AtariDos.rb in ripxplore-0.15.1

- old
+ new
@@ -13,23 +13,25 @@
 
 
 def self.host_system
   Atari800
 end  
-  
-#for now, assume that anything on an Atari compatable image format is Atari DOS
-is_valid_file_system_if lambda {true}
 
 ATARI_DOS_FILE_RECORD_LENGTH=16
 ATARI_DOS_CATALOG_START_SECTOR=361
 ATARI_DOS_CATALOG_END_SECTOR=368
+  
+#for now, assume that anything on a large enought Atari compatable image format is Atari DOS
+is_valid_file_system_if lambda {file_system_image.image_format.sector_count>=ATARI_DOS_CATALOG_END_SECTOR}
 
 
 def self.files(file_system_image)
+  return [] unless file_system_image.image_format.sector_count>=ATARI_DOS_CATALOG_END_SECTOR
   files=FileContainer.new
 #  @file_start_sectors={}
 	ATARI_DOS_CATALOG_START_SECTOR.upto(ATARI_DOS_CATALOG_END_SECTOR) do |sector_no|
 		catalog_sector_data=file_system_image.get_sector(0,sector_no)
+		raise "invalid sector no #{sector_no} (max sector number is #{file_system_image.image_format.sector_count})" if catalog_sector_data.nil?
 		0.upto(7) do |record_no|
 			catalog_record_data=catalog_sector_data[record_no*ATARI_DOS_FILE_RECORD_LENGTH,ATARI_DOS_FILE_RECORD_LENGTH]
 			directory_flag,file_length,start_sector,filename_prefix,filename_ext=catalog_record_data.unpack("CvvA8A3")
 			file_name="#{filename_prefix}.#{filename_ext}"
 #			puts "%08b %02x %02x %s" % [directory_flag,file_length,start_sector,file_name]