fix coverity (false) warning in codec-list vty

Since there were complaints about this old parsing code during recent
code review in Ifdc9e04bf1d623da65bfb8a2fddea765601f6d9b, and now also
coverity finds something odd in it, just rewrite this.

Related: CID#310912
Change-Id: I96cd5d88ec6808a2915c6bccd0c0140216f328f2

src/osmo-bsc/bsc_vty.c

@@ -2712,6 +2712,7 @@ DEFUN_USRATTR(cfg_net_msc_codec_list,
 {
 	struct bsc_msc_data *data = bsc_msc_data(vty);
 	struct gsm_audio_support tmp[ARRAY_SIZE(data->audio_support)];
+	const char *arg = NULL;
 	int i;
 
 	/* Nr of arguments must fit in the array */
@@ -2724,30 +2725,23 @@ DEFUN_USRATTR(cfg_net_msc_codec_list,
 	/* check all given arguments first */
 	for (i = 0; i < argc; i++) {
 		int j;
+		int ver;
+		arg = argv[i];
 
-		/* check for hrX or frX */
-		if (strlen(argv[i]) != 3
-				|| argv[i][1] != 'r'
-				|| (argv[i][0] != 'h' && argv[i][0] != 'f')
-				|| argv[i][2] < '0'
-				|| argv[i][2] > '9') {
-			vty_out(vty, "Codec name must be hrX or frX. Was '%s'%s", argv[i], VTY_NEWLINE);
-			return CMD_WARNING;
-		}
-
-		/* store in tmp[] first, to not overwrite data->audio_support[] in case of error */
-		tmp[i].ver = atoi(argv[i] + 2);
-		if (strncmp("hr", argv[i], 2) == 0)
+		if (strncmp("hr", arg, 2) == 0)
 			tmp[i].hr = 1;
-		else if (strncmp("fr", argv[i], 2) == 0)
+		else if (strncmp("fr", arg, 2) == 0)
 			tmp[i].hr = 0;
+		else
+			goto invalid_arg;
 
-		/* forbid invalid versions */
-		if (tmp[i].ver < 1 || tmp[i].ver > 7
-		    || (tmp[i].hr && tmp[i].ver == 2)) {
-			vty_out(vty, "'%s' is not a valid codec version%s", argv[i], VTY_NEWLINE);
-			return CMD_WARNING;
-		}
+		ver = atoi(arg + 2);
+		if (ver < 1 || ver > 7)
+			goto invalid_arg;
+		tmp[i].ver = ver;
+
+		if (tmp[i].hr == 1 && ver == 2)
+			goto invalid_arg;
 
 		/* prevent duplicate entries */
 		for (j = 0; j < i; j++) {
@@ -2762,6 +2756,10 @@ DEFUN_USRATTR(cfg_net_msc_codec_list,
 	data->audio_length = argc;
 
 	return CMD_SUCCESS;
+
+invalid_arg:
+	vty_out(vty, "%s is not a valid codec version%s", osmo_quote_cstr_c(OTC_SELECT, arg, -1), VTY_NEWLINE);
+	return CMD_WARNING;
 }
 
 #define LEGACY_STR "This command has no effect, it is kept to support legacy config files\n"

tests/msc.vty

@@ -33,16 +33,16 @@ msc 0
 ...
 
 OsmoBSC(config-msc)# codec-list foo
-Codec name must be hrX or frX. Was 'foo'
+"foo" is not a valid codec version
 
 OsmoBSC(config-msc)# codec-list fr10
-Codec name must be hrX or frX. Was 'fr10'
+"fr10" is not a valid codec version
 
 OsmoBSC(config-msc)# codec-list hr10
-Codec name must be hrX or frX. Was 'hr10'
+"hr10" is not a valid codec version
 
 OsmoBSC(config-msc)# codec-list FR1
-Codec name must be hrX or frX. Was 'FR1'
+"FR1" is not a valid codec version
 
 OsmoBSC(config-msc)# # Ensure the codec-list with wrong args did not change the config
 OsmoBSC(config-msc)# show running-config
@@ -62,7 +62,7 @@ msc 0
 ...
 
 OsmoBSC(config-msc)# codec-list fr0 fr1
-'fr0' is not a valid codec version
+"fr0" is not a valid codec version
 OsmoBSC(config-msc)# show running-config
 ...
 msc 0
@@ -71,7 +71,7 @@ msc 0
 ...
 
 OsmoBSC(config-msc)# codec-list hr0 hr1
-'hr0' is not a valid codec version
+"hr0" is not a valid codec version
 OsmoBSC(config-msc)# show running-config
 ...
 msc 0
@@ -80,7 +80,7 @@ msc 0
 ...
 
 OsmoBSC(config-msc)# codec-list fr8 fr9
-'fr8' is not a valid codec version
+"fr8" is not a valid codec version
 OsmoBSC(config-msc)# show running-config
 ...
 msc 0
@@ -89,7 +89,7 @@ msc 0
 ...
 
 OsmoBSC(config-msc)# codec-list hr8 hr9
-'hr8' is not a valid codec version
+"hr8" is not a valid codec version
 OsmoBSC(config-msc)# show running-config
 ...
 msc 0
@@ -98,7 +98,7 @@ msc 0
 ...
 
 OsmoBSC(config-msc)# codec-list fr2 hr2
-'hr2' is not a valid codec version
+"hr2" is not a valid codec version
 OsmoBSC(config-msc)# show running-config
 ...
 msc 0