FYI, I've just pushed the patch below.
I added test cases to this stand-alone Makefile,
but added the final one (for (void*)0) only after
pushing the patch below. Then I realized that
current limitations prevent detection of that
variant of 0/NULL, so have just revised the script accordingly.
u = ./useless-if-before-free
do_diff = \
diff -u <($u <(printf "$$i")|sed 's/.*: //') \
<(printf "$$i"'\n'|sed 's/;$$//')
SHELL = /bin/bash
all:
i='if (p) free(p);'; $(do_diff)
$u <(printf 'if (p) free(q);') > /dev/null && exit 1 || :
i='if (p) free((void)p);'; $(do_diff)
i='if (p) free( (void)p);'; $(do_diff)
i='if (p) free((T *) p);'; $(do_diff)
i='if (*p) free(*p);'; $(do_diff)
i='if (p)\nfree(p);'; $(do_diff)
i='if ( p ) free(p);'; $(do_diff)
i='if (p) free( p );'; $(do_diff)
i='if(p) free (p);'; $(do_diff)
i='if(p){free (p);}'; $(do_diff)
i='if(p){\nfree (p);}'; $(do_diff)
$u --name=z <(printf 'if (p) z (p);') > /dev/null
$u --name=z <(printf 'if(p)z(p);') > /dev/null
$u <(printf 'if(p[i + 1]) free(p[i + 1]);') > /dev/null
$u <(printf 'if(p[i + 1]) free(p[i+1]);') > /dev/null
test $$($u --name=z <(printf 'if(p)z(p);if(p)z(p);')|wc -l) = 2
i='if(NULL != p){\nfree (p);}'; $(do_diff)
i='if(p != NULL){\nfree (p);}'; $(do_diff)
i='if(p != 0){\nfree (p);}'; $(do_diff)
# i='if((void *)0 != p){\nfree (p);}'; $(do_diff)
>From 471cbb075f76e489fa96fad80bca65da7e01f683 Mon Sep 17 00:00:00 2001
From: Jim Meyering <meyer...@redhat.com>
Date: Wed, 28 Jan 2009 09:19:28 +0100
Subject: [PATCH] useless-if-before-free: recognize more variants
* build-aux/useless-if-before-free: Also recognize e.g.,
if (NULL != p) free (p);
---
ChangeLog | 6 +++++
build-aux/useless-if-before-free | 40 ++++++++++++++++++++++++++++---------
2 files changed, 36 insertions(+), 10 deletions(-)
diff --git a/ChangeLog b/ChangeLog
index 3b3a0f0..3a3244e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2009-01-28 Jim Meyering <meyer...@redhat.com>
+
+ useless-if-before-free: recognize more variants
+ * build-aux/useless-if-before-free: Also recognize e.g.,
+ if (NULL != p) free (p);
+
2009-01-27 Mark McLoughlin <mar...@redhat.com>
test-getaddrinfo: skip (don't fail) this test when there's no network
diff --git a/build-aux/useless-if-before-free b/build-aux/useless-if-before-free
index 0bae2c4..a2fc773 100755
--- a/build-aux/useless-if-before-free
+++ b/build-aux/useless-if-before-free
@@ -1,14 +1,16 @@
#!/usr/bin/perl -T
# Detect instances of "if (p) free (p);".
# Likewise for "if (p != NULL) free (p);". And with braces.
+# Also detect "if (NULL != p) free (p);".
+# And with 0 or "(void *)0" in place of NULL.
-my $VERSION = '2008-05-25 17:36'; # UTC
+my $VERSION = '2009-01-28 08:16'; # 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 Free Software Foundation, Inc.
+# Copyright (C) 2008, 2009 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
@@ -60,7 +62,7 @@ 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;
+ --name=N add name N to the list of \`free\'-like functions to detect;
may be repeated
--help display this help and exit
@@ -84,6 +86,14 @@ EOF
exit $exit_code;
}
+sub is_NULL ($)
+{
+ my ($expr) = @_;
+ return ($expr eq 'NULL'
+ || $expr eq '0'
+ || $expr =~ /^\(\s*(char|void)\s*\*\s*\)\s*0$/);
+}
+
{
sub EXIT_MATCH {0}
sub EXIT_NO_MATCH {1}
@@ -122,21 +132,31 @@ EOF
while (defined (my $line = <FH>))
{
while ($line =~
- /\b(if\s*\(\s*([^)]+?)(?:\s*!=\s*NULL)?\s*\)
+ /\b(if\s*\(\s*([^)]+?)(?:\s*!=\s*([^)]+?))?\s*\)
+ # 1 2 3
(?: \s*$regexp\s*\((?:\s*\([^)]+\))?\s*([^)]+)\)|
\s*\{\s*$regexp\s*\((?:\s*\([^)]+\))?\s*([^)]+)\)\s*;\s*\}))/sxg)
{
- # Compare "if" expression and free'd expression,
- # without regard to white space.
- (my $e1 = $2) =~ tr/ \t//d;
- my $e2 = defined $3 ? $3 : $4;
+ 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;
$e2 =~ tr/ \t//d;
- if ($e1 eq $e2)
+ if ($non_NULL eq $e2)
{
$found_match = 1;
$list
and (print "$file\0"), next FILE;
- print "$file: $1\n";
+ print "$file: $all\n";
}
}
}
--
1.6.1.1.374.g0d9d7
