build/wrapper.py.in

#!/usr/bin/env python3

"""
Runs an application in a manner that allows it to discover various engine
resources that may be in unexpected locations.

In particular: this allows running an application 'in-tree' under a debugger
with dependencies and resources out of line.

The base assumption is that this is probably a special circumstance and hence
should be run reasonably verbose but not interfere with a probable debugger
session.
"""

import platform
import os
import subprocess
import sys

# We need these ASAN options set so that nVidia's driver doesn't force an
# immediate halt.
#
# invalid_pointer_pairs gives overly verbose reports from deep within some
# core dependencies so it's not enabled by default.
asan_options = {
    'protect_shadow_gap': 0,
    'detect_stack_use_after_return': 1,
    #'detect_invalid_pointer_pairs': 1,
}


# A path that contains our application, the resources, and the runtime
# configuration.
#
# It is probably assumed that the root will directly contain a 'config.json';
# but there's a definitely an assumption that we won't travel deeper into a
# hierarchy without foreknowledge that we're dealing with a good path, so don't
# set this to something stupid like '/'.
#
# By default we find the first path below us that contains a 'config.json'
# file under the assumption this script sits within a game directory structure.

def find_root(init, default):
    cursor = init

    while True:
        if os.path.isfile(os.path.join(cursor, 'config.json')):
            return cursor

        parent = os.path.dirname(cursor)
        if parent == cursor:
            return default

        cursor = parent

root = os.path.abspath(os.path.dirname(__file__))
root = find_root(root, default=root)


defaults = {
    # don't break terrifically often, given we're probably running a debugger,
    # but write a lot of information to the console.
    'BREAK_LEVEL': 'CRITICAL',
    'LOG_LEVEL': 'DEBUG',

    'CL_VENDOR_IGNORE': 'intel64.icd',

    'ROOT': root,

    'ASAN_OPTIONS': ':'.join (f"{k}={v}" for k,v in asan_options.items())
}

# Overwrite our defaults with the current environment. This ensures a user can
# override any of the above variables easily from the commandline.

env = defaults.copy()
env.update(os.environ)

def host_platform(tuple: str) -> str:
    return {
        'x86_64-w64-mingw32': 'Windows'
    }[tuple]


# Don't use `platform.system()` as MinGW will pretend to be its own platform,
# and cross compiling will give you CBUILD rather than CHOST.
def is_really_windows() -> bool:
    return "@CMAKE_SYSTEM_NAME@" == "Windows"


# MSYS2 wants to fuck us over by supplying a CMake that gives something
# approximating native paths, and by _also_ providing an environment that
# cannot use these paths in places like PATH.
#
# Break the paths to conform to their expectations if we're under Windows.
def break_path_for_msys2(path):
    if not is_really_windows():
        return path

    # Test if we have a path of the form "C:/foo" (as opposed to a
    # relative path, or an MSYS2 path like "/c/foo")
    if path[1] != ':':
        return path

    return '/' + path[0] + path[2:]


# Windows has its own unique rules for library lookups. We record the
# environment variable which effects path lookups and the separator and the
# target directory for Windows and for every single other system we're likely
# to ever deal with...
if is_really_windows():
    separator = ';'
    depsdir = [ 'bin', 'lib']

    # Add the likely path to runtime dependencies for Linux/mingw.
    #
    # We want to promote this over the practice of copying DLLs into the
    # `.wine/windows/system32/` directory because it reduces the chances of
    # stale DLLs when we upgrade the compiler.
    depsdir.append("/usr/lib/gcc/x86_64-w64-mingw32/@CMAKE_CXX_COMPILER_VERSION@/")
    searchvar = 'WINEPATH'
    env['WINEDEBUG'] = '-all'
else:
    separator = ':'
    depsdir = ['lib', 'lib64']
    searchvar = 'LD_LIBRARY_PATH'

depsdir = [ f"@CMAKE_CURRENT_BINARY_DIR@/deps/{dir}" for dir in depsdir ]

# append the in-tree dependencies to the library path
search = separator.join(
    break_path_for_msys2(i) for i in depsdir
)

if searchvar in env:
    env[searchvar] = search + separator + env[searchvar]
else:
    env[searchvar] = search

env['RESOURCE_PREPEND'] = "@COMPILED_RESOURCE_DIR@"

# It's probably unnecessary to pipe std
res = subprocess.run(sys.argv[1:], env=env, stderr=sys.stderr, stdout=sys.stdout)
sys.exit(res.returncode)