[PATCH bpf-next v3] selftests/bpf: Remove xxd util dependency

[Mykyta Yatsenko <mykyta.yatsenko5@gmail.com>]

From: Mykyta Yatsenko <yatsenko@meta.com>

The verification signature header generation requires converting a
binary certificate to a C array. Previously this only worked with
xxd (part of vim-common package).
As xxd may not be available on some systems building selftests, it makes
sense to substitute it with more common utils: hexdump, wc, sed to
generate equivalent C array output.

Tested by generating header with both xxd and hexdump and comparing
them.

Tested-by: Alan Maguire <alan.maguire@oracle.com>
Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
---
 tools/testing/selftests/bpf/.gitignore |  1 -
 tools/testing/selftests/bpf/Makefile   | 10 ++++++----
 2 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/tools/testing/selftests/bpf/.gitignore b/tools/testing/selftests/bpf/.gitignore
index b8bf51b7a0b0..a3ea98211ea6 100644
--- a/tools/testing/selftests/bpf/.gitignore
+++ b/tools/testing/selftests/bpf/.gitignore
@@ -23,7 +23,6 @@ test_tcpnotify_user
 test_libbpf
 xdping
 test_cpp
-test_progs_verification_cert
 *.d
 *.subskel.h
 *.skel.h
diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index 2c2f68a171ed..c6bf4dfb1495 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -720,9 +720,12 @@ $(VERIFICATION_CERT) $(PRIVATE_KEY): $(VERIFY_SIG_SETUP)
 	$(Q)mkdir -p $(BUILD_DIR)
 	$(Q)$(VERIFY_SIG_SETUP) genkey $(BUILD_DIR)
 
+# Generates a header with C array declaration, containing test_progs_verification_cert bytes
 $(VERIFY_SIG_HDR): $(VERIFICATION_CERT)
-	$(Q)ln -fs $< test_progs_verification_cert && \
-	xxd -i test_progs_verification_cert > $@
+	$(Q)(echo "unsigned char test_progs_verification_cert[] = {"; \
+	 hexdump -v -e '12/1 "  0x%02x," "\n"' $< | sed 's/0x  ,//g; $$s/,$$//'; \
+	 echo "};"; \
+	 echo "unsigned int test_progs_verification_cert_len = $$(wc -c < $<);") > $@
 
 # Define test_progs test runner.
 TRUNNER_TESTS_DIR := prog_tests
@@ -898,8 +901,7 @@ EXTRA_CLEAN := $(SCRATCH_DIR) $(HOST_SCRATCH_DIR)			\
 			       *.BTF *.BTF_ids *.BTF.base		\
 			       no_alu32 cpuv4 bpf_gcc			\
 			       liburandom_read.so)			\
-	$(OUTPUT)/FEATURE-DUMP.selftests				\
-	test_progs_verification_cert
+	$(OUTPUT)/FEATURE-DUMP.selftests
 
 .PHONY: docs docs-clean
 
-- 
2.52.0