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GH-50009: [R] FinalizeS3 segfaults for stale connection #50081

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Merged
thisisnic merged 2 commits into from
Jun 8, 2026
+28 −3
Merged

GH-50009: [R] FinalizeS3 segfaults for stale connection #50081

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62da44f
enable sigpipe handler
thisisnic Jun 2, 2026
a30f295
Address copilot PR feedback
thisisnic Jun 4, 2026
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31 changes: 28 additions & 3 deletions r/src/filesystem.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -256,10 +256,23 @@ std::string fs___SubTreeFileSystem__base_path(
return file_system->base_path();
}

// Forward declaration - defined in the ARROW_R_WITH_S3 block below.
#if defined(ARROW_R_WITH_S3)
void EnsureS3InitializedWithSigpipeHandler();
#endif

// [[arrow::export]]
cpp11::writable::list fs___FileSystemFromUri(const std::string& path) {
using cpp11::literals::operator""_nm;

#if defined(ARROW_R_WITH_S3)
// Initialize S3 before FileSystemFromUri so our options (with SIGPIPE handler)
// take effect before the C++ library's internal EnsureS3Initialized() call.
if (path.substr(0, 5) == "s3://") {
EnsureS3InitializedWithSigpipeHandler();
}
#endif

std::string out_path;
auto io_context = MainRThread::GetInstance().CancellableIOContext();
return cpp11::writable::list({"fs"_nm = cpp11::to_r6(ValueOrStop(
Expand All @@ -281,6 +294,20 @@ void fs___CopyFiles(const std::shared_ptr<fs::FileSystem>& source_fs,

#include <arrow/filesystem/s3fs.h>

// Initialize S3 with the SIGPIPE handler enabled. Without it, stale connections
// in the SDK's connection pool can trigger SIGPIPE during Aws::ShutdownAPI(),
// which causes R's signal handler to longjmp out of the teardown and segfault
// (GH-50009, GH-32026).
void EnsureS3InitializedWithSigpipeHandler() {
fs::S3GlobalOptions options = fs::S3GlobalOptions::Defaults();
options.install_sigpipe_handler = true;
auto status = fs::InitializeS3(options);
// InitializeS3 returns Invalid if already initialized - that's fine
if (!status.ok() && !fs::IsS3Initialized()) {
StopIfNotOk(status);
}
}

// [[s3::export]]
std::shared_ptr<fs::S3FileSystem> fs___S3FileSystem__create(
bool anonymous = false, std::string access_key = "", std::string secret_key = "",
Expand All @@ -291,9 +318,7 @@ std::shared_ptr<fs::S3FileSystem> fs___S3FileSystem__create(
bool allow_bucket_creation = false, bool allow_bucket_deletion = false,
bool check_directory_existence_before_creation = false, double connect_timeout = -1,
double request_timeout = -1) {
// We need to ensure that S3 is initialized before we start messing with the
// options
StopIfNotOk(fs::EnsureS3Initialized());
EnsureS3InitializedWithSigpipeHandler();
fs::S3Options s3_opts;
// Handle auth (anonymous, keys, default)
// (validation/internal coherence handled in R)
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