scripts: fix west launcher for macOS

The $(readlink -f) call in scripts/west doesn't work on macOS.

Let's just ensure compatibility on all the platforms by moving
scripts/west-launcher.py to scripts/west, making it executable on
macOS and Linux, and launching it from the Windows doskey macro.

Signed-off-by: Marti Bolivar <marti@foundries.io>

scripts/west

@@ -1,6 +1,105 @@
-#!/bin/sh
+#!/usr/bin/env python3
 
-# Zephyr meta-tool (west) launcher alias, which keeps
-# monorepo Zephyr installations' 'make flash' etc. working.
-here=$(readlink -f $(dirname $0))
-python3 "$here/west-launcher.py" $@
+# Zephyr launcher which is interoperable with:
+#
+# 1. "mono-repo" Zephyr installations that have 'make flash'
+#    etc. supplied by a copy of some west code in scripts/meta.
+#
+# 2. "multi-repo" Zephyr installations where west is provided in a
+#    separate Git repository elsewhere.
+#
+# This is basically a copy of the "wrapper" functionality in the west
+# bootstrap script for the multi-repo case, plus a fallback onto the
+# copy in scripts/meta/west for mono-repo installs.
+
+import os
+import subprocess
+import sys
+
+if sys.version_info < (3,):
+    sys.exit('fatal error: you are running Python 2')
+
+# Top-level west directory, containing west itself and the manifest.
+WEST_DIR = 'west'
+# Subdirectory to check out the west source repository into.
+WEST = 'west'
+# File inside of WEST_DIR which marks it as the top level of the
+# Zephyr project installation.
+#
+# (The WEST_DIR name is not distinct enough to use when searching for
+# the top level; other directories named "west" may exist elsewhere,
+# e.g. zephyr/doc/west.)
+WEST_MARKER = '.west_topdir'
+
+
+class WestError(RuntimeError):
+    pass
+
+
+class WestNotFound(WestError):
+    '''Neither the current directory nor any parent has a West installation.'''
+
+
+def find_west_topdir(start):
+    '''Find the top-level installation directory, starting at ``start``.
+
+    If none is found, raises WestNotFound.'''
+    cur_dir = start
+
+    while True:
+        if os.path.isfile(os.path.join(cur_dir, WEST_DIR, WEST_MARKER)):
+            return cur_dir
+
+        parent_dir = os.path.dirname(cur_dir)
+        if cur_dir == parent_dir:
+            # At the root
+            raise WestNotFound('Could not find a West installation '
+                               'in this or any parent directory')
+        cur_dir = parent_dir
+
+
+def append_to_pythonpath(directory):
+    pp = os.environ.get('PYTHONPATH')
+    os.environ['PYTHONPATH'] = ':'.join(([pp] if pp else []) + [directory])
+
+
+def wrap(topdir, argv):
+    # Replace the wrapper process with the "real" west
+
+    # sys.argv[1:] strips the argv[0] of the wrapper script itself
+    west_git_repo = os.path.join(topdir, WEST_DIR, WEST)
+    argv = ([sys.executable,
+             os.path.join(west_git_repo, 'src', 'west', 'main.py')] +
+            argv)
+
+    try:
+        append_to_pythonpath(os.path.join(west_git_repo, 'src'))
+        subprocess.check_call(argv)
+    except subprocess.CalledProcessError as e:
+        sys.exit(e.returncode)
+
+
+def run_scripts_meta_west():
+    try:
+        subprocess.check_call([sys.executable,
+                               os.path.join(os.environ['ZEPHYR_BASE'],
+                                            'scripts', 'meta', 'west',
+                                            'main.py')] + sys.argv[1:])
+    except subprocess.CalledProcessError as e:
+        sys.exit(e.returncode)
+
+
+def main():
+    try:
+        topdir = find_west_topdir(__file__)
+    except WestNotFound:
+        topdir = None
+
+    if topdir is not None:
+        wrap(topdir, sys.argv[1:])
+    else:
+        run_scripts_meta_west()
+
+
+if __name__ == '__main__':
+    main()

zephyr-env.cmd

@@ -11,7 +11,7 @@ rem https://www.python.org/dev/peps/pep-0486/ for details on the
 rem virtualenv-related pieces. (We need to implement this manually
 rem because Zephyr's minimum supported Python version is 3.4.)
 if defined VIRTUAL_ENV (
-	doskey west=python %ZEPHYR_BASE%\scripts\west-launcher.py $*
+	doskey west=python %ZEPHYR_BASE%\scripts\west $*
 ) else (
-	doskey west=py -3 %ZEPHYR_BASE%\scripts\west-launcher.py $*
+	doskey west=py -3 %ZEPHYR_BASE%\scripts\west $*
 )