Improve python script launching the regression tests

regression_test.py

@@ -1,33 +1,81 @@
 import os
 import sys
 from pathlib import Path
+import subprocess
 
-#example of use:
-# on linux
-#python regression_test.py /home/epernod/projects/regression_test_sofa/build/bin/Regression_test ~/projects/sofa-src ~/projects/regression_test_sofa/src/references ~/projects/sofa-build/
-# on windows
-#python ./sofa-src/applications/projects/Regression/regression_test.py /c/projects/sofa-build/bin/Release/Regression_test.exe /c/projects/sofa-src/ /c/projects/sofa-src/applications/projects/Regression/references/ /c/projects/sofa-build/
+def print_help(exit_code: int = 0) -> None:
+    script = Path(__file__).name
+    msg = f"""
+Usage:
+  python {script} <Regression_test binary> <regression_scenes_dir> <sofa_root> [<reference_plugin_dir>]
 
-#arguments:
-# 0 - script name
-# 1 - regression_test binary path
-# 2 - regression scenes dir
-# 3 - sofa build dir
-# 4 (optional) - Refrence plugin directory. If not set, will take the parent dir of this file.
+Description:
+  Prepares the environment variables needed to run the SOFA regression tests and launches the given Regression_test binary.
 
+Positional arguments:
+  <Regression_test binary>   Path to the Regression_test executable to run.
+  <regression_scenes_dir>    Directory containing the regression scenes.
+  <sofa_root>                Path to the SOFA build/install directory.
+  [<reference_plugin_dir>]   Optional. Directory of the reference plugin. Defaults to this script's parent directory.
 
-os.environ["REGRESSION_SCENES_DIR"] = sys.argv[2]
+Examples:
+  Linux:
+    python {script} /home/user/build/bin/Regression_test ~/projects/sofa-src ~/projects/sofa-build ~/projects/regression/references
+  Windows:
+    python {script} C:\\projects\\sofa-build\\bin\\Release\\Regression_test.exe C:\\projects\\sofa-src C:\\projects\\sofa-build C:\\projects\\sofa-src\\applications\\projects\\Regression\\references
+""".strip()
+    print(msg)
+    sys.exit(exit_code)
 
-os.environ["SOFA_ROOT"] = sys.argv[3]
-os.environ["SOFA_PLUGIN_PATH"] = sys.argv[3] + '/lib'
 
+# Help flag handling and argument count validation
+if len(sys.argv) == 2 and sys.argv[1] in ("-h", "--help"):
+    print_help(0)
 
-if len(sys.argv) == 5:
-    os.environ["REGRESSION_DIR"] = sys.argv[4]
-else:
-    script_dir = Path( __file__ ).parent.absolute()
-    os.environ["REGRESSION_DIR"] = script_dir
+# We expect 4 or 5 arguments total including the script name
+if len(sys.argv) not in (4, 5):
+    print("Error: invalid number of arguments.\n", file=sys.stderr)
+    print_help(1)
 
+# Securely access argv with bounds checks done above
+bin_path = Path(sys.argv[1])
+scenes_dir = Path(sys.argv[2])
+sofa_root = Path(sys.argv[3])
+regression_dir = Path(sys.argv[4]) if len(sys.argv) == 5 else Path(__file__).parent.absolute()
 
+# Validate paths before using them
+errors = []
+if not bin_path.exists():
+    errors.append(f"Regression_test binary not found: {bin_path}")
+elif bin_path.is_dir():
+    errors.append(f"Regression_test binary points to a directory, expected a file: {bin_path}")
 
-os.system(sys.argv[1])
+if not scenes_dir.exists() or not scenes_dir.is_dir():
+    errors.append(f"Invalid regression scenes directory: {scenes_dir}")
+
+if not sofa_root.exists() or not sofa_root.is_dir():
+    errors.append(f"Invalid SOFA root directory: {sofa_root}")
+
+if not regression_dir.exists() or not regression_dir.is_dir():
+    errors.append(f"Invalid reference plugin directory: {regression_dir}")
+
+if errors:
+    print("\n".join(["Argument validation failed:"] + errors), file=sys.stderr)
+    sys.exit(1)
+
+# Set required environment variables
+os.environ["REGRESSION_SCENES_DIR"] = str(scenes_dir)
+os.environ["SOFA_ROOT"] = str(sofa_root)
+os.environ["SOFA_PLUGIN_PATH"] = str(sofa_root / "lib")
+os.environ["REGRESSION_DIR"] = str(regression_dir)
+
+# Launch the binary without invoking a shell to avoid command injection issues
+try:
+    result = subprocess.run([str(bin_path)], check=False)
+    sys.exit(result.returncode)
+except FileNotFoundError:
+    print(f"Failed to execute binary (not found): {bin_path}", file=sys.stderr)
+    sys.exit(1)
+except PermissionError:
+    print(f"Failed to execute binary (permission denied): {bin_path}", file=sys.stderr)
+    sys.exit(1)