[build] Pad .rom, .dsk, and .hd images to 512-byte boundaries

QEMU will silently round down a disk or ROM image file to the nearest
512 bytes.  Fix by always padding .rom, .dsk and .hd images to the
nearest 512-byte boundary.

Originally-fixed-by: Stefan Hajnoczi <stefanha@gmail.com>

contrib/bochs/README.qemu

@@ -47,13 +47,13 @@ To get qemu running is fairly simple:
 
 8.  Build gPXE floppy disk images and pad to 1.44MB
       pushd ../../src
-      make bin/rtl8139.pdsk
+      make bin/rtl8139.dsk
       popd
 
 9.  Start qemu
       ./qemu/i386-softmmu/qemu -L qemu/pc-bios \
 			       -net nic,model=rtl8139 -net tap,ifname=tap0 \
-			       -boot a -fda ../../src/bin/rtl8139.pdsk 
+			       -boot a -fda ../../src/bin/rtl8139.dsk
 
 You should see qemu start up, load up gPXE and attempt to boot from
 the network.

src/Makefile

@@ -35,6 +35,7 @@ PARSEROM	:= $(PERL) ./util/parserom.pl
 MAKEROM		:= $(PERL) ./util/makerom.pl
 SYMCHECK	:= $(PERL) ./util/symcheck.pl
 SORTOBJDUMP	:= $(PERL) ./util/sortobjdump.pl
+PADIMG		:= $(PERL) ./util/padimg.pl
 NRV2B		:= ./util/nrv2b
 ZBIN		:= ./util/zbin
 ELF2EFI32	:= ./util/elf2efi32

src/Makefile.housekeeping

@@ -724,6 +724,7 @@ define media_template
 	@$(ECHO_E) '$$(BIN)/%.$(1) : $$(BIN)/%.$(1).zbin' \
 		  '\n\t$$(QM)$(ECHO) "  [FINISH] $$@"' \
 		  '\n\t$$(Q)$$(CP) $$< $$@' \
+		  '\n\t$$(Q)$$(PAD_$(1))' \
 		  '\n\t$$(Q)$$(FINALISE_$(1))' \
 		> $(2)
 

src/arch/i386/Makefile

@@ -114,13 +114,6 @@ NON_AUTO_MEDIA	+= fd0
 	$(Q)dd if=$< bs=512 conv=sync of=/dev/fd0
 	$(Q)sync
 
-# rule to create padded disk images
-NON_AUTO_MEDIA	+= pdsk
-%pdsk : %dsk
-	$(QM)$(ECHO) "  [DSKPAD] $@"
-	$(Q)cp $< $@
-	$(Q)$(PERL) ./util/dskpad.pl $@
-
 # Add NON_AUTO_MEDIA to the media list, so that they show up in the
 # output of "make"
 #

src/arch/i386/Makefile.pcbios

@@ -27,6 +27,12 @@ MEDIA		+= raw
 MEDIA		+= com
 MEDIA		+= exe
 
+# Padding rules
+#
+PAD_rom		= $(PADIMG) --blksize=512 --byte=0xff $@
+PAD_dsk		= $(PADIMG) --blksize=512 $@
+PAD_hd		= $(PADIMG) --blksize=512 $@
+
 # rule to make a non-emulation ISO boot image
 NON_AUTO_MEDIA	+= iso
 %iso:	%lkrn util/geniso

src/util/dskpad.pl

@@ -1,12 +0,0 @@
-#!/usr/bin/perl -w
-
-use strict;
-use warnings;
-
-use constant FLOPPYSIZE => 1440 * 1024;
-
-while ( my $filename = shift ) {
-  die "$filename is not a file\n" unless -f $filename;
-  die "$filename is too large\n" unless ( -s $filename <= FLOPPYSIZE );
-  truncate $filename, FLOPPYSIZE or die "Could not truncate: $!\n";
-}

src/util/padimg.pl

@@ -0,0 +1,44 @@
+#!/usr/bin/perl -w
+
+use strict;
+use warnings;
+use Getopt::Long;
+use Fcntl;
+
+my $verbosity = 0;
+my $blksize = 512;
+my $byte = 0;
+
+my $opts = {
+  'verbose|v+' => sub { $verbosity++; },
+  'quiet|q+' => sub { $verbosity--; },
+  'blksize|s=o' => sub { $blksize = $_[1]; },
+  'byte|b=o' => sub { $byte = $_[1]; },
+};
+
+Getopt::Long::Configure ( 'bundling', 'auto_abbrev' );
+GetOptions ( { map { /^(\w+)/; $1 => $opts->{$_} } keys %$opts }, keys %$opts )
+    or die "Could not parse command-line options\n";
+
+while ( my $filename = shift ) {
+  die "$filename is not a file\n" unless -f $filename;
+  my $oldsize = -s $filename;
+  my $newsize = ( ( $oldsize + $blksize - 1 ) & ~( $blksize - 1 ) );
+  my $padsize = ( $newsize - $oldsize );
+  next unless $padsize;
+  if ( $verbosity >= 1 ) {
+      printf "Padding %s from %d to %d bytes with %d x 0x%02x\n",
+	     $filename, $oldsize, $newsize, $padsize, $byte;
+  }
+  if ( $byte ) {
+    sysopen ( my $fh, $filename, ( O_WRONLY | O_APPEND ) )
+	or die "Could not open $filename for appending: $!\n";
+    syswrite $fh, ( chr ( $byte ) x $padsize )
+	or die "Could not append to $filename: $!\n";
+    close ( $fh );
+  } else {
+    truncate $filename, $newsize
+	or die "Could not resize $filename: $!\n";
+  }
+  die "Failed to pad $filename\n" unless -s $filename == $newsize;
+}