From c4fe3a39f7eda6a1abb5f82e02876c7f90364bdf Mon Sep 17 00:00:00 2001
From: Leon White <l.white@interstellarlab.earth>
Date: Wed, 16 Jul 2025 11:57:16 +0200
Subject: [PATCH] testing/opentelemetry-cpp: enable on s390x

---
 testing/opentelemetry-cpp/APKBUILD            |  4 ++-
 .../opentelemetry-cpp/s390x-endianness.patch  | 32 +++++++++++++++++++
 2 files changed, 35 insertions(+), 1 deletion(-)
 create mode 100644 testing/opentelemetry-cpp/s390x-endianness.patch

diff --git a/testing/opentelemetry-cpp/APKBUILD b/testing/opentelemetry-cpp/APKBUILD
index 3c07ce5a14c..81f57ee5704 100644
--- a/testing/opentelemetry-cpp/APKBUILD
+++ b/testing/opentelemetry-cpp/APKBUILD
@@ -6,7 +6,7 @@ pkgrel=0
 _opentelemetryproto_ver=1.7.0
 pkgdesc="OpenTelemetry C++"
 url="https://opentelemetry.io/"
-arch="all !s390x" # failing test (TraceIdRatioBasedSampler.ShouldSampleWithoutContext)
+arch="all"
 license="Apache-2.0"
 depends_dev="
 	$pkgname=$pkgver-r$pkgrel
@@ -40,6 +40,7 @@ subpackages="
 source="
 	https://github.com/open-telemetry/opentelemetry-cpp/archive/v$pkgver/opentelemetry-cpp-v$pkgver.tar.gz
 	opentelemetry-proto-$_opentelemetryproto_ver.tar.gz::https://github.com/open-telemetry/opentelemetry-proto/archive/refs/tags/v$_opentelemetryproto_ver.tar.gz
+	s390x-endianness.patch
 	"
 
 build() {
@@ -96,4 +97,5 @@ zipkin() {
 sha512sums="
 a85869d2858f350e4a3b85e5d68e669a5fff42a2222ba7782bba92f5fe6856a110b3ddc9744a6c3e68c1ddfdc7bdb2b570bbeff78275a4e98cea889a8fda0120  opentelemetry-cpp-v1.22.0.tar.gz
 488ebeab036c4d202ff40a3c21fdbb6f0ab58338e680240d47ae439d5975da3ff31114325a10c8ca18d3034ed15b1b86454d853405c460891c202e3b4b8c000e  opentelemetry-proto-1.7.0.tar.gz
+f98157b0f111e0da51b67b930687ae4fe54af2c31d682729651a31c70661837495a4f6b71f28a0eaa75e6b4ac6e2000ef9379f79a50fb0c6002cf07cb39208de  s390x-endianness.patch
 "
diff --git a/testing/opentelemetry-cpp/s390x-endianness.patch b/testing/opentelemetry-cpp/s390x-endianness.patch
new file mode 100644
index 00000000000..ec2cdbb1265
--- /dev/null
+++ b/testing/opentelemetry-cpp/s390x-endianness.patch
@@ -0,0 +1,32 @@
+diff --git a/sdk/src/trace/samplers/trace_id_ratio.cc b/sdk/src/trace/samplers/trace_id_ratio.cc
+index fcb074ff..0a12c3b0 100644
+--- a/sdk/src/trace/samplers/trace_id_ratio.cc
++++ b/sdk/src/trace/samplers/trace_id_ratio.cc
+@@ -56,8 +56,13 @@ uint64_t CalculateThresholdFromBuffer(const trace_api::TraceId &trace_id) noexce
+   // We only use the first 8 bytes of TraceId.
+   static_assert(trace_api::TraceId::kSize >= 8, "TraceID must be at least 8 bytes long.");
+ 
++  // Always interpret as big-endian
++  const uint8_t *data = trace_id.Id().data();
+   uint64_t res = 0;
+-  std::memcpy(&res, &trace_id, 8);
++  for (int i = 0; i < 8; ++i)
++  {
++    res = (res << 8) | data[i];
++  }
+ 
+   double ratio = static_cast<double>(res) / static_cast<double>(UINT64_MAX);
+ 
+diff --git a/sdk/test/trace/trace_id_ratio_sampler_test.cc b/sdk/test/trace/trace_id_ratio_sampler_test.cc
+index 86aaeb40..fd509281 100644
+--- a/sdk/test/trace/trace_id_ratio_sampler_test.cc
++++ b/sdk/test/trace/trace_id_ratio_sampler_test.cc
+@@ -99,7 +99,7 @@ TEST(TraceIdRatioBasedSampler, ShouldSampleWithoutContext)
+   ASSERT_EQ(Decision::RECORD_AND_SAMPLE, sampling_result.decision);
+   ASSERT_EQ(nullptr, sampling_result.attributes);
+ 
+-  constexpr uint8_t buf[] = {0, 0, 0, 0, 0, 0, 0, 0x80, 0, 0, 0, 0, 0, 0, 0, 0};
++  constexpr uint8_t buf[] = {0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
+   trace_api::TraceId valid_trace_id(buf);
+ 
+   sampling_result = s1.ShouldSample(trace_api::SpanContext::GetInvalid(), valid_trace_id, "",