repair: say when a file had to be rebuilt to be read

[tannevaled]

Doc.Repaired() reports whether any file this document's pages came from had to be rebuilt before it could be read, and pdfops repair writes the result out. -check answers the question without writing anything.

This closes BentoPDF's repair-pdf.

⛔ The rebuilding is not new, and is not this verb's doing

go-pdfkit/reader repairs a damaged file on its own and quietly, which is the right behaviour for a reader — a caller asking for page three wants page three, not a lecture. What was missing was a way to say it happened and to keep the result. That is the whole of this verb.

It reports on any source, not all: a merged document's pages come from several files, and one damaged source is the answer to "did this need repairing". A true that depended on every source being broken would be false for every real merge — and the test asserts both orders, because "any" is not "the first".

⛔ A positive control comes first

Without it, Repaired() == false would pass on a fixture that was never broken and the whole test would be measuring nothing. The fixture helper also fails loudly if the file it is handed has no startxref to break — the same guard from the other side.

And what comes out is asserted clean: repair -check on the result says there was nothing to do. A repair whose output still needs repairing is not one.

The scope is reader's, and the README says so rather than implying QPDF's

What is recovered is a cross-reference table that is wrong, missing, or points into the middle of something else — the commonest damage, and the kind where the objects are all still there. It is not a general salvage engine, and a file whose objects are themselves truncated may still be unreadable.

A file that did not need repairing is said out loud and is not an error, so that "repair everything in this directory" can be scripted.

Checks

100 % statement coverage on both packages with zero uncovered statements, go vet and gofmt clean. Both branches of the verb have their own save, so both have their own unwritable-output test — a healthy file and a damaged one take different paths, and the first draft covered only one.

🤖 Generated with Claude Code