[lldb/Test] Fix ASan/TSan workaround for Xcode Python 3

[JDevlieghere]

Summary

The Python 3 interpreter in Xcode has a relative RPATH and dyld fails to load it when we copy it into the build directory. Provide a workaround for the workaround...

dyld: Library not loaded: @executable_path/../../../../Python3
  Referenced from: /Users/jonas/llvm/build-tsan/lldb-test-build.noindex/copied-python
  Reason: image not found

[JDevlieghere]

Avoid a race that would result in another test finding the copied python before it has been tested.

[JDevlieghere]

Fix typo

[JDevlieghere]

Move work out of LLDBTest so we only have to compute it once.

[vsk]

lldb/test/API/lit.cfg.py

56

This isn't relevant for the unit or shell tests because the API tests are the only ones that are executed within a python process, right?

58

Is the part about synchronization still applicable? Maybe it is, if you run llvm-lit test/API from two different directories?

101

What does setting python_executable do? I looked this up in llvm and found:

test/lit.cfg.py:    ('%llvm-locstats', "'%s' %s" % (config.python_executable, llvm_locstats_tool)))
test/lit.site.cfg.py.in:config.python_executable = "@PYTHON_EXECUTABLE@"
test/tools/UpdateTestChecks/lit.local.cfg:            config.python_executable, script_path, extra_args)))

Am I missing something, or does something here translate into a lit directive to run python files under python_interpreter?

[JDevlieghere]

lldb/test/API/lit.cfg.py

56

Correct.

58

I guess it is, but not something I'd optimize for. I'll remove the comment.

101

test/lit.site.cfg.py.in will be configured with the path to the real python executable in the build dir.

[vsk]

Lgtm, thanks.

lldb/test/API/lit.cfg.py

101

This is what I was missing: lldb/test/API/lldbtest.py: executable = test.config.python_executable.

lldb/test/API/lldbtest.py

51

.. so by the time this is reached, executable should point to a known-good python binary.

[JDevlieghere]

lldb/test/API/lldbtest.py

51

Yep!

lldb/test/API/lit.cfg.py

 config.suffixes = ['.py']
 
 # test_source_root: The root path where tests are located.
 # test_exec_root: The root path where tests should be run.
 config.test_source_root = os.path.dirname(__file__)
 config.test_exec_root = config.test_source_root
 
 
+def mkdir_p(path):
+    import errno
+    try:
+        os.makedirs(path)
+    except OSError as e:
+        if e.errno != errno.EEXIST:
+            raise
+    if not os.path.isdir(path):
+        raise OSError(errno.ENOTDIR, "%s is not a directory"%path)
+
+
 def find_sanitizer_runtime(name):
   import subprocess
   resource_dir = subprocess.check_output(
       [config.cmake_cxx_compiler,
        '-print-resource-dir']).decode('utf-8').strip()
   return os.path.join(resource_dir, 'lib', 'darwin', name)
 
 
 def find_shlibpath_var():
   if platform.system() in ['Linux', 'FreeBSD', 'NetBSD', 'SunOS']:
     yield 'LD_LIBRARY_PATH'
   elif platform.system() == 'Darwin':
     yield 'DYLD_LIBRARY_PATH'
   elif platform.system() == 'Windows':
     yield 'PATH'
 
 
+# On macOS, we can't do the DYLD_INSERT_LIBRARIES trick with a shim python
+# binary as the ASan interceptors get loaded too late. Also, when SIP is
+# enabled, we can't inject libraries into system binaries at all, so we need a
+# copy of the "real" python to work with.
+def find_python_interpreter():
+  # Avoid doing any work if we already copied the binary.
+  copied_python = os.path.join(config.lldb_build_directory, 'copied-python')
+  if os.path.isfile(copied_python):
+    return copied_python
+
+  # Find the "real" python binary.
+  import shutil, subprocess
+  real_python = subprocess.check_output([
+      config.python_executable,
+      os.path.join(os.path.dirname(os.path.realpath(__file__)),
+                   'get_darwin_real_python.py')
+  ]).decode('utf-8').strip()
+
+  shutil.copy(real_python, copied_python)
+
+  # Now make sure the copied Python works. The Python in Xcode has a relative
+  # RPATH and cannot be copied.
+  try:
+    # We don't care about the output, just make sure it runs.
+    subprocess.check_output([copied_python, '-V'], stderr=subprocess.STDOUT)
+  except subprocess.CalledProcessError:
+    # The copied Python didn't work. Assume we're dealing with the Python
+    # interpreter in Xcode. Given that this is not a system binary SIP
+    # won't prevent us form injecting the interceptors so we get away with
+    # not copying the executable.
+    os.remove(copied_python)
+    return real_python
+
+  # The copied Python works.
+  return copied_python
+
+
 if 'Address' in config.llvm_use_sanitizer:
   config.environment['ASAN_OPTIONS'] = 'detect_stack_use_after_return=1'
   if 'Darwin' in config.host_os and 'x86' in config.host_triple:
     config.environment['DYLD_INSERT_LIBRARIES'] = find_sanitizer_runtime(
         'libclang_rt.asan_osx_dynamic.dylib')
 
 if 'Thread' in config.llvm_use_sanitizer:
   if 'Darwin' in config.host_os and 'x86' in config.host_triple:
     config.environment['DYLD_INSERT_LIBRARIES'] = find_sanitizer_runtime(
         'libclang_rt.tsan_osx_dynamic.dylib')
 
