CPIO - Empty Archive (trailer only)
An empty cpio archive is a single TRAILER!!! header record - a full 110-byte newc header with every numeric field zero - plus its alignment padding. Readers that look for member data before checking the name find none and must still report a valid, empty archive.
| structurestring | valuestring |
|---|---|
| container | cpio newc (SVR4) |
| members | 0 |
| magic | 070701 |
| trailer record | TRAILER!!! |
| total file size | 124 bytes |
Specifications
- Seed
- 20260807
- Members
- 0
- File Bytes
- 124
- Format
- cpio newc (SVR4, magic 070701)
- Content
- a single TRAILER!!! record and its 4-byte alignment padding
- Note
- the trailer is a real header record, not a sentinel byte
Testing contract
Expected to pass- Scenario
- Read the cpio stream to its trailer record and list the members found before it.
- Expected result
- The archive opens, reports 0 members, and consumes exactly 124 bytes; the trailer is recognised by its name field rather than listed as a zero-length member called TRAILER!!!.
What is a .cpio file?
cpio (.cpio) is a classic Unix archive format that concatenates files with per-file headers, used by initramfs images and RPM payloads. The 'newc' (SVR4) variant is the modern portable form.
How to use this file
Use an example .cpio archive to test cpio extractors, initramfs tooling, and newc-format parsers.
How to use this file for testing
“CPIO - Empty Archive (trailer only)” is a deterministic Novus Examples fixture for Conversion testing, Error handling. The same content exported across many formats and linked as a group, so you can convert one and diff against the expected twin.
Documented properties for this file: seed 20260807 · cpio newc (SVR4, magic 070701). Compare results against paired or grouped companions on this page when present (clean↔damaged, searchable↔scanned, or format twins) so scores stay reproducible across runs.
Download the file once, keep the path stable in CI or local scripts, and treat the spec table as the contract: dimensions, seeds, field lists, and roles are intentional. Corrupt or invalid samples are labelled as such — expect parsers to fail loudly rather than silently accept them.
Archive fixtures are documented down to their member list (shown on this page) and are deliberately safe — no zip bombs, executables, or hidden payloads. Test extractors against nested, unicode, empty, and encrypted variants.
Related files
- tarTAR - FIFO and Device Node RecordsA FIFO, a character device and a block device, each a header with no data blocks and with the device numbers in the devmajor/devminor fields. Unprivileged extraction cannot create the two device nodes, so the correct behaviour is to skip them with a warning rather than to abort the whole archive or to create empty regular files in their place.
- tarTAR - GNU Long Name RecordA 125-character path whose long component contains no slash at all, so the USTAR prefix field cannot store it. This archive uses a preceding 'L' (GNUTYPE_LONGNAME) record whose payload is the full path. Its group siblings encode the same class of path with the other two mechanisms.
- tarTAR - Large UID/GID (GNU base-256)The uid and gid fields hold 7 octal digits, so they top out at 2097151. This member is owned by uid 3000000, which needs GNU base-256 encoding: the field's high bit is set and the remaining bytes are a big-endian integer. Its group sibling encodes the same ownership the other way, so a reader can be checked against both without a second variable.
- tarTAR - Large UID/GID (PAX records)The uid and gid fields hold 7 octal digits, so they top out at 2097151. This member is owned by uid 3000000, which needs PAX uid=/gid= records in an 'x' extended header, with the classic field left at its maximum. Its group sibling encodes the same ownership the other way, so a reader can be checked against both without a second variable.
- tarTAR - Missing End-of-Archive BlocksA tar that ends immediately after its last member, with none of the two 512-byte zero blocks the format calls for. Plenty of writers do this and GNU tar reads it with a warning; readers that treat a missing end marker as a truncated archive reject three perfectly good members.
- tarTAR - PAX Path HeaderA 125-character path whose long component contains no slash at all, so the USTAR prefix field cannot store it. This archive uses a preceding 'x' extended header carrying a path= record in UTF-8. Its group siblings encode the same class of path with the other two mechanisms.
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