improve probes lookup by dropping use of regex

Ref: #526
bpftrace · Apr 25, 2019 · 5ed8717 · 5ed8717
1 parent ee449b7
commit 5ed8717
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Showing 6 changed files with 132 additions and 25 deletions.
diff --git a/src/bpftrace.cpp b/src/bpftrace.cpp
@@ -153,25 +153,31 @@ std::set<std::string> BPFtrace::find_wildcard_matches(const std::string &prefix,
 {
   if (!has_wildcard(func))
     return std::set<std::string>({func});
-  // Turn glob into a regex
-  auto regex_str = "(" + std::regex_replace(func, std::regex("\\*"), "[^\\s]*") + ")";
-  if (prefix != "")
-    regex_str = prefix + ":" + regex_str;
-  regex_str = "^" + regex_str;
-  std::regex func_regex(regex_str);
-  std::smatch match;
+  bool start_wildcard = func[0] == '*';
+  bool end_wildcard = func[func.length() - 1] == '*';
+
+  std::vector<std::string> tokens = split_string(func, '*');
+  tokens.erase(std::remove(tokens.begin(), tokens.end(), ""), tokens.end());
 
   std::string line;
   std::set<std::string> matches;
+  std::string full_prefix = prefix.empty() ? "" : (prefix + ":");
   while (std::getline(symbol_name_stream, line))
   {
-    if (std::regex_search(line, match, func_regex))
-    {
-      assert(match.size() == 2);
-      // skip the ".part.N" kprobe variants, as they can't be traced:
-      if (std::strstr(match.str(1).c_str(), ".part.") == NULL)
-        matches.insert(match[1]);
+    if (!full_prefix.empty()) {
+      if (line.find(full_prefix, 0) != 0)
+        continue;
+      line = line.substr(full_prefix.length());
     }
+
+    if (!wildcard_match(line, tokens, start_wildcard, end_wildcard))
+      continue;
+
+    // skip the ".part.N" kprobe variants, as they can't be traced:
+    if (line.find(".part.") != std::string::npos)
+      continue;
+
+    matches.insert(line);
   }
   return matches;
 }
@@ -1499,17 +1505,6 @@ std::string BPFtrace::resolve_uid(uintptr_t addr)
   return username;
 }
 
-std::vector<std::string> BPFtrace::split_string(std::string &str, char split_by)
-{
-  std::vector<std::string> elems;
-  std::stringstream ss(str);
-  std::string value;
-  while(std::getline(ss, value, split_by)) {
-      elems.push_back(value);
-  }
-  return elems;
-}
-
 std::string BPFtrace::resolve_ksym(uintptr_t addr, bool show_offset)
 {
   struct bcc_symbol ksym;

diff --git a/src/bpftrace.h b/src/bpftrace.h
@@ -136,7 +136,6 @@ class BPFtrace
   static uint64_t read_address_from_output(std::string output);
   static std::string hist_index_label(int power);
   static std::string lhist_index_label(int number);
-  static std::vector<std::string> split_string(std::string &str, char split_by);
   std::vector<uint8_t> find_empty_key(IMap &map, size_t size) const;
   static int spawn_child(const std::vector<std::string>& args);
   static bool is_pid_alive(int pid);

diff --git a/src/utils.cpp b/src/utils.cpp
@@ -4,6 +4,7 @@
 #include <map>
 #include <string>
 #include <tuple>
+#include <sstream>
 #include <fstream>
 #include <memory>
 
@@ -76,6 +77,38 @@ bool has_wildcard(const std::string &str)
           str.find("]") != std::string::npos);
 }
 
+std::vector<std::string> split_string(const std::string &str, char delimiter) {
+  std::vector<std::string> elems;
+  std::stringstream ss(str);
+  std::string value;
+  while(std::getline(ss, value, delimiter)) {
+    elems.push_back(value);
+  }
+  return elems;
+}
+
+bool wildcard_match(const std::string &str, std::vector<std::string> &tokens, bool start_wildcard, bool end_wildcard) {
+  size_t next = 0;
+
+  if (!start_wildcard)
+    if (str.find(tokens[0], next) != next)
+      return false;
+
+  for (std::string token : tokens) {
+    size_t found = str.find(token, next);
+    if (found == std::string::npos)
+      return false;
+
+    next = found + token.length();
+  }
+
+  if (!end_wildcard)
+    if (str.length() != next)
+      return false;
+
+  return true;
+}
+
 std::vector<int> get_online_cpus()
 {
   return read_cpu_range("/sys/devices/system/cpu/online");

diff --git a/src/utils.h b/src/utils.h
@@ -30,6 +30,8 @@ static std::vector<DeprecatedName> DEPRECATED_LIST =
 
 
 bool has_wildcard(const std::string &str);
+std::vector<std::string> split_string(const std::string &str, char delimiter);
+bool wildcard_match(const std::string &str, std::vector<std::string> &tokens, bool start_wildcard, bool end_wildcard);
 std::vector<int> get_online_cpus();
 std::vector<int> get_possible_cpus();
 std::vector<std::string> get_kernel_cflags(

diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
@@ -12,6 +12,7 @@ add_executable(bpftrace_test
   probe.cpp
   semantic_analyser.cpp
   tracepoint_format_parser.cpp
+  utils.cpp
 
