[antlir2][package] configurable prefix for standard tests

Summary:
In advance of supporting incremental sendstreams with the same test setup, we
need to be able to configure a prefix in which to install and inspect the
standard features.

Test Plan:
```
❯ buck2 test fbcode//antlir/antlir2/test_images/package/...
Buck UI: https://www.internalfb.com/buck2/7c92159a-e96e-49b4-9c1e-1d7da11e69c7
Test UI: https://www.internalfb.com/intern/testinfra/testrun/11821949074804378
Network: Up: 2.6GiB  Down: 6.9GiB  (reSessionID-f2577f23-a638-44f6-99c4-13b9438a2013)
Jobs completed: 1045620. Time elapsed: 9:03.0s.
Cache hits: 99%. Commands: 59717 (cached: 59208, remote: 98, local: 411). Fallback: 12/509
Tests finished: Pass 178. Fail 0. Fatal 0. Skip 0. Build failure 0
```

Reviewed By: epilatow

Differential Revision: D64186147

fbshipit-source-id: b8902b5cef81c2ed03a20fe6cd9b78b488fd8f8e

antlir/antlir2/test_images/package/BUCK

@@ -1,7 +1,7 @@
 load("//antlir/antlir2/bzl/feature:defs.bzl", "feature")
 load("//antlir/antlir2/bzl/image:defs.bzl", "image")
 load("//antlir/bzl:build_defs.bzl", "buck_genrule", "export_file")
-load(":defs.bzl", "package_feature", "test_in_layer")
+load(":defs.bzl", "package_feature", "standard_features", "test_in_layer")
 
 oncall("antlir")
 
@@ -14,67 +14,7 @@ buck_genrule(
 image.layer(
     name = "standard",
     features = [
-        feature.install(
-            src = ":antlir2-large-file-256M",
-            dst = "/antlir2-large-file-256M",
-        ),
-        feature.ensure_dirs_exist(dirs = "/default-dir"),
-        feature.install_text(
-            dst = "/only-readable-by-root",
-            mode = 0o000,
-            text = "Only readable by root",
-        ),
-        feature.install_text(
-            dst = "/default-dir/executable",
-            mode = "a+rx",
-            text = "#!/bin/bash\necho hello",
-        ),
-        feature.install_text(
-            dst = "/i-am-owned-by-nonstandard",
-            group = 43,
-            text = "42:43",
-            user = 42,
-        ),
-        feature.install_text(
-            dst = "/i-have-xattrs",
-            text = "xattrs are cool",
-            xattrs = {
-                "user.baz": "qux",
-                "user.foo": "bar",
-            },
-        ),
-        feature.install(
-            src = "antlir//antlir:empty",
-            dst = "/i-have-caps",
-            xattrs = {
-                "security.capability": "0sAQAAAoAAAAAAAAAAAAAAAAAAAAA=",
-            },
-        ),
-        feature.ensure_file_symlink(
-            link = "/absolute-file-symlink",
-            target = "/default-dir/executable",
-        ),
-        feature.ensure_file_symlink(
-            link = "/default-dir/relative-file-symlink",
-            target = "executable",
-        ),
-        feature.ensure_dir_symlink(
-            link = "/absolute-dir-symlink",
-            target = "/default-dir",
-        ),
-        feature.ensure_dir_symlink(
-            link = "/relative-dir-symlink",
-            target = "default-dir",
-        ),
-        feature.ensure_dirs_exist(dirs = "/hardlink"),
-        feature.install_text(
-            dst = "/hardlink/hello",
-            text = "Hello world\n",
-        ),
-        feature.hardlink(
-            link = "/hardlink/aloha",
-            target = "/hardlink/hello",
-        ),
+        standard_features(prefix = "/"),
     ],
 )
 

antlir/antlir2/test_images/package/cpio/stub.rs

@@ -10,19 +10,23 @@ use std::process::Command;
 
 use cap_std::fs::Dir;
 
