implements PR-011b assets.pa bootstrap and header loading

crates/console/prometeu-hal/src/cartridge.rs

@@ -2,6 +2,10 @@ use crate::asset::{AssetEntry, PreloadEntry};
 use crate::syscalls::CapFlags;
 use serde::{Deserialize, Serialize};
 
+pub const ASSETS_PA_MAGIC: [u8; 4] = *b"ASPA";
+pub const ASSETS_PA_SCHEMA_VERSION: u32 = 1;
+pub const ASSETS_PA_PRELUDE_SIZE: usize = 32;
+
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Deserialize, Serialize)]
 pub enum AppMode {
     Game,
@@ -55,6 +59,58 @@ impl From<CartridgeDTO> for Cartridge {
     }
 }
 
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct AssetsPackPrelude {
+    pub magic: [u8; 4],
+    pub schema_version: u32,
+    pub header_len: u32,
+    pub payload_offset: u64,
+    pub flags: u32,
+    pub reserved: u32,
+    pub header_checksum: u32,
+}
+
+impl AssetsPackPrelude {
+    pub fn from_bytes(bytes: &[u8]) -> Option<Self> {
+        if bytes.len() < ASSETS_PA_PRELUDE_SIZE {
+            return None;
+        }
+
+        let mut magic = [0_u8; 4];
+        magic.copy_from_slice(&bytes[0..4]);
+
+        Some(Self {
+            magic,
+            schema_version: u32::from_le_bytes(bytes[4..8].try_into().ok()?),
+            header_len: u32::from_le_bytes(bytes[8..12].try_into().ok()?),
+            payload_offset: u64::from_le_bytes(bytes[12..20].try_into().ok()?),
+            flags: u32::from_le_bytes(bytes[20..24].try_into().ok()?),
+            reserved: u32::from_le_bytes(bytes[24..28].try_into().ok()?),
+            header_checksum: u32::from_le_bytes(bytes[28..32].try_into().ok()?),
+        })
+    }
+
+    pub fn to_bytes(self) -> [u8; ASSETS_PA_PRELUDE_SIZE] {
+        let mut bytes = [0_u8; ASSETS_PA_PRELUDE_SIZE];
+        bytes[0..4].copy_from_slice(&self.magic);
+        bytes[4..8].copy_from_slice(&self.schema_version.to_le_bytes());
+        bytes[8..12].copy_from_slice(&self.header_len.to_le_bytes());
+        bytes[12..20].copy_from_slice(&self.payload_offset.to_le_bytes());
+        bytes[20..24].copy_from_slice(&self.flags.to_le_bytes());
+        bytes[24..28].copy_from_slice(&self.reserved.to_le_bytes());
+        bytes[28..32].copy_from_slice(&self.header_checksum.to_le_bytes());
+        bytes
+    }
+}
+
+#[derive(Debug, Clone, Deserialize, Serialize)]
+pub struct AssetsPackHeader {
+    #[serde(default)]
+    pub asset_table: Vec<AssetEntry>,
+    #[serde(default)]
+    pub preload: Vec<PreloadEntry>,
+}
+
 #[derive(Debug)]
 pub enum CartridgeError {
     NotFound,
@@ -62,6 +118,7 @@ pub enum CartridgeError {
     InvalidManifest,
     UnsupportedVersion,
     MissingProgram,
+    MissingAssets,
     IoError,
 }
 
@@ -90,8 +147,4 @@ pub struct CartridgeManifest {
     pub entrypoint: String,
     #[serde(default)]
     pub capabilities: Vec<Capability>,
-    #[serde(default)]
-    pub asset_table: Vec<AssetEntry>,
-    #[serde(default)]
-    pub preload: Vec<PreloadEntry>,
 }

crates/console/prometeu-hal/src/cartridge_loader.rs

@@ -1,4 +1,7 @@
-use crate::cartridge::{Capability, Cartridge, CartridgeDTO, CartridgeError, CartridgeManifest};
+use crate::cartridge::{
+    ASSETS_PA_MAGIC, ASSETS_PA_PRELUDE_SIZE, ASSETS_PA_SCHEMA_VERSION, AssetsPackHeader,
+    AssetsPackPrelude, Capability, Cartridge, CartridgeDTO, CartridgeError, CartridgeManifest,
+};
 use crate::syscalls::{CapFlags, caps};
 use std::collections::HashSet;
 use std::fs;
@@ -55,10 +58,16 @@ impl DirectoryCartridgeLoader {
         let program = fs::read(program_path).map_err(|_| CartridgeError::IoError)?;
 
