Account discriminators (#14)

Author: armaniferrante

.travis.yml

@@ -21,7 +21,7 @@ _examples: &examples
   - export PATH="/home/travis/.local/share/solana/install/active_release/bin:$PATH"
   - export NODE_PATH="/home/travis/.nvm/versions/node/v$NODE_VERSION/lib/node_modules/:$NODE_PATH"
   - yes | solana-keygen new
-  - cargo install --git https://github.com/project-serum/anchor anchor-cli
+  - cargo install --git https://github.com/project-serum/anchor anchor-cli --locked
 
 jobs:
   include:

Cargo.lock

@@ -13,15 +13,16 @@ default = []
 thiserror = "1.0.20"
 solana-program = "1.4.3"
 solana-sdk = { version = "1.3.14", default-features = false, features = ["program"] }
-anchor-derive = { path = "./derive" }
-anchor-attributes-program = { path = "./attributes/program" }
-anchor-attributes-access-control = { path = "./attributes/access-control" }
+anchor-derive-accounts = { path = "./derive/accounts" }
+anchor-attribute-program = { path = "./attribute/program" }
+anchor-attribute-access-control = { path = "./attribute/access-control" }
+anchor-attribute-account = { path = "./attribute/account" }
 borsh = { git = "https://github.com/project-serum/borsh", branch = "serum", features = ["serum-program"] }
 
 [workspace]
 members = [
     "cli",
     "syn",
-    "attributes/*",
-    "derive",
+    "attribute/*",
+    "derive/*",
 ]

Cargo.toml

@@ -91,6 +91,7 @@ purposes of the Accounts macro) that can be specified on a struct deriving `Acco
 |:--|:--|:--|
 | `#[account(signer)]` | On raw `AccountInfo` structs. | Checks the given account signed the transaction. |
 | `#[account(mut)]` | On `ProgramAccount` structs. | Marks the account as mutable and persists the state transition. |
+| `#[account(init)]` | On `ProgramAccount` structs. | Marks the account as being initialized, skipping the account discriminator check. |
 | `#[account(belongs_to = <target>)]` | On `ProgramAccount` structs | Checks the `target` field on the account matches the `target` field in the accounts array. |
 | `#[account(owner = program \| skip)]` | On `ProgramAccount` and `AccountInfo` structs | Checks the owner of the account is the current program or skips the check. |
 | `#[account("<literal>")]` | On `ProgramAccount` structs | Executes the given code literal as a constraint. The literal should evaluate to a boolean. |

README.md

@@ -1,5 +1,5 @@
 [package]
-name = "anchor-attributes-program"
+name = "anchor-attribute-access-control"
 version = "0.1.0"
 authors = ["armaniferrante <[email protected]>"]
 edition = "2018"

attributes/program/Cargo.toml renamed to attribute/access-control/Cargo.toml

@@ -3,6 +3,9 @@ extern crate proc_macro;
 use quote::quote;
 use syn::parse_macro_input;
 
+/// Executes the given access control method before running the decorated
+/// instruction handler. Any method in scope of the attribute can be invoked
+/// with any arguments from the associated instruction handler.
 #[proc_macro_attribute]
 pub fn access_control(
     args: proc_macro::TokenStream,

attributes/access-control/src/lib.rs renamed to attribute/access-control/src/lib.rs

@@ -1,5 +1,5 @@
 [package]
-name = "anchor-attributes-access-control"
+name = "anchor-attribute-account"
 version = "0.1.0"
 authors = ["armaniferrante <[email protected]>"]
 edition = "2018"
@@ -12,4 +12,4 @@ proc-macro2 = "1.0"
 quote = "1.0"
 syn = { version = "1.0.54", features = ["full"] }
 anyhow = "1.0.32"
-anchor-syn = { path = "../../syn" }
+anchor-syn = { path = "../../syn" }

attributes/access-control/Cargo.toml renamed to attribute/account/Cargo.toml

@@ -0,0 +1,75 @@
+extern crate proc_macro;
+
+use quote::quote;
+use syn::parse_macro_input;
+
+/// A data structure representing a Solana account.
+#[proc_macro_attribute]
+pub fn account(
+    _args: proc_macro::TokenStream,
+    input: proc_macro::TokenStream,
+) -> proc_macro::TokenStream {
+    let account_strct = parse_macro_input!(input as syn::ItemStruct);
+    let account_name = &account_strct.ident;
+    // Namespace the discriminator to prevent future collisions, e.g.,
+    // if we (for some unforseen reason) wanted to hash other parts of the
+    // program.
+    let discriminator_preimage = format!("account:{}", account_name.to_string());
+
+    let coder = quote! {
+        impl anchor::AccountSerialize for #account_name {
+            fn try_serialize<W: std::io::Write>(&self, writer: &mut W) -> Result<(), ProgramError> {
+                // TODO: we shouldn't have to hash at runtime. However, rust
+                //       is not happy when trying to include solana-sdk from
+                //       the proc-macro crate.
+                let mut discriminator = [0u8; 8];
+                discriminator.copy_from_slice(
+                    &solana_program::hash::hash(
+                        #discriminator_preimage.as_bytes(),
+                    ).to_bytes()[..8],
+                );
+
+                writer.write_all(&discriminator).map_err(|_| ProgramError::InvalidAccountData)?;
+                AnchorSerialize::serialize(
+                    self,
+                    writer
+                )
+                    .map_err(|_| ProgramError::InvalidAccountData)?;
+                Ok(())
+            }
+        }
+
+        impl anchor::AccountDeserialize for #account_name {
+            fn try_deserialize(buf: &mut &[u8]) -> Result<Self, ProgramError> {
+                let mut discriminator = [0u8; 8];
+                discriminator.copy_from_slice(
+                    &solana_program::hash::hash(
+                        #discriminator_preimage.as_bytes(),
+                    ).to_bytes()[..8],
+                );
+
+                if buf.len() < discriminator.len() {
+                    return Err(ProgramError::AccountDataTooSmall);
+                }
+                let given_disc = &buf[..8];
+                if &discriminator != given_disc {
+                    return Err(ProgramError::InvalidInstructionData);
+                }
+                Self::try_deserialize_unchecked(buf)
+            }
+
+            fn try_deserialize_unchecked(buf: &mut &[u8]) -> Result<Self, ProgramError> {
+                let mut data: &[u8] = &buf[8..];
+                AnchorDeserialize::deserialize(&mut data)
+                    .map_err(|_| ProgramError::InvalidAccountData)
+            }
+        }
+    };
+
+    proc_macro::TokenStream::from(quote! {
+        #[derive(AnchorSerialize, AnchorDeserialize)]
+        #account_strct
+
+        #coder
+    })
+}

attribute/account/src/lib.rs

@@ -0,0 +1,15 @@
+[package]
+name = "anchor-attribute-program"
+version = "0.1.0"
+authors = ["armaniferrante <[email protected]>"]
+edition = "2018"
+
+[lib]
+proc-macro = true
+
+[dependencies]
+proc-macro2 = "1.0"
+quote = "1.0"
+syn = { version = "1.0.54", features = ["full"] }
+anyhow = "1.0.32"
+anchor-syn = { path = "../../syn" }

attribute/program/Cargo.toml

@@ -4,6 +4,8 @@ use anchor_syn::codegen::program as program_codegen;
 use anchor_syn::parser::program as program_parser;
 use syn::parse_macro_input;
 
+/// The module containing all instruction handlers defining all entries to the
+/// Solana program.
 #[proc_macro_attribute]
 pub fn program(
     _args: proc_macro::TokenStream,