deltarpm suite V3.6

A) Programs

makedeltarpm [-V version] [-s seqfile] oldrpm newrpm deltarpm

Extracts the usable files (i.e. no config files) from oldrpm and
diffs them against newrpm.

Options:
  -V: create a specific version, default is V3
  -s: write sequence info into file (useful for creating
  yast patchfiles)

applydeltarpm [-v] [-p] [-c] [-C] [-r oldrpm] deltarpm newrpm
applydeltarpm -i deltarpm
applydeltarpm [-c] -s seq

Reconstruct newrpm from the delta rpm. May run in filesystem mode
or in rpm mode.

Options:
  -v: verbose mode, print statistics
  -p: print percent completed (use -p -p for parsable output)
  -c: just check if the rpm can be reconstructed
  -C: fast check, don't verify md5 sums of the used files
  -r: reconstruct from the specified rpm, not from filesystem
      data
  -s: check if rpm can be reconstructed based on sequence info

combinedeltarpm deltarpm1 deltarpm2... newdeltarpm

Combine multiple deltarpms to a new one

B) License

delta.c is distributed under a 2-clause BSD license, see the head of the file for details. All other files are distributed under BSD license, see LICENSE.BSD.

C) Thanks

Many thanks to Carl-Daniel Hailfinger who started the deltarpm project with his ideas and discussions.

D) Size limitations and compilation options

Deltarpms are (as all rpms) limited to 2GB size. The rpm archive is compressed, though, and thus can exceed this limit. There are two compile options that allow deltarpms to deal with rpms whose archive exceeds 4GB:

DELTARPM_64BIT Allows applydeltarpm to deal with deltarpms that where created for rpms that have an archive bigger that 4GB. Applying such a deltarpm works on a 32bit architecture.

BSDIFF_SIZET Changes the diff algorithm to use size_t instead of unsigned int. This allows the creation of deltarpms for oversized rpms. You need a 64bit architecture for this to work (and DELTARPM_64BIT must also be defined). Defining BSDIFF_SIZET changes the memory requirements needed for creating the deltarpm. If your uncompressed archive size is N GB, you need about 3N GB if BSDIFF_SIZET is not defined, but 4N GB if it is.

E) delta.rpm file format

standard deltarpms:

96 bytes rpm lead

x bytes rpm signature header 

x bytes rpm header 
        (the is an exact copy of the header of new.rpm, the
         only difference is that the PAYLOADFORMAT is patched
         to "drpm")

[[ the rest of the deltarpm may be compressed, like a normal rpm ]]

4 bytes id: "DLT1" (V2: "DLT2", V3: "DLT3")

4 bytes source nevr length
x bytes source nevr (name-epoch:version-release)

4 bytes seqlength (always 16 if header included in diff)
x bytes sequence, containing
        16 bytes seq md5sum
        x bytes compressed sequence
        (the sequence defines which files get included from the rpm
         filelist in which order)

16 bytes fullmd5, md5sum of the complete rpm V2: 4 bytes fullsize, size of the complete rpm V2: 4 bytes compression type V2: 4 bytes compression parameter block len V2: x bytes compression parameter block

V3: target header len, zero if header not included in diff

V3: 4 bytes number of adjust elements (offadjn) V3: 2 offadjn 4 bytes adjust elements

4 bytes leadlen
x bytes lead     (lead/signatures of the new rpm)

4 bytes payloadformatoffset
                 (used to change the format back to "cpio")

4 bytes number of copies from internal data (inn)
4 bytes number of copies from external data (outn)
inn * 4 bytes number of external copies to do before internal copy
inn * 4 bytes length of internal copy
outn * 4 bytes offset adjustment of external copy
outn * 4 bytes length of external copy

V3: 4 bytes length of external data MSB 4 bytes length of external data

4 bytes length of add data
x bytes add data, bzip2 or gzip compressed

V3: 4 bytes length of internal data MSB 4 bytes length of internal data x bytes internal data

rpm-only deltarpms:

4 bytes magic: "drpm"
4 bytes id: (V3: "DLT3")
4 bytes target nevr length
x bytes target nevr (name-epoch:version-release)
4 bytes length of add data
x bytes add data, bzip2 or gzip compressed

[[ rest of the deltarpm compressed, same format as a standard deltarpm starting with the id, add data has to be zero. the sequence will always be 16 bytes, the md5 sum of the header and the compressed payload (i.e. exactly the md5sum rpm stores in the signature header). the target-header len will be non-zero as the header is included in the diff. ]]

"rpm-only no diff" deltarpms are like rpm-only deltarpms, but the target compression is "uncompressed" and there are no delta instructions, i.e. inn and outn are both zero.

2005-06-14 mls