Class: Fat32::FileData
- Inherits:
-
Object
- Object
- Fat32::FileData
- Defined in:
- lib/fs/fat32/file_data.rb
Instance Attribute Summary collapse
-
#pos ⇒ Object
readonly
Returns the value of attribute pos.
Instance Method Summary collapse
- #close ⇒ Object
- #firstCluster ⇒ Object
- #getCluster(vcn) ⇒ Object
- #getLCN(relClus) ⇒ Object
-
#initialize(dirEntry, bootSector) ⇒ FileData
constructor
Initialization.
- #putCluster(vcn, buf) ⇒ Object
- #read(bytes = @de.length) ⇒ Object
- #rewind ⇒ Object
- #seek(offset, method = IO::SEEK_SET) ⇒ Object
- #write(buf, bytes = buf.length) ⇒ Object
Constructor Details
#initialize(dirEntry, bootSector) ⇒ FileData
Initialization
9 10 11 12 13 14 15 16 |
# File 'lib/fs/fat32/file_data.rb', line 9 def initialize(dirEntry, bootSector) raise "Nil directory entry" if dirEntry.nil? raise "Nil boot sector" if bootSector.nil? @bs = bootSector @de = dirEntry rewind end |
Instance Attribute Details
#pos ⇒ Object (readonly)
Returns the value of attribute pos.
6 7 8 |
# File 'lib/fs/fat32/file_data.rb', line 6 def pos @pos end |
Instance Method Details
#close ⇒ Object
113 114 115 |
# File 'lib/fs/fat32/file_data.rb', line 113 def close @de.close(@bs) end |
#firstCluster ⇒ Object
22 23 24 25 |
# File 'lib/fs/fat32/file_data.rb', line 22 def firstCluster return -1 if !@clusterMap || @clusterMap.size == 0 @clusterMap[0] end |
#getCluster(vcn) ⇒ Object
96 97 98 99 100 101 102 |
# File 'lib/fs/fat32/file_data.rb', line 96 def getCluster(vcn) lcn = getLCN(vcn) # puts "vcn=#{vcn}, lcn=#{lcn}" if $track_pos return MemoryBuffer.create(@bs.bytesPerCluster) if lcn == -1 raise "LCN is nill" if lcn.nil? @bs.getCluster(lcn) end |
#getLCN(relClus) ⇒ Object
117 118 119 120 121 122 123 124 125 126 |
# File 'lib/fs/fat32/file_data.rb', line 117 def getLCN(relClus) return -1 if relClus >= @clusterMap.size || @clusterMap.size == 0 lcn = @clusterMap[relClus] if lcn.nil? # puts "LCN is nil for VCN #{relClus}; Map size is #{@clusterMap.size}, cluster map follows:" # puts @clusterMap.inspect raise "Bad cluster map." end lcn end |
#putCluster(vcn, buf) ⇒ Object
104 105 106 107 108 109 110 111 |
# File 'lib/fs/fat32/file_data.rb', line 104 def putCluster(vcn, buf) lcn = getLCN(vcn) if lcn == -1 lcn = @bs.allocClusters(@clusterMap.size == 0 ? 0 : @clusterMap[@clusterMap.size - 1]) @clusterMap << lcn end @bs.writeClusters(lcn, buf) end |
#read(bytes = @de.length) ⇒ Object
38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 |
# File 'lib/fs/fat32/file_data.rb', line 38 def read(bytes = @de.length) return nil if @pos >= @de.length @clusterMap = @bs.mkClusterMap(@de.firstCluster) unless @clusterMap # Get start & end locs. bpc = @bs.bytesPerCluster startCluster, startOffset = @pos.divmod(bpc) endCluster, endOffset = (@pos + (bytes - 1)).divmod(bpc) # Single cluster. if startCluster == endCluster @pos += (endOffset - startOffset) return getCluster(startCluster)[startOffset..endOffset] end # Span clusters. out = MemoryBuffer.create(bytes) totalLen = 0 (startCluster..endCluster).each do |clus| offset = 0; len = bpc if clus == startCluster offset = startOffset len -= offset end len -= (bpc - (endOffset + 1)) if clus == endCluster out[totalLen, len] = getCluster(clus)[offset, len] totalLen += len @pos += len end out[0..totalLen] end |
#rewind ⇒ Object
18 19 20 |
# File 'lib/fs/fat32/file_data.rb', line 18 def rewind @pos = 0 end |
#seek(offset, method = IO::SEEK_SET) ⇒ Object
27 28 29 30 31 32 33 34 35 36 |
# File 'lib/fs/fat32/file_data.rb', line 27 def seek(offset, method = IO::SEEK_SET) @pos = case method when IO::SEEK_SET then offset when IO::SEEK_CUR then @pos + offset when IO::SEEK_END then @de.length - offset end @pos = 0 if @pos < 0 @pos = @de.length if @pos > @de.length @pos end |
#write(buf, bytes = buf.length) ⇒ Object
70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 |
# File 'lib/fs/fat32/file_data.rb', line 70 def write(buf, bytes = buf.length) @clusterMap = @bs.mkClusterMap(@de.firstCluster) unless @clusterMap # Get start & end locs. bytesWritten = 0; bpc = @bs.bytesPerCluster startCluster, startOffset = @pos.divmod(bpc) endCluster, endOffset = (@pos + (bytes - 1)).divmod(bpc) # For each cluster, read, deposit & write. (startCluster..endCluster).each do |clus| offset = 0; len = bpc if clus == startCluster offset = startOffset len -= offset end len -= (bpc - (endOffset + 1)) if clus == endCluster current = getCluster(clus) current[startOffset, len] = buf[bytesWritten, len] putCluster(clus, current) @pos += len; bytesWritten += len end @de.length = @pos if @pos > @de.length @de.firstCluster = @clusterMap[0] if @de.firstCluster == 0 bytesWritten end |