         let assets_pa_path = path.join("assets.pa");
-        let assets = if assets_pa_path.exists() {
+        let (assets, asset_table, preload) = if assets_pa_path.exists() {
-            fs::read(assets_pa_path).map_err(|_| CartridgeError::IoError)?
+            let assets_pa = fs::read(assets_pa_path).map_err(|_| CartridgeError::IoError)?;
+            let parsed = parse_assets_pack(&assets_pa)?;
+            (parsed.payload.to_vec(), parsed.header.asset_table, parsed.header.preload)
         } else {
-            Vec::new()
+            if capabilities & caps::ASSET != 0 {
+                return Err(CartridgeError::MissingAssets);
+            }
+
+            (Vec::new(), Vec::new(), Vec::new())
         };
 
         let dto = CartridgeDTO {
@@ -70,8 +79,8 @@ impl DirectoryCartridgeLoader {
             capabilities,
             program,
             assets,
-            asset_table: manifest.asset_table,
+            asset_table,
-            preload: manifest.preload,
+            preload,
         };
 
         Ok(Cartridge::from(dto))
@@ -111,9 +120,44 @@ fn normalize_capabilities(capabilities: &[Capability]) -> Result<CapFlags, Cartr
     Ok(normalized)
 }
 
+struct ParsedAssetsPack<'a> {
+    header: AssetsPackHeader,
+    payload: &'a [u8],
+}
+
+fn parse_assets_pack(bytes: &[u8]) -> Result<ParsedAssetsPack<'_>, CartridgeError> {
+    let prelude =
+        AssetsPackPrelude::from_bytes(bytes).ok_or(CartridgeError::InvalidFormat)?;
+
+    if prelude.magic != ASSETS_PA_MAGIC || prelude.schema_version != ASSETS_PA_SCHEMA_VERSION {
+        return Err(CartridgeError::InvalidFormat);
+    }
+
+    let header_start = ASSETS_PA_PRELUDE_SIZE;
+    let header_end = header_start
+        .checked_add(prelude.header_len as usize)
+        .ok_or(CartridgeError::InvalidFormat)?;
+    let payload_offset = usize::try_from(prelude.payload_offset).map_err(|_| CartridgeError::InvalidFormat)?;
+
+    if payload_offset < header_start || header_end > bytes.len() || payload_offset > bytes.len() {
+        return Err(CartridgeError::InvalidFormat);
+    }
+    if header_end != payload_offset {
+        return Err(CartridgeError::InvalidFormat);
+    }
+
+    let header_bytes = &bytes[header_start..header_end];
+    let header: AssetsPackHeader =
+        serde_json::from_slice(header_bytes).map_err(|_| CartridgeError::InvalidFormat)?;
+
+    Ok(ParsedAssetsPack { header, payload: &bytes[payload_offset..] })
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
+    use crate::asset::{AssetEntry, BankType, PreloadEntry};
+    use crate::cartridge::{ASSETS_PA_MAGIC, ASSETS_PA_SCHEMA_VERSION, AssetsPackPrelude};
     use serde_json::json;
     use std::path::{Path, PathBuf};
     use std::sync::atomic::{AtomicU64, Ordering};
@@ -149,6 +193,31 @@ mod tests {
         fn path(&self) -> &Path {
             &self.path
         }
+
+        fn write_assets_pa(
+            &self,
+            asset_table: Vec<AssetEntry>,
+            preload: Vec<PreloadEntry>,
+            payload: &[u8],
+        ) {
+            let header = serde_json::to_vec(&AssetsPackHeader { asset_table, preload })
+                .expect("assets header must serialize");
+            let payload_offset = (ASSETS_PA_PRELUDE_SIZE + header.len()) as u64;
+            let prelude = AssetsPackPrelude {
+                magic: ASSETS_PA_MAGIC,
+                schema_version: ASSETS_PA_SCHEMA_VERSION,
+                header_len: header.len() as u32,
+                payload_offset,
+                flags: 0,
+                reserved: 0,
+                header_checksum: 0,
+            };
+
+            let mut bytes = prelude.to_bytes().to_vec();
+            bytes.extend_from_slice(&header);
+            bytes.extend_from_slice(payload);
+            fs::write(self.path.join("assets.pa"), bytes).expect("must write assets.pa");
+        }
     }
 
     impl Drop for TestCartridgeDir {
@@ -205,6 +274,7 @@ mod tests {
     #[test]
     fn load_with_all_capability_normalizes_to_all_flags() {
         let dir = TestCartridgeDir::new(manifest_with_capabilities(Some(vec!["all"])));
+        dir.write_assets_pa(vec![], vec![], &[]);
 
         let cartridge = DirectoryCartridgeLoader::load(dir.path()).expect("cartridge must load");
 
