lang: add `realloc` constraint group (#1943)

.github/workflows/tests.yaml

@@ -360,6 +360,8 @@ jobs:
             path: tests/escrow
           - cmd: cd tests/pyth && anchor test --skip-lint && npx tsc --noEmit
             path: tests/pyth
+          - cmd: cd tests/realloc && anchor test --skip-lint && npx tsc --noEmit
+            path: tests/realloc
           - cmd: cd tests/system-accounts && anchor test --skip-lint
             path: tests/system-accounts
           - cmd: cd tests/misc && anchor test --skip-lint && npx tsc --noEmit

CHANGELOG.md

@@ -12,6 +12,7 @@ The minor version will be incremented upon a breaking change and the patch versi
 
 ### Features
 
+* lang: Add `realloc`, `realloc::payer`, and `realloc::zero` as a new constraint group for program accounts ([#1943](https://github.com/project-serum/anchor/pull/1943)).
 * lang: Add `PartialEq` and `Eq` for `anchor_lang::Error` ([#1544](https://github.com/project-serum/anchor/pull/1544)).
 * cli: Add `--skip-build` to `anchor publish` ([#1786](https://github.
 com/project-serum/anchor/pull/1841)).

lang/derive/accounts/src/lib.rs

@@ -44,6 +44,7 @@ use syn::parse_macro_input;
 ///
 /// - [Normal Constraints](#normal-constraints)
 /// - [SPL Constraints](#spl-constraints)
+///
 /// # Normal Constraints
 /// <table>
 ///     <thead>
@@ -418,6 +419,44 @@ use syn::parse_macro_input;
 ///                 </code></pre>
 ///             </td>
 ///         </tr>
+///         <tr>
+///             <td>
+///                 <code>#[account(realloc = &lt;space&gt;, realloc::payer = &lt;target&gt;, realloc::zero = &lt;bool&gt;)]</code>
+///             </td>
+///             <td>
+///                 Used to <a href="https://docs.rs/solana-program/latest/solana_program/account_info/struct.AccountInfo.html#method.realloc" target = "_blank" rel = "noopener noreferrer">realloc</a>
+///                 program account space at the beginning of an instruction.
+///                 <br><br>
+///                 The account must be marked as <code>mut</code> and applied to either <code>Account</code> or <code>AccountLoader</code> types.
+///                 <br><br>
+///                 If the change in account data length is additive, lamports will be transferred from the <code>realloc::payer</code> into the
+///                 program account in order to maintain rent exemption. Likewise, if the change is subtractive, lamports will be transferred from
+///                 the program account back into the <code>realloc::payer</code>.
+///                 <br><br>
+///                 The <code>realloc::zero</code> constraint is required in order to determine whether the new memory should be zero initialized after
+///                 reallocation. Please read the documentation on the <code>AccountInfo::realloc</code> function linked above to understand the
+///                 caveats regarding compute units when providing <code>true</code or <code>false</code> to this flag.
+///                 <br><br>
+///                 Example:
+///                 <pre>
+/// #[derive(Accounts)]
+/// pub struct Example {
+///     #[account(mut)]
+///     pub payer: Signer<'info>,
+///     #[account(
+///         mut,
+///         seeds = [b"example"],
+///         bump,
+///         realloc = 8 + std::mem::size_of::<MyType>() + 100,
+///         realloc::payer = payer,
+///         realloc::zero = false,
+///     )]
+///     pub acc: Account<'info, MyType>,
+///     pub system_program: Program<'info, System>,
+/// }
+///                 </pre>
+///             </td>
+///         </tr>
 ///     </tbody>
 /// </table>
 ///

lang/syn/src/codegen/accounts/constraints.rs

@@ -59,6 +59,7 @@ pub fn linearize(c_group: &ConstraintGroup) -> Vec<Constraint> {
         associated_token,
         token_account,
         mint,
+        realloc,
     } = c_group.clone();
 
     let mut constraints = Vec::new();
@@ -69,6 +70,9 @@ pub fn linearize(c_group: &ConstraintGroup) -> Vec<Constraint> {
     if let Some(c) = init {
         constraints.push(Constraint::Init(c));
     }
+    if let Some(c) = realloc {
+        constraints.push(Constraint::Realloc(c));
+    }
     if let Some(c) = seeds {
         constraints.push(Constraint::Seeds(c));
     }
@@ -130,6 +134,7 @@ fn generate_constraint(f: &Field, c: &Constraint) -> proc_macro2::TokenStream {
         Constraint::AssociatedToken(c) => generate_constraint_associated_token(f, c),
         Constraint::TokenAccount(c) => generate_constraint_token_account(f, c),
         Constraint::Mint(c) => generate_constraint_mint(f, c),
+        Constraint::Realloc(c) => generate_constraint_realloc(f, c),
     }
 }
 
@@ -320,6 +325,46 @@ pub fn generate_constraint_rent_exempt(
     }
 }
 
+fn generate_constraint_realloc(f: &Field, c: &ConstraintReallocGroup) -> proc_macro2::TokenStream {
+    let field = &f.ident;
+    let new_space = &c.space;
+    let payer = &c.payer;
+    let zero = &c.zero;
+
+    quote! {
+        let __anchor_rent = Rent::get()?;
+        let __field_info = #field.to_account_info();
+        let __additive = #new_space > __field_info.data_len();
+
+        let __delta_space = if __additive {
+            #new_space.checked_sub(__field_info.data_len()).unwrap()
+        } else {
+            __field_info.data_len().checked_sub(#new_space).unwrap()
+        };
+
+        if __delta_space > 0 {
+            if __additive {
+                anchor_lang::system_program::transfer(
+                    anchor_lang::context::CpiContext::new(
+                        system_program.to_account_info(),
+                        anchor_lang::system_program::Transfer {
+                            from: #payer.to_account_info(),
+                            to: __field_info.clone(),
+                        },
+                    ),
+                    __anchor_rent.minimum_balance(#new_space).checked_sub(__field_info.lamports()).unwrap(),
+                )?;
+            } else {
+                let __lamport_amt = __field_info.lamports().checked_sub(__anchor_rent.minimum_balance(#new_space)).unwrap();
+                **#payer.to_account_info().lamports.borrow_mut() = #payer.to_account_info().lamports().checked_add(__lamport_amt).unwrap();
+                **__field_info.lamports.borrow_mut() = __field_info.lamports().checked_sub(__lamport_amt).unwrap();
+            }
+
+            #field.to_account_info().realloc(#new_space, #zero)?;
+        }
+    }
+}
+
 fn generate_constraint_init_group(f: &Field, c: &ConstraintInitGroup) -> proc_macro2::TokenStream {
     let field = &f.ident;
     let name_str = f.ident.to_string();

lang/syn/src/lib.rs

@@ -635,6 +635,7 @@ pub struct ConstraintGroup {
     associated_token: Option<ConstraintAssociatedToken>,
     token_account: Option<ConstraintTokenAccountGroup>,
     mint: Option<ConstraintTokenMintGroup>,
+    realloc: Option<ConstraintReallocGroup>,
 }
 
 impl ConstraintGroup {
@@ -678,6 +679,7 @@ pub enum Constraint {
     Address(ConstraintAddress),
     TokenAccount(ConstraintTokenAccountGroup),
     Mint(ConstraintTokenMintGroup),
+    Realloc(ConstraintReallocGroup),
 }
 
 // Constraint token is a single keyword in a `#[account(<TOKEN>)]` attribute.
@@ -709,6 +711,9 @@ pub enum ConstraintToken {
     MintDecimals(Context<ConstraintMintDecimals>),
     Bump(Context<ConstraintTokenBump>),
     ProgramSeed(Context<ConstraintProgramSeed>),
+    Realloc(Context<ConstraintRealloc>),
+    ReallocPayer(Context<ConstraintReallocPayer>),
+    ReallocZero(Context<ConstraintReallocZero>),
 }
 
 impl Parse for ConstraintToken {
@@ -733,6 +738,28 @@ pub struct ConstraintMut {
     pub error: Option<Expr>,
 }
 
+#[derive(Debug, Clone)]
+pub struct ConstraintReallocGroup {
+    pub payer: Expr,
+    pub space: Expr,
+    pub zero: Expr,
+}
+
+#[derive(Debug, Clone)]
+pub struct ConstraintRealloc {
+    pub space: Expr,
+}
+
+#[derive(Debug, Clone)]
+pub struct ConstraintReallocPayer {
+    pub target: Expr,
+}
+
+#[derive(Debug, Clone)]
+pub struct ConstraintReallocZero {
+    pub zero: Expr,
+}
+
 #[derive(Debug, Clone)]
 pub struct ConstraintSigner {
     pub error: Option<Expr>,

lang/syn/src/parser/accounts/constraints.rs

@@ -196,6 +196,47 @@ pub fn parse_token(stream: ParseStream) -> ParseResult<ConstraintToken> {
                 ))
             }
         }
+        "realloc" => {
+            if stream.peek(Token![=]) {
+                stream.parse::<Token![=]>()?;
+                let span = ident
+                    .span()
+                    .join(stream.span())
+                    .unwrap_or_else(|| ident.span());
+                ConstraintToken::Realloc(Context::new(
+                    span,
+                    ConstraintRealloc {
+                        space: stream.parse()?,
+                    },
+                ))
+            } else {
+                stream.parse::<Token![:]>()?;
+                stream.parse::<Token![:]>()?;
+                let kw = stream.call(Ident::parse_any)?.to_string();
+                stream.parse::<Token![=]>()?;
+
+                let span = ident
+                    .span()
+                    .join(stream.span())
+                    .unwrap_or_else(|| ident.span());
+
+                match kw.as_str() {
+                    "payer" => ConstraintToken::ReallocPayer(Context::new(
+                        span,
+                        ConstraintReallocPayer {
+                            target: stream.parse()?,
+                        },
+                    )),
+                    "zero" => ConstraintToken::ReallocZero(Context::new(
+                        span,
+                        ConstraintReallocZero {
+                            zero: stream.parse()?,
+                        },
+                    )),
+                    _ => return Err(ParseError::new(ident.span(), "Invalid attribute. realloc::payer and realloc::zero are the only valid attributes")),
+                }
+            }
+        }
         _ => {
             stream.parse::<Token![=]>()?;
             let span = ident
@@ -313,6 +354,9 @@ pub struct ConstraintGroupBuilder<'ty> {
     pub mint_decimals: Option<Context<ConstraintMintDecimals>>,
     pub bump: Option<Context<ConstraintTokenBump>>,
     pub program_seed: Option<Context<ConstraintProgramSeed>>,
+    pub realloc: Option<Context<ConstraintRealloc>>,
+    pub realloc_payer: Option<Context<ConstraintReallocPayer>>,
+    pub realloc_zero: Option<Context<ConstraintReallocZero>>,
 }
 
 impl<'ty> ConstraintGroupBuilder<'ty> {
@@ -344,6 +388,9 @@ impl<'ty> ConstraintGroupBuilder<'ty> {
             mint_decimals: None,
             bump: None,
             program_seed: None,
+            realloc: None,
+            realloc_payer: None,
+            realloc_zero: None,
         }
     }
 
@@ -439,6 +486,22 @@ impl<'ty> ConstraintGroupBuilder<'ty> {
             }
         }
 
+        // Realloc.
+        if let Some(r) = &self.realloc {
+            if self.realloc_payer.is_none() {
+                return Err(ParseError::new(
+                    r.span(),
+                    "realloc::payer must be provided when using realloc",
+                ));
+            }
+            if self.realloc_zero.is_none() {
+                return Err(ParseError::new(
+                    r.span(),
+                    "realloc::zero must be provided when using realloc",
+                ));
+            }
+        }
+
         // Zero.
         if let Some(z) = &self.zeroed {
             match self.mutable {
@@ -526,6 +589,9 @@ impl<'ty> ConstraintGroupBuilder<'ty> {
             mint_decimals,
             bump,
             program_seed,
+            realloc,
+            realloc_payer,
+            realloc_zero,
         } = self;
 
         // Converts Option<Context<T>> -> Option<T>.
@@ -644,6 +710,11 @@ impl<'ty> ConstraintGroupBuilder<'ty> {
                     }
                 },
             })).transpose()?,
+            realloc: realloc.as_ref().map(|r| ConstraintReallocGroup {
+                payer: into_inner!(realloc_payer).unwrap().target,
+                space: r.space.clone(),
+                zero: into_inner!(realloc_zero).unwrap().zero,
+            }),
             zeroed: into_inner!(zeroed),
             mutable: into_inner!(mutable),
             signer: into_inner!(signer),
@@ -690,6 +761,9 @@ impl<'ty> ConstraintGroupBuilder<'ty> {
             ConstraintToken::MintDecimals(c) => self.add_mint_decimals(c),
             ConstraintToken::Bump(c) => self.add_bump(c),
             ConstraintToken::ProgramSeed(c) => self.add_program_seed(c),
+            ConstraintToken::Realloc(c) => self.add_realloc(c),
+            ConstraintToken::ReallocPayer(c) => self.add_realloc_payer(c),
+            ConstraintToken::ReallocZero(c) => self.add_realloc_zero(c),
         }
     }
 
@@ -757,6 +831,56 @@ impl<'ty> ConstraintGroupBuilder<'ty> {
         Ok(())
     }
 
+    fn add_realloc(&mut self, c: Context<ConstraintRealloc>) -> ParseResult<()> {
+        if !matches!(self.f_ty, Some(Ty::Account(_)))
+            && !matches!(self.f_ty, Some(Ty::AccountLoader(_)))
+        {
+            return Err(ParseError::new(
+                c.span(),
+                "realloc must be on an Account or AccountLoader",
+            ));
+        }
+        if self.mutable.is_none() {
+            return Err(ParseError::new(
+                c.span(),
+                "mut must be provided before realloc",
+            ));
+        }
+        if self.realloc.is_some() {
+            return Err(ParseError::new(c.span(), "realloc already provided"));
+        }
+        self.realloc.replace(c);
+        Ok(())
+    }
+
+    fn add_realloc_payer(&mut self, c: Context<ConstraintReallocPayer>) -> ParseResult<()> {
+        if self.realloc.is_none() {
+            return Err(ParseError::new(
+                c.span(),
+                "realloc must be provided before realloc::payer",
+            ));
+        }
+        if self.realloc_payer.is_some() {
+            return Err(ParseError::new(c.span(), "realloc::payer already provided"));
+        }
+        self.realloc_payer.replace(c);
+        Ok(())
+    }
+
+    fn add_realloc_zero(&mut self, c: Context<ConstraintReallocZero>) -> ParseResult<()> {
+        if self.realloc.is_none() {
+            return Err(ParseError::new(
+                c.span(),
+                "realloc must be provided before realloc::zero",
+            ));
+        }
+        if self.realloc_zero.is_some() {
+            return Err(ParseError::new(c.span(), "realloc::zero already provided"));
+        }
+        self.realloc_zero.replace(c);
+        Ok(())
+    }
+
     fn add_close(&mut self, c: Context<ConstraintClose>) -> ParseResult<()> {
         if !matches!(self.f_ty, Some(Ty::ProgramAccount(_)))
             && !matches!(self.f_ty, Some(Ty::Account(_)))

