refactor: consolidate platform engines into senbei-engine

senbei-elf/src/lib.rs

@@ -0,0 +1,54 @@
+//! Basic ELF format parsing shared by the unpacking engine.
+
+use goblin::elf::{Elf, header::EM_AARCH64, program_header::PT_LOAD};
+use thiserror::Error;
+
+#[derive(Debug, Error)]
+pub enum Error {
+    #[error("ELF parse failed: {0}")]
+    Parse(#[from] goblin::error::Error),
+    #[error("input is not an ELF64 little-endian image")]
+    NotElf64,
+    #[error("input is not an AArch64 image")]
+    NotAarch64,
+}
+
+pub type Result<T> = std::result::Result<T, Error>;
+
+/// Parse an ELF64 little-endian image.
+pub fn parse(data: &[u8]) -> Result<Elf<'_>> {
+    let elf = Elf::parse(data)?;
+    if elf.header.e_ident[4] != 2 || elf.header.e_ident[5] != 1 {
+        return Err(Error::NotElf64);
+    }
+    Ok(elf)
+}
+
+/// Return true when `data` starts with a valid AArch64 ELF64 image.
+pub fn is_aarch64(data: &[u8]) -> bool {
+    parse(data)
+        .map(|elf| elf.header.e_machine == EM_AARCH64)
+        .unwrap_or(false)
+}
+
+/// Return the maximum file end among PT_LOAD segments.
+pub fn load_file_end(data: &[u8]) -> Result<u64> {
+    let elf = parse(data)?;
+    Ok(elf
+        .program_headers
+        .iter()
+        .filter(|ph| ph.p_type == PT_LOAD)
+        .map(|ph| ph.p_offset.saturating_add(ph.p_filesz))
+        .max()
+        .unwrap_or(0))
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn rejects_non_elf() {
+        assert!(matches!(parse(b"not elf"), Err(Error::Parse(_))));
+    }
+}