Fix python version detection in filename

CMakeLists.txt

@@ -5,7 +5,6 @@ project(pstack LANGUAGES C CXX VERSION "${PSTACK_VERSION}" )
 
 include (GNUInstallDirs)
 enable_testing()
-add_subdirectory(tests)
 
 option(PYTHON3 "Compile with python 3 support" OFF)
 option(PYTHON2 "Compile with python 2 support" ON)
@@ -181,9 +180,14 @@ add_test(NAME procself COMMAND tests/procself)
 if (PTRACE_TESTS)
 add_test(NAME suspend COMMAND tests/suspend)
 endif()
+if (Python3_Development_FOUND OR Python2_Development_FOUND)
+   add_test(NAME python_path_test COMMAND tests/python_path_test)
+endif()
 if (PYTHON3 AND Python3_Development_FOUND)
    add_test(NAME pydict COMMAND env PSTACK_BIN=${PSTACK_BIN}${CMAKE_CURRENT_SOURCE_DIR}/tests/pydict_test.py)
 endif()
 
+add_subdirectory(tests)
+
 # for automake and rpmbuild
 add_custom_target(check COMMAND make test)

libpstack/python.h

@@ -85,6 +85,7 @@ struct PythonPrinter {
 };
 bool pthreadTidOffset(Procman::Process &proc, size_t *offsetp);
 PyInterpInfo getPyInterpInfo(Procman::Process &proc);
+std::pair<int, int> getPythonVersionFromFilename(const std::string &filename);
 template <int PyV, typename T> ssize_t pyRefcnt(const T *t);
 
 template <int V>

python.cc

@@ -19,29 +19,41 @@ getPyInterpInfo(Procman::Process &proc) {
     if (libpython == nullptr)
         return PyInterpInfo {nullptr, 0, 0, "", 0};
 
-    std::string filename = libpython->io->filename();
+    auto [major, minor] = getPythonVersionFromFilename(libpython->io->filename());
 
-    auto index = filename.find("python");
+    if (proc.context.verbose > 0)
+        *proc.context.debug << "python version is: " << major << "." << minor << std::endl;
+
+    return PyInterpInfo {
+        libpython, libpythonAddr, interpreterHead,
+        "v" + std::to_string(major) + "." + std::to_string(minor),
+        V2HEX(major, minor)};
+}
+
+std::pair<int, int>
+getPythonVersionFromFilename(const std::string &filename) {
+    auto lastSlash = filename.rfind('/');
+    auto index = filename.find("python", lastSlash == std::string::npos ? 0 : lastSlash);
+
+    if (index == std::string::npos)
+        throw Exception() << "Could not find 'python' in filename: " << filename;
 
     if (filename.length() < index + 9) //index + len("pythonX.Y")
-        throw Exception() << "Can't parse python version from lib/exec name: " << filename;
+        throw Exception() << "Can't parse python version from lib/exec name: "
+            << filename << " (too short)";
 
     char majorChar = filename[index + 6];
     char minorChar = filename[index + 8];
 
     if (!isdigit(majorChar) || !isdigit(minorChar))
-        throw Exception() << "lib/exec name doesn't match \"*pythonX.Y.*\" format";
+        throw Exception()
+            << "lib/exec name " << filename
+            << " doesn't match \"*pythonX.Y.*\" format. Found '"
+            << majorChar << "' and '" << minorChar << "' where digits were expected.";
 
     int major = majorChar - '0';
     int minor = minorChar - '0';
-
-    if (proc.context.verbose > 0)
-        *proc.context.debug << "python version is: " << major << "." << minor << std::endl;
-
-    return PyInterpInfo {
-        libpython, libpythonAddr, interpreterHead,
-        "v" + std::to_string(major) + "." + std::to_string(minor),
-        V2HEX(major, minor)};
+    return {major, minor};
 }
 
 std::tuple<Elf::Object::sptr, Elf::Addr, Elf::Addr>

tests/CMakeLists.txt

@@ -37,6 +37,10 @@ target_link_libraries(procself dwelf procman)
 target_link_libraries(suspend dwelf procman)
 SET_TARGET_PROPERTIES(noreturn PROPERTIES COMPILE_FLAGS "-O2 -g")
 
+if (Python3_Development_FOUND OR Python2_Development_FOUND)
+   add_executable(python_path_test python_path_test.cc)
+   target_link_libraries(python_path_test procman dwelf)
+endif()
 
 add_custom_command(
    OUTPUT basic-no-unwind-gen

tests/python_path_test.cc

@@ -0,0 +1,63 @@
+#include <iostream>
+#include <string>
+#include <cassert>
+#include <vector>
+#include <err.h>
+#include "libpstack/python.h"
+#include "libpstack/exception.h"
+
+// Mock Exception for standalone testing if needed, but we are linking against libpstack/procman
+// which contains the Exception class.
+
+void test_py_version_from_filename(const std::string& path, int expected_major, int expected_minor, bool should_throw) {
+    try {
+        auto [major, minor] = pstack::getPythonVersionFromFilename(path);
+        if (should_throw) {
+            errx(1, "Expected exception for path: %s, but got %d.%d", path.c_str(), major, minor);
+        }
+        if (major != expected_major || minor != expected_minor) {
+            errx(1, "Failed for path: %s. Expected %d.%d, got %d.%d", path.c_str(), expected_major, expected_minor, major, minor);
+        }
+        std::cout << "PASS: " << path << " -> " << major << "." << minor << std::endl;
+    } catch (const std::exception& e) {
+        if (!should_throw) {
+             errx(1, "Unexpected exception for path: %s: %s", path.c_str(), e.what());
+        }
+        std::cout << "PASS: " << path << " -> threw exception as expected (" << e.what() << ")" << std::endl;
+    }
+}
+
+int main() {
+    // Standard cases
+    test_py_version_from_filename("/usr/lib/libpython3.9.so", 3, 9, false);
+    test_py_version_from_filename("/usr/lib/python3.9/config-3.9-x86_64-linux-gnu/libpython3.9.so", 3, 9, false);
+    test_py_version_from_filename("libpython2.7.so", 2, 7, false);
+    // Complex paths (Bazel-like)
+    test_py_version_from_filename("/execroot/_main/bazel-out/k8-opt/bin/Foo/Foo.runfiles/+_repo_rules+RPM/python39/_python3.9_dc/libpython3.9.so.1.0", 3, 9, false);
+
+    // Filename only cases
+    test_py_version_from_filename("python3.9", 3, 9, false);
+    test_py_version_from_filename("python3.9.so", 3, 9, false);
+
+    // Additional separators (should be handled by standard path logic, but good to check)
+    test_py_version_from_filename("/usr//lib//python3.8//libpython3.8.so", 3, 8, false);
+
+    // Edge cases for length and format
+    // Too short
+    test_py_version_from_filename("/usr/bin/python", 0, 0, true);
+    // Too short for X.Y logic
+    test_py_version_from_filename("/usr/bin/python3", 0, 0, true);
+    // Missing dot/digit at expected pos
+    test_py_version_from_filename("libpython39.so", 0, 0, true); 
+
+    // Directory contains "python", filename does not
+    test_py_version_from_filename("/opt/python/bin/my_app", 0, 0, true);
+
+    // other invalid names
+    test_py_version_from_filename("/usr/lib/libpython.so", 0, 0, true);
+    test_py_version_from_filename("not_a_python_lib.so", 0, 0, true);
+    // Ends in slash, no filename python
+    test_py_version_from_filename("/usr/lib/python3.9/", 0, 0, true);
+
+    return 0;
+}