elf: add very simplistic build.zig-based test harness

build.zig

@@ -85,6 +85,10 @@ pub fn build(b: *std.Build.Builder) void {
 
     const test_step = b.step("test", "Run library and end-to-end tests");
     test_step.dependOn(&b.addRunArtifact(tests).step);
+
+    const elf_step = @import("test/test.zig").addElfTests(b);
+    elf_step.dependOn(&symlinks.step);
+    test_step.dependOn(elf_step);
 }
 
 fn addSymlinks(

test/elf.zig

@@ -0,0 +1,11 @@
+pub const Case = struct {
+    build_root: []const u8,
+    import: type,
+};
+
+pub const cases = [_]Case{
+    .{
+        .build_root = "test/elf/dso-ifunc",
+        .import = @import("elf/dso-ifunc/build.zig"),
+    },
+};

test/elf/dso-ifunc/a.c

@@ -0,0 +1,14 @@
+#include <stdio.h>
+
+__attribute__((ifunc("resolve_foobar")))
+void foobar(void);
+
+static void real_foobar(void) {
+  printf("Hello world\n");
+}
+
+typedef void Func();
+
+static Func *resolve_foobar(void) {
+  return real_foobar;
+}

test/elf/dso-ifunc/build.zig

@@ -0,0 +1,25 @@
+const std = @import("std");
+
+pub fn build(b: *std.Build) void {
+    const test_step = b.step("test", "Test it");
+    b.default_step = test_step;
+
+    const lib_step = b.addSystemCommand(&.{
+        "cc",      "-fno-lto", "-fPIC",                  "-shared", "-o",
+        "liba.so", "a.c",      "-B../../../zig-out/bin",
+    });
+    test_step.dependOn(&lib_step.step);
+
+    const exe_step = b.addSystemCommand(&.{
+        "cc",                     "-fno-lto", "main.c",
+        "-la",                    "-L.",      "-Wl,-rpath,.",
+        "-B../../../zig-out/bin",
+    });
+    exe_step.step.dependOn(&lib_step.step);
+    test_step.dependOn(&exe_step.step);
+
+    const run_step = b.addSystemCommand(&.{"./a.out"});
+    run_step.expectStdOutEqual("Hello world\n");
+    run_step.step.dependOn(&exe_step.step);
+    test_step.dependOn(&run_step.step);
+}

test/elf/dso-ifunc/main.c

@@ -0,0 +1,5 @@
+void foobar(void);
+
+int main() {
+  foobar();
+}

test/test.zig

@@ -1,7 +1,10 @@
 const std = @import("std");
+const builtin = @import("builtin");
 const CrossTarget = std.zig.CrossTarget;
 const TestContext = @import("../src/test.zig").TestContext;
 
+const elf = @import("elf.zig");
+
 const linux_x86_64 = CrossTarget{
     .cpu_arch = .x86_64,
     .os_tag = .linux,
@@ -201,3 +204,18 @@ pub fn addCases(ctx: *TestContext) !void {
         }
     }
 }
+
+pub fn addElfTests(b: *std.Build) *std.Build.Step {
+    const step = b.step("test-elf", "Run ELF tests");
+
+    if (builtin.target.ofmt == .elf)
+        inline for (elf.cases) |case| {
+            const dep = b.anonymousDependency(case.build_root, case.import, .{});
+            const dep_step = dep.builder.default_step;
+            const dep_prefix_adjusted = dep.builder.dep_prefix["test".len..];
+            dep_step.name = b.fmt("{s}{s}", .{ dep_prefix_adjusted, dep_step.name });
+            step.dependOn(dep_step);
+        };
+
+    return step;
+}