blob: 72a684797f15f1d575d47bfd1deba66ff7340ac8 [file] [log] [blame]
#!/usr/bin/env python
# On Darwin, dynamic libraries have an install name. At link time, the
# linker can work with a dylib anywhere in the filesystem, but it will
# write the dylib's install name into the resulting image, and at load
# time that dylib will normally be expected to be found at exactly that
# path. However, if the install name in an image begins with `@rpath`,
# it will instead be searched for in the image's runtime search path
# list. That list may contain absolute paths, but it may also contain
# paths beginning with `@executable_path` or `@loader_path`, meaning the
# path containing the running executable or the image being loaded,
# respectively.
# Many of Swift's dylibs are meant to be installed on the system, which
# means they have install names like this:
# /usr/lib/swift/libswiftFoo.dylib
# To support back-deployment, they also provide magic override symbols
# ($ld$install_name) for all the OS versions preceding the addition of
# of the library. When the linker finds a dylib with a matching override
# for the OS deployment target, it ignores the normal install name and
# uses the override path in the linked image's load command. Swift's
# libraries use override paths that begin with `@rpath`, and Swift
# builds images with a runtime search path list that starts with
# /usr/lib/swift but then falls back on a path relative to the image;
# thus, apps will use the system libraries if available but will
# otherwise use fallback libraries.
# When we're working on Swift, we usually want to test the libraries
# we just built rather than the system libraries. There are two ways
# to achieve that. The first is to override dyld's runtime search path
# with DYLD_LIBRARY_PATH; this will take precedence over even an
# absolute install name. The second is to make sure the dylibs are
# loaded via an @rpath install name and then link the program with an
# rpath that will use the just-built libraries. Unfortunately, the
# toolchain will ordinarily use an absolute install name instead of
# an @rpath if the deployment target is old enough, subverting testing.
# This script looks for dependent dylibs with an absolute path in
# /usr/lib/swift and changes them to use @rpath.
import argparse
import re
import subprocess
import sys
def main(arguments):
parser = argparse.ArgumentParser(
description='Change absolute install names to use @rpath')
parser.add_argument('bin', help='the binary')
args = parser.parse_args(arguments)
def rpathize(filename):
dylibsOutput = subprocess.check_output(
['xcrun', 'dyldinfo', '-dylibs', filename])
# The output from dyldinfo -dylibs is a line of header followed by one
# install name per line, indented with spaces.
dylib_regex = re.compile(
# Build a command to invoke install_name_tool.
command = ['install_name_tool']
for binaryline in dylibsOutput.splitlines():
line = binaryline.decode("utf-8", "strict")
match = dylib_regex.match(line)
if match:
command.append('@rpath/' +'filename'))
# Don't run the command if we didn't find any dylibs to change:
# it's invalid to invoke install_name_tool without any operations.
if len(command) == 1:
# The last argument is the filename to operate on.