These files are used by the performance_check script in the qpdf source tree.
Here is where the files came from:
- abuild-manual-1-100.pdf — the first 100 pages of the manual from abuild, a retired open source project by the same author as qpdf
- many-nulls.pdf — created by test_many_nulls in the qpdf repository
- pdf-spec-1-100.pdf — The first 100 pages of the original ISO PDF spec, decrypted by qpdf
- The actual file is from an older download but as the same ID as the current download
- pdf-spec-1-100.json — A qpdf JSON file created from pdf-spec-1-100.pdf
The performance_check script looks for a clone of this repository in the same parent directory as extracted qpdf source tree, but the location can be overridden. See the script for details.