kvm: Use strlcat helper for copying cmdline params

Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>

include/kvm/util.h

@@ -44,4 +44,6 @@ do {								\
 		__stringify(cnd) "\n");				\
 } while (0)
 
+extern size_t strlcat(char *dest, const char *src, size_t count);
+
 #endif /* KVM__UTIL_H */

main.c

@@ -69,7 +69,7 @@ int main(int argc, char *argv[])
 
 	strcpy(real_cmdline, "notsc nolapic nosmp noacpi earlyprintk=serial,keep");
 	if (kernel_cmdline) {
-		strncat(real_cmdline, kernel_cmdline, sizeof(real_cmdline));
+		strlcat(real_cmdline, kernel_cmdline, sizeof(real_cmdline));
 		real_cmdline[sizeof(real_cmdline)-1] = '\0';
 	}
 

util.c

@@ -74,3 +74,28 @@ void die_perror(const char *s)
 	perror(s);
 	exit(1);
 }
+
+/**
+ * strlcat - Append a length-limited, %NUL-terminated string to another
+ * @dest: The string to be appended to
+ * @src: The string to append to it
+ * @count: The size of the destination buffer.
+ */
+size_t strlcat(char *dest, const char *src, size_t count)
+{
+	size_t dsize = strlen(dest);
+	size_t len = strlen(src);
+	size_t res = dsize + len;
+
+	DIE_IF(dsize >= count);
+
+	dest += dsize;
+	count -= dsize;
+	if (len >= count)
+		len = count - 1;
+
+	memcpy(dest, src, len);
+	dest[len] = 0;
+
+	return res;
+}