nealrichardson commented on code in PR #41969:
URL: https://github.com/apache/arrow/pull/41969#discussion_r1638208631
##########
r/R/metadata.R:
##########
@@ -44,23 +44,110 @@
}
.deserialize_arrow_r_metadata <- function(x) {
- tryCatch(
- expr = {
- out <- unserialize(charToRaw(x))
-
- # if this is still raw, try decompressing
- if (is.raw(out)) {
- out <- unserialize(memDecompress(out, type = "gzip"))
- }
- out
- },
+ tryCatch(unserialize_r_metadata(x),
error = function(e) {
+ if (getOption("arrow.debug", FALSE)) {
+ print(conditionMessage(e))
+ }
warning("Invalid metadata$r", call. = FALSE)
NULL
}
)
}
+unserialize_r_metadata <- function(x) {
+ # Check that this is ASCII serialized data (as in, what we wrote)
+ if (!identical(substr(unclass(x), 1, 1), "A")) {
+ stop("Invalid serialized data")
+ }
+ out <- safe_unserialize(charToRaw(x))
+ # If it's still raw, decompress and unserialize again
+ if (is.raw(out)) {
+ decompressed <- memDecompress(out, type = "gzip")
+ if (!identical(rawToChar(decompressed[1]), "A")) {
+ stop("Invalid serialized compressed data")
+ }
+ out <- safe_unserialize(decompressed)
+ }
+ if (!is.list(out)) {
+ stop("Invalid serialized data: must be a list")
+ }
+ safe_r_metadata(out)
+}
+
+safe_unserialize <- function(x) {
+ # By capturing the data in a list, we can inspect it for promises without
+ # triggering their evaluation.
Review Comment:
I'm not sure this is more accurate--I can `obj <- deserialize(charToRaw())`
the data in
https://github.com/apache/arrow/pull/41969/files#diff-0386351ec2a20934987de3d32d4aee6fc609fbfbe3af3bf287a66941e8d563a7R121-R141
and the promise doesn't evaluate; it only evaluates if I touch `obj`. (This is
on R 4.3.)
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