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a10313ec51
Namely, in scripts that alter the search paths for dylibs, ensure to invoke `/usr/bin/xcrun` directly to run `dyld_info` and `install_name_tool`, and validate that each argument is a valid path. Addresses rdar://160463033
106 lines
4.2 KiB
Python
Executable File
106 lines
4.2 KiB
Python
Executable File
#!/usr/bin/env python3
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# On Darwin, dynamic libraries have an install name. At link time, the
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# linker can work with a dylib anywhere in the filesystem, but it will
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# write the dylib's install name into the resulting image, and at load
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# time that dylib will normally be expected to be found at exactly that
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# path. However, if the install name in an image begins with `@rpath`,
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# it will instead be searched for in the image's runtime search path
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# list. That list may contain absolute paths, but it may also contain
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# paths beginning with `@executable_path` or `@loader_path`, meaning the
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# path containing the running executable or the image being loaded,
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# respectively.
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#
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# Many of Swift's dylibs are meant to be installed on the system, which
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# means they have install names like this:
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# /usr/lib/swift/libswiftFoo.dylib
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# To support back-deployment, they also provide magic override symbols
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# ($ld$install_name) for all the OS versions preceding the addition of
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# of the library. When the linker finds a dylib with a matching override
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# for the OS deployment target, it ignores the normal install name and
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# uses the override path in the linked image's load command. Swift's
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# libraries use override paths that begin with `@rpath`, and Swift
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# builds images with a runtime search path list that starts with
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# /usr/lib/swift but then falls back on a path relative to the image;
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# thus, apps will use the system libraries if available but will
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# otherwise use fallback libraries.
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#
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# When we're working on Swift, we usually want to test the libraries
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# we just built rather than the system libraries. There are two ways
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# to achieve that. The first is to override dyld's runtime search path
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# with DYLD_LIBRARY_PATH; this will take precedence over even an
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# absolute install name. The second is to make sure the dylibs are
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# loaded via an @rpath install name and then link the program with an
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# rpath that will use the just-built libraries. Unfortunately, the
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# toolchain will ordinarily use an absolute install name instead of
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# an @rpath if the deployment target is old enough, subverting testing.
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#
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# This script looks for dependent dylibs with an absolute path in
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# /usr/lib/swift and changes them to use @rpath.
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import argparse
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import os
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import re
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import subprocess
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import sys
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def file_path(string):
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if os.path.isfile(string):
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return string
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else:
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raise argparse.ArgumentTypeError(f"{string} is not a valid path")
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def main(arguments):
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parser = argparse.ArgumentParser(
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description='Change absolute install names to use @rpath')
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parser.add_argument('bin', type=file_path, help='the binary')
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args = parser.parse_args(arguments)
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rpathize(args.bin)
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def rpathize(filename):
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dylibsOutput = None
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try:
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# `dyldinfo` has been replaced with `dyld_info`, so we try it first
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# before falling back to `dyldinfo`
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dylibsOutput = subprocess.check_output(
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['/usr/bin/xcrun', 'dyld_info', '-dependents', filename],
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universal_newlines=True)
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except subprocess.CalledProcessError:
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sys.stderr.write("falling back to 'xcrun dyldinfo' ...\n")
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dylibsOutput = subprocess.check_output(
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['/usr/bin/xcrun', 'dyldinfo', '-dylibs', filename],
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universal_newlines=True)
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# The output from dyldinfo -dylibs is a line of header followed by one
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# install name per line, indented with spaces.
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dylib_regex = re.compile(
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r"(^|.*\s)(?P<path>/usr/lib/swift/(?P<filename>.*\.dylib))\s*$")
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# Build a command to invoke install_name_tool.
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command = ['/usr/bin/xcrun', 'install_name_tool']
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for line in dylibsOutput.splitlines():
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match = dylib_regex.match(line)
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if match:
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command.append('-change')
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command.append(match.group('path'))
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command.append('@rpath/' + match.group('filename'))
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continue
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# Don't run the command if we didn't find any dylibs to change:
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# it's invalid to invoke install_name_tool without any operations.
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if len(command) == 2:
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return
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# The last argument is the filename to operate on.
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command.append(filename)
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subprocess.check_call(command)
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sys.exit(main(sys.argv[1:]))
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