ANDROID: Convert build_config to a class in create-tracefile.py

create-tracefile.py supports --repo-dir followed by the root directory
of kernel source. By default, the script assumes the root directory is
its fifth parent directory. This argument lets the user run the script
outside of the source tree. To validate the paths under --repo-dir,
build_config is converted to a class. It checks the paths when they are
needed.

Test: ./create-tracefile.py -t logs --repo-dir src
Bug: 355559072
Change-Id: If9032f9706081bbf6e5898b913d9c2713a63659d
Signed-off-by: Hsin-Yi Chen <hsinyichen@google.com>

tools/testing/android/bin/create-tracefile.py

@@ -368,29 +368,58 @@ def get_kernel_repo_dir() -> str:
   return get_parent_path(this_script_full_path, 6)
 
 
-def build_config(llvm_cov_path: str, tmp_dir: str) -> {}:
-  """Build configuration.
+class Config:
+  """The input and output paths of this script."""
 
-  Returns:
-    A dictionary containing the configuration.
-  """
-  config = {}
-  config["repo_dir"] = get_kernel_repo_dir()
-  config["output_dir"] = f'{config["repo_dir"]}/out'
-  config["output_cov_dir"] = (
-      os.path.abspath(tmp_dir) if tmp_dir else
-      os.path.join(config["repo_dir"], OUTPUT_COV_DIR)
-  )
+  def __init__(self, repo_dir: str, llvm_cov_path: str, tmp_dir: str):
+    """Each argument can be empty."""
+    self._repo_dir = os.path.abspath(repo_dir) if repo_dir else None
+    self._llvm_cov_path = (
+        os.path.abspath(llvm_cov_path) if llvm_cov_path else None
+    )
+    self._tmp_dir = os.path.abspath(tmp_dir) if tmp_dir else None
+    self._repo_out_dir = None
 
-  config["llvm_cov_filename"] = (
-      os.path.abspath(llvm_cov_path) if llvm_cov_path else
-      os.path.join(config["repo_dir"], PREBUILT_LLVM_COV_PATH)
-  )
+  @property
+  def repo_dir(self) -> str:
+    if not self._repo_dir:
+      self._repo_dir = get_kernel_repo_dir()
+    return self._repo_dir
 
-  config["llvm_gcov_sh_filename"] = (
-      f'{config["output_cov_dir"]}/tmp/llvm-gcov.sh'
-  )
-  return config
+  def _get_repo_path(self, rel_path: str) -> str:
+    repo_path = os.path.join(self.repo_dir, rel_path)
+    if not os.path.exists(repo_path):
+      logging.error(
+          "%s does not exist. If this script is not in the source directory,"
+          " specify --repo-dir. If you do not have full kernel source,"
+          " specify --llvm-cov, --gcno-dir, and --tmp-dir.",
+          repo_path,
+      )
+      sys.exit(-1)
+    return repo_path
+
+  @property
+  def llvm_cov_path(self) -> str:
+    if not self._llvm_cov_path:
+      self._llvm_cov_path = self._get_repo_path(PREBUILT_LLVM_COV_PATH)
+    return self._llvm_cov_path
+
+  @property
+  def repo_out_dir(self) -> str:
+    if not self._repo_out_dir:
+      self._repo_out_dir = self._get_repo_path("out")
+    return self._repo_out_dir
+
+  @property
+  def tmp_dir(self) -> str:
+    if not self._tmp_dir:
+      # Temporary directory does not have to exist.
+      self._tmp_dir = os.path.join(self.repo_dir, OUTPUT_COV_DIR)
+    return self._tmp_dir
+
+  @property
+  def llvm_gcov_sh_path(self) -> str:
+    return os.path.join(self.tmp_dir, "tmp", "llvm-gcov.sh")
 
 
 def main() -> None:
@@ -429,6 +458,11 @@ def main() -> None:
           " included."
       ),
   )
+  arg_parser.add_argument(
+      "--repo-dir",
+      required=False,
+      help="Root directory of kernel source"
+  )
   arg_parser.add_argument(
       "--gcno-dir",
       dest="gcno_dirs",
@@ -475,6 +509,10 @@ def main() -> None:
     logging.critical("       https://github.com/linux-test-project/lcov")
     sys.exit(-1)
 
+  if args.repo_dir and not os.path.isdir(args.repo_dir):
+    logging.error("%s is not a directory.", args.repo_dir)
+    sys.exit(-1)
+
   if args.llvm_cov and not os.path.isfile(args.llvm_cov):
     logging.error("%s is not a file.", args.llvm_cov)
     sys.exit(-1)
@@ -484,21 +522,20 @@ def main() -> None:
       logging.error("%s is not a directory.", gcno_dir)
       sys.exit(-1)
 
-  config = build_config(args.llvm_cov, args.tmp_dir)
+  config = Config(args.repo_dir, args.llvm_cov, args.tmp_dir)
 
   if args.gcno_dirs:
     gcno_mappings = read_gcno_dirs(args.gcno_dirs)
+    if not gcno_mappings:
+      logging.error("No gcno mapping files in %s", " ".join(args.gcno_dirs))
+      sys.exit(-1)
   else:
     gcno_mappings = read_gcno_mapping_files(
-        config["output_dir"], config["repo_dir"]
+        config.repo_out_dir, config.repo_dir
     )
-
-  if not gcno_mappings:
-    logging.error(
-        "Either 'to' or 'from' fields not found in the %s.",
-        config["output_dir"],
-    )
-    sys.exit(-1)
+    if not gcno_mappings:
+      logging.error("No gcno mapping files in %s", config.repo_out_dir)
+      sys.exit(-1)
 
   tar_file = find_most_recent_tarfile(
       args.tar_location, pattern="*kernel_coverage_*.tar.gz"
@@ -507,18 +544,18 @@ def main() -> None:
     logging.error("Unable to find a gcov tar under %s", args.tar_location)
     sys.exit(-1)
 
-  gcov_dir = unpack_gcov_tar(tar_file, config["output_cov_dir"])
+  gcov_dir = unpack_gcov_tar(tar_file, config.tmp_dir)
   correct_symlinks_in_directory(gcov_dir, gcno_mappings)
 
   create_llvm_gcov_sh(
-      config["llvm_cov_filename"],
-      config["llvm_gcov_sh_filename"],
+      config.llvm_cov_path,
+      config.llvm_gcov_sh_path,
   )
 
   generate_lcov_tracefile(
       gcov_dir,
-      config["repo_dir"],
-      config["llvm_gcov_sh_filename"],
+      config.repo_dir,
+      config.llvm_gcov_sh_path,
       args.out_file,
       args.include,
   )