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Run R Code in webR (WebAssembly)

Source: R/rw.R
rw.Rd

Executes R code in a sandboxed WebAssembly environment via the rw CLI tool and webR.

Usage

rw(
  expr = NULL,
  file = NULL,
  prologue_expr = NULL,
  epilogue_expr = NULL,
  prologue = NULL,
  epilogue = NULL,
  r_libs = NULL,
  binds = NULL,
  stage = NULL,
  shims = NULL,
  timeout = 0,
  vanilla = FALSE,
  debug = FALSE,
  args = NULL
)

Arguments

expr

(character vector) R expressions to evaluate. Each element is passed as a separate --expr argument.

file

(character string) Path to an R script file to execute. Cannot be used together with expr.

prologue_expr, epilogue_expr

(character vector) R expressions to evaluate before/after the main code. These have access to the stage directory if specified.

prologue, epilogue

(character string) Paths to R script files to source before/after the main code.

r_libs

(character string) Path to an R package library on the host to mount in webR. The recommended path is rw_r_libs_user().

binds

(named character vector) Host directories to mount in webR. Names are the webR mount paths, values are the host paths. For example, c("/host/data" = "/path/to/data").

stage

(character string) Path to a staging directory on the host. This directory is mounted only during prologue and epilogue execution, allowing trusted code to pass data to/from the sandboxed main code.

shims

(character vector) Shims to install in R. Default is "install.packages". Set to character(0) to disable.

timeout

(numeric) Maximum execution time in seconds. If exceeded, an interrupt signal is sent to R. Use 0.0 (default) for no timeout.

vanilla

(logical) If TRUE, run R with --vanilla flag.

debug

(logical) If TRUE, output debug information.

args

(character vector) Additional arguments to pass to the R script (accessible via commandArgs(trailingOnly = TRUE) in webR).

Value

A character vector containing the captured output (stdout and stderr combined) from the R code execution.

Sandboxing Model

The security model uses webR's isolation with controlled host directory access:

  • Main code: Runs without access to the stage directory

  • Prologue/Epilogue code: Has access to stage for data transfer

  • binds directories: Available to all phases

  • r_libs: Mounted R package library available to all phases

See also

rw_source()

Examples

if (FALSE) { # \dontrun{
# Evaluate a simple expression
rw(expr = "sum(1:100)")

# Run an R script
rw(file = "analysis.R")

# With timeout
rw(expr = "Sys.sleep(10)", timeout = 3.0)

# Pass data via stage directory
stage_dir <- tempdir()
saveRDS(list(a = 1, b = 2), file.path(stage_dir, "input.rds"))
rw(
  prologue_expr = "data <- readRDS('/host/stage/input.rds')",
  expr = "result <- lapply(data, sqrt)",
  epilogue_expr = "saveRDS(result, '/host/stage/output.rds')",
  stage = stage_dir
)
result <- readRDS(file.path(stage_dir, "output.rds"))
} # }