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authorFlorian Weimer <fweimer@redhat.com>2020-12-04 19:32:56 +0100
committerFlorian Weimer <fweimer@redhat.com>2020-12-04 19:33:36 +0100
commit7dc2f14bb340bce9a6283dfa7dfde18ec2cb24a2 (patch)
treed16738b8a193c9de27482cb69d8c29784ecbde01
parent4c38c1a229bc3628269ad98bd7e8d31d118d91f6 (diff)
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Add scripts/move-symbol-to-libc.py
This helper script can be used to move symbols to libc.abilist across all architectures, while preserving their symbol version.
-rw-r--r--scripts/move-symbol-to-libc.py217
1 files changed, 217 insertions, 0 deletions
diff --git a/scripts/move-symbol-to-libc.py b/scripts/move-symbol-to-libc.py
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+#!/usr/bin/python3
+# Move symbols from other shared objects into libc.so.
+# Copyright (C) 2020 Free Software Foundation, Inc.
+# This file is part of the GNU C Library.
+#
+# The GNU C Library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; either
+# version 2.1 of the License, or (at your option) any later version.
+#
+# The GNU C Library is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public
+# License along with the GNU C Library; if not, see
+# <https://www.gnu.org/licenses/>.
+
+"""Move symbols from other shared objects into libc.so.
+
+This script moves ABI symbols from non-libc abilists in to
+libc.abilist. Symbol versions are preserved. The script must be
+called from the top of the glibc source tree.
+
+"""
+
+import argparse
+import os.path
+import sys
+
+def replace_file(path, new_contents):
+ """Atomically replace PATH with lines from NEW_CONTENTS.
+
+ NEW_CONTENTS must be a sequence of strings.
+
+ """
+ temppath = path + 'T'
+ with open(temppath, 'w') as out:
+ for line in new_contents:
+ out.write(line)
+ os.rename(temppath, path)
+
+class VersionedSymbol:
+ """A combination of a symbol and its version."""
+
+ def __init__(self, symbol, version):
+ """Construct a new versioned symbol."""
+ assert symbol
+ assert version
+ self.symbol = symbol
+ self.version = version
+
+ def __str__(self):
+ return self.symbol + '@' + self.version
+
+ def __eq__(self, other):
+ return self.symbol == other.symbol and self.version == other.version
+
+ def __hash__(self):
+ return hash(self.symbol) ^ hash(self.version)
+
+def read_abilist(path):
+ """Read the abilist file at PATH.
+
+ Return a dictionary from VersionedSymbols to their flags (as
+ strings).
+
+ """
+ result = {}
+ with open(path) as inp:
+ for line in inp:
+ version, symbol, flags = line.strip().split(' ', 2)
+ result[VersionedSymbol(symbol, version)] = flags
+ return result
+
+def abilist_lines(symbols):
+ """Build the abilist file contents (as a list of lines).
+
+ SYMBOLS is a dictionary from VersionedSymbols to their flags.
+
+ """
+ result = []
+ for versym, flags in symbols.items():
+ result.append('{} {} {}\n'.format(
+ versym.version, versym.symbol, flags))
+ result.sort()
+ return result
+
+def add_to_libc_path(path, new_symbols):
+ """Add SYMBOLS to the abilist file PATH.
+
+ NEW_SYMBOLS is a dictionary from VersionedSymbols to their flags.
+
+ """
+ original_symbols = read_abilist(path)
+ updated_symbols = original_symbols.copy()
+ updated_symbols.update(new_symbols)
+ if updated_symbols != original_symbols:
+ sys.stdout.write('updating libc abilist {}\n'.format(path))
+ replace_file(path, abilist_lines(updated_symbols))
+
+# The name of the libc.so abilist file.
+libc_abilist = 'libc.abilist'
+
+def add_to_libc_fallback(directory, subdirs, symbol_lines):
+ """Add SYMBOL_LINES to the libc.abilist files in SUBDIRS in DIRECTORY.
