Support python in other than /usr/bin/python

[emaste]

Summary

Use /usr/local/bin/python if it exists and /usr/bin/python does not. If that also does not exist, try python from $PATH.

This allows check_lint.sh to work on FreeBSD without the need to manually specify PYTHON_EXECUTABLE.

[samsonov]

lib/sanitizer_common/scripts/check_lint.sh

15

You never set PYTHON_EXECUTABLE to /usr/bin/python, is it intentional, or you believe it would always be in PATH in this case?

16

I'd prefer to have this flattened:

if [ -z "${PYTHON_EXECUTABLE}" ] && [ -x /usr/bin/python ]; then
  PYTHON_EXECUTABLE = /usr/bin/python
fi
if [ -z "${PYTHON_EXECUTABLE}" ] && [ -x /usr/bin/local/python ]; then
  ....

then you may also factor this out to function.
Please make sure to not introduce bash-isms.

17

Maybe, we should just print the value ${PYTHON_EXECUTABLE} if it's non-empty below?

[MatzeB]

Why not use "/usr/bin/env python" to call the python that is in the users PATH?

[emaste]

I'm happy to just switch to /usr/bin/env python in the scripts if everyone's happy with that (leaving the explicit PYTHON_EXECUTABLE override as it was).

lib/sanitizer_common/scripts/check_lint.sh

15

If it's in /usr/bin/python the PTYHON_EXECUTABLE can remain empty and #!/usr/bin/python at the beginning of the python scripts will take effect.

[emaste]

That is to say, it seemed like this intentionally used /usr/bin/python if it exists, rather than relying on python in the user's path, and I tried to keep that behaviour. I'm happy with either of

• #!/usr/bin/env python
• A find_python shell function that sets PYTHON_EXECUTABLE to the first match from /usr/bin/python, /usr/local/bin/python, $(which python)

[samsonov]

Let's try /usr/bin/env python then.

[emaste]

Just use /usr/bin/env python instead

[samsonov]

LGTM

lib/sanitizer_common/scripts/check_lint.sh

 #!/bin/sh
 
 SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
 
 # Guess path to LLVM_CHECKOUT if not provided
 if [ "${LLVM_CHECKOUT}" = "" ]; then
   LLVM_CHECKOUT="${SCRIPT_DIR}/../../../../../"
 fi
 
 # python tools setup
 CPPLINT=${SCRIPT_DIR}/cpplint.py
 LITLINT=${SCRIPT_DIR}/litlint.py
+if [ -z "${PYTHON_EXECUTABLE}" ] && [ ! -x /usr/bin/python ]; then
+  if [ -x /usr/local/bin/python ]; then
+    PYTHON_EXECUTABLE=/usr/local/bin/python
+  elif PYTHON_EXECUTABLE=$(which python 2>/dev/null); then
+    echo "Using python executable $PYTHON_EXECUTABLE from \$PATH."
+  else
+    echo "Python not found in /usr/bin/python, /usr/local/bin/python, or \$PATH."
+    echo "Set the PYTHON_EXECUTABLE environment variable to the path to your python."
+    exit 1
+  fi
+fi
 if [ "${PYTHON_EXECUTABLE}" != "" ]; then
   CPPLINT="${PYTHON_EXECUTABLE} ${CPPLINT}"
   LITLINT="${PYTHON_EXECUTABLE} ${LITLINT}"
 fi
 
 # Filters
 # TODO: remove some of these filters
 COMMON_LINT_FILTER=-build/include,-build/header_guard,-legal/copyright,-whitespace/comments,-readability/casting,\