isdn/gigaset: restructure modem response parser (4)

Restructure the control structure of the modem response parser
to improve readability and error handling.

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

diff --git a/drivers/isdn/gigaset/ev-layer.c b/drivers/isdn/gigaset/ev-layer.c
index dc6e6a3..1cfcea6 100644 (file)
--- a/drivers/isdn/gigaset/ev-layer.c
+++ b/drivers/isdn/gigaset/ev-layer.c
@@ -389,6 +389,20 @@ zsau_resp[] =
        {NULL,                          ZSAU_UNKNOWN}
 };
 
+/* check for and remove fixed string prefix
+ * If s starts with prefix terminated by a non-alphanumeric character,
+ * return pointer to the first character after that, otherwise return NULL.
+ */
+static char *skip_prefix(char *s, const char *prefix)
+{
+       while (*prefix)
+               if (*s++ != *prefix++)
+                       return NULL;
+       if (isalnum(*s))
+               return NULL;
+       return s;
+}
+
 /* queue event with CID */
 static void add_cid_event(struct cardstate *cs, int cid, int type,
                          void *ptr, int parameter)
@@ -430,15 +444,11 @@ static void add_cid_event(struct cardstate *cs, int cid, int type,
  */
 void gigaset_handle_modem_response(struct cardstate *cs)
 {
-       unsigned char *argv[MAX_REC_PARAMS + 1];
-       int params;
-       int i, j;
-       char *psep, *ptr;
+       char *eoc, *psep, *ptr;
        const struct resp_type_t *rt;
        const struct zsau_resp_t *zr;
-       int curarg;
-       int abort;
        int cid, parameter;
+       u8 type, value;
 
        if (!cs->cbytes) {
                /* ignore additional LFs/CRs (M10x config mode or cx100) */
@@ -456,6 +466,19 @@ void gigaset_handle_modem_response(struct cardstate *cs)
                return;
        }
 
+       /* look up response type */
+       for (rt = resp_type; rt->response; ++rt) {
+               eoc = skip_prefix(cs->respdata, rt->response);
+               if (eoc)
+                       break;
+       }
+       if (!rt->response) {
+               add_cid_event(cs, 0, RSP_NONE, NULL, 0);
+               gig_dbg(DEBUG_EVENT, "unknown modem response: '%s'\n",
+                       cs->respdata);
+               return;
+       }
+
        /* check for CID */
        psep = strrchr(cs->respdata, ';');
        if (psep &&
@@ -468,120 +491,141 @@ void gigaset_handle_modem_response(struct cardstate *cs)
                cid = 0;
        }
 
-       /* parse line */
-       argv[0] = cs->respdata;
-       params = 1;
-       for (i = 0; i < cs->cbytes; i++)
-               switch (cs->respdata[i]) {
-               case ';':
-               case ',':
-               case '=':
-                       cs->respdata[i] = 0;
-                       if (params > MAX_REC_PARAMS)
-                               dev_warn(cs->dev,
-                                        "too many parameters in response\n");
-                       else
-                               argv[params++] = cs->respdata + i + 1;
-               }
-
-       gig_dbg(DEBUG_EVENT, "CMD received: %s", argv[0]);
+       gig_dbg(DEBUG_EVENT, "CMD received: %s", cs->respdata);
        if (cid)
                gig_dbg(DEBUG_EVENT, "CID: %d", cid);
-       gig_dbg(DEBUG_EVENT, "available params: %d", params - 1);
-       for (j = 1; j < params; j++)
-               gig_dbg(DEBUG_EVENT, "param %d: %s", j, argv[j]);
-
-       abort = 1;
-       curarg = 0;
-       while (curarg < params) {
-               for (rt = resp_type; rt->response; ++rt)
-                       if (!strcmp(argv[curarg], rt->response))
-                               break;
 
-               if (!rt->response) {
-                       add_cid_event(cs, 0, RSP_NONE, NULL, 0);
-                       gig_dbg(DEBUG_EVENT, "unknown modem response: '%s'\n",
-                               argv[curarg]);
-                       break;
-               }
+       switch (rt->type) {
+       case RT_NOTHING:
+               /* check parameter separator */
+               if (*eoc)
+                       goto bad_param; /* extra parameter */
 
-               ++curarg;
+               add_cid_event(cs, cid, rt->resp_code, NULL, 0);
+               break;
 
