Add more documentation; check for malloc/free etc

lib/XS/Check.pm

@@ -20,6 +20,16 @@ sub new
     return bless {};
 }
 
+# Report an error $message in $var
+
+sub report
+{
+    my ($o, $var, $message) = @_;
+    my $file = $o->get_file ();
+    my $line = $o->get_line_number ($var);
+    warn "$file$line: $message";
+}
+
 # Match a call to SvPV
 
 my $svpv_re = qr/
@@ -38,24 +48,31 @@ my $svpv_re = qr/
 sub check_svpv
 {
     my ($o, $xs) = @_;
-    my $file = $o->get_file ();
     while ($xs =~ /($svpv_re)/g) {
 	my $match = $1;
 	my $lvar = $2;
 	my $arg2 = $4;
 	my $lvar_type = $o->get_type ($lvar);
 	my $arg2_type = $o->get_type ($arg2);
 	if ($lvar_type && $lvar_type !~ /const\s+char\s+\*/) {
-	    my $lineno = $o->get_line_number ($xs);
-	    warn "$file$lineno: $lvar not const char *";
+	    $o->report ($xs, "$lvar not const char *");
 	}
 	if ($arg2_type && $arg2_type !~ /STRLEN/) {
-	    my $lineno = $o->get_line_number ($xs);
-	    warn "$file$lineno: $arg2 not STRLEN, type = $arg2_type";
+	    $o->report ($xs, "$lvar not const char *");
 	}
     }
 }
 
+# Look for malloc/calloc/realloc/free and suggest replacing them.
+
+sub check_malloc
+{
+my ($o, $xs) = @_;
+while ($xs =~ /((?:m|c|re)alloc|free)/g) {
+$o->report ("Change $1 to Newx/Newz/Safefree");
+}
+}
+
 # Regular expression to match a C declaration.
 
 my $declare_re = qr/
@@ -138,6 +155,7 @@ sub check
     $o->line_numbers ($xs);
     $o->read_declarations ($xs);
     $o->check_svpv ($xs);
+    $o->check_malloc ($xs);
 }
 
 sub check_file

lib/XS/Check.pod.tmpl

@@ -33,24 +33,74 @@ commit.commit %]> released on [% commit.date %].
 
 =head1 DESCRIPTION
 
+Check XS files for errors.
+
 =head1 METHODS
 
+=head2 new
+
+    my $check = XS::Check->new ();
+
 =head2 check
 
-=head2 new
+    $check->check ($xs);
+
+See L</SUGGESTIONS> for what this reports.
 
 =head2 check_file
 
+    $check->check ($xs_file);
+
+Convenience method to read in $xs_file then run L</check> on it.
+
+This assumes UTF-8 encoding of $xs_file.
+
+=head1 SUGGESTIONS
+
+This section details the possible suggestions made by the module and
+the motivations behind them.
+
+=head2 Use STRLEN in SvPV
+
+Using an int type for the second argument to SvPV may cause errors on
+64-bit Perls.
+
+=head2 Use const char * for return value of SvPV
+
+Be careful to not overwrite Perl's own buffer, which SvPV returns.
+
+=head2 Don't use malloc/calloc/realloc/free
+
+Replace with Newx etc. 
+
+These cause "free to wrong pool" errors on multithreaded Windows
+Perls.
+
 =head1 DEPENDENCIES
 
 =over
 
-=item L<File::Slurper>
+=item L<File::Slurper/read_text>
+
+This is used by L</check_file>.
+
+=item L<Text::LineNumber>
 
-=item L<Text::LineNumbers>
+This is used to get the line numbers.
 
 =item L<Carp>
 
 =back
 
+=head1 SEE ALSO
+
+=over
+
+=item L<Perl XS modules and CPAN testers|https://www.lemoda.net/perl/perl-xs-cpan-testers/index.html>
+
+A collection of more or less obscure bugs found by CPAN testers, the
+original inspiration for this module.
+
+=back
+
 [% INCLUDE "author" %]

t/xs-check.t

@@ -30,6 +30,12 @@ STRLEN len;
 x = SvPV (sv, len);
 EOF
 ok ($warning, "Warning with not const char *");
+$warning = undef;
+$checker->check (<<EOF);
+const char * x;
+x = malloc (100);
+EOF
+ok ($warning, "Warning with malloc");
 
 done_testing ();
 # Local variables: