Bug: Cached zip treated as valid but yields empty archive on install

[jkylearmstrong-temple]

Bug: Cached zip treated as valid but yields empty archive on install

Labels: bug, cache

Description

When installing packages via pak::pak(), a cached .zip that pak reports as valid ("Cached copy … is the latest build") is later found to be an empty archive during extraction, causing a hard error. The cache lookup succeeds but the cached file is corrupt/empty, so no download is attempted and installation fails.

Steps to reproduce

pak::pak(c('jsonlite', 'rlang'))

Expected behavior

Either the cached file is validated before skipping the download (and re-downloaded if corrupt), or the error is caught and pak falls back to a fresh download automatically.

Actual behavior

pak reports the cache is fresh and skips the download, then fails during extraction with:

! C:\Users\…\jsonlite_2.0.0.zip is not a valid R package, it is an empty archive.

Error output

Error: 
! error in pak subprocess
Caused by error in `verify_extracted_package(filename, pkg_cache)`:
! C:\Users\tus75918\AppData\Local\Temp\RtmpovMw7R\file431c6a465617/bin/windows/contrib/4.6/jsonlite_2.0.0.zip is not a valid R package, it is an empty archive.

Subprocess backtrace:
 1. base::withCallingHandlers(...)
 2. get("pkg_install_do_plan", asNamespace("pak"))(...)
 3. proposal$install()
 4. pkgdepends::install_package_plan(...)
 5. base::withCallingHandlers({...})
 6. pkgdepends:::handle_events(state, events)
 7. pkgdepends:::handle_event(state, i)
 8. proc$get_result()
 9. processx:::process_get_result(self, private)
10. private$post_process()
11. pkgdepends:::install_extracted_binary(...)
12. pkgdepends:::verify_extracted_package(filename, pkg_cache)
13. base::throw(...)

Environment

• Platform: Windows (x86_64-w64-mingw32)
• R version: 4.6.x (inferred from contrib path)
• Packages affected: jsonlite 2.0.0, rlang 1.2.0
• Cache path: %LOCALAPPDATA%\Temp\RtmpovMw7R\

Suggested fix

In pkgdepends:::install_extracted_binary (or the cache-hit logic upstream), validate that the cached zip is non-empty and well-formed before deciding to skip the download. If validation fails, evict the entry from the cache and re-download.