Issue #250: python-parser/utils: Check if the Python command exists

src/engines/python-engine.cc

@@ -55,11 +55,21 @@ class PythonEngine : public ScriptEngineBase
 
 	bool start(IEventListener &listener, const std::string &executable)
 	{
+		IConfiguration &conf = IConfiguration::getInstance();
+		std::string command = conf.keyAsString("python-command");
+
 		std::string kcov_python_pipe_path =
 				IOutputHandler::getInstance().getOutDirectory() + "kcov-python.pipe";
 		std::string kcov_python_path =
 				IOutputHandler::getInstance().getBaseDirectory() + "python-helper.py";
 
+		if (!executable_exists_in_path(command))
+		{
+			error("Cannot find Python parser '%s'", command.c_str());
+
+			return false;
+		}
+
 		if (write_file(python_helper_data.data(), python_helper_data.size(),
 				"%s", kcov_python_path.c_str()) < 0) {
 				error("Can't write python helper at %s", kcov_python_path.c_str());
@@ -85,12 +95,11 @@ class PythonEngine : public ScriptEngineBase
 		/* Launch the python helper */
 		m_child = fork();
 		if (m_child == 0) {
-			IConfiguration &conf = IConfiguration::getInstance();
 			const char **argv = conf.getArgv();
 			unsigned int argc = conf.getArgc();
 
 			std::string s = fmt("%s %s ",
-					conf.keyAsString("python-command").c_str(),
+					command.c_str(),
 					kcov_python_path.c_str());
 			for (unsigned int i = 0; i < argc; i++)
 				s += "'" + std::string(argv[i]) + "' ";

src/include/utils.hh

@@ -112,6 +112,8 @@ extern std::string dir_concat(const std::string &dir, const std::string &filenam
 
 extern bool file_exists(const std::string &path);
 
+extern bool executable_exists_in_path(const std::string &path);
+
 extern uint64_t get_file_timestamp(const std::string &path);
 
 extern int concat_files(const char *dst, const char *file_a, const char *file_b);

src/utils.cc

@@ -288,6 +288,32 @@ bool file_exists(const std::string &path)
 	return out;
 }
 
+bool executable_exists_in_path(const std::string &executableName)
+{
+	// Full path to it
+	if (file_exists(executableName))
+	{
+		return true;
+	}
+
+	std::string path = getenv("PATH");
+	std::vector<std::string> parts = split_string(path, ":");
+
+	for (std::vector<std::string>::iterator it = parts.begin();
+			it != parts.end();
+			++it)
+	{
+		std::string cur = fmt("%s/%s", it->c_str(), executableName.c_str());
+
+		if (file_exists(cur))
+		{
+			return true;
+		}
+	}
+
+	return false;
+}
+
 void mock_read_file(void *(*callback)(size_t *out_size, const char *path))
 {
 	mocked_read_callback = callback;

tests/tools/python.py

@@ -10,6 +10,20 @@ def runTest(self):
 
         assert rv == noKcovRv
 
+class python_can_set_illegal_parser(testbase.KcovTestCase):
+    def runTest(self):
+        self.setUp()
+        rv,o = self.do(testbase.kcov + " --python-parser=python7 " + testbase.outbase + "/kcov " + testbase.sources + "/tests/python/main 5")
+
+        assert o.find("Cannot find Python parser 'python7'") != -1
+
+class python_can_set_legal_parser(testbase.KcovTestCase):
+    def runTest(self):
+        self.setUp()
+        rv,o = self.do(testbase.kcov + " --python-parser=python3 " + testbase.outbase + "/kcov " + testbase.sources + "/tests/python/main 5")
+
+        assert o.find("Cannot find Python parser 'python3'") == -1
+
 class python_unittest(testbase.KcovTestCase):
     def runTest(self):
         self.setUp()