Merge pull request #1450 from sandip4n/fix-test-libbcc

Fix 'test_libbcc' from failing in certain scenarios

tests/cc/CMakeLists.txt

@@ -17,7 +17,8 @@ add_executable(test_libbcc
 	test_bpf_table.cc
 	test_hash_table.cc
 	test_usdt_args.cc
-	test_usdt_probes.cc)
+	test_usdt_probes.cc
+	utils.cc)
 
 target_link_libraries(test_libbcc bcc-shared dl)
 add_test(NAME test_libbcc COMMAND ${TEST_WRAPPER} c_test_all sudo ${CMAKE_CURRENT_BINARY_DIR}/test_libbcc)

tests/cc/test_c_api.cc

@@ -193,6 +193,8 @@ static int mntns_func(void *arg) {
   return 0;
 }
 
+extern int cmd_scanf(const char *cmd, const char *fmt, ...);
+
 TEST_CASE("resolve symbol addresses for a given PID", "[c_api]") {
   struct bcc_symbol sym;
   void *resolver = bcc_symcache_new(getpid(), nullptr);
@@ -230,7 +232,32 @@ TEST_CASE("resolve symbol addresses for a given PID", "[c_api]") {
     REQUIRE(sym.module);
     REQUIRE(sym.module[0] == '/');
     REQUIRE(string(sym.module).find("libc") != string::npos);
-    REQUIRE(string("strtok") == sym.name);
+
+    // In some cases, a symbol may have multiple aliases. Since
+    // bcc_symcache_resolve() returns only the first alias of a
+    // symbol, this may not always be "strtok" even if it points
+    // to the same address.
+    bool sym_match = (string("strtok") == sym.name);
+    if (!sym_match) {
+      uint64_t exp_addr, sym_addr;
+      char cmd[256];
+      const char *cmdfmt = "nm %s | grep \" %s$\" | cut -f 1 -d \" \"";
+
+      // Find address of symbol by the expected name
+      sprintf(cmd, cmdfmt, sym.module, "strtok");
+      REQUIRE(cmd_scanf(cmd, "%lx", &exp_addr) == 0);
+
+      // Find address of symbol by the name that was
+      // returned by bcc_symcache_resolve()
+      sprintf(cmd, cmdfmt, sym.module, sym.name);
+      REQUIRE(cmd_scanf(cmd, "%lx", &sym_addr) == 0);
+
+      // If both addresses match, they are definitely
+      // aliases of the same symbol
+      sym_match = (exp_addr == sym_addr);
+    }
+
+    REQUIRE(sym_match);
   }
 
   SECTION("resolve in separate mount namespace") {

tests/cc/test_usdt_probes.cc

@@ -86,6 +86,35 @@ public:
   pid_t pid() const { return pid_; }
 };
 
+extern int cmd_scanf(const char *cmd, const char *fmt, ...);
+
+static int probe_num_locations(const char *bin_path, const char *func_name) {
+  int num_locations;
+  char cmd[512];
+  const char *cmdfmt = "readelf -n %s | grep -c \"Name: %s$\"";
+
+  sprintf(cmd, cmdfmt, bin_path, func_name);
+  if (cmd_scanf(cmd, "%d", &num_locations) != 0) {
+    return -1;
+  }
+
+  return num_locations;
+}
+
+static int probe_num_arguments(const char *bin_path, const char *func_name) {
+  int num_arguments;
+  char cmd[512];
+  const char *cmdfmt = "readelf -n %s | grep -m 1 -A 2 \" %s$\" | " \
+                       "tail -1 | cut -d \" \" -f 6- | wc -w";
+
+  sprintf(cmd, cmdfmt, bin_path, func_name);
+  if (cmd_scanf(cmd, "%d", &num_arguments) != 0) {
+    return -1;
+  }
+
+  return num_arguments;
+}
+
 TEST_CASE("test listing all USDT probes in Ruby/MRI", "[usdt]") {
   size_t mri_probe_count = 0;
 
@@ -99,40 +128,63 @@ TEST_CASE("test listing all USDT probes in Ruby/MRI", "[usdt]") {
     mri_probe_count = ctx.num_probes();
 
     SECTION("GC static probe") {
-      auto probe = ctx.get("gc__mark__begin");
+      auto name = "gc__mark__begin";
+      auto probe = ctx.get(name);
       REQUIRE(probe);
 
       REQUIRE(probe->in_shared_object() == true);
-      REQUIRE(probe->name() == "gc__mark__begin");
+      REQUIRE(probe->name() == name);
       REQUIRE(probe->provider() == "ruby");
-      REQUIRE(probe->bin_path().find("/ruby") != std::string::npos);
 
