repo-add: enforce maximum .sig file size

This prevents user error in adding a file generated via `gpg --sign`
rather than `--detach-sign`, for example. The same 16KiB limit is used
we use in our pacman download code.

The section is moved above the checksum generation to avoid presenting
info messages to the user if the signature isn't valid.

Addresses a shortcoming pointed out in FS#27453.

Signed-off-by: Dan McGee <dan@archlinux.org>

1 files changed, 12 insertions, 7 deletions

diff --git a/scripts/repo-add.sh.in b/scripts/repo-add.sh.in
index 5e1d7702..4708086c 100644
--- a/scripts/repo-add.sh.in
+++ b/scripts/repo-add.sh.in
@@ -245,7 +245,7 @@ db_write_entry() {
 	local pkgfile="$1"
 	local -a _groups _licenses _replaces _depends _conflicts _provides _optdepends
 	local pkgname pkgver pkgdesc csize size url arch builddate packager \
-		md5sum sha256sum pgpsig
+		md5sum sha256sum pgpsig pgpsigsize
 
 	# read info from the zipped package
 	local line var val
@@ -284,6 +284,17 @@ db_write_entry() {
 		fi
 	fi
 
+	# compute base64'd PGP signature
+	if [[ -f "$pkgfile.sig" ]]; then
+		pgpsigsize=$(@SIZECMD@ "$pkgfile.sig")
+		if (( pgpsigsize > 16384 )); then
+			error "$(gettext "Invalid package signature file '%s'.")" "$pkgfile.sig"
+			return 1
+		fi
+		msg2 "$(gettext "Adding package signature...")"
+		pgpsig=$(openssl base64 -in "$pkgfile.sig" | tr -d '\n')
+	fi
+
 	csize=$(@SIZECMD@ "$pkgfile")
 
 	# compute checksums
@@ -293,12 +304,6 @@ db_write_entry() {
 	sha256sum="$(openssl dgst -sha256 "$pkgfile")"
 	sha256sum="${sha256sum##* }"
 
-	# compute base64'd PGP signature
-	if [[ -f "$pkgfile.sig" ]]; then
-		msg2 "$(gettext "Adding package signature...")"
-		pgpsig=$(openssl base64 -in "$pkgfile.sig" | tr -d '\n')
-	fi
-
 	# remove an existing entry if it exists, ignore failures
 	db_remove_entry "$pkgname"