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Fix locating system python when it's not in $PATH (weird but happens, apparently) #1856

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merged 1 commit into from Jun 10, 2019
Merged

Fix locating system python when it's not in $PATH (weird but happens, apparently) #1856

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53 changes: 48 additions & 5 deletions pythonforandroid/pythonpackage.py
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Original file line number Diff line number Diff line change
Expand Up @@ -34,6 +34,7 @@


from io import open # needed for python 2
import functools
import os
from pep517.envbuild import BuildEnvironment
from pep517.wrappers import Pep517HookCaller
Expand Down Expand Up @@ -172,11 +173,23 @@ def _get_system_python_executable():

def python_binary_from_folder(path):
def binary_is_usable(python_bin):
""" Helper function to see if a given binary name refers
to a usable python interpreter binary
"""

# Abort if path isn't present at all or a directory:
if not os.path.exists(
os.path.join(path, python_bin)
) or os.path.isdir(os.path.join(path, python_bin)):
return
# We should check file not found anyway trying to run it,
# since it might be a dead symlink:
try:
filenotfounderror = FileNotFoundError
except NameError: # Python 2
filenotfounderror = OSError
try:
# Run it and see if version output works with no error:
subprocess.check_output([
os.path.join(path, python_bin), "--version"
], stderr=subprocess.STDOUT)
Expand All @@ -202,19 +215,26 @@ def binary_is_usable(python_bin):
bad_candidates = []
good_candidates = []
ever_had_nonvenv_path = False
ever_had_path_starting_with_prefix = False
for p in os.environ.get("PATH", "").split(":"):
# Skip if not possibly the real system python:
if not os.path.normpath(p).startswith(
os.path.normpath(search_prefix)
):
continue

ever_had_path_starting_with_prefix = True

# First folders might be virtualenv/venv we want to avoid:
if not ever_had_nonvenv_path:
sep = os.path.sep
if ("system32" not in p.lower() and "usr" not in p) or \
{"home", ".tox"}.intersection(set(p.split(sep))) or \
"users" in p.lower():
if (
("system32" not in p.lower() and
"usr" not in p and
not p.startswith("/opt/python")) or
{"home", ".tox"}.intersection(set(p.split(sep))) or
"users" in p.lower()
):
# Doesn't look like bog-standard system path.
if (p.endswith(os.path.sep + "bin") or
p.endswith(os.path.sep + "bin" + os.path.sep)):
Expand All @@ -226,14 +246,37 @@ def binary_is_usable(python_bin):

good_candidates.append(p)

# If we have a bad env with PATH not containing any reference to our
# real python (travis, why would you do that to me?) then just guess
# based from the search prefix location itself:
if not ever_had_path_starting_with_prefix:
# ... and yes we're scanning all the folders for that, it's dumb
# but i'm not aware of a better way: (@JonasT)
for root, dirs, files in os.walk(search_prefix, topdown=True):
for name in dirs:
bad_candidates.append(os.path.join(root, name))

# Sort candidates by length (to prefer shorter ones):
def candidate_cmp(a, b):
return len(a) - len(b)
good_candidates = sorted(
good_candidates, key=functools.cmp_to_key(candidate_cmp)
)
bad_candidates = sorted(
bad_candidates, key=functools.cmp_to_key(candidate_cmp)
)

# See if we can now actually find the system python:
for p in good_candidates + bad_candidates:
result = python_binary_from_folder(p)
if result is not None:
return result

raise RuntimeError("failed to locate system python in: " +
sys.real_prefix)
raise RuntimeError(
"failed to locate system python in: {}"
" - checked candidates were: {}, {}"
.format(sys.real_prefix, good_candidates, bad_candidates)
)


def get_package_as_folder(dependency):
Expand Down