-pub(crate) fn open() -> Dir {
-    let archive = File::open("/package.cpio").expect("could not open /package.cpio");
-    let out = Command::new("cpio")
-        .arg("-idmv")
-        .current_dir("/package")
-        .stdin(archive)
-        .output()
-        .expect("failed to run cpio");
-    assert!(
-        out.status.success(),
-        "cpio failed:{}",
-        String::from_utf8_lossy(&out.stderr)
-    );
-    Dir::open_ambient_dir("/package", cap_std::ambient_authority())
-        .expect("could not open /package")
+pub(crate) struct StubImpl;
+
+impl crate::Stub for StubImpl {
+    fn open() -> Dir {
+        let archive = File::open("/package.cpio").expect("could not open /package.cpio");
+        let out = Command::new("cpio")
+            .arg("-idmv")
+            .current_dir("/package")
+            .stdin(archive)
+            .output()
+            .expect("failed to run cpio");
+        assert!(
+            out.status.success(),
+            "cpio failed:{}",
+            String::from_utf8_lossy(&out.stderr)
+        );
+        Dir::open_ambient_dir("/package", cap_std::ambient_authority())
+            .expect("could not open /package")
+    }
 }

antlir/antlir2/test_images/package/defs.bzl

@@ -3,6 +3,7 @@
 # This source code is licensed under the MIT license found in the
 # LICENSE file in the root directory of this source tree.
 
+load("@prelude//:paths.bzl", "paths")
 load("//antlir/antlir2/bzl/feature:defs.bzl", "feature")
 load("//antlir/antlir2/bzl/image:defs.bzl", "image")
 load("//antlir/antlir2/testing:image_test.bzl", "image_rust_test")
@@ -68,3 +69,70 @@ def test_in_layer(
             omit_features = omit_package_features,
         )
     )
+
+def standard_features(
+        *,
+        prefix: str):
+    return [
+        feature.install(
+            src = "//antlir/antlir2/test_images/package:antlir2-large-file-256M",
+            dst = paths.join(prefix, "antlir2-large-file-256M"),
+        ),
+        feature.ensure_dirs_exist(dirs = paths.join(prefix, "default-dir")),
+        feature.install_text(
+            dst = paths.join(prefix, "only-readable-by-root"),
+            mode = 0o000,
+            text = "Only readable by root",
+        ),
+        feature.install_text(
+            dst = paths.join(prefix, "default-dir/executable"),
+            mode = "a+rx",
+            text = "#!/bin/bash\necho hello",
+        ),
+        feature.install_text(
+            dst = paths.join(prefix, "i-am-owned-by-nonstandard"),
+            group = 43,
+            text = "42:43",
+            user = 42,
+        ),
+        feature.install_text(
+            dst = paths.join(prefix, "i-have-xattrs"),
+            text = "xattrs are cool",
+            xattrs = {
+                "user.baz": "qux",
+                "user.foo": "bar",
+            },
+        ),
+        feature.install(
+            src = "antlir//antlir:empty",
+            dst = paths.join(prefix, "i-have-caps"),
+            xattrs = {
+                "security.capability": "0sAQAAAoAAAAAAAAAAAAAAAAAAAAA=",
+            },
+        ),
+        feature.ensure_file_symlink(
+            link = paths.join(prefix, "absolute-file-symlink"),
+            target = paths.join(prefix, "default-dir/executable"),
+        ),
+        feature.ensure_file_symlink(
+            link = paths.join(prefix, "default-dir/relative-file-symlink"),
+            target = "executable",
+        ),
+        feature.ensure_dir_symlink(
+            link = paths.join(prefix, "absolute-dir-symlink"),
+            target = paths.join(prefix, "default-dir"),
+        ),
+        feature.ensure_dir_symlink(
+            link = paths.join(prefix, "relative-dir-symlink"),
+            target = "default-dir",
+        ),
+        feature.ensure_dirs_exist(dirs = paths.join(prefix, "hardlink")),
+        feature.install_text(
+            dst = paths.join(prefix, "hardlink/hello"),
+            text = "Hello world\n",
+        ),
+        feature.hardlink(
+            link = paths.join(prefix, "hardlink/aloha"),
+            target = paths.join(prefix, "hardlink/hello"),
+        ),
+    ]

antlir/antlir2/test_images/package/erofs/stub.rs

@@ -9,17 +9,21 @@ use std::process::Command;
 
 use cap_std::fs::Dir;
 
