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# This file was pulled from the R code base as of
# Thursday, November 22, 2012 at 6:24:55 AM UTC
# and edited to remove everything but the copyright
# header and untar2, and to make untar2 more tolerant
# of the 'x' and 'g' extended block indicators, the
# latter of which is used in tar files generated by
# GitHub.
# File src/library/utils/R/tar.R
# Part of the R package, http://www.R-project.org
#
# Copyright (C) 1995-2012 The R Core Team
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# A copy of the GNU General Public License is available at
# http://www.r-project.org/Licenses/
untar2 <- function(tarfile, files = NULL, list = FALSE, exdir = ".")
{
getOct <- function(x, offset, len)
{
x <- 0L
for(i in offset + seq_len(len)) {
z <- block[i]
if(!as.integer(z)) break; # terminate on nul
switch(rawToChar(z),
" " = {},
"0"=,"1"=,"2"=,"3"=,"4"=,"5"=,"6"=,"7"=
{x <- 8*x + (as.integer(z)-48)},
stop("invalid octal digit")
)
}
x
}
mydir.create <- function(path, ...) {
## for Windows' sake
path <- sub("[\\/]$", "", path)
if(utils::file_test("-d", path)) return()
if(!dir.create(path, showWarnings = TRUE, recursive = TRUE, ...))
stop(gettextf("failed to create directory %s", sQuote(path)),
domain = NA)
}
warn1 <- character()
## A tar file is a set of 512 byte records,
## a header record followed by file contents (zero-padded).
## See http://en.wikipedia.org/wiki/Tar_%28file_format%29
if(is.character(tarfile) && length(tarfile) == 1L) {
con <- gzfile(path.expand(tarfile), "rb") # reads compressed formats
on.exit(close(con))
} else if(inherits(tarfile, "connection")) con <- tarfile
else stop("'tarfile' must be a character string or a connection")
if (!missing(exdir)) {
mydir.create(exdir)
od <- setwd(exdir)
on.exit(setwd(od), add = TRUE)
}
contents <- character()
llink <- lname <- NULL
repeat{
block <- readBin(con, "raw", n = 512L)
if(!length(block)) break
if(length(block) < 512L) stop("incomplete block on file")
if(all(block == 0)) break
ns <- max(which(block[1:100] > 0))
name <- rawToChar(block[seq_len(ns)])
magic <- rawToChar(block[258:262])
if ((magic == "ustar") && block[346] > 0) {
ns <- max(which(block[346:500] > 0))
prefix <- rawToChar(block[345+seq_len(ns)])
name <- file.path(prefix, name)
}
## mode zero-padded 8 bytes (including nul) at 101
## Aargh: bsdtar has this one incorrectly with 6 bytes+space
mode <- as.octmode(getOct(block, 100, 8))
size <- getOct(block, 124, 12)
ts <- getOct(block, 136, 12)
ft <- as.POSIXct(as.numeric(ts), origin="1970-01-01", tz="UTC")
csum <- getOct(block, 148, 8)
block[149:156] <- charToRaw(" ")
xx <- as.integer(block)
checksum <- sum(xx) %% 2^24 # 6 bytes
if(csum != checksum) {
## try it with signed bytes.
checksum <- sum(ifelse(xx > 127, xx - 128, xx)) %% 2^24 # 6 bytes
if(csum != checksum)
warning(gettextf("checksum error for entry '%s'", name),
domain = NA)
}
type <- block[157L]
ctype <- rawToChar(type)
if(type == 0L || ctype == "0") {
if(!is.null(lname)) {name <- lname; lname <- NULL}
contents <- c(contents, name)
remain <- size
dothis <- !list
if(dothis && length(files)) dothis <- name %in% files
if(dothis) {
mydir.create(dirname(name))
out <- file(name, "wb")
}
for(i in seq_len(ceiling(size/512L))) {
block <- readBin(con, "raw", n = 512L)
if(length(block) < 512L)
stop("incomplete block on file")
if (dothis) {
writeBin(block[seq_len(min(512L, remain))], out)
remain <- remain - 512L
}
}
if(dothis) {
close(out)
Sys.chmod(name, mode, FALSE) # override umask
Sys.setFileTime(name, ft)
}
} else if(ctype %in% c("1", "2")) { # hard and symbolic links
contents <- c(contents, name)
ns <- max(which(block[158:257] > 0))
name2 <- rawToChar(block[157L + seq_len(ns)])
if(!is.null(lname)) {name <- lname; lname <- NULL}
if(!is.null(llink)) {name2 <- llink; llink <- NULL}
if(!list) {
if(ctype == "1") {
if (!file.link(name2, name)) { # will give a warning
## link failed, so try a file copy
if(file.copy(name2, name))
warn1 <- c(warn1, "restoring hard link as a file copy")
else
warning(gettextf("failed to copy %s to %s", sQuote(name2), sQuote(name)), domain = NA)
}
} else {
if(isWindows()) {
## this will not work for links to dirs
from <- file.path(dirname(name), name2)
if (!file.copy(from, name))
warning(gettextf("failed to copy %s to %s", sQuote(from), sQuote(name)), domain = NA)
else
warn1 <- c(warn1, "restoring symbolic link as a file copy")
} else {
if(!file.symlink(name2, name)) { # will give a warning
## so try a file copy: will not work for links to dirs
from <- file.path(dirname(name), name2)
if (file.copy(from, name))
warn1 <- c(warn1, "restoring symbolic link as a file copy")
else
warning(gettextf("failed to copy %s to %s", sQuote(from), sQuote(name)), domain = NA)
}
}
}
}
} else if(ctype == "5") {
contents <- c(contents, name)
if(!list) {
mydir.create(name)
Sys.chmod(name, mode, TRUE) # FIXME: check result
## no point is setting time, as dir will be populated later.
}
} else if(ctype %in% c("L", "K")) {
## This is a GNU extension that should no longer be
## in use, but it is.
name_size <- 512L * ceiling(size/512L)
block <- readBin(con, "raw", n = name_size)
if(length(block) < name_size)
stop("incomplete block on file")
ns <- max(which(block > 0)) # size on file may or may not include final nul
if(ctype == "L")
lname <- rawToChar(block[seq_len(ns)])
else
llink <- rawToChar(block[seq_len(ns)])
} else if(ctype %in% c("x", "g")) {
readBin(con, "raw", n = 512L*ceiling(size/512L))
} else stop("unsupported entry type ", sQuote(ctype))
}
if(length(warn1)) {
warn1 <- unique(warn1)
for (w in warn1) warning(w, domain = NA)
}
if(list) contents else invisible(0L)
}
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