Consistently use snprintf instead of sprintf

There was a last instance of sprintf which somehow was not converted.
I know it can't fail, but for consistency, let's use snprintf and
check for truncation as we already do in gather_i2c_busses().

Signed-off-by: Jean Delvare <jdelvare@suse.de>

CHANGES

@@ -2,6 +2,7 @@ i2c-tools CHANGES
 -----------------
 
 master
+  tools: Consistently use snprintf instead of sprintf
   decode-dimms: Print SPD revision for DDR3 too
                 Move SDR-specific code
 

tools/i2cbusses.c

@@ -406,14 +406,21 @@ int parse_i2c_address(const char *address_arg, int all_addrs)
 
 int open_i2c_dev(int i2cbus, char *filename, size_t size, int quiet)
 {
-	int file;
+	int file, len;
 
-	snprintf(filename, size, "/dev/i2c/%d", i2cbus);
-	filename[size - 1] = '\0';
+	len = snprintf(filename, size, "/dev/i2c/%d", i2cbus);
+	if (len >= (int)size) {
+		fprintf(stderr, "%s: path truncated\n", filename);
+		return -EOVERFLOW;
+	}
 	file = open(filename, O_RDWR);
 
 	if (file < 0 && (errno == ENOENT || errno == ENOTDIR)) {
-		sprintf(filename, "/dev/i2c-%d", i2cbus);
+		len = snprintf(filename, size, "/dev/i2c-%d", i2cbus);
+		if (len >= (int)size) {
+			fprintf(stderr, "%s: path truncated\n", filename);
+			return -EOVERFLOW;
+		}
 		file = open(filename, O_RDWR);
 	}