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|
require 'zlib'
require 'git/raw/internal/object'
require 'git/raw/internal/mmap'
module Git
module Raw
module Internal
class PackFormatError < StandardError
end
class PackStorage
OBJ_OFS_DELTA = 6
OBJ_REF_DELTA = 7
FanOutCount = 256
SHA1Size = 20
IdxOffsetSize = 4
OffsetSize = 4
OffsetStart = FanOutCount * IdxOffsetSize
SHA1Start = OffsetStart + OffsetSize
EntrySize = OffsetSize + SHA1Size
def initialize(file)
if file =~ /\.idx$/
file = file[0...-3] + 'pack'
end
@name = file
@packfile = File.open(file)
@idxfile = File.open(file[0...-4]+'idx')
@idx = Mmap.new(@idxfile)
@offsets = [0]
FanOutCount.times do |i|
pos = @idx[i * IdxOffsetSize,IdxOffsetSize].unpack('N')[0]
if pos < @offsets[i]
raise PackFormatError, "pack #@name has discontinuous index #{i}"
end
@offsets << pos
end
@size = @offsets[-1]
end
def name
@name
end
def close
@packfile.close
@idx.unmap
@idxfile.close
end
def [](sha1)
offset = find_object(sha1)
return nil if !offset
return parse_object(offset)
end
def each_entry
pos = OffsetStart
@size.times do
offset = @idx[pos,OffsetSize].unpack('N')[0]
sha1 = @idx[pos+OffsetSize,SHA1Size]
pos += EntrySize
yield sha1, offset
end
end
def each_sha1
# unpacking the offset is quite expensive, so
# we avoid using #each
pos = SHA1Start
@size.times do
sha1 = @idx[pos,SHA1Size]
pos += EntrySize
yield sha1
end
end
def find_object(sha1)
slot = sha1[0]
first, last = @offsets[slot,2]
while first < last
mid = (first + last) / 2
midsha1 = @idx[SHA1Start + mid * EntrySize,SHA1Size]
cmp = midsha1 <=> sha1
if cmp < 0
first = mid + 1
elsif cmp > 0
last = mid
else
pos = OffsetStart + mid * EntrySize
offset = @idx[pos,OffsetSize].unpack('N')[0]
return offset
end
end
nil
end
private :find_object
def parse_object(offset)
data, type = unpack_object(offset)
RawObject.new(OBJ_TYPES[type], data)
end
protected :parse_object
def unpack_object(offset)
obj_offset = offset
@packfile.seek(offset)
c = @packfile.read(1)[0]
size = c & 0xf
type = (c >> 4) & 7
shift = 4
offset += 1
while c & 0x80 != 0
c = @packfile.read(1)[0]
size |= ((c & 0x7f) << shift)
shift += 7
offset += 1
end
case type
when OBJ_OFS_DELTA, OBJ_REF_DELTA
data, type = unpack_deltified(type, offset, obj_offset, size)
when OBJ_COMMIT, OBJ_TREE, OBJ_BLOB, OBJ_TAG
data = unpack_compressed(offset, size)
else
raise PackFormatError, "invalid type #{type}"
end
[data, type]
end
private :unpack_object
def unpack_deltified(type, offset, obj_offset, size)
@packfile.seek(offset)
data = @packfile.read(SHA1Size)
if type == OBJ_OFS_DELTA
i = 0
c = data[i]
base_offset = c & 0x7f
while c & 0x80 != 0
c = data[i += 1]
base_offset += 1
base_offset <<= 7
base_offset |= c & 0x7f
end
base_offset = obj_offset - base_offset
offset += i + 1
else
base_offset = find_object(data)
offset += SHA1Size
end
base, type = unpack_object(base_offset)
delta = unpack_compressed(offset, size)
[patch_delta(base, delta), type]
end
private :unpack_deltified
def unpack_compressed(offset, destsize)
outdata = ""
@packfile.seek(offset)
zstr = Zlib::Inflate.new
while outdata.size < destsize
indata = @packfile.read(4096)
if indata.size == 0
raise PackFormatError, 'error reading pack data'
end
outdata += zstr.inflate(indata)
end
if outdata.size > destsize
raise PackFormatError, 'error reading pack data'
end
zstr.close
outdata
end
private :unpack_compressed
def patch_delta(base, delta)
src_size, pos = patch_delta_header_size(delta, 0)
if src_size != base.size
raise PackFormatError, 'invalid delta data'
end
dest_size, pos = patch_delta_header_size(delta, pos)
dest = ""
while pos < delta.size
c = delta[pos]
pos += 1
if c & 0x80 != 0
pos -= 1
cp_off = cp_size = 0
cp_off = delta[pos += 1] if c & 0x01 != 0
cp_off |= delta[pos += 1] << 8 if c & 0x02 != 0
cp_off |= delta[pos += 1] << 16 if c & 0x04 != 0
cp_off |= delta[pos += 1] << 24 if c & 0x08 != 0
cp_size = delta[pos += 1] if c & 0x10 != 0
cp_size |= delta[pos += 1] << 8 if c & 0x20 != 0
cp_size |= delta[pos += 1] << 16 if c & 0x40 != 0
cp_size = 0x10000 if cp_size == 0
pos += 1
dest += base[cp_off,cp_size]
elsif c != 0
dest += delta[pos,c]
pos += c
else
raise PackFormatError, 'invalid delta data'
end
end
dest
end
private :patch_delta
def patch_delta_header_size(delta, pos)
size = 0
shift = 0
begin
c = delta[pos]
if c == nil
raise PackFormatError, 'invalid delta header'
end
pos += 1
size |= (c & 0x7f) << shift
shift += 7
end while c & 0x80 != 0
[size, pos]
end
private :patch_delta_header_size
end
end
end
end
if $0 == __FILE__
ARGV.each do |path|
storage = Git::Internal::PackStorage.new(path)
storage.each_sha1 do |sha1|
obj = storage[sha1]
puts "%s %s" % [obj.sha1.unpack('H*'), obj.type]
end
end
end
|
