R/call_system.R

In mrc-ide/provisionr: Provision a Library

## This is directly from callr; once that's on CRAN I'll set up a
## direct dependency I think.
##' @importFrom utils head tail
call_system <- function(command, args, env = character(), max_lines = 20,
                        p = 0.8) {
  res <- withr::with_envvar(
    env,
    suppressWarnings(system2(command, args, stdout = TRUE, stderr = TRUE)))
  ok <- attr(res, "status")
  if (!is.null(ok) && ok != 0) {
    max_nc <- getOption("warning.length")
    cmd <- paste(c(shQuote(command), args), collapse = " ")
    msg <- sprintf("Running command:\n  %s\nhad status %d", cmd, ok)
    errmsg <- attr(cmd, "errmsg")
    if (!is.null(errmsg)) {
      msg <- c(msg, sprintf("%s\nerrmsg: %s", errmsg))
    }
    sep <- paste(rep("-", getOption("width")), collapse = "")

    ## Truncate message:
    if (length(res) > max_lines) {
      n <- ceiling(max_lines * p)
      res <- c(head(res, ceiling(max_lines - n)),
               sprintf("[[... %d lines dropped ...]]", length(res) - max_lines),
               tail(res, ceiling(n)))
    }

    ## compute the number of characters so far, including three new lines:
    nc <- (nchar(msg) + nchar(sep) * 2) + 3
    i <- max(1, which(cumsum(rev(nchar(res) + 1L)) < (max_nc - nc)))
    res <- res[(length(res) - i + 1L):length(res)]
    msg <- c(msg, "Program output:", sep, res, sep)
    stop(paste(msg, collapse = "\n"))
  }
  invisible(res)
}

call_r <- function(...) {
  call_system(file.path(R.home("bin"), "R"), ...)
}