BaseTools: Improve shell wrappers for Python build commands

- Use `python2` executable if it exists, to avoid breakage on systems (such as
  Arch Linux) where `python` is Python 3.
- Quote all references to `$0`, for safety when located in a directory
  containing spaces in its name.
- Use the `exec` shell command to avoid leaving the shell wrapper in the
  process table when invoking the actual build tool.
- Use `"$@"` rather than `$*` to pass arguments through directly rather than
  concatenating to a string, and then string-splitting and glob-expanding its
  contents.
- Use `$BASH_SOURCE` in preference to `$0` (which is only guaranteed to be
  process name, *not* source path).

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Charles Duffy <chaduffy@cisco.com>
Reviewed-by: Yonghong Zhu <yonghong.zhu@intel.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19694 6f19259b-4bc3-4df7-8a09-765794883524

1 files changed, 11 insertions, 2 deletions

diff --git a/BaseTools/Bin/CYGWIN_NT-5.1-i686/Trim b/BaseTools/Bin/CYGWIN_NT-5.1-i686/Trim
index 2cb8b86a99..7cac4f7c4f 100755
--- a/BaseTools/Bin/CYGWIN_NT-5.1-i686/Trim
+++ b/BaseTools/Bin/CYGWIN_NT-5.1-i686/Trim
@@ -1,5 +1,14 @@
 #!/usr/bin/env bash
 #python `dirname $0`/RunToolFromSource.py `basename $0` $*
-PYTHONPATH="`dirname $0`/../../Source/Python" \
-    python "`dirname $0`/../../Source/Python"/`basename $0`/`basename $0`.py $*
 
+# If a python2 command is available, use it in preference to python
+if command -v python2 >/dev/null 2>&1; then
+    python_exe=python2
+fi
+
+full_cmd=${BASH_SOURCE:-$0} # see http://mywiki.wooledge.org/BashFAQ/028 for a discussion of why $0 is not a good choice here
+dir=$(dirname "$full_cmd")
+exe=$(basename "$full_cmd")
+
+export PYTHONPATH="$dir/../../Source/Python"
+exec "${python_exe:-python}" "$dir/../../Source/Python/$exe/$exe.py" "$@"