This is my cheat sheet for the RPM file format. While there is an article about the RPM file format, it is far from complete. Still, have a look: http://rpm.org/wiki/DevelDocs/FileFormat
Lead
The lead section seems to be pretty much dead. (also see 2.3. Lead format)
Signature header
| TAG | Type | Description |
|---|---|---|
SIZE |
int32_t | The size of the package header and payload section in bytes |
MD5 |
BLOB | The MD5 digest of the package header and payload as they are stored on the file system. |
SHA1HEADER |
STRING | The SHA1 digest of the package header only. Stored as lowercase hex string. |
PAYLOAD_SIZE |
int32_t | The uncompressed size in bytes of the CPIO archive in the payload section. |
Signature padding
After the signature header has been written the file is aligned to 8 bytes. This makes the following package header start of in a file index dividable by 8.
Package header
The package header has the same format as the signature header, but does use different tags.
Tags
| TAG | Type | Description |
|---|---|---|
PAYLOAD_FORMAT |
STRING | The type of the archive format, currently only cpio can be used. |
PAYLOAD_CODING |
STRING | The way the file archive is compressed: e.g. gzip. |
FILE_SIZES |
int32_t | For each file and directory stored in the archive the size in bytes. Directories do count 4096 each. |
Payload data
The payload data is the actual file data. It is a CPIO archive, compressed either by GZIP, BZIP2 or XZ. Also see tags PAYLOAD_FORMAT and PAYLOAD_CODING.
Also see: