14
votes
Accepted
How can I increase an existing account size?
You can do this in Anchor with realloc* constraints.
#[derive(Accounts)]
pub struct Example {
#[account(mut)]
pub payer: Signer<'info>,
#[account(
mut,
seeds = [b&...
- 1,851
8
votes
Accepted
How to check if a PDA account has/hasn't been initialized?
Without constraints
Check initialized
Account::try_from will check
the account is owned by the correct program
the account is initialized
the account has the correct discriminator
and can be ...
- 2,949
3
votes
Accepted
What is an "account revival attack"? Regarding the "#[account(close = <target_account>)]" constraint
In your Solana program the #[account] attribute for a data type assigns a unique 8-byte discriminator for accounts of that type.
i.e:
#[account]
pub struct MyType {}
When an account of that type is ...
- 3,944
3
votes
How to check if a PDA account has/hasn't been initialized?
What "(de)initialized" looks like is up to your program. Typically it's a some combination of the assigned owner program, lamports balance, allocated data size and/or value(s) stored in the ...
- 4,585
3
votes
Accepted
Reducing calls to .load() in constraints
You might have to chain all your constraints into a single constraint. For example:
#[account(
mut,
constraint = {
let acc = some_acc.load()?;
(acc.admin == *admin.key || acc....
- 3,944
3
votes
Accepted
Is there a way I can use find_program_address used to derive a PDA as an anchor constraint
You can use the seeds and bump constraints, and then also specify the program that the pda should be derived from.
For example:
#[account(
seeds = [b"some_seed"],
bump,
...
- 7,794
2
votes
Accepted
Check for negative "unsign" interger does not work
rate is defined as u64, an unsigned 64-bit integer, meaning that the 8 bytes that make up the number will always be interpreted as unsigned, greater than or equal to 0.
When you pass -10, that creates ...
- 19.6k
2
votes
Accepted
Error Code: ConstraintMut. Error Number: 2000. Error Message: A mut constraint was violated.'
Just ran into the same error. The issue (in my case) was my IDL was out-of-sync with the program I invoking on dev-net. The program was expecting a mutable account but the IDL had the account marked ...
- 36
2
votes
What is an "account revival attack"? Regarding the "#[account(close = <target_account>)]" constraint
The idea is just that you can send solana to the closed accounts and revive them. Program accounts that have had all their lamports removed don't get their ownership transferred to the system program ...
- 2,949
1
vote
Signer added when using has_one
The answer is actually on the TS side. If you are sending the tx from some specific user like so:
const program = workspace.someProgram as Program<SomeProgram>;
await admin.userProgram....
- 3,607
1
vote
How to check if a PDA account has/hasn't been initialized?
Everyone here posted pretty good answers but without code to back it up, so I will probably end up going with my own answer now that I have figured this issue out.
I realized that AccountInfo holds ...
- 438
1
vote
How to check if a PDA account has/hasn't been initialized?
There may be a better way to check if an account has been initialised, but personally I just check if it has lamports:
if **destination_account_info.try_borrow_lamports()? > 0 {
msg!("...
- 597
Only top scored, non community-wiki answers of a minimum length are eligible