lang/syn/src/parser/accounts/mod.rs

@@ -55,7 +55,7 @@ fn constraints_cross_checks(fields: &[AccountField]) -> ParseResult<()> {
                 init_fields[0].ident.span(),
                 "the init constraint requires \
                 the system_program field to exist in the account \
-                validation struct. Use the program type to add \
+                validation struct. Use the Program type to add \
                 the system_program field to your validation struct.",
             ));
         }
@@ -70,7 +70,7 @@ fn constraints_cross_checks(fields: &[AccountField]) -> ParseResult<()> {
                         init_fields[0].ident.span(),
                         "the init constraint requires \
                             the token_program field to exist in the account \
-                            validation struct. Use the program type to add \
+                            validation struct. Use the Program type to add \
                             the token_program field to your validation struct.",
                     ));
                 }
@@ -86,7 +86,7 @@ fn constraints_cross_checks(fields: &[AccountField]) -> ParseResult<()> {
                     init_fields[0].ident.span(),
                     "the init constraint requires \
                     the associated_token_program field to exist in the account \
-                    validation struct. Use the program type to add \
+                    validation struct. Use the Program type to add \
                     the associated_token_program field to your validation struct.",
                 ));
             }
@@ -141,6 +141,61 @@ fn constraints_cross_checks(fields: &[AccountField]) -> ParseResult<()> {
             }
         }
     }
+
+    // REALLOC
+    let realloc_fields: Vec<&Field> = fields
+        .iter()
+        .filter_map(|f| match f {
+            AccountField::Field(field) if field.constraints.realloc.is_some() => Some(field),
+            _ => None,
+        })
+        .collect();
+
+    if !realloc_fields.is_empty() {
+        // realloc needs system program.
+        if fields.iter().all(|f| f.ident() != "system_program") {
+            return Err(ParseError::new(
+                realloc_fields[0].ident.span(),
+                "the realloc constraint requires \
+                the system_program field to exist in the account \
+                validation struct. Use the Program type to add \
+                the system_program field to your validation struct.",
+            ));
+        }
+
+        for field in realloc_fields {
+            // Get allocator for realloc-ed account
+            let associated_payer_name = match field.constraints.realloc.clone().unwrap().payer {
+                // composite allocator, check not supported
+                Expr::Field(_) => continue,
+                field_name => field_name.to_token_stream().to_string(),
+            };
+
+            // Check allocator is mutable
+            let associated_payer_field = fields.iter().find_map(|f| match f {
+                AccountField::Field(field) if *f.ident() == associated_payer_name => Some(field),
+                _ => None,
+            });
+
+            match associated_payer_field {
+                Some(associated_payer_field) => {
+                    if !associated_payer_field.constraints.is_mutable() {
+                        return Err(ParseError::new(
+                            field.ident.span(),
+                            "the realloc::payer specified for an realloc constraint must be mutable.",
+                        ));
+                    }
+                }
+                _ => {
+                    return Err(ParseError::new(
+                        field.ident.span(),
+                        "the realloc::payer specified does not exist.",
+                    ));
+                }
+            }
+        }
+    }
+
     Ok(())
 }
 

tests/package.json

@@ -24,6 +24,7 @@
     "permissioned-markets",
     "pda-derivation",
     "pyth",
+    "realloc",
     "spl/token-proxy",
     "swap",
     "system-accounts",

tests/realloc/Anchor.toml

@@ -0,0 +1,15 @@
+[features]
+seeds = false
+
+[programs.localnet]
+realloc = "Fg6PaFpoGXkYsidMpWTK6W2BeZ7FEfcYkg476zPFsLnS"
+
+[registry]
+url = "https://anchor.projectserum.com"
+
+[provider]
+cluster = "localnet"
+wallet = "~/.config/solana/id.json"
+
+[scripts]
+test = "yarn run ts-mocha -p ./tsconfig.json -t 1000000 tests/**/*.ts"

tests/realloc/Cargo.toml

@@ -0,0 +1,4 @@
+[workspace]
+members = [
+    "programs/*"
+]

tests/realloc/package.json

@@ -0,0 +1,20 @@
+{
+    "name": "realloc",
+    "version": "0.24.2",
+    "license": "(MIT OR Apache-2.0)",
+    "homepage": "https://github.com/project-serum/anchor#readme",
+    "bugs": {
+      "url": "https://github.com/project-serum/anchor/issues"
+    },
+    "repository": {
+      "type": "git",
+      "url": "https://github.com/project-serum/anchor.git"
+    },
+    "engines": {
+      "node": ">=11"
+    },
+    "scripts": {
+      "test": "anchor test"
+    }
+  }
+  

tests/realloc/programs/realloc/Cargo.toml

@@ -0,0 +1,22 @@
+[package]
+name = "realloc"
+version = "0.1.0"
+description = "Created with Anchor"
+edition = "2021"
+
+[lib]
+crate-type = ["cdylib", "lib"]
+name = "realloc"
+
+[features]
+no-entrypoint = []
+no-idl = []
+no-log-ix-name = []
+cpi = ["no-entrypoint"]
+default = []
+
+[profile.release]
+overflow-checks = true
+
+[dependencies]
+anchor-lang = { path = "../../../../lang" }

