- The header appears at the beginning and consists of the following:
- 4-byte signature
- 4-byte version number (network byte order)
+ 4-byte signature:
+ The signature is: {'P', 'A', 'C', 'K'}
+
+ 4-byte version number (network byte order):
+ GIT currently accepts version number 2 or 3 but
+ generates version 2 only.
+
4-byte number of objects contained in the pack (network byte order)
Observation: we cannot have more than 4G versions ;-) and
which looks like this:
(undeltified representation)
- n-byte type and length (4-bit type, (n-1)*7+4-bit length)
+ n-byte type and length (3-bit type, (n-1)*7+4-bit length)
compressed data
(deltified representation)
- n-byte type and length (4-bit type, (n-1)*7+4-bit length)
+ n-byte type and length (3-bit type, (n-1)*7+4-bit length)
20-byte base object name
compressed delta data
8-byte integers to go beyond 4G objects per pack, but it is
not strictly necessary.
- - The header is followed by sorted 28-byte entries, one entry
+ - The header is followed by sorted 24-byte entries, one entry
per object in the pack. Each entry is:
4-byte network byte order integer, recording where the
Pack file entry: <+
packed object header:
- 1-byte type (upper 4-bit)
+ 1-byte size extension bit (MSB)
+ type (next 3 bit)
size0 (lower 4-bit)
n-byte sizeN (as long as MSB is set, each 7-bit)
size0..sizeN form 4+7+7+..+7 bit integer, size0
- is the most significant part.
+ is the least significant part, and sizeN is the
+ most significant part.
packed object data:
If it is not DELTA, then deflated bytes (the size above
is the size before compression).