+
+ All subdirectories must exist. If they do, return True. If not,
+ skip processing and return False.
+
+ """
+ abilists = [os.path.join(directory, subdir, libc_abilist)
+ for subdir in subdirs]
+ for abilist in abilists:
+ if not os.path.exists(abilist):
+ return False
+ for abilist in abilists:
+ add_to_libc_path(abilist, symbol_lines)
+ return True
+
+def add_to_libc(directory, symbol_lines):
+
+ """Add SYMBOL_LINES (a list of strings) to libc.abilist in DIRECTORY.
+
+ Try specific subdirectories as well if libc.abilist is not found
+ in DIRECTORY.
+
+ """
+ libc_path = os.path.join(directory, libc_abilist)
+ if os.path.exists(libc_path):
+ add_to_libc_path(libc_path, symbol_lines)
+ return
+
+ # Special case for powerpc32 and mips32 variants.
+ if add_to_libc_fallback(directory, ('fpu', 'nofpu'), symbol_lines):
+ return
+
+ # Special case for mips64.
+ if add_to_libc_fallback(directory, ('n32', 'n64'), symbol_lines):
+ return
+
+ raise IOError('No libc.abilist found for: {}'.format(directory))
+
+def move_symbols_1(path, to_move, moved_symbols):
+ """Move SYMBOLS from the abilist file PATH to MOVED_SYMBOLS.
+
+ TO_MOVE must be a set of strings. MOVED_SYMBOLS is a dictionary.
+
+ """
+ suffix = '.abilist'
+ assert path.endswith('.abilist')
+ library = os.path.basename(path)[:-len(suffix)]
+ placeholder = '__{}_version_placeholder'.format(library)
+
+ new_lines = []
+ changed = False
+
+ old_symbols = read_abilist(path)
+ old_versions = set(versym.version for versym in old_symbols.keys())
+ matching_symbols = dict(e for e in old_symbols.items()
+ if e[0].symbol in to_move)
+ if matching_symbols:
+ sys.stdout.write('updating {} abilist {}\n'.format(library, path))
+ new_symbols = dict(e for e in old_symbols.items()
+ if e[0].symbol not in to_move)
+
+ # Add placeholder symbols to prevent symbol versions from
+ # going away completely.
+ new_versions = set(versym.version for versym in new_symbols.keys())
+ for missing_version in old_versions - new_versions:
+ new_symbols[VersionedSymbol(placeholder, missing_version)] = 'F'
+
+ replace_file(path, abilist_lines(new_symbols))
+
+ moved_symbols.update(matching_symbols)
+
+def move_symbols(directory, files, symbols):
+ """Move SYMBOLS from FILES (a list of abilist file names) in DIRECTORY.
+
+ SYMBOLS must be a set of strings.
+
+ """
+ moved_symbols = {}
+ for filename in files:
+ move_symbols_1(os.path.join(directory, filename), symbols,
+ moved_symbols)
+ if moved_symbols:
+ add_to_libc(directory, moved_symbols)
+
+def get_parser():
+ """Return an argument parser for this module."""
+ parser = argparse.ArgumentParser(description=__doc__)
+ parser.add_argument('--only-linux', action='store_true',
+ help='Restrict the operation to Linux abilists')
+ parser.add_argument('symbols', help='name of the symbol to move',
+ nargs='+')
+ return parser
+
+def main(argv):
+ """The main entry point."""
+ parser = get_parser()
+ opts = parser.parse_args(argv)
+ if opts.only_linux:
+ sysdeps = 'sysdeps/unix/sysv/linux'
+ else:
+ sysdeps = 'sysdeps'
+
+ symbols = frozenset(opts.symbols)
+
+ for directory, dirs, files in os.walk(sysdeps):
+ move_symbols(directory, [name for name in files
+ if name != 'libc.abilist'
+ and name.endswith('.abilist')], symbols)
+
+if __name__ == '__main__':
+ main(sys.argv[1:])