-      REQUIRE(probe->num_locations() == 1);
-      REQUIRE(probe->num_arguments() == 0);
+      auto bin_path = probe->bin_path();
+      bool bin_path_match =
+            (bin_path.find("/ruby") != std::string::npos) ||
+            (bin_path.find("/libruby") != std::string::npos);
+      REQUIRE(bin_path_match);
+
+      int exp_locations, exp_arguments;
+      exp_locations = probe_num_locations(bin_path.c_str(), name);
+      exp_arguments = probe_num_arguments(bin_path.c_str(), name);
+      REQUIRE(probe->num_locations() == exp_locations);
+      REQUIRE(probe->num_arguments() == exp_arguments);
       REQUIRE(probe->need_enable() == true);
     }
 
     SECTION("object creation probe") {
-      auto probe = ctx.get("object__create");
+      auto name = "object__create";
+      auto probe = ctx.get(name);
       REQUIRE(probe);
 
       REQUIRE(probe->in_shared_object() == true);
-      REQUIRE(probe->name() == "object__create");
+      REQUIRE(probe->name() == name);
       REQUIRE(probe->provider() == "ruby");
-      REQUIRE(probe->bin_path().find("/ruby") != std::string::npos);
 
-      REQUIRE(probe->num_locations() == 1);
-      REQUIRE(probe->num_arguments() == 3);
+      auto bin_path = probe->bin_path();
+      bool bin_path_match =
+            (bin_path.find("/ruby") != std::string::npos) ||
+            (bin_path.find("/libruby") != std::string::npos);
+      REQUIRE(bin_path_match);
+
+      int exp_locations, exp_arguments;
+      exp_locations = probe_num_locations(bin_path.c_str(), name);
+      exp_arguments = probe_num_arguments(bin_path.c_str(), name);
+      REQUIRE(probe->num_locations() == exp_locations);
+      REQUIRE(probe->num_arguments() == exp_arguments);
       REQUIRE(probe->need_enable() == true);
     }
 
     SECTION("array creation probe") {
-      auto probe = ctx.get("array__create");
+      auto name = "array__create";
+      auto probe = ctx.get(name);
       REQUIRE(probe);
-      REQUIRE(probe->name() == "array__create");
-
-      REQUIRE(probe->num_locations() == 7);
-      REQUIRE(probe->num_arguments() == 3);
+      REQUIRE(probe->name() == name);
+
+      auto bin_path = probe->bin_path().c_str();
+      int exp_locations, exp_arguments;
+      exp_locations = probe_num_locations(bin_path, name);
+      exp_arguments = probe_num_arguments(bin_path, name);
+      REQUIRE(probe->num_locations() == exp_locations);
+      REQUIRE(probe->num_arguments() == exp_arguments);
       REQUIRE(probe->need_enable() == true);
     }
   }
@@ -149,16 +201,25 @@ TEST_CASE("test listing all USDT probes in Ruby/MRI", "[usdt]") {
     REQUIRE(ctx.num_probes() >= mri_probe_count);
 
     SECTION("get probe in running process") {
-      auto probe = ctx.get("gc__mark__begin");
+      auto name = "gc__mark__begin";
+      auto probe = ctx.get(name);
       REQUIRE(probe);
 
       REQUIRE(probe->in_shared_object() == true);
-      REQUIRE(probe->name() == "gc__mark__begin");
+      REQUIRE(probe->name() == name);
       REQUIRE(probe->provider() == "ruby");
-      REQUIRE(probe->bin_path().find("/ruby") != std::string::npos);
 
-      REQUIRE(probe->num_locations() == 1);
-      REQUIRE(probe->num_arguments() == 0);
+      auto bin_path = probe->bin_path();
+      bool bin_path_match =
+            (bin_path.find("/ruby") != std::string::npos) ||
+            (bin_path.find("/libruby") != std::string::npos);
+      REQUIRE(bin_path_match);
+
+      int exp_locations, exp_arguments;
+      exp_locations = probe_num_locations(bin_path.c_str(), name);
+      exp_arguments = probe_num_arguments(bin_path.c_str(), name);
+      REQUIRE(probe->num_locations() == exp_locations);
+      REQUIRE(probe->num_arguments() == exp_arguments);
       REQUIRE(probe->need_enable() == true);
     }
   }

tests/cc/utils.cc

+/*
+ * Copyright (c) 2017 IBM Corporation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#include <stdarg.h>
+#include <stdio.h>
+
+int cmd_scanf(const char *cmd, const char *fmt, ...) {
+  va_list args;
+  FILE *pipe;
+
+  va_start(args, fmt);
+  pipe = popen(cmd, "r");
+  if (pipe == NULL) {
+    va_end(args);
+    return -1;
+  }
+
+  vfscanf(pipe, fmt, args);
+  va_end(args);
+  pclose(pipe);
+  return 0;
+}