dol: implement helpers for virtual reads into the dol

Co-authored-by: Richard Patel <me@terorie.dev>

dol/src/lib.rs

@@ -24,6 +24,8 @@ pub enum Error {
     OverlappingSections(u32, u32),
     #[error("Section sizes too large")]
     SectionsTooLarge,
+    #[error("Attempted to access {0:08X} past DOL bounds")]
+    OutOfBounds(u32),
 }
 
 impl From<bincode::Error> for Error {
@@ -107,11 +109,38 @@ impl Dol {
         })
     }
 
-    /// Reads bytes into a destination buffer given a virtual address.
-    pub fn virtual_read(&self, dest: &mut [u8], virtual_addr: u32) {
+    pub fn section_data(&self, section: &DolSection) -> &[u8] {
+        self.virtual_data_at(section.target, section.size).unwrap()
+    }
+
+    /// Returns a slice of DOL data. Does not support bss.
+    pub fn virtual_data_at(&self, virtual_addr: u32, read_len: u32) -> Result<&[u8]> {
+        if virtual_addr < self.memory_offset {
+            return Err(Error::OutOfBounds(virtual_addr));
+        }
+
         let offset = (virtual_addr - self.memory_offset) as usize;
-        // TODO Gracefully handle errors.
-        dest.copy_from_slice(&self.memory[offset..offset + dest.len()])
+        if offset + (read_len as usize) < self.memory.len() {
+            Ok(&self.memory[offset..offset + (read_len as usize)])
+        } else {
+            Err(Error::OutOfBounds(virtual_addr + read_len))
+        }
+    }
+
+    /// Reads bytes into a destination buffer given a virtual address.
+    pub fn virtual_read(&self, data: &mut [u8], virtual_addr: u32) -> Result<()> {
+        if virtual_addr < self.memory_offset {
+            return Err(Error::OutOfBounds(virtual_addr));
+        }
+
+        let offset = (virtual_addr - self.memory_offset) as usize;
+        let read_len = data.len();
+        if offset + read_len < self.memory.len() {
+            data.copy_from_slice(&self.memory[offset..offset + data.len()]);
+            Ok(())
+        } else {
+            Err(Error::OutOfBounds(virtual_addr + (read_len as u32)))
+        }
     }
 }
 
@@ -132,6 +161,7 @@ pub struct DolSection {
 
 pub struct DolHeader {
     pub sections: Vec<DolSection>,
+    pub entry_point: u32,
 }
 
 impl From<&DolHeaderData> for DolHeader {
@@ -159,7 +189,21 @@ impl From<&DolHeaderData> for DolHeader {
         }
         // Sort sections by target address to prepare them for mapping.
         sections.sort_by_key(|s| s.target);
-        Self { sections }
+        Self {
+            sections,
+            entry_point: header.entry_point,
+        }
+    }
+}
+
+impl DolHeader {
+    pub fn section_at(&self, addr: u32) -> Option<&DolSection> {
+        for section in &self.sections {
+            if (section.target..(section.target + section.size)).contains(&addr) {
+                return Some(section);
+            }
+        }
+        None
     }
 }
 

flow-graph/src/main.rs

@@ -44,7 +44,8 @@ fn main() {
     let dol = Dol::read_from(&dol_file).expect("Invalid DOL file");
     drop(dol_file);
     let mut bytes = vec![0u8; (stop_addr - start_addr) as usize];
-    dol.virtual_read(&mut bytes, start_addr);
+    dol.virtual_read(&mut bytes, start_addr)
+        .expect("Invalid address range");
 
     // Create control flow graph.
     let ins_list: Vec<Ins> = disasm_iter(&bytes, start_addr).collect();