how to get signer for the CPI?

Question

Here's my solana program,

use my-rust-crate::do_cpi;


pub fn do_something(ctx:Context<DoSomething>) => Result<()>{
    do_cpi(ctx);
}

so this my rust crate is where the CPI happens, its not a solana program, its a rust program. In order to do the CPI i need a signer.

so how should i proceed with this.

this is the solana program function i'm try to CPI

pub fn register_client(ctx: Context<RegisterClient>, client_name: String) -> Result<()> {
        let name = client_name.as_bytes();

        if validate_name(name) == false {
            return err!(AgentError::InvalidName);
        }
        let client = &mut ctx.accounts.client.load_init()?;
        client.owner = ctx.accounts.owner.to_account_info().key();
        Ok(())
    }

Answer 1

Let's say we have puppet-master which is our main program that wants to CPI into puppet program.

CPIs extend the privileges of the caller to the callee. If an account is passed as a mutable account to the puppet-master then it was still mutable in the puppet program as well, The same applies to signatures (Signers).

Source: https://book.anchor-lang.com/anchor_in_depth/CPIs.html#privilege-extension

Example with authority as the signer.

 let cpi_program = self.puppet_program.to_account_info();
        let cpi_accounts = SetData {
            puppet: self.puppet.to_account_info(),
            authority: self.authority.to_account_info()
        };
        CpiContext::new(cpi_program, cpi_accounts)