mailinfo: decode underscore used in "Q" encoding properly.

Quoted-Printable (RFC 2045) and the "Q" encoding (RFC 2047) are
subtly different; the latter is used on the mail header and an
underscore needs to be decoded to 0x20.

Signed-off-by: Junio C Hamano <junkio@cox.net>

diff --git a/mailinfo.c b/mailinfo.c
index 3c56f8c..b276519 100644 (file)
--- a/mailinfo.c
+++ b/mailinfo.c
@@ -405,7 +405,7 @@ static unsigned hexval(int c)
        return ~0;
 }
 
-static int decode_q_segment(char *in, char *ot, char *ep)
+static int decode_q_segment(char *in, char *ot, char *ep, int rfc2047)
 {
        int c;
        while ((c = *in++) != 0 && (in <= ep)) {
@@ -414,9 +414,11 @@ static int decode_q_segment(char *in, char *ot, char *ep)
                        if (d == '\n' || !d)
                                break; /* drop trailing newline */
                        *ot++ = ((hexval(d) << 4) | hexval(*in++));
+                       continue;
                }
-               else
-                       *ot++ = c;
+               if (rfc2047 && c == '_') /* rfc2047 4.2 (2) */
+                       c = 0x20;
+               *ot++ = c;
        }
        *ot = 0;
        return 0;
@@ -547,7 +549,7 @@ static void decode_header_bq(char *it)
                        sz = decode_b_segment(cp + 3, piecebuf, ep);
                        break;
                case 'q':
-                       sz = decode_q_segment(cp + 3, piecebuf, ep);
+                       sz = decode_q_segment(cp + 3, piecebuf, ep, 1);
                        break;
                }
                if (sz < 0)
@@ -569,7 +571,7 @@ static void decode_transfer_encoding(char *line)
        switch (transfer_encoding) {
        case TE_QP:
                ep = line + strlen(line);
-               decode_q_segment(line, line, ep);
+               decode_q_segment(line, line, ep, 0);
                break;
        case TE_BASE64:
                ep = line + strlen(line);