lc15: rewrite and refactor code to print hwversion description

Also print a newline at the end of print_hwversion().

In the process of rewrite, fix several warnings in the few lines of this functions:
osmo-bts/src/osmo-bts-litecell15/main.c: In function ‘print_hwversion’:
osmo-bts/src/osmo-bts-litecell15/main.c:162:12: warning: passing argument 1 to restrict-qualified parameter aliases with argument 4 [-Wrestrict]
   snprintf(model_name, sizeof(model_name), "%s Rev %c",
            ^~~~~~~~~~
    model_name, (char)rev);
    ~~~~~~~~~~
osmo-bts/src/osmo-bts-litecell15/main.c:168:12: warning: passing argument 1 to restrict-qualified parameter aliases with argument 4 [-Wrestrict]
   snprintf(model_name, sizeof(model_name), "%s (%05X)",
            ^~~~~~~~~~
    model_name, model);
    ~~~~~~~~~~
osmo-bts/src/osmo-bts-litecell15/main.c:162:47: warning: ‘ Rev ’ directive output may be truncated writing 5 bytes into a region of size between 1 and 64 [-Wformat-truncation=]
   snprintf(model_name, sizeof(model_name), "%s Rev %c",
                                               ^~~~~
osmo-bts/src/osmo-bts-litecell15/main.c:162:3: note: ‘snprintf’ output between 7 and 70 bytes into a destination of size 64
   snprintf(model_name, sizeof(model_name), "%s Rev %c",
   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    model_name, (char)rev);
    ~~~~~~~~~~~~~~~~~~~~~~
osmo-bts/src/osmo-bts-litecell15/main.c:168:47: warning: ‘ (’ directive output may be truncated writing 2 bytes into a region of size between 1 and 64 [-Wformat-truncation=]
   snprintf(model_name, sizeof(model_name), "%s (%05X)",
                                               ^~
osmo-bts/src/osmo-bts-litecell15/main.c:168:44: note: using the range [0, 4294967295] for directive argument
   snprintf(model_name, sizeof(model_name), "%s (%05X)",
                                            ^~~~~~~~~~~
osmo-bts/src/osmo-bts-litecell15/main.c:168:3: note: ‘snprintf’ output between 9 and 75 bytes into a destination of size 64
   snprintf(model_name, sizeof(model_name), "%s (%05X)",
   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    model_name, model);
    ~~~~~~~~~~~~~~~~~~

Change-Id: I079b056a04fe77d2f7f361ff5899232cb70b5a93

src/osmo-bts-litecell15/main.c

@@ -151,25 +151,8 @@ void bts_model_print_help()
 
 static void print_hwversion()
 {
-	int rev;
+	printf(get_hwversion_desc());
-	int model;
+	printf("\n");
-	static char model_name[64] = {0, };
-
-	snprintf(model_name, sizeof(model_name), "NuRAN Litecell 1.5 BTS");
-
-	rev = lc15bts_rev_get();
-	if (rev >= 0) {
-		snprintf(model_name, sizeof(model_name), "%s Rev %c", 
-			model_name, (char)rev);
-	} 
-
-	model = lc15bts_model_get();
-	if (model >= 0) {
-		snprintf(model_name, sizeof(model_name), "%s (%05X)", 
-			model_name, model);
-	}
-
-	printf(model_name);
 }
 
 int bts_model_handle_options(int argc, char **argv)

src/osmo-bts-litecell15/misc/lc15bts_bid.c

@@ -138,3 +138,25 @@ int lc15bts_option_get(enum lc15bts_option_type type)
 
 	return option;	
 }
+
+const char* get_hwversion_desc()
+{
+        int rev;
+        int model;
+        size_t len;
+        static char model_name[64] = {0, };
+        len = snprintf(model_name, sizeof(model_name), "NuRAN Litecell 1.5 BTS");
+
+        rev = lc15bts_rev_get();
+        if (rev >= 0) {
+                len += snprintf(model_name + len, sizeof(model_name) - len,
+                                " Rev %c", (char)rev);
+        }
+
+        model = lc15bts_model_get();
+        if (model >= 0) {
+                snprintf(model_name + len, sizeof(model_name) - len,
+                         "%s (%05X)", model_name, model);
+        }
+        return model_name;
+}

src/osmo-bts-litecell15/misc/lc15bts_bid.h

@@ -47,5 +47,6 @@ enum lc15bts_gsm_band {
 int lc15bts_rev_get(void);
 int lc15bts_model_get(void);
 int lc15bts_option_get(enum lc15bts_option_type type);
+const char* get_hwversion_desc();
 
 #endif

src/osmo-bts-litecell15/misc/lc15bts_mgr_nl.c

@@ -104,8 +104,6 @@ static void respond_to(struct sockaddr_in *src, struct osmo_fd *fd,
 	if (!fetched_info) {
 		int fd_eth;
 		int serno;
-		int model;
-		int rev;
 
 		/* fetch the MAC */
 		fd_eth = open(ETH0_ADDR_SYSFS, O_RDONLY);
@@ -119,20 +117,7 @@ static void respond_to(struct sockaddr_in *src, struct osmo_fd *fd,
 		lc15bts_par_get_int(tall_mgr_ctx, LC15BTS_PAR_SERNR, &serno);
 		snprintf(ser_str, sizeof(ser_str), "%d", serno);
 
-		/* fetch the model and trx number */
+		strncpy(model_name, get_hwversion_desc(), sizeof(model_name)-1);
-		snprintf(model_name, sizeof(model_name), "Litecell 1.5 BTS");
-
-		rev = lc15bts_rev_get();
-		if (rev >= 0) {
-			snprintf(model_name, sizeof(model_name), "%s Rev %c", 
-				model_name, rev);
-		} 
-
-		model = lc15bts_model_get();
-		if (model >= 0) {
-			snprintf(model_name, sizeof(model_name), "%s (%05X)", 
-				model_name, model);
-		}
 		fetched_info = 1;
 	}