serialport_write could loop endlessly when used with a seemingly valid port
that does always return 0 on writes instead of an error.
Give up after about 125 ms i.e. 250 tries with a period of 500 us.

Signed-off-by: Stefan Tauner <[email protected]>
---
 serial.c |   14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/serial.c b/serial.c
index 7e47dcc..794763e 100644
--- a/serial.c
+++ b/serial.c
@@ -262,6 +262,7 @@ int serialport_write(unsigned char *buf, unsigned int 
writecnt)
 #else
        ssize_t tmp = 0;
 #endif
+       unsigned int empty_writes = 250; /* results in a ca. 125ms timeout */
 
        while (writecnt > 0) {
 #ifdef _WIN32
@@ -273,9 +274,16 @@ int serialport_write(unsigned char *buf, unsigned int 
writecnt)
                        msg_perr("Serial port write error!\n");
                        return 1;
                }
-               if (!tmp)
-                       msg_pdbg("Empty write\n");
-               writecnt -= tmp; 
+               if (!tmp) {
+                       msg_pdbg2("Empty write\n");
+                       empty_writes--;
+                       programmer_delay(500);
+                       if (empty_writes == 0) {
+                               msg_perr("Serial port seems dead!\n");
+                               return 1;
+                       }
+               }
+               writecnt -= tmp;
                buf += tmp;
        }
 
-- 
Kind regards, Stefan Tauner


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