bas_gigaset: collapse CR/LF at end of AT response

Copy the mechanism from ser_/usb_gigaset to avoid producing
spurious empty responses for CR/LF sequences from the device.
Add a comment in all drivers documenting that behaviour.
Correct an off by one error that might result in a one byte
buffer overflow when receiving an unexpectedly long reply.

Impact: minor bugfix
Signed-off-by: Tilman Schmidt <tilman@imap.cc>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/isdn/gigaset/asyncdata.c b/drivers/isdn/gigaset/asyncdata.c
index ccb2a7b..e913beb 100644 (file)
--- a/drivers/isdn/gigaset/asyncdata.c
+++ b/drivers/isdn/gigaset/asyncdata.c
@@ -40,6 +40,8 @@ static inline int muststuff(unsigned char c)
  * Append received bytes to the command response buffer and forward them
  * line by line to the response handler. Exit whenever a mode/state change
  * might have occurred.
+ * Note: Received lines may be terminated by CR, LF, or CR LF, which will be
+ * removed before passing the line to the response handler.
  * Return value:
  *     number of processed bytes
  */

diff --git a/drivers/isdn/gigaset/gigaset.h b/drivers/isdn/gigaset/gigaset.h
index e963a6c..c9ccf7d 100644 (file)
--- a/drivers/isdn/gigaset/gigaset.h
+++ b/drivers/isdn/gigaset/gigaset.h
@@ -38,7 +38,7 @@
 #define GIG_COMPAT  {0, 4, 0, 0}
 
 #define MAX_REC_PARAMS 10      /* Max. number of params in response string */
-#define MAX_RESP_SIZE 512      /* Max. size of a response string */
+#define MAX_RESP_SIZE 511      /* Max. size of a response string */
 
 #define MAX_EVENTS 64          /* size of event queue */
 
@@ -498,7 +498,7 @@ struct cardstate {
        spinlock_t ev_lock;
 
        /* current modem response */
-       unsigned char respdata[MAX_RESP_SIZE];
+       unsigned char respdata[MAX_RESP_SIZE+1];
        unsigned cbytes;
 
        /* private data of hardware drivers */

diff --git a/drivers/isdn/gigaset/isocdata.c b/drivers/isdn/gigaset/isocdata.c
index 85394a6..16fd3bd 100644 (file)
--- a/drivers/isdn/gigaset/isocdata.c
+++ b/drivers/isdn/gigaset/isocdata.c
@@ -905,29 +905,49 @@ void gigaset_isoc_receive(unsigned char *src, unsigned count,
 
 /* == data input =========================================================== */
 
+/* process a block of received bytes in command mode (mstate != MS_LOCKED)
+ * Append received bytes to the command response buffer and forward them
+ * line by line to the response handler.
+ * Note: Received lines may be terminated by CR, LF, or CR LF, which will be
+ * removed before passing the line to the response handler.
+ */
 static void cmd_loop(unsigned char *src, int numbytes, struct inbuf_t *inbuf)
 {
        struct cardstate *cs = inbuf->cs;
        unsigned cbytes      = cs->cbytes;
+       unsigned char c;
 
        while (numbytes--) {
-               /* copy next character, check for end of line */
-               switch (cs->respdata[cbytes] = *src++) {
-               case '\r':
+               c = *src++;
+               switch (c) {
                case '\n':
-                       /* end of line */
-                       gig_dbg(DEBUG_TRANSCMD, "%s: End of Command (%d Bytes)",
-                               __func__, cbytes);
-                       if (cbytes >= MAX_RESP_SIZE - 1)
-                               dev_warn(cs->dev, "response too large\n");
+                       if (cbytes == 0 && cs->respdata[0] == '\r') {
+                               /* collapse LF with preceding CR */
+                               cs->respdata[0] = 0;
+                               break;
+                       }
+                       /* --v-- fall through --v-- */
+               case '\r':
+                       /* end of message line, pass to response handler */
+                       if (cbytes >= MAX_RESP_SIZE) {
+                               dev_warn(cs->dev, "response too large (%d)\n",
+                                        cbytes);
+                               cbytes = MAX_RESP_SIZE;
+                       }
                        cs->cbytes = cbytes;
+                       gigaset_dbg_buffer(DEBUG_TRANSCMD, "received response",
+                                          cbytes, cs->respdata);
                        gigaset_handle_modem_response(cs);
                        cbytes = 0;
+
+                       /* store EOL byte for CRLF collapsing */
+                       cs->respdata[0] = c;
                        break;
                default:
-                       /* advance in line buffer, checking for overflow */
-                       if (cbytes < MAX_RESP_SIZE - 1)
-                               cbytes++;
+                       /* append to line buffer if possible */
+                       if (cbytes < MAX_RESP_SIZE)
+                               cs->respdata[cbytes] = c;
+                       cbytes++;
                }
        }
 
@@ -958,8 +978,6 @@ void gigaset_isoc_input(struct inbuf_t *inbuf)
                                           numbytes, src);
                        gigaset_if_receive(inbuf->cs, src, numbytes);
                } else {
-                       gigaset_dbg_buffer(DEBUG_CMD, "received response",
-                                          numbytes, src);
                        cmd_loop(src, numbytes, inbuf);
                }