-pub(crate) fn open() -> Dir {
-    let out = Command::new("erofsfuse")
-        .arg("/package.erofs")
-        .arg("/package")
-        .output()
-        .expect("failed to run erofsfuse");
-    assert!(
-        out.status.success(),
-        "erofsfuse failed:{}",
-        String::from_utf8_lossy(&out.stderr)
-    );
-    Dir::open_ambient_dir("/package", cap_std::ambient_authority())
-        .expect("could not open /package")
+pub(crate) struct StubImpl;
+
+impl crate::Stub for StubImpl {
+    fn open() -> Dir {
+        let out = Command::new("erofsfuse")
+            .arg("/package.erofs")
+            .arg("/package")
+            .output()
+            .expect("failed to run erofsfuse");
+        assert!(
+            out.status.success(),
+            "erofsfuse failed:{}",
+            String::from_utf8_lossy(&out.stderr)
+        );
+        Dir::open_ambient_dir("/package", cap_std::ambient_authority())
+            .expect("could not open /package")
+    }
 }

antlir/antlir2/test_images/package/ext3/stub.rs

@@ -9,17 +9,21 @@ use std::process::Command;
 
 use cap_std::fs::Dir;
 
-pub(crate) fn open() -> Dir {
-    let out = Command::new("fuse2fs")
-        .arg("/package.ext3")
-        .arg("/package")
-        .output()
-        .expect("failed to run fuse2fs");
-    assert!(
-        out.status.success(),
-        "fuse2fs failed:{}",
-        String::from_utf8_lossy(&out.stderr)
-    );
-    Dir::open_ambient_dir("/package", cap_std::ambient_authority())
-        .expect("could not open /package")
+pub(crate) struct StubImpl;
+
+impl crate::Stub for StubImpl {
+    fn open() -> Dir {
+        let out = Command::new("fuse2fs")
+            .arg("/package.ext3")
+            .arg("/package")
+            .output()
+            .expect("failed to run fuse2fs");
+        assert!(
+            out.status.success(),
+            "fuse2fs failed:{}",
+            String::from_utf8_lossy(&out.stderr)
+        );
+        Dir::open_ambient_dir("/package", cap_std::ambient_authority())
+            .expect("could not open /package")
+    }
 }

antlir/antlir2/test_images/package/raw_layer.rs

@@ -7,6 +7,11 @@
 
 use cap_std::fs::Dir;
 
-pub(crate) fn open() -> Dir {
-    Dir::open_ambient_dir("/layer", cap_std::ambient_authority()).expect("could not open /layer")
+pub(crate) struct StubImpl;
+
+impl crate::Stub for StubImpl {
+    fn open() -> Dir {
+        Dir::open_ambient_dir("/layer", cap_std::ambient_authority())
+            .expect("could not open /layer")
+    }
 }

antlir/antlir2/test_images/package/sendstream/BUCK

@@ -1,7 +1,7 @@
 load("//antlir/antlir2/bzl/feature:defs.bzl", "feature")
 load("//antlir/antlir2/bzl/image:defs.bzl", "image")
 load("//antlir/antlir2/bzl/package:defs.bzl", "package")
-load("//antlir/antlir2/test_images/package:defs.bzl", "package_feature", "test_in_layer")
+load("//antlir/antlir2/test_images/package:defs.bzl", "package_feature", "standard_features", "test_in_layer")
 load("//antlir/bzl:build_defs.bzl", "rust_unittest")
 
 oncall("antlir")
@@ -20,11 +20,19 @@ VARIANTS = {
     },
 }
 
+image.layer(
+    name = "standard",
+    features = [
+        feature.ensure_dirs_exist(dirs = "/standard"),
+        standard_features(prefix = "/standard"),
+    ],
+)
+
 [
     [
         package.sendstream_v2(
             name = name + ".sendstream.v2",
-            layer = "//antlir/antlir2/test_images/package:standard",
+            layer = ":standard",
             rootless = args.get("rootless", None),
             volume_name = args.get("volume_name", None),
         ),

antlir/antlir2/test_images/package/sendstream/stub.rs

@@ -5,9 +5,19 @@
  * LICENSE file in the root directory of this source tree.
  */
 
+use std::path::Path;
+
 use cap_std::fs::Dir;
 
-pub(crate) fn open() -> Dir {
-    Dir::open_ambient_dir("/package", cap_std::ambient_authority())
-        .expect("could not open /package")
+pub(crate) struct StubImpl;
+
+impl crate::Stub for StubImpl {
+    fn open() -> Dir {
+        Dir::open_ambient_dir("/package/standard", cap_std::ambient_authority())
+            .expect("could not open /package")
+    }
+
+    fn absolute_symlink_root() -> &'static Path {
+        Path::new("/standard")
+    }
 }