input/protocoldata: Check if lookup_protocol_name is valid

As of today, the code does not crash because all protocols have names.
But the name of the first element is not checked to be non-NULL
before calling strcmp(). This can result in a future crash if the
code logic changes.

This is mostly a change to robustify the lookup_protocol_name() function.

Also, this commit simplifies the indexing logic of the protocols array.

diff --git a/src/input/protocoldata.c b/src/input/protocoldata.c
index 905e33e4b2a3bbb2836ada750b4e42e2d94f576c..22454b3bc8130be2466e09e0ef2a93ea939e0757 100644 (file)
--- a/src/input/protocoldata.c
+++ b/src/input/protocoldata.c
@@ -408,7 +408,8 @@ struct context {
                enum textinput_t textinput;
                enum proto_type_t {
                        PROTO_TYPE_NONE,
-                       PROTO_TYPE_UART,
+                       PROTO_TYPE_FIRST,
+                       PROTO_TYPE_UART = PROTO_TYPE_FIRST,
                        PROTO_TYPE_SPI,
                        PROTO_TYPE_I2C,
                        PROTO_TYPE_COUNT,
@@ -2520,13 +2521,13 @@ static int lookup_protocol_name(struct context *inc)
        name = inc->curr_opts.proto_name;
        if (!name || !*name) {
                /* Fallback to first item after NONE slot. */
-               handler = &protocols[PROTO_TYPE_NONE + 1];
+               handler = &protocols[PROTO_TYPE_FIRST];
                name = handler->name;
+               if (!name)
+                       return SR_ERR_ARG;
        }
 
-       for (idx = 0; idx < ARRAY_SIZE(protocols); idx++) {
-               if (idx == PROTO_TYPE_NONE)
-                       continue;
+       for (idx = PROTO_TYPE_FIRST; idx < ARRAY_SIZE(protocols); idx++) {
                handler = &protocols[idx];
                if (!handler->name || !*handler->name)
                        continue;