Test takers of certain countries have to follow specific regulations to take the test in those countries. For example, when taking the test in the US, citizens and permanent residents (green card holders) of the US can choose from a range of identification documents, whereas non-citizens MUST present a valid passport.
In India – and most other parts of the world – the testing centers only accept the test taker's passport as a form of identification. No exceptions are allowed.
To find out the exact requirements for the country where you will take the test, visit this official web page:
You cannot take anything into the exam area with you, whether it is food, water, or even a calculator. Whatever you need for the exam will be provided to you by the staff at the test center.
However, you will be provided with a locker to store your belongings. During breaks, you will be allowed to have food and water.