Overflow in tbh handling routines when char != unsigned char

[fayoh]

It seems that the tbh handling functions (get_tbh_size and set_tbh_size) are suffering from an arithmetic overflow when all 8 lower bits are used, making the connection close when dealing with messages between 128 and 255 bytes.

Simplistic patch that at least makes the issues go away in my environment.

diff --git a/c_src/serial.c b/c_src/serial.c
index 8751be6..895e0aa 100644
--- a/c_src/serial.c
+++ b/c_src/serial.c
@@ -214,7 +214,7 @@ void set_tty_speed(int fd, speed_t new_ispeed, speed_t     new_ospeed)
  * Desc: returns the size of a two_byte_header message (from Erlang).
  */

-int get_tbh_size(char buf[])
+int get_tbh_size(unsigned char buf[])
 {
   return (((int) buf[0]) << 8) + ((int) buf[1]);
 }
@@ -441,7 +441,7 @@ main(int argc, char *argv[])
   {
     fd_set readfds;           /* file descriptor bit field for select */
     int    maxfd;             /* max file descriptor for select */
-    char   buf[MAXLENGTH];    /* buffer for transfer between serial-user */
+    unsigned char buf[MAXLENGTH];/* buffer for transfer between serial-user */
     int    escapes;           /* number of consecutive escapes in cbreak */

     /* Set up initial bit field for select */

[tonyg]

Switch to unsigned-char buffer. Closed by 6e0138f.

[tonyg]

Hi fayoh, I hope this fixes the issue for you.

[tonyg]

And thank you very much for pointing out the problem and the patch!