xref: /openbmc/linux/scripts/diffconfig (revision 35e6bcd1) 
1#!/usr/bin/env python3
2# SPDX-License-Identifier: GPL-2.0
3#
4# diffconfig - a tool to compare .config files.
5#
6# originally written in 2006 by Matt Mackall
7#  (at least, this was in his bloatwatch source code)
8# last worked on 2008 by Tim Bird
9#
10
11import sys, os
12
13def usage():
14    print("""Usage: diffconfig [-h] [-m] [<config1> <config2>]
15
16Diffconfig is a simple utility for comparing two .config files.
17Using standard diff to compare .config files often includes extraneous and
18distracting information.  This utility produces sorted output with only the
19changes in configuration values between the two files.
20
21Added and removed items are shown with a leading plus or minus, respectively.
22Changed items show the old and new values on a single line.
23
24If -m is specified, then output will be in "merge" style, which has the
25changed and new values in kernel config option format.
26
27If no config files are specified, .config and .config.old are used.
28
29Example usage:
30 $ diffconfig .config config-with-some-changes
31-EXT2_FS_XATTR  n
32 CRAMFS  n -> y
33 EXT2_FS  y -> n
34 LOG_BUF_SHIFT  14 -> 16
35 PRINTK_TIME  n -> y
36""")
37    sys.exit(0)
38
39# returns a dictionary of name/value pairs for config items in the file
40def readconfig(config_file):
41    d = {}
42    for line in config_file:
43        line = line[:-1]
44        if line[:7] == "CONFIG_":
45            name, val = line[7:].split("=", 1)
46            d[name] = val
47        if line[-11:] == " is not set":
48            d[line[9:-11]] = "n"
49    return d
50
51def print_config(op, config, value, new_value):
52    global merge_style
53
54    if merge_style:
55        if new_value:
56            if new_value=="n":
57                print("# CONFIG_%s is not set" % config)
58            else:
59                print("CONFIG_%s=%s" % (config, new_value))
60    else:
61        if op=="-":
62            print("-%s %s" % (config, value))
63        elif op=="+":
64            print("+%s %s" % (config, new_value))
65        else:
66            print(" %s %s -> %s" % (config, value, new_value))
67
68def show_diff():
69    global merge_style
70
71    # parse command line args
72    if ("-h" in sys.argv or "--help" in sys.argv):
73        usage()
74
75    merge_style = 0
76    if "-m" in sys.argv:
77        merge_style = 1
78        sys.argv.remove("-m")
79
80    argc = len(sys.argv)
81    if not (argc==1 or argc == 3):
82        print("Error: incorrect number of arguments or unrecognized option")
83        usage()
84
85    if argc == 1:
86        # if no filenames given, assume .config and .config.old
87        build_dir=""
88        if "KBUILD_OUTPUT" in os.environ:
89            build_dir = os.environ["KBUILD_OUTPUT"]+"/"
90        configa_filename = build_dir + ".config.old"
91        configb_filename = build_dir + ".config"
92    else:
93        configa_filename = sys.argv[1]
94        configb_filename = sys.argv[2]
95
96    try:
97        a = readconfig(open(configa_filename))
98        b = readconfig(open(configb_filename))
99    except (IOError):
100        e = sys.exc_info()[1]
101        print("I/O error[%s]: %s\n" % (e.args[0],e.args[1]))
102        usage()
103
104    # print items in a but not b (accumulate, sort and print)
105    old = []
106    for config in a:
107        if config not in b:
108            old.append(config)
109    old.sort()
110    for config in old:
111        print_config("-", config, a[config], None)
112        del a[config]
113
114    # print items that changed (accumulate, sort, and print)
115    changed = []
116    for config in a:
117        if a[config] != b[config]:
118            changed.append(config)
119        else:
120            del b[config]
121    changed.sort()
122    for config in changed:
123        print_config("->", config, a[config], b[config])
124        del b[config]
125
126    # now print items in b but not in a
127    # (items from b that were in a were removed above)
128    new = sorted(b.keys())
129    for config in new:
130        print_config("+", config, None, b[config])
131
132def main():
133    try:
134        show_diff()
135    except BrokenPipeError:
136        # Python flushes standard streams on exit; redirect remaining output
137        # to devnull to avoid another BrokenPipeError at shutdown
138        devnull = os.open(os.devnull, os.O_WRONLY)
139        os.dup2(devnull, sys.stdout.fileno())
140        sys.exit(1)  # Python exits with error code 1 on EPIPE
141
142
143if __name__ == '__main__':
144    main()
145