Support resolving cgroupid only if name_to_handle_at exists

Currently used image of alpine has a version of musl libc that does
not have name_to_handle_at function that is required to resolve the
cgroup id. In such case we just use an implementation that says that
resolving cgroupid is not supported.

CMakeLists.txt

@@ -60,6 +60,11 @@ add_flex_bison_dependency(flex_lexer bison_parser)
 add_library(parser ${BISON_bison_parser_OUTPUTS} ${FLEX_flex_lexer_OUTPUTS})
 target_include_directories(parser PUBLIC src src/ast ${CMAKE_BINARY_DIR})
 
+include(CheckSymbolExists)
+set(CMAKE_REQUIRED_DEFINITIONS -D_GNU_SOURCE)
+check_symbol_exists(name_to_handle_at "sys/types.h;sys/stat.h;fcntl.h" HAVE_NAME_TO_HANDLE_AT)
+set(CMAKE_REQUIRED_DEFINITIONS)
+
 find_package(LLVM REQUIRED)
 include_directories(${LLVM_INCLUDE_DIRS})
 add_definitions(${LLVM_DEFINITIONS})

src/CMakeLists.txt

@@ -13,6 +13,9 @@ add_executable(bpftrace
   list.cpp
 )
 
+if(HAVE_NAME_TO_HANDLE_AT)
+  target_compile_definitions(bpftrace PRIVATE HAVE_NAME_TO_HANDLE_AT=1)
+endif(HAVE_NAME_TO_HANDLE_AT)
 target_link_libraries(bpftrace arch ast parser resources)
 
 ExternalProject_Get_Property(bcc source_dir binary_dir)

src/bpftrace.cpp

@@ -1287,6 +1287,8 @@ uint64_t BPFtrace::resolve_kname(const std::string &name)
   return addr;
 }
 
+#ifdef HAVE_NAME_TO_HANDLE_AT
+
 namespace
 {
 
@@ -1333,6 +1335,15 @@ uint64_t BPFtrace::resolve_cgroupid(const std::string &path)
   return cfh.cgid;
 }
 
+#else
+
+uint64_t BPFtrace::resolve_cgroupid(const std::string &path)
+{
+  throw std::runtime_error("cgroupid is not supported on this system");
+}
+
+#endif
+
 uint64_t BPFtrace::resolve_uname(const std::string &name, const std::string &path)
 {
   uint64_t addr = 0;

tests/CMakeLists.txt

@@ -24,6 +24,9 @@ add_executable(bpftrace_test
   ${CMAKE_SOURCE_DIR}/src/types.cpp
 )
 
+if(HAVE_NAME_TO_HANDLE_AT)
+  target_compile_definitions(bpftrace_test PRIVATE HAVE_NAME_TO_HANDLE_AT=1)
+endif(HAVE_NAME_TO_HANDLE_AT)
 target_link_libraries(bpftrace_test arch ast parser resources)
 
 ExternalProject_Get_Property(bcc source_dir binary_dir)

tests/codegen.cpp

@@ -1128,6 +1128,8 @@ TEST(codegen, call_uaddr)
   // TODO: test uaddr()
 }
 
+#ifdef HAVE_NAME_TO_HANDLE_AT
+
 TEST(codegen, call_cgroup)
 {
   test("tracepoint:syscalls:sys_enter_openat /cgroup == 0x100000001/ { @x = cgroup }",
@@ -1172,6 +1174,8 @@ attributes #1 = { argmemonly nounwind }
 )EXPECTED");
 }
 
+#endif
+
 TEST(codegen, call_hist)
 {
   test("kprobe:f { @x = hist(pid) }",