Able to sign
Aleix Vidal's injury during yesterday's game against Alavés and the time he is estimated to be sidelined means that Barcelona are eligible to sign a player as a replacement. While the club have not mentioned whether they intend to sign anyone, the rules would them to as they will be without a first team member due to long-term injury - five months or longer.
Srna not an option
To bring in a player to replace Vidal, Barça would need to adhere to two requisites: it must be a player who is out of contract or who plays in LaLiga Santander. For example, one of the options which Barcelona were considering in the winter transfer window, Dario Srna, would not be able to join the Blaugranas for the moment as he doesn't comply with either of those two conditions.
Mucho ánimo y fuerza a Aleix 🙏🏾— Samuel Umtiti (@UmtitiSam) 11 February 2017