1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
|
eval '(exit $?0)' && eval 'exec perl -wST "$0" "$@"'
& eval 'exec perl -wST "$0" $argv:q'
if 0;
# Detect instances of "if (p) free (p);".
# Likewise "if (p != 0)", "if (0 != p)", or with NULL; and with braces.
my $VERSION = '2016-08-01 17:47'; # UTC
# The definition above must lie within the first 8 lines in order
# for the Emacs time-stamp write hook (at end) to update it.
# If you change this file with Emacs, please let the write hook
# do its job. Otherwise, update this string manually.
# Copyright (C) 2008-2017 Free Software Foundation, Inc.
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
# This program 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 General Public License for more details.
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
# Written by Jim Meyering
use strict;
use warnings;
use Getopt::Long;
(my $ME = $0) =~ s|.*/||;
# use File::Coda; # http://meyering.net/code/Coda/
END {
defined fileno STDOUT or return;
close STDOUT and return;
warn "$ME: failed to close standard output: $!\n";
$? ||= 1;
}
sub usage ($)
{
my ($exit_code) = @_;
my $STREAM = ($exit_code == 0 ? *STDOUT : *STDERR);
if ($exit_code != 0)
{
print $STREAM "Try '$ME --help' for more information.\n";
}
else
{
print $STREAM <<EOF;
Usage: $ME [OPTIONS] FILE...
Detect any instance in FILE of a useless "if" test before a free call, e.g.,
"if (p) free (p);". Any such test may be safely removed without affecting
the semantics of the C code in FILE. Use --name=FOO --name=BAR to also
detect free-like functions named FOO and BAR.
OPTIONS:
--list print only the name of each matching FILE (\\0-terminated)
--name=N add name N to the list of \'free\'-like functions to detect;
may be repeated
--help display this help and exit
--version output version information and exit
Exit status:
0 one or more matches
1 no match
2 an error
EXAMPLE:
For example, this command prints all removable "if" tests before "free"
and "kfree" calls in the linux kernel sources:
git ls-files -z |xargs -0 $ME --name=kfree
EOF
}
exit $exit_code;
}
sub is_NULL ($)
{
my ($expr) = @_;
return ($expr eq 'NULL' || $expr eq '0');
}
{
sub EXIT_MATCH {0}
sub EXIT_NO_MATCH {1}
sub EXIT_ERROR {2}
my $err = EXIT_NO_MATCH;
my $list;
my @name = qw(free);
GetOptions
(
help => sub { usage 0 },
version => sub { print "$ME version $VERSION\n"; exit },
list => \$list,
'name=s@' => \@name,
) or usage 1;
# Make sure we have the right number of non-option arguments.
# Always tell the user why we fail.
@ARGV < 1
and (warn "$ME: missing FILE argument\n"), usage EXIT_ERROR;
my $or = join '|', @name;
my $regexp = qr/(?:$or)/;
# Set the input record separator.
# Note: this makes it impractical to print line numbers.
$/ = '"';
my $found_match = 0;
FILE:
foreach my $file (@ARGV)
{
open FH, '<', $file
or (warn "$ME: can't open '$file' for reading: $!\n"),
$err = EXIT_ERROR, next;
while (defined (my $line = <FH>))
{
# Skip non-matching lines early to save time
$line =~ /\bif\b/
or next;
while ($line =~
/\b(if\s*\(\s*([^)]+?)(?:\s*!=\s*([^)]+?))?\s*\)
# 1 2 3
(?: \s*$regexp\s*\((?:\s*\([^)]+\))?\s*([^)]+)\)\s*;|
\s*\{\s*$regexp\s*\((?:\s*\([^)]+\))?\s*([^)]+)\)\s*;\s*\}))/sxg)
{
my $all = $1;
my ($lhs, $rhs) = ($2, $3);
my ($free_opnd, $braced_free_opnd) = ($4, $5);
my $non_NULL;
if (!defined $rhs) { $non_NULL = $lhs }
elsif (is_NULL $rhs) { $non_NULL = $lhs }
elsif (is_NULL $lhs) { $non_NULL = $rhs }
else { next }
# Compare the non-NULL part of the "if" expression and the
# free'd expression, without regard to white space.
$non_NULL =~ tr/ \t//d;
my $e2 = defined $free_opnd ? $free_opnd : $braced_free_opnd;
$e2 =~ tr/ \t//d;
if ($non_NULL eq $e2)
{
$found_match = 1;
$list
and (print "$file\0"), next FILE;
print "$file: $all\n";
}
}
}
}
continue
{
close FH;
}
$found_match && $err == EXIT_NO_MATCH
and $err = EXIT_MATCH;
exit $err;
}
my $foo = <<'EOF';
# The above is to *find* them.
# This adjusts them, removing the unnecessary "if (p)" part.
# FIXME: do something like this as an option (doesn't do braces):
free=xfree
git grep -l -z "$free *(" \
| xargs -0 useless-if-before-free -l --name="$free" \
| xargs -0 perl -0x3b -pi -e \
's/\bif\s*\(\s*(\S+?)(?:\s*!=\s*(?:0|NULL))?\s*\)\s+('"$free"'\s*\((?:\s*\([^)]+\))?\s*\1\s*\)\s*;)/$2/s'
# Use the following to remove redundant uses of kfree inside braces.
# Note that -0777 puts perl in slurp-whole-file mode;
# but we have plenty of memory, these days...
free=kfree
git grep -l -z "$free *(" \
| xargs -0 useless-if-before-free -l --name="$free" \
| xargs -0 perl -0777 -pi -e \
's/\bif\s*\(\s*(\S+?)(?:\s*!=\s*(?:0|NULL))?\s*\)\s*\{\s*('"$free"'\s*\((?:\s*\([^)]+\))?\s*\1\s*\);)\s*\}[^\n]*$/$2/gms'
Be careful that the result of the above transformation is valid.
If the matched string is followed by "else", then obviously, it won't be.
When modifying files, refuse to process anything other than a regular file.
EOF
## Local Variables:
## mode: perl
## indent-tabs-mode: nil
## eval: (add-hook 'write-file-hooks 'time-stamp)
## time-stamp-start: "my $VERSION = '"
## time-stamp-format: "%:y-%02m-%02d %02H:%02M"
## time-stamp-time-zone: "UTC0"
## time-stamp-end: "'; # UTC"
## End:
|
