DevinLeamy commented on code in PR #501:
URL: https://github.com/apache/mesos/pull/501#discussion_r1518170872
##########
src/linux/ebpf.cpp:
##########
@@ -14,4 +14,126 @@
// See the License for the specific language governing permissions and
// limitations under the License.
-#include "linux/ebpf.hpp"
\ No newline at end of file
+#include "linux/ebpf.hpp"
+
+#include <linux/bpf.h>
+#include <sys/syscall.h>
+
+#include <string>
+#include <vector>
+
+#include "stout/error.hpp"
+#include "stout/try.hpp"
+
+using std::string;
+using std::vector;
+
+namespace ebpf {
+
+#define syscall_bpf(cmd, attr, size) (int) syscall(__NR_bpf, cmd, attr, size);
+
+// Wrapper around the BPF syscall.
+Try<int> bpf(int cmd, bpf_attr* attr, size_t size)
+{
+ int result = syscall_bpf(cmd, attr, size);
+ if (result == -1) {
+ ErrnoError error;
+ return Error("BPF syscall failed with error '" + error.message + "'");
+ }
+ return result;
+}
+
+
+Program::Program(bpf_prog_type _type) : type(_type) {}
+
+
+void Program::append(vector<bpf_insn>&& instructions)
+{
+ program.insert(
+ program.end(),
+ std::make_move_iterator(instructions.begin()),
+ std::make_move_iterator(instructions.end()));
+}
+
+
+bpf_attr Program::createAttribute() const
+{
+ bpf_attr attribute;
+ std::memset(&attribute, 0, sizeof(attribute));
+
+ attribute.prog_type = type;
+ attribute.insn_cnt = program.size();
+ attribute.insns = reinterpret_cast<uint64_t>(program.data());
+ attribute.license = reinterpret_cast<uint64_t>("Apache 2.0");
+
+ return attribute;
+}
+
+
+Try<int> load(const Program&& program)
+{
+ bpf_attr attribute = program.createAttribute();
+ string logs = "";
+
+ // The BPF system call is repeated based on whether it succeeds and the
+ // return value. If it succeeds, we don't retry. It it fails with 'EAGAIN'
+ // we retry with the same parameters. If it fails with 'EACCES' - a
+ // verification error - when we retry once with an additional buffer to
+ // capture the verifier error logs.
+ //
+ // We attempt a maximum of 3 times, to avoid an infinite loop if 'EAGAIN' is
+ // returned multiple times.
+ int attempts = 0;
+ bool retry = false;
+ bool retriedWithLogs = false;
+
+ Try<int> fd = 0; // '0' because Try<int> has no default constructor.
+ do {
Review Comment:
Updated.
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