tests/realloc/programs/realloc/Xargo.toml

@@ -0,0 +1,2 @@
+[target.bpfel-unknown-unknown.dependencies.std]
+features = []

tests/realloc/programs/realloc/src/lib.rs

@@ -0,0 +1,70 @@
+use anchor_lang::prelude::*;
+
+declare_id!("Fg6PaFpoGXkYsidMpWTK6W2BeZ7FEfcYkg476zPFsLnS");
+
+#[program]
+pub mod realloc {
+    use super::*;
+
+    pub fn initialize(ctx: Context<Initialize>) -> Result<()> {
+        ctx.accounts.sample.data = vec![0];
+        ctx.accounts.sample.bump = *ctx.bumps.get("sample").unwrap();
+        Ok(())
+    }
+
+    pub fn realloc(ctx: Context<Realloc>, len: u8) -> Result<()> {
+        ctx.accounts
+            .sample
+            .data
+            .resize_with(len as usize, Default::default);
+        Ok(())
+    }
+}
+
+#[derive(Accounts)]
+pub struct Initialize<'info> {
+    #[account(mut)]
+    pub authority: Signer<'info>,
+
+    #[account(
+        init,
+        payer = authority,
+        seeds = [b"sample"],
+        bump,
+        space = Sample::space(1),
+    )]
+    pub sample: Account<'info, Sample>,
+
+    pub system_program: Program<'info, System>,
+}
+
+#[derive(Accounts)]
+#[instruction(len: u8)]
+pub struct Realloc<'info> {
+    #[account(mut)]
+    pub authority: Signer<'info>,
+
+    #[account(
+        mut,
+        seeds = [b"sample"],
+        bump = sample.bump,
+        realloc = Sample::space(len as usize),
+        realloc::payer = authority,
+        realloc::zero = false,
+    )]
+    pub sample: Account<'info, Sample>,
+
+    pub system_program: Program<'info, System>,
+}
+
+#[account]
+pub struct Sample {
+    pub data: Vec<u8>,
+    pub bump: u8,
+}
+
+impl Sample {
+    pub fn space(len: usize) -> usize {
+        8 + (4 + len) + 1
+    }
+}

tests/realloc/tests/realloc.ts

@@ -0,0 +1,52 @@
+import * as anchor from "@project-serum/anchor";
+import { Program } from "@project-serum/anchor";
+import { assert } from "chai";
+import { Realloc } from "../target/types/realloc";
+
+describe("realloc", () => {
+  // Configure the client to use the local cluster.
+  anchor.setProvider(anchor.AnchorProvider.env());
+
+  const program = anchor.workspace.Realloc as Program<Realloc>;
+  const authority = (program.provider as any).wallet
+    .payer as anchor.web3.Keypair;
+
+  let sample: anchor.web3.PublicKey;
+
+  before(async () => {
+    [sample] = await anchor.web3.PublicKey.findProgramAddress(
+      [Buffer.from("sample")],
+      program.programId
+    );
+  });
+
+  it("Is initialized!", async () => {
+    await program.methods
+      .initialize()
+      .accounts({ authority: authority.publicKey, sample })
+      .rpc();
+
+    const s = await program.account.sample.fetch(sample);
+    assert.lengthOf(s.data, 1);
+  });
+
+  it("realloc additive", async () => {
+    await program.methods
+      .realloc(5)
+      .accounts({ authority: authority.publicKey, sample })
+      .rpc();
+
+    const s = await program.account.sample.fetch(sample);
+    assert.lengthOf(s.data, 5);
+  });
+
+  it("realloc substractive", async () => {
+    await program.methods
+      .realloc(1)
+      .accounts({ authority: authority.publicKey, sample })
+      .rpc();
+
+    const s = await program.account.sample.fetch(sample);
+    assert.lengthOf(s.data, 1);
+  });
+});

tests/realloc/tsconfig.json

@@ -0,0 +1,10 @@
+{
+  "compilerOptions": {
+    "types": ["mocha", "chai"],
+    "typeRoots": ["./node_modules/@types"],
+    "lib": ["es2015"],
+    "module": "commonjs",
+    "target": "es6",
+    "esModuleInterop": true
+  }
+}