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95 lines
3.1 KiB
95 lines
3.1 KiB
#' Retrieve 'magic' attributes from files and directories
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#'
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#' @param path character vector of files to use magic on
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#' @param magic_db either "\code{system}" (the default) to use the system
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#' \code{magic} database or an atomic character vector with a
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#' colon-separated list of full paths to custom \code{magic} database(s). This parameter
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#' is (for the moment) ignored on Windows.
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#' @return a \code{tibble} / \code{data.frame} of file magic attributes.
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#' Specifically, mime type, encoding, possible file extensions and
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#' type description are returned as colums in the data frame along
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#' with \code{path}.
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#' @note Various fields might not be available depending on the version
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#' of \code{libmagic} you have installed.
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#' @references See \url{http://openpreservation.org/blog/2012/08/09/magic-editing-and-creation-primer/}
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#' for information on how to create your own \code{magic} database
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#' @export
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#' @examples
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#' library(dplyr)
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#'
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#' system.file("img", package="filemagic") %>%
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#' list.files(full.names=TRUE) %>%
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#' incant() %>%
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#' glimpse()
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incant <- function(path, magic_db="system") {
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if (get_os() == "win") {
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found_file <- FALSE
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file_exe <- Sys.which("file.exe")
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found_file <- file_exe != ""
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if (found_file) {
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file_version <- suppressWarnings(system2(file_exe, "--version", stdout=TRUE, stderr=TRUE))
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found_file <- any(grepl("magic file", file_version))
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}
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if (!found_file) {
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stop(paste0("'file.exe' not found. Please install 'Rtools' and restart R. ",
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"See 'https://github.com/stan-dev/rstan/wiki/Install-Rtools-for-Windows' ",
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"for more information on how to install 'Rtools'", collapse=""),
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call.=FALSE)
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}
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magic_db <- normalizePath(magic_wand_file())
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tf <- tempfile()
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writeLines(path, tf)
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suppressMessages(
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suppressWarnings(
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system2(file_exe,
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c("--mime-type", "--mime-encoding", "--no-buffer", "--preserve-date",
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'--separator "||"',
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sprintf('--files-from "%s"', tf)),
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stdout=TRUE))) -> output_1
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suppressMessages(
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suppressWarnings(system2(file_exe,
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c("--no-buffer", "--preserve-date", '--separator "||"',
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sprintf('--files-from "%s"', tf)),
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stdout=TRUE))) -> output_2
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unlink(tf)
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stri_split_fixed(output_1, "||", n=2, simplify=TRUE) %>%
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as_data_frame() %>%
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setNames(c("file", "response")) %>%
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separate(response, c("mime_type", "encoding"), sep=";", extra="drop", fill="right") %>%
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mutate(encoding=stri_replace_first_regex(encoding, "charset=", "")) -> df1
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stri_split_fixed(output_2, "||", n=2, simplify=TRUE) %>%
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as_data_frame() %>%
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setNames(c("file", "description")) -> df2
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left_join(df1, df2, by="file") %>%
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mutate_all(stri_trim_both)
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} else {
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incant_(path, magic_db)
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}
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}
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#' ripped from rappdirs (ty Hadley!)
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get_os <- function () {
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if (.Platform$OS.type == "windows") {
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"win"
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} else if (Sys.info()["sysname"] == "Darwin") {
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"mac"
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} else if (.Platform$OS.type == "unix") {
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"unix"
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} else {
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stop("Unknown OS")
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}
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}
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