Skip to contents

Class for an external unzip process

Source: R/process.R
unzip_process.Rd

unzip_process() returns an R6 class that represents an unzip process. It is implemented as a subclass of processx::process.

Usage

unzip_process()

Value

An unzip_process R6 class object, a subclass of processx::process, or a subclass of callr::r_process when the fallback is active (see the Fallback section below).

Using the unzip_process class

up <- unzip_process()$new(zipfile, exdir = ".", poll_connection = TRUE,
                           stderr = tempfile(), ...)

See processx::process for the class methods.

Arguments:

  • zipfile: Path to the zip file to uncompress.

  • exdir: Directory to uncompress the archive to. If it does not exist, it will be created.

  • poll_connection: passed to the initialize method of processx::process, it allows using processx::poll() or the poll_io() method to poll for the completion of the process.

  • stderr: passed to the initialize method of processx::process, by default the standard error is written to a temporary file. This file can be used to diagnose errors if the process failed.

  • ... passed to the initialize method of processx::process.

Fallback

unzip_process() normally runs the bundled cmdunzip native executable via processx::process. If the executable cannot be found or fails its self-test it falls back to running unzip() in a background R process via callr::r_process. This may happen when system policies do not allow starting the cmdunzip executable., The fallback class has the same interface but inherits from callr::r_process instead of processx::process.

Set the environment variable R_ZIP_PROCESS_FALLBACK=true to force the fallback unconditionally.

Encoding

The unzip_process class does not support the encoding argument of unzip(). Non-UTF-8 filenames are decoded using the IBM CP437 fallback. Use unzip() directly if you need to handle ZIP files with filenames in other encodings (e.g. CP932).

Examples

ex <- system.file("example.zip", package = "zip")
tmp <- tempfile()
up <- unzip_process()$new(ex, exdir = tmp)
up$wait()
up$get_exit_status()
#> [1] 0
dir(tmp)
#> [1] "example"