+if 'DYLD_INSERT_LIBRARIES' in config.environment and platform.system() == 'Darwin':
+  config.python_executable = find_python_interpreter()
+
 # Shared library build of LLVM may require LD_LIBRARY_PATH or equivalent.
 if config.shared_libs:
   for shlibpath_var in find_shlibpath_var():
     # In stand-alone build llvm_shlib_dir specifies LLDB's lib directory while
     # llvm_libs_dir specifies LLVM's lib directory.
     shlibpath = os.path.pathsep.join(
         (config.llvm_shlib_dir, config.llvm_libs_dir,
          config.environment.get(shlibpath_var, '')))

lldb/test/API/lit.site.cfg.py.in

 config.lldb_libs_dir = "@LLDB_LIBS_DIR@"
 config.cmake_cxx_compiler = "@CMAKE_CXX_COMPILER@"
 config.host_os = "@HOST_OS@"
 config.host_triple = "@LLVM_HOST_TRIPLE@"
 config.shared_libs = @LLVM_ENABLE_SHARED_LIBS@
 config.llvm_use_sanitizer = "@LLVM_USE_SANITIZER@"
 config.target_triple = "@TARGET_TRIPLE@"
 config.lldb_build_directory = "@LLDB_TEST_BUILD_DIRECTORY@"
+config.lldb_reproducer_directory = os.path.join("@LLDB_TEST_BUILD_DIRECTORY@", "reproducers")
 config.python_executable = "@PYTHON_EXECUTABLE@"
 config.dotest_path = "@LLDB_SOURCE_DIR@/test/API/dotest.py"
 config.dotest_args_str = "@LLDB_DOTEST_ARGS@"
 config.lldb_enable_python = @LLDB_ENABLE_PYTHON@
 config.dotest_lit_args_str = None
 config.enabled_plugins = []
 config.lldb_executable = '@LLDB_TEST_EXECUTABLE@'
 config.test_arch = '@LLDB_TEST_ARCH@'

lldb/test/API/lldbtest.py

 from __future__ import absolute_import
 import os
 import tempfile
 import subprocess
 import sys
 import platform
 
 import lit.Test
 import lit.TestRunner
 import lit.util
 from lit.formats.base import TestFormat
 
-def getBuildDir(cmd):
-    found = False
-    for arg in cmd:
-        if found:
-            return arg
-        if arg == '--build-dir':
-            found = True
-    return None
-
-def mkdir_p(path):
-    import errno
-    try:
-        os.makedirs(path)
-    except OSError as e:
-        if e.errno != errno.EEXIST:
-            raise
-    if not os.path.isdir(path):
-        raise OSError(errno.ENOTDIR, "%s is not a directory"%path)
 
 class LLDBTest(TestFormat):
     def __init__(self, dotest_cmd):
         self.dotest_cmd = dotest_cmd
 
     def getTestsInDirectory(self, testSuite, path_in_suite, litConfig,
                             localConfig):
         source_path = testSuite.getSourcePath(path_in_suite)
def execute(self, test, litConfig):
 
         if test.config.unsupported:
             return (lit.Test.UNSUPPORTED, 'Test is unsupported')
 
         testPath, testFile = os.path.split(test.getSourcePath())
 
         # The Python used to run lit can be different from the Python LLDB was
         # build with.
         executable = test.config.python_executable
 
         # On Windows, the system does not always correctly interpret
         # shebang lines.  To make sure we can execute the tests, add
         # python exe as the first parameter of the command.
         cmd = [executable] + self.dotest_cmd + [testPath, '-p', testFile]
 
-        builddir = getBuildDir(cmd)
-        mkdir_p(builddir)
-
-        # On macOS, we can't do the DYLD_INSERT_LIBRARIES trick with a shim
-        # python binary as the ASan interceptors get loaded too late. Also,
-        # when SIP is enabled, we can't inject libraries into system binaries
-        # at all, so we need a copy of the "real" python to work with.
-        #
-        # Find the "real" python binary, copy it, and invoke it.
-        if 'DYLD_INSERT_LIBRARIES' in test.config.environment and \
-                platform.system() == 'Darwin':
-            copied_python = os.path.join(builddir, 'copied-system-python')
-            if not os.path.isfile(copied_python):
-                import shutil, subprocess
-                python = subprocess.check_output([
-                    executable,
-                    os.path.join(os.path.dirname(os.path.realpath(__file__)),
-                        'get_darwin_real_python.py')
-                ]).decode('utf-8').strip()
-                shutil.copy(python, copied_python)
-            cmd[0] = copied_python
-
         if 'lldb-repro-capture' in test.config.available_features or \
            'lldb-repro-replay' in test.config.available_features:
-            reproducer_root = os.path.join(builddir, 'reproducers')
-            mkdir_p(reproducer_root)
-            reproducer_path = os.path.join(reproducer_root, testFile)
+            reproducer_path = os.path.join(
+                test.config.lldb_reproducer_directory, testFile)
             if 'lldb-repro-capture' in test.config.available_features:
                 cmd.extend(['--capture-path', reproducer_path])
             else:
                 cmd.extend(['--replay-path', reproducer_path])
 
         timeoutInfo = None
         try:
             out, err, exitCode = lit.util.executeCommand(