[PATCH v4 3/3] oeqa/selftest: add oe-selftest for kernel module pre-filter

[Sam Kent <sam.john.kent@gmail.com>]

Add selftest-ko-filter recipe and a PackageTests.test_kmodule_prefilter
oe-selftest that builds it to verify process_split_and_strip_files()
handles .ko.xz/.ko.gz alongside a real .ko without corrupting them.
Regression test for YOCTO #2348.

AI-Generated: Uses Claude Sonnet 4.6

Signed-off-by: Sam Kent <sam.john.kent@gmail.com>
---
 .../selftest-ko-filter/files/module.c         |  3 ++
 .../selftest-ko-filter/selftest-ko-filter.bb  | 29 +++++++++++++++++++
 meta/lib/oeqa/selftest/cases/package.py       | 22 ++++++++++++++
 3 files changed, 54 insertions(+)
 create mode 100644 meta-selftest/recipes-test/selftest-ko-filter/files/module.c
 create mode 100644 meta-selftest/recipes-test/selftest-ko-filter/selftest-ko-filter.bb

diff --git a/meta-selftest/recipes-test/selftest-ko-filter/files/module.c b/meta-selftest/recipes-test/selftest-ko-filter/files/module.c
new file mode 100644
index 0000000..f6d50ba
--- /dev/null
+++ b/meta-selftest/recipes-test/selftest-ko-filter/files/module.c
@@ -0,0 +1,3 @@
+/* SPDX-License-Identifier: MIT */
+/* Minimal relocatable object used as a .ko stand-in for pre-filter testing. */
+int selftest_ko_filter_marker = 42;
diff --git a/meta-selftest/recipes-test/selftest-ko-filter/selftest-ko-filter.bb b/meta-selftest/recipes-test/selftest-ko-filter/selftest-ko-filter.bb
new file mode 100644
index 0000000..1b8cc73
--- /dev/null
+++ b/meta-selftest/recipes-test/selftest-ko-filter/selftest-ko-filter.bb
@@ -0,0 +1,29 @@
+#
+# Copyright OpenEmbedded Contributors
+#
+# SPDX-License-Identifier: MIT
+#
+SUMMARY = "Test fixture for the kernel-module file pre-filter in package.py"
+LICENSE = "MIT"
+LIC_FILES_CHKSUM = "file://${COMMON_LICENSE_DIR}/MIT;md5=0835ade698e0bcf8506ecda2f7b4f302"
+
+SRC_URI = "file://module.c"
+S = "${UNPACKDIR}"
+
+MODDIR = "${libdir}/selftest-ko-filter"
+
+do_compile () {
+    ${CC} ${CFLAGS} -c module.c -o module.ko
+}
+
+do_install () {
+    install -d ${D}${MODDIR}
+    install -m 0644 module.ko ${D}${MODDIR}/
+
+    # Fake compressed modules — the pre-filter must not pass these to strip.
+    # Use octal escapes: dash (the OE recipe shell) does not support \xHH in printf.
+    printf '\375\067\172\130\132\000' > ${D}${MODDIR}/module.ko.xz
+    printf '\037\213'                 > ${D}${MODDIR}/module.ko.gz
+}
+
+FILES:${PN} = "${MODDIR}/*"
diff --git a/meta/lib/oeqa/selftest/cases/package.py b/meta/lib/oeqa/selftest/cases/package.py
index 38ed717..d33424b 100644
--- a/meta/lib/oeqa/selftest/cases/package.py
+++ b/meta/lib/oeqa/selftest/cases/package.py
@@ -185,6 +185,28 @@ class PackageTests(OESelftestTestCase):
                 if not gdbtest(qemu, binary):
                     self.fail('GDB %s failed' % binary)
 
+    def test_kmodule_prefilter(self):
+        # Regression test for YOCTO #2348: process_split_and_strip_files() must
+        # use f.endswith(".ko") so that compressed modules (.ko.xz, .ko.gz) are
+        # not fed to is_elf() / strip.
+        bitbake("selftest-ko-filter -c package")
+
+        pkgdest = get_bb_var('PKGDEST', 'selftest-ko-filter')
+        libdir  = get_bb_var('libdir',  'selftest-ko-filter')
+        moddir  = pkgdest + "/selftest-ko-filter" + libdir + "/selftest-ko-filter"
+
+        self.assertTrue(os.path.exists(moddir + "/module.ko"),
+                        "module.ko missing from PKGDEST")
+
+        for fname, magic in [("module.ko.xz", b"\xfd\x37\x7a\x58\x5a\x00"),
+                             ("module.ko.gz", b"\x1f\x8b")]:
+            path = moddir + "/" + fname
+            self.assertTrue(os.path.exists(path),
+                            "%s missing from PKGDEST" % fname)
+            with open(path, "rb") as f:
+                self.assertEqual(f.read(len(magic)), magic,
+                                 "%s header corrupted in PKGDEST" % fname)
+
     def test_preserve_ownership(self):
         features = 'IMAGE_INSTALL:append = " selftest-chown"\n'
         self.write_config(features)
-- 
2.34.1