LibExeObjStep = struct {
         if (self.entitlements) |entitlements| {
             try zig_args.appendSlice(&[_][]const u8{ "--entitlements", entitlements });
         }
+        if (self.pagezero_size) |pagezero_size| {
+            const size = try std.fmt.allocPrint(builder.allocator, "{x}", .{pagezero_size});
+            try zig_args.appendSlice(&[_][]const u8{ "-pagezero_size", size });
+        }
 
         if (self.bundle_compiler_rt) |x| {
             if (x) {

test/link.zig

@@ -28,6 +28,10 @@ pub fn addCases(cases: *tests.StandaloneContext) void {
     });
 
     if (builtin.os.tag == .macos) {
+        cases.addBuildFile("test/link/pagezero/build.zig", .{
+            .build_modes = false,
+        });
+
         cases.addBuildFile("test/link/dylib/build.zig", .{
             .build_modes = true,
         });

test/link/pagezero/build.zig

@@ -0,0 +1,34 @@
+const std = @import("std");
+const Builder = std.build.Builder;
+
+pub fn build(b: *Builder) void {
+    const mode = b.standardReleaseOptions();
+
+    const test_step = b.step("test", "Test");
+
+    const exe = b.addExecutable("main", null);
+    exe.setBuildMode(mode);
+    exe.addCSourceFile("main.c", &.{});
+    exe.linkLibC();
+    exe.pagezero_size = 0x4000;
+
+    var name: [16]u8 = undefined;
+    std.mem.set(u8, &name, 0);
+    std.mem.copy(u8, &name, "__PAGEZERO");
+    const pagezero_seg = std.macho.segment_command_64{
+        .cmdsize = @sizeOf(std.macho.segment_command_64),
+        .segname = name,
+        .vmaddr = 0,
+        .vmsize = 0x4000,
+        .fileoff = 0,
+        .filesize = 0,
+        .maxprot = 0,
+        .initprot = 0,
+        .nsects = 0,
+        .flags = 0,
+    };
+    const check_file = std.build.CheckFileStep.create(b, exe.getOutputSource(), &[_][]const u8{std.mem.asBytes(&pagezero_seg)});
+
+    test_step.dependOn(b.getInstallStep());
+    test_step.dependOn(&check_file.step);
+}

test/link/pagezero/main.c

@@ -0,0 +1,3 @@
+int main(int argc, char* argv[]) {
+  return 0;
+}