qwraps2 (version 0.6.1)

file_check: File and Working Directory Check

Description

This check is three-fold: 1) verify the current working directory is as expected, 2) verify the user can access the file, and 3) verify the file contents are as expected (via md5sum).

Usage

file_check(
  paths,
  md5sums = NULL,
  absolute_paths = c("warn", "stop", "silent"),
  stop = FALSE
)

Value

The function will return a single TRUE/FALSE value with attributes attr(, "checks").

Arguments

paths

a character path to the target file

md5sums

a character string for the expected md5sum of the target file. If NULL then only a file.exists check will be done.

absolute_paths

a character string to set the behavior of warning (default), stopping, or silent if/when absolute file paths are used.

stop

if TRUE then an error is thrown if any of the checks fail, else returns a logical. If FALSE (default) a logical is returned.

Details

The test for the file access is done to verify the file can be read by the current user.

The return of the function is TRUE if all the files in paths are accessible, are case matched (optional), and all of requested md5sum checks pass. Windows and macOS are generally case-insensitive systems, but many Linux systems are case-sensitive. As such file.exists and file.access may return different values depending the OS that is active. file_check looks for a case match as part of its checks to hopefully prevent issues across operating systems.

By default, if the return is TRUE then only TRUE will be printed to the console. If the return is FALSE then the attr(, "checks") is printed by default as well.

Good practice would be to use relative paths, a warning will be given if any of the paths are determined to be absolute paths. That said, there are cases when an absolute path is needed, e.g., a common data file on a server with multiple users accessing the file(s). Set absolute_paths = c("silent") to silence the warnings.

Examples

# create example files

relative_example_file1 <-
  basename(
    tempfile(
      pattern = "QWRAPS2_EXAMPLE_1"
      , fileext = ".txt"
      , tmpdir = getwd()
    )
  )

relative_example_file2 <-
  basename(
    tempfile(
      pattern = "QWRAPS2_EXAMPLE_2"
      , fileext = ".txt"
      , tmpdir = getwd()
    )
  )

absolute_example_file <- tempfile()

cat("example file.", file = relative_example_file1)
cat("Another example file.", file = relative_example_file2)
cat("Another example file.", file = absolute_example_file)

# Check that you have access to the files in the working directory.
test1 <- file_check(c(relative_example_file1, relative_example_file2))
test1

# By default, when the checks return TRUE the details of the checks are not
# printed.  You can view the details of the checks as follows:
attr(test1, "checks")

# access to absolute_example_file will generate a warning about
# absolute_paths by default
test2 <- file_check(absolute_example_file)
test2 <- file_check(absolute_example_file, absolute_paths = "silent")
test2

# Case Match
test_case_match <-
  file_check(
    c(relative_example_file1, tolower(relative_example_file1))
  )
test_case_match

# If one or more files is not accessable then return is FALSE and the meta data
# is printed by default.
test_non_existent_file <-
  file_check(
    c("UNLIKELYFILENAME", relative_example_file1, relative_example_file2)
  )
test_non_existent_file

# Or have an error thrown:
if (FALSE) {
file_check(
  c("UNLIKELYFILENAME", relative_example_file1, relative_example_file2)
, stop = TRUE
)
}

# Verify the md5sums as well as file access:
md5_check1 <- file_check(relative_example_file1, "7a3409e17f9de067740e64448a86e708")
md5_check1

# If you only need to verify a subset of md5sums then use an NA in the md5sums
# argument:
md5_check2 <-
  file_check(c(relative_example_file1, relative_example_file2),
             c("7a3409e17f9de067740e64448a86e708", NA))
md5_check2

# Verify all the md5sums
md5_check3 <-
  file_check(c(relative_example_file1, relative_example_file2),
             c("7a3409e17f9de067740e64448a86e708", "798e52b92e0ae0e60f3f3db1273235d0"))
md5_check3

# clean up working directory
unlink(relative_example_file1)
unlink(relative_example_file2)
unlink(absolute_example_file)