1 files changed, 50 insertions, 0 deletions
diff --git a/scripts/unanon b/scripts/unanon
new file mode 100755
index 0000000..5336825
--- /dev/null
+++ b/scripts/unanon
@@ -0,0 +1,50 @@
+#!/usr/bin/env perl
+#
+# Post-process files generated by protoc-c to remove anonymous unions.
+# Works on the generated files but probably little else.
+
+use warnings;
+use strict;
+
+sub unanon {
+    my $hfile = shift;
+    my $cfile = shift;
+    my ($fh, $content);
+    my %members;
+
+    open $fh, "<", $hfile or die $!;
+    local $/; # enable localized slurp mode
+    $content = <$fh>;
+    close $fh;
+
+    # Detect and replace anonymous unions in .h file.
+    # Assumes there is only one anonymous union in scope.
+    while ($content =~ s/^(struct\s+_(\w+)[^}]+)(union\s+{([^}]+)}\s*);/$1$3 u;/sm) {
+	my $s = $2;
+	my $u = $4;
+	$u =~ s:/\*((?!\*/).)*\*/::sg;
+	foreach (split(/\n+/, $u)) {
+	    if (/^.*\s+\**([^;]+);/) {
+		$members{$1} = $s;
+	    }
+	}
+    }
+    open $fh, ">", $hfile or die $!;
+    print $fh $content;
+    close $fh;
+
+    # Replace anonymous union access in generated .c file.
+    open $fh, "<", $cfile or die $!;
+    $content = <$fh>;
+    close $fh;
+
+    while (my ($key, $val) = each %members) {
+	# We only support access via offsetof()
+	$content =~ s/offsetof\($val, $key\)/offsetof($val, u.$key)/g;
+    }
+    open $fh, ">", $cfile or die $!;
+    print $fh $content;
+    close $fh;
+}
+
+unanon(@ARGV);