-               switch (rt->type) {
-               case RT_NOTHING:
-                       add_cid_event(cs, cid, rt->resp_code, NULL, 0);
-                       break;
-               case RT_RING:
-                       if (!cid) {
-                               dev_err(cs->dev,
-                                       "received RING without CID!\n");
-                               add_cid_event(cs, 0, RSP_INVAL, NULL, 0);
-                               abort = 1;
-                       } else {
-                               add_cid_event(cs, 0, rt->resp_code, NULL, cid);
-                               abort = 0;
-                       }
-                       break;
-               case RT_ZSAU:
-                       if (curarg >= params) {
-                               add_cid_event(cs, cid, rt->resp_code, NULL,
-                                             ZSAU_NONE);
-                               break;
-                       }
-                       for (zr = zsau_resp; zr->str; ++zr)
-                               if (!strcmp(argv[curarg], zr->str))
+       case RT_RING:
+               /* check parameter separator */
+               if (!*eoc)
+                       eoc = NULL;     /* no parameter */
+               else if (*eoc++ != ',')
+                       goto bad_param;
+
+               add_cid_event(cs, 0, rt->resp_code, NULL, cid);
+
+               /* process parameters as individual responses */
+               while (eoc) {
+                       /* look up parameter type */
+                       psep = NULL;
+                       for (rt = resp_type; rt->response; ++rt) {
+                               psep = skip_prefix(eoc, rt->response);
+                               if (psep)
                                        break;
-                       if (!zr->str)
+                       }
+
+                       /* all legal parameters are of type RT_STRING */
+                       if (!psep || rt->type != RT_STRING) {
                                dev_warn(cs->dev,
-                                        "%s: unknown parameter %s after ZSAU\n",
-                                        __func__, argv[curarg]);
-                       add_cid_event(cs, cid, rt->resp_code, NULL, zr->code);
-                       ++curarg;
-                       break;
-               case RT_STRING:
-                       if (curarg < params) {
-                               ptr = kstrdup(argv[curarg], GFP_ATOMIC);
-                               if (!ptr)
-                                       dev_err(cs->dev, "out of memory\n");
-                               ++curarg;
-                       } else {
-                               ptr = NULL;
+                                        "illegal RING parameter: '%s'\n",
+                                        eoc);
+                               return;
                        }
-                       gig_dbg(DEBUG_EVENT, "string==%s", ptr ? ptr : "NULL");
+
+                       /* skip parameter value separator */
+                       if (*psep++ != '=')
+                               goto bad_param;
+
+                       /* look up end of parameter */
+                       eoc = strchr(psep, ',');
+                       if (eoc)
+                               *eoc++ = 0;
+
+                       /* retrieve parameter value */
+                       ptr = kstrdup(psep, GFP_ATOMIC);
+
+                       /* queue event */
                        add_cid_event(cs, cid, rt->resp_code, ptr, 0);
-                       break;
-               case RT_ZCAU:
-                       parameter = -1;
-                       if (curarg + 1 < params) {
-                               u8 type, value;
-
-                               i = kstrtou8(argv[curarg++], 16, &type);
-                               j = kstrtou8(argv[curarg++], 16, &value);
-                               if (i == 0 && j == 0)
-                                       parameter = (type << 8) | value;
-                       } else
-                               curarg = params - 1;
-                       add_cid_event(cs, cid, rt->resp_code, NULL, parameter);
-                       break;
-               case RT_NUMBER:
-                       if (curarg >= params ||
-                           kstrtoint(argv[curarg++], 10, &parameter))
-                               parameter = -1;
-                       gig_dbg(DEBUG_EVENT, "parameter==%d", parameter);
-                       add_cid_event(cs, cid, rt->resp_code, NULL, parameter);
-                       if (rt->resp_code == RSP_ZDLE)
-                               cs->dle = parameter;
-                       break;
                }
+               break;
 
-               if (abort)
+       case RT_ZSAU:
+               /* check parameter separator */
+               if (!*eoc) {
+                       /* no parameter */
+                       add_cid_event(cs, cid, rt->resp_code, NULL, ZSAU_NONE);
                        break;
-       }
+               }
+               if (*eoc++ != '=')
+                       goto bad_param;
 
-       if (curarg != params)
-               gig_dbg(DEBUG_EVENT,
-                       "invalid number of processed parameters: %d/%d",
-                       curarg, params);
+               /* look up parameter value */
+               for (zr = zsau_resp; zr->str; ++zr)
+                       if (!strcmp(eoc, zr->str))
+                               break;
+               if (!zr->str)
+                       goto bad_param;
+
+               add_cid_event(cs, cid, rt->resp_code, NULL, zr->code);
+               break;
+
+       case RT_STRING:
+               /* check parameter separator */
+               if (*eoc++ != '=')
+                       goto bad_param;
+
+               /* retrieve parameter value */
+               ptr = kstrdup(eoc, GFP_ATOMIC);
+
+               /* queue event */
+               add_cid_event(cs, cid, rt->resp_code, ptr, 0);
+               break;
+
+       case RT_ZCAU:
+               /* check parameter separators */
+               if (*eoc++ != '=')
+                       goto bad_param;
+               psep = strchr(eoc, ',');
+               if (!psep)
+                       goto bad_param;
+               *psep++ = 0;
+
+               /* decode parameter values */
+               if (kstrtou8(eoc, 16, &type) || kstrtou8(psep, 16, &value)) {
+                       *--psep = ',';
+                       goto bad_param;
+               }
+               parameter = (type << 8) | value;
+
+               add_cid_event(cs, cid, rt->resp_code, NULL, parameter);
+               break;
+
+       case RT_NUMBER:
+               /* check parameter separator */
+               if (*eoc++ != '=')
+                       goto bad_param;
+
+               /* decode parameter value */
+               if (kstrtoint(eoc, 10, &parameter))
+                       goto bad_param;
+
+               /* special case ZDLE: set flag before queueing event */
+               if (rt->resp_code == RSP_ZDLE)
+                       cs->dle = parameter;
+
+               add_cid_event(cs, cid, rt->resp_code, NULL, parameter);
+               break;
+
+bad_param:
+               /* parameter unexpected, incomplete or malformed */
+               dev_warn(cs->dev, "bad parameter in response '%s'\n",
+                        cs->respdata);
+               add_cid_event(cs, cid, rt->resp_code, NULL, -1);
+               break;
+
+       default:
+               dev_err(cs->dev, "%s: internal error on '%s'\n",
+                       __func__, cs->respdata);
+       }
 }
 EXPORT_SYMBOL_GPL(gigaset_handle_modem_response);