   ${CMAKE_SOURCE_DIR}/src/attached_probe.cpp
   ${CMAKE_SOURCE_DIR}/src/bpftrace.cpp

diff --git a/tests/utils.cpp b/tests/utils.cpp
@@ -0,0 +1,77 @@
+#include "gtest/gtest.h"
+#include "utils.h"
+
+namespace bpftrace {
+namespace test {
+namespace utils {
+
+TEST(utils, split_string)
+{
+  std::vector<std::string> tokens_empty = {};
+  std::vector<std::string> tokens_one_empty = {""};
+  std::vector<std::string> tokens_two_empty = {"", ""};
+  std::vector<std::string> tokens_f = {"", "f"};
+  std::vector<std::string> tokens_foo_bar = {"foo", "bar"};
+  std::vector<std::string> tokens_empty_foo_bar = {"", "foo", "bar"};
+  std::vector<std::string> tokens_empty_foo_empty_bar = {"", "foo", "", "bar"};
+  std::vector<std::string> tokens_empty_foo_bar_biz = {"", "foo", "bar", "biz"};
+
+  EXPECT_EQ(split_string("", '-'), tokens_empty);
+  EXPECT_EQ(split_string("-", '-'), tokens_one_empty);
+  EXPECT_EQ(split_string("--", '-'), tokens_two_empty);
+  EXPECT_EQ(split_string("-f-", '-'), tokens_f);
+  EXPECT_EQ(split_string("-foo-bar-", '-'), tokens_empty_foo_bar);
+  EXPECT_EQ(split_string("-foo--bar-", '-'), tokens_empty_foo_empty_bar);
+  EXPECT_EQ(split_string("-foo-bar-biz-", '-'), tokens_empty_foo_bar_biz);
+  EXPECT_EQ(split_string("-foo-bar", '-'), tokens_empty_foo_bar);
+  EXPECT_EQ(split_string("foo-bar-", '-'), tokens_foo_bar);
+  EXPECT_EQ(split_string("foo-bar", '-'), tokens_foo_bar);
+}
+
+TEST(utils, wildcard_match)
+{
+  std::vector<std::string> tokens_not = {"not"};
+  std::vector<std::string> tokens_bar = {"bar"};
+  std::vector<std::string> tokens_bar_not = {"bar", "not"};
+  std::vector<std::string> tokens_foo = {"foo"};
+  std::vector<std::string> tokens_biz = {"biz"};
+  std::vector<std::string> tokens_foo_biz = {"foo", "biz"};
+
+
+  // start: true, end: true
+  EXPECT_EQ(wildcard_match("foobarbiz", tokens_not, true, true), false);
+  EXPECT_EQ(wildcard_match("foobarbiz", tokens_bar, true, true), true);
+  EXPECT_EQ(wildcard_match("foobarbiz", tokens_bar_not, true, true), false);
+  EXPECT_EQ(wildcard_match("foobarbiz", tokens_foo, true, true), true);
+  EXPECT_EQ(wildcard_match("foobarbiz", tokens_biz, true, true), true);
+  EXPECT_EQ(wildcard_match("foobarbiz", tokens_foo_biz, true, true), true);
+
+  // start: false, end: true
+  EXPECT_EQ(wildcard_match("foobarbiz", tokens_not, false, true), false);
+  EXPECT_EQ(wildcard_match("foobarbiz", tokens_bar, false, true), false);
+  EXPECT_EQ(wildcard_match("foobarbiz", tokens_bar_not, false, true), false);
+  EXPECT_EQ(wildcard_match("foobarbiz", tokens_foo, false, true), true);
+  EXPECT_EQ(wildcard_match("foobarbiz", tokens_biz, false, true), false);
+  EXPECT_EQ(wildcard_match("foobarbiz", tokens_foo_biz, false, true), true);
+
+  // start: true, end: false
+  EXPECT_EQ(wildcard_match("foobarbiz", tokens_not, true, false), false);
+  EXPECT_EQ(wildcard_match("foobarbiz", tokens_bar, true, false), false);
+  EXPECT_EQ(wildcard_match("foobarbiz", tokens_bar_not, true, false), false);
+  EXPECT_EQ(wildcard_match("foobarbiz", tokens_foo, true, false), false);
+  EXPECT_EQ(wildcard_match("foobarbiz", tokens_biz, true, false), true);
+  EXPECT_EQ(wildcard_match("foobarbiz", tokens_foo_biz, true, false), true);
+
+  // start: false, end: false
+  EXPECT_EQ(wildcard_match("foobarbiz", tokens_not, false, false), false);
+  EXPECT_EQ(wildcard_match("foobarbiz", tokens_bar, false, false), false);
+  EXPECT_EQ(wildcard_match("foobarbiz", tokens_bar_not, false, false), false);
+  EXPECT_EQ(wildcard_match("foobarbiz", tokens_foo, false, false), false);
+  EXPECT_EQ(wildcard_match("foobarbiz", tokens_biz, false, false), false);
+  EXPECT_EQ(wildcard_match("foobarbiz", tokens_foo_biz, false, false), true);
+}
+
+} // namespace ast
+} // namespace test
+} // namespace bpftrace
+