smb_getplaintext() now returns NULL if there is no MIME-encoded plain-text.

This allows a message displayer to indicate to the user that some MIME-decoding
took place.

src/smblib/smbtxt.c

@@ -184,8 +184,11 @@ char* SMBCALL smb_getmsgtxt(smb_t* smb, smbmsg_t* msg, ulong mode)
 		*(buf+l)=0; 
 	}
 
-	if(mode&GETMSGTXT_PLAIN)
-		buf = smb_getplaintext(msg, buf);
+	if(mode&GETMSGTXT_PLAIN) {
+		char* plaintext = smb_getplaintext(msg, buf);
+		if(plaintext != NULL)
+			return plaintext;
+	}
 	return(buf);
 }
 
@@ -381,6 +384,7 @@ static char* mime_getcontent(char* buf, const char* content_type, const char* co
 }
 
 /* Get just the plain-text portion of a MIME-encoded message body */
+/* Returns NULL if there is no MIME-encoded plain-text portion of the message */
 char* SMBCALL smb_getplaintext(smbmsg_t* msg, char* buf)
 {
 	int		i;
@@ -397,23 +401,24 @@ char* SMBCALL smb_getplaintext(smbmsg_t* msg, char* buf)
         }
     }
 	if(content_type == NULL)	/* not MIME */
-		return buf;
+		return NULL;
 	txt = mime_getcontent(buf, content_type, "text/plain", 0, &xfer_encoding
 		,/* attachment: */NULL, /* index: */0);
-	if(txt != NULL) {
-		memmove(buf, txt, strlen(txt)+1);
-		if(*buf == 0)
-			return buf;
-		if(xfer_encoding == CONTENT_TRANFER_ENCODING_QUOTED_PRINTABLE)
-			qp_decode(buf);
-		else if(xfer_encoding == CONTENT_TRANFER_ENCODING_BASE64) {
-			char* decoded = strdup(buf);
-			if(decoded == NULL)
-				return buf;
-			if(b64_decode(decoded, strlen(decoded), buf, strlen(buf)) > 0)
-				strcpy(buf, decoded);
-			free(decoded);
-		}
+	if(txt == NULL)
+		return NULL;
+
+	memmove(buf, txt, strlen(txt)+1);
+	if(*buf == 0)	/* No decoding necessary */
+		return buf;
+	if(xfer_encoding == CONTENT_TRANFER_ENCODING_QUOTED_PRINTABLE)
+		qp_decode(buf);
+	else if(xfer_encoding == CONTENT_TRANFER_ENCODING_BASE64) {
+		char* decoded = strdup(buf);
+		if(decoded == NULL)
+			return NULL;
+		if(b64_decode(decoded, strlen(decoded), buf, strlen(buf)) > 0)
+			strcpy(buf, decoded);
+		free(decoded);
 	}
 
 	return buf;