fix(random): return number of bytes received

src/random.c

@@ -18,7 +18,8 @@
 
 /***
 Generate random bytes.
-This uses `getrandom()` on Linux, `CryptGenRandom()` on Windows, and `/dev/urandom` on macOS.
+This uses `getrandom()` on Linux, `CryptGenRandom()` on Windows, and `/dev/urandom` on macOS. The number of
+bytes returned can be less than `length` if the system is unable to generate that many bytes or was interrupted.
 @function random
 @tparam[opt=1] int length number of bytes to get, must be less than or equal to `MAX_RANDOM_BUFFER_SIZE` (1024)
 @treturn[1] string string of random bytes
@@ -53,6 +54,7 @@ static int lua_get_random_bytes(lua_State* L) {
  CryptReleaseContext(hCryptProv, 0);
  return 2;
  }
+ n = num_bytes; // CryptGenRandom() returns a BOOL, not the number of bytes
 
  CryptReleaseContext(hCryptProv, 0);
 #else
@@ -85,7 +87,7 @@ static int lua_get_random_bytes(lua_State* L) {
 
 #endif
 
- lua_pushlstring(L, (const char*)buffer, num_bytes);
+ lua_pushlstring(L, (const char*)buffer, n);
  return 1;
 }