core rpc: core.shmmem can take an optional size parameter

core.shmmem can take now an optional size parameter, which can
have one of the following values: b - bytes, k or kb - kilobytes,
m or mb - megabytes, g or gb - gigabytes. By default (no
parameter) the values displayed are in bytes. Note that when using
something different from bytes the value are truncated (no
floating point).
The new parameter can be used as workaround on 64 bits systems
when sr is started with more then 2Gb of memory (due to the RPC
interface limitation to int32 in this case the values displayed
would be negative or 0).
E.g:
sercmd> core.shmmem k

core_cmd.c

@@ -435,21 +435,54 @@ static void core_shmmem(rpc_t* rpc, void* c)
 {
 	struct mem_info mi;
 	void *handle;
-
+	char* param;
+	long rs;
+
+	rs=0;
+	/* look for optional size/divisor parameter */
+	if (rpc->scan(c, "*s", &param)>0){
+		switch(*param){
+			case 'b':
+			case 'B':
+				rs=0;
+				break;
+			case 'k':
+			case 'K':
+				rs=10; /* K -> 1024 */
+				break;
+			case 'm':
+			case 'M':
+				rs=20; /* M -> 1048576 */
+				break;
+			case 'g':
+			case 'G':
+				rs=30; /* G -> 1024M */
+				break;
+			default:
+				rpc->fault(c, 500, "bad param, (use b|k|m|g)");
+				return;
+		}
+		if (param[1] && ((param[1]!='b' && param[1]!='B') || param[2])){
+				rpc->fault(c, 500, "bad param, (use b|k|m|g)");
+				return;
+		}
+	}
 	shm_info(&mi);
 	rpc->add(c, "{", &handle);
 	rpc->struct_add(handle, "dddddd",
-		"total", (unsigned int)mi.total_size,
-		"free", (unsigned int)mi.free,
-		"used", (unsigned int)mi.used,
-		"real_used",(unsigned int)mi.real_used,
-		"max_used", (unsigned int)mi.max_used,
+		"total", (unsigned int)(mi.total_size>>rs),
+		"free", (unsigned int)(mi.free>>rs),
+		"used", (unsigned int)(mi.used>>rs),
+		"real_used",(unsigned int)(mi.real_used>>rs),
+		"max_used", (unsigned int)(mi.max_used>>rs),
 		"fragments", (unsigned int)mi.total_frags
 	);
 }
 
 static const char* core_shmmem_doc[] = {
-	"Returns shared memory info.",  /* Documentation string */
+	"Returns shared memory info. It has an optional parameter that specifies"
+	" the measuring unit: b - bytes (default), k or kb, m or mb, g or gb. "
+	"Note: when using something different from bytes, the value is truncated.",
 	0                               /* Method signature(s) */
 };