@@ -246,4 +316,91 @@ mod tests {
 
         assert!(matches!(error, CartridgeError::InvalidManifest));
     }
+
+    fn test_asset_entry(offset: u64, size: u64) -> AssetEntry {
+        AssetEntry {
+            asset_id: 7,
+            asset_name: "tiles".to_string(),
+            bank_type: BankType::TILES,
+            offset,
+            size,
+            decoded_size: size,
+            codec: "RAW".to_string(),
+            metadata: json!({
+                "tile_size": 16,
+                "width": 16,
+                "height": 16
+            }),
+        }
+    }
+
+    #[test]
+    fn load_with_asset_capability_requires_assets_pa() {
+        let dir = TestCartridgeDir::new(manifest_with_capabilities(Some(vec!["asset"])));
+
+        let error = DirectoryCartridgeLoader::load(dir.path()).unwrap_err();
+
+        assert!(matches!(error, CartridgeError::MissingAssets));
+    }
+
+    #[test]
+    fn load_without_asset_capability_accepts_missing_assets_pa() {
+        let dir = TestCartridgeDir::new(manifest_with_capabilities(Some(vec!["gfx"])));
+
+        let cartridge = DirectoryCartridgeLoader::load(dir.path()).expect("cartridge must load");
+
+        assert!(cartridge.assets.is_empty());
+        assert!(cartridge.asset_table.is_empty());
+        assert!(cartridge.preload.is_empty());
+    }
+
+    #[test]
+    fn load_reads_asset_table_and_preload_from_assets_pa_header() {
+        let dir = TestCartridgeDir::new(manifest_with_capabilities(Some(vec!["asset"])));
+        let payload = vec![1_u8, 2, 3, 4];
+        dir.write_assets_pa(
+            vec![test_asset_entry(0, payload.len() as u64)],
+            vec![PreloadEntry { asset_name: "tiles".to_string(), slot: 2 }],
+            &payload,
+        );
+
+        let cartridge = DirectoryCartridgeLoader::load(dir.path()).expect("cartridge must load");
+
+        assert_eq!(cartridge.assets, payload);
+        assert_eq!(cartridge.asset_table.len(), 1);
+        assert_eq!(cartridge.asset_table[0].asset_name, "tiles");
+        assert_eq!(cartridge.preload.len(), 1);
+        assert_eq!(cartridge.preload[0].slot, 2);
+    }
+
+    #[test]
+    fn load_rejects_invalid_assets_pa_prelude() {
+        let dir = TestCartridgeDir::new(manifest_with_capabilities(Some(vec!["asset"])));
+        fs::write(dir.path().join("assets.pa"), b"not-a-valid-pack").expect("must write assets.pa");
+
+        let error = DirectoryCartridgeLoader::load(dir.path()).unwrap_err();
+
+        assert!(matches!(error, CartridgeError::InvalidFormat));
+    }
+
+    #[test]
+    fn load_rejects_invalid_assets_pa_header_json() {
+        let dir = TestCartridgeDir::new(manifest_with_capabilities(Some(vec!["asset"])));
+        let prelude = AssetsPackPrelude {
+            magic: ASSETS_PA_MAGIC,
+            schema_version: ASSETS_PA_SCHEMA_VERSION,
+            header_len: 4,
+            payload_offset: (ASSETS_PA_PRELUDE_SIZE + 4) as u64,
+            flags: 0,
+            reserved: 0,
+            header_checksum: 0,
+        };
+        let mut bytes = prelude.to_bytes().to_vec();
+        bytes.extend_from_slice(b"{no}");
+        fs::write(dir.path().join("assets.pa"), bytes).expect("must write assets.pa");
+
+        let error = DirectoryCartridgeLoader::load(dir.path()).unwrap_err();
+
+        assert!(matches!(error, CartridgeError::InvalidFormat));
+    }
 }