useless-if-before-free

#!/usr/bin/perl -T
# Detect instances of "if (p) free (p);".
# Likewise for "if (p != NULL) free (p);".

my $VERSION = '2008-02-04 22:25'; # 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.

# Exit status is like grep: 0 for no match. 1 for any number.
# Note: giving line numbers isn't practical, since I've reset the
# input record separator.
use strict;
use warnings;
use Getopt::Long;

(my $ME = $0) =~ s|.*/||;

my $debug = 0;
my $verbose = 0;

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...

OPTIONS:

   --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
   --verbose    generate verbose output

EXAMPLE:

    git ls-files -z |xargs -0 $ME

EOF
    }
  exit $exit_code;
}

{
  my @name = qw(free);
  GetOptions
    (
     debug => \$debug,
     verbose => \$verbose,
     help => sub { usage 0 },
     version => sub { print "$ME version $VERSION\n"; exit },
     '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 1;

  my $or = join '|', @name;
  my $regexp = qr/(?:$or)/;

  # Set the input record separator.
  $/ = '"';

  my $found_match = 0;
  foreach my $file (@ARGV)
    {
      open FH, '<', $file
        or die "$ME: can't open `$file' for reading: $!\n";
      while (defined (my $line = <FH>))
        {
          if ($line =~
              /\b(if\s*\(\s*(\S+?)(?:\s*!=\s*NULL)?\s*\)
               (?:   \s*$regexp\s*\(\s*\2\s*\)|
                \s*\{\s*$regexp\s*\(\s*\2\s*\)\s*;\s*\}))/sx)
            {
              print "$file: $1\n";
              $found_match = 1;
            }
        }
      close FH;
    }
  exit !$found_match;
}

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.
git ls-files -z --exclude=$ME |xargs -0 \
perl -0x3b -pi -e 's/\bif\s*\(\s*(\S+?)(?:\s*!=\s*NULL)?\s*\)\s+((?:sexpr_)?free\s*\(\s*\1\s*\))/$2/s'

When modifying files, refuse to process anything other than a regular file.

# Or this one-liner to detect them:
git ls-files -z |xargs -0 perl -00 -ne '/\b(if\s*\(\s*(\S+?)(?:\s*!=\s*NULL)?\s*\)(?:\s*(?:sexpr_)?free\s*\(\s*\2\s*\)|\s*\{\s*(?:sexpr_)?free\s*\(\s*\2\s*\)\s*;\s*\}))/sx and print "$1\n"'
EOF

## Local Variables:
## 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: "UTC"
## time-stamp-end: "'; # UTC"
## End: