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![Masahiro Yamada](/assets/img/avatar_default.png)
In the follow-up of commitfb3041d61f
("kbuild: fix SIGPIPE error message for AR=gcc-ar and AR=llvm-ar"), Kees Cook pointed out that tools should _not_ catch their own SIGPIPEs [1] [2]. Based on his feedback, LLVM was fixed [3]. However, Python's default behavior is to show noisy bracktrace when SIGPIPE is sent. So, scripts written in Python are basically in the same situation as the buggy llvm tools. Example: $ make -s allnoconfig $ make -s allmodconfig $ scripts/diffconfig .config.old .config | head -n1 -ALIX n Traceback (most recent call last): File "/home/masahiro/linux/scripts/diffconfig", line 132, in <module> main() File "/home/masahiro/linux/scripts/diffconfig", line 130, in main print_config("+", config, None, b[config]) File "/home/masahiro/linux/scripts/diffconfig", line 64, in print_config print("+%s %s" % (config, new_value)) BrokenPipeError: [Errno 32] Broken pipe Python documentation [4] notes how to make scripts die immediately and silently: """ Piping output of your program to tools like head(1) will cause a SIGPIPE signal to be sent to your process when the receiver of its standard output closes early. This results in an exception like BrokenPipeError: [Errno 32] Broken pipe. To handle this case, wrap your entry point to catch this exception as follows: import os import sys def main(): try: # simulate large output (your code replaces this loop) for x in range(10000): print("y") # flush output here to force SIGPIPE to be triggered # while inside this try block. sys.stdout.flush() except BrokenPipeError: # Python flushes standard streams on exit; redirect remaining output # to devnull to avoid another BrokenPipeError at shutdown devnull = os.open(os.devnull, os.O_WRONLY) os.dup2(devnull, sys.stdout.fileno()) sys.exit(1) # Python exits with error code 1 on EPIPE if __name__ == '__main__': main() Do not set SIGPIPE’s disposition to SIG_DFL in order to avoid BrokenPipeError. Doing that would cause your program to exit unexpectedly whenever any socket connection is interrupted while your program is still writing to it. """ Currently, tools/perf/scripts/python/intel-pt-events.py seems to be the only script that fixes the issue that way. tools/perf/scripts/python/compaction-times.py uses another approach signal.signal(signal.SIGPIPE, signal.SIG_DFL) but the Python documentation clearly says "Don't do it". I cannot fix all Python scripts since there are so many. I fixed some in the scripts/ directory. [1]: https://lore.kernel.org/all/202211161056.1B9611A@keescook/ [2]: https://github.com/llvm/llvm-project/issues/59037 [3]:4787efa380
[4]: https://docs.python.org/3/library/signal.html#note-on-sigpipe Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
144 lines
4.1 KiB
Python
Executable file
144 lines
4.1 KiB
Python
Executable file
#!/usr/bin/env python3
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# SPDX-License-Identifier: GPL-2.0
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#
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# diffconfig - a tool to compare .config files.
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#
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# originally written in 2006 by Matt Mackall
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# (at least, this was in his bloatwatch source code)
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# last worked on 2008 by Tim Bird
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#
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import sys, os
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def usage():
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print("""Usage: diffconfig [-h] [-m] [<config1> <config2>]
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Diffconfig is a simple utility for comparing two .config files.
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Using standard diff to compare .config files often includes extraneous and
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distracting information. This utility produces sorted output with only the
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changes in configuration values between the two files.
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Added and removed items are shown with a leading plus or minus, respectively.
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Changed items show the old and new values on a single line.
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If -m is specified, then output will be in "merge" style, which has the
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changed and new values in kernel config option format.
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If no config files are specified, .config and .config.old are used.
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Example usage:
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$ diffconfig .config config-with-some-changes
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-EXT2_FS_XATTR n
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CRAMFS n -> y
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EXT2_FS y -> n
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LOG_BUF_SHIFT 14 -> 16
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PRINTK_TIME n -> y
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""")
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sys.exit(0)
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# returns a dictionary of name/value pairs for config items in the file
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def readconfig(config_file):
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d = {}
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for line in config_file:
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line = line[:-1]
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if line[:7] == "CONFIG_":
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name, val = line[7:].split("=", 1)
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d[name] = val
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if line[-11:] == " is not set":
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d[line[9:-11]] = "n"
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return d
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def print_config(op, config, value, new_value):
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global merge_style
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if merge_style:
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if new_value:
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if new_value=="n":
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print("# CONFIG_%s is not set" % config)
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else:
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print("CONFIG_%s=%s" % (config, new_value))
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else:
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if op=="-":
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print("-%s %s" % (config, value))
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elif op=="+":
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print("+%s %s" % (config, new_value))
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else:
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print(" %s %s -> %s" % (config, value, new_value))
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def show_diff():
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global merge_style
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# parse command line args
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if ("-h" in sys.argv or "--help" in sys.argv):
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usage()
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merge_style = 0
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if "-m" in sys.argv:
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merge_style = 1
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sys.argv.remove("-m")
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argc = len(sys.argv)
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if not (argc==1 or argc == 3):
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print("Error: incorrect number of arguments or unrecognized option")
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usage()
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if argc == 1:
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# if no filenames given, assume .config and .config.old
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build_dir=""
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if "KBUILD_OUTPUT" in os.environ:
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build_dir = os.environ["KBUILD_OUTPUT"]+"/"
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configa_filename = build_dir + ".config.old"
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configb_filename = build_dir + ".config"
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else:
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configa_filename = sys.argv[1]
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configb_filename = sys.argv[2]
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try:
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a = readconfig(open(configa_filename))
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b = readconfig(open(configb_filename))
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except (IOError):
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e = sys.exc_info()[1]
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print("I/O error[%s]: %s\n" % (e.args[0],e.args[1]))
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usage()
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# print items in a but not b (accumulate, sort and print)
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old = []
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for config in a:
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if config not in b:
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old.append(config)
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old.sort()
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for config in old:
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print_config("-", config, a[config], None)
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del a[config]
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# print items that changed (accumulate, sort, and print)
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changed = []
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for config in a:
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if a[config] != b[config]:
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changed.append(config)
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else:
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del b[config]
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changed.sort()
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for config in changed:
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print_config("->", config, a[config], b[config])
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del b[config]
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# now print items in b but not in a
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# (items from b that were in a were removed above)
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new = sorted(b.keys())
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for config in new:
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print_config("+", config, None, b[config])
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def main():
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try:
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show_diff()
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except BrokenPipeError:
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# Python flushes standard streams on exit; redirect remaining output
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# to devnull to avoid another BrokenPipeError at shutdown
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devnull = os.open(os.devnull, os.O_WRONLY)
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os.dup2(devnull, sys.stdout.fileno())
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sys.exit(1) # Python exits with error code 1 on EPIPE
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if __name__ == '__main__':
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main()
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