[pmg-devel] [PATCH pmg-api v3 1/8] utils: return perl string from decode_rfc1522

[Stoiko Ivanov <s.ivanov@proxmox.com>]

decode_rfc1522 is a more robust version of decode_mimewords (in
scalar context) - adapt it to return a perlstring, under the
assumption that data is utf-8 encoded (holds true for ascii and
smtputf8 mails)

the try_decode_utf8 helper sub backwards will be used extensively in
later patches and is inspired by commit
43f8112f0bb424f99057106d57d32276d7d422a6 in pve-storage:
We consider that the valid multibyte utf-8 characters do not really
yield sensible combinations of single-byte perl characters (starting
with a byte > 127 - e.g. "£") so if something decodes without error
from utf-8 it will in all likelyhood have been utf-8 to begin with

Signed-off-by: Stoiko Ivanov <s.ivanov@proxmox.com>
---
 src/PMG/Utils.pm | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/src/PMG/Utils.pm b/src/PMG/Utils.pm
index cef232b..cfb8852 100644
--- a/src/PMG/Utils.pm
+++ b/src/PMG/Utils.pm
@@ -1088,6 +1088,7 @@ sub decode_to_html {
     return $res;
 }
 
+# assume enc contains utf-8 and mime-encoded data returns a perl-string (with wide characters)
 sub decode_rfc1522 {
     my ($enc) = @_;
 
@@ -1102,7 +1103,7 @@ sub decode_rfc1522 {
 		if ($cs) {
 		    $res .= decode($cs, $d);
 		} else {
-		    $res .= $d;
+		    $res .= try_decode_utf8($d);
 		}
 	    }
 	}
@@ -1542,4 +1543,9 @@ sub get_existing_object_id {
     return;
 }
 
+sub try_decode_utf8 {
+    my ($data) = @_;
+    return eval { decode('UTF-8', $data, 1) } // $data;
+}
+
 1;
-- 
2.30.2