First working version

src/util/symcheck.pl

@@ -0,0 +1,73 @@
+#!/usr/bin/perl -w
+
+use strict;
+use warnings;
+
+my $symbols = {};
+
+# Scan output of "nm -o -g bin/blib.a" and build up symbol cross-ref table
+#
+while ( <> ) {
+  chomp;
+  ( my $object, my $type, my $symbol ) = /^.*?:(.*?\.o):.*?\s(\S)\s(.*)$/;
+  my $category = $type eq 'U' ? "requires" : "provides";
+  $symbols->{$symbol}->{$category}->{$object} = 1;
+}
+
+# Add symbols that we know will be generated or required by the linker
+#
+while ( ( my $symbol, my $info ) = each %$symbols ) {
+  $info->{requires}->{LINKER} = 1 if $symbol =~ /^obj_/;
+}
+$symbols->{$_}->{provides}->{LINKER} = 1
+    foreach qw ( _prefix _eprefix _decompress _edecompress _text
+		 _etext _data _edata _bss _ebss _end device_drivers
+		 device_drivers_end bus_drivers bus_drivers_end
+		 type_drivers type_drivers_end console_drivers
+		 console_drivers_end post_reloc_fns post_reloc_fns_end
+		 init_fns init_fns_end );
+
+# Check for multiply defined, never-defined and unused symbols
+#
+my $problems = {};
+while ( ( my $symbol, my $info ) = each %$symbols ) {
+  my @provides = keys %{$info->{provides}};
+  my @requires = keys %{$info->{requires}};
+
+  if ( @provides == 0 ) {
+    # No object provides this symbol
+    $problems->{$_}->{nonexistent}->{$symbol} = 1 foreach @requires;
+  } elsif ( @provides > 1 ) {
+    # Symbol defined in multiple objects
+    $problems->{$_}->{multiples}->{$symbol} = 1 foreach @requires;
+  }
+  if ( @requires == 0 ) {
+    # Symbol not required
+    $problems->{$_}->{unused}->{$symbol} = 1 foreach @provides;
+  }
+}
+
+# Print out error messages
+#
+my $errors = 0;
+my $warnings = 0;
+foreach my $object ( sort keys %$problems ) {
+  my @nonexistent = sort keys %{$problems->{$object}->{nonexistent}};
+  my @multiples = sort keys %{$problems->{$object}->{multiples}};
+  my @unused = sort keys %{$problems->{$object}->{unused}};
+
+  print "WARN $object provides unused symbol $_\n" foreach @unused;
+  $warnings += @unused;
+  print "ERR  $object requires non-existent symbol $_\n" foreach @nonexistent;
+  $errors += @nonexistent;
+  foreach my $symbol ( @multiples ) {
+    my @other_objects = sort grep { $_ ne $object }
+		        keys %{$symbols->{$symbol}->{provides}};
+    print "ERR  $object provides symbol $symbol"
+	." (also provided by @other_objects)\n";
+  }
+  $errors += @multiples;
+}
+
+print "$errors error(s), $warnings warning(s)\n";
+exit ( $errors ? 1 : 0 );