Function find_acpi_table

dstack-mr/src/acpi.rs:426–456

Searches for an ACPI table with the given signature and returns its offset, checksum offset, and length.

(tables: &[u8], signature: &str)

/// Searches for an ACPI table with the given signature and returns its offset,
/// checksum offset, and length.
fn find_acpi_table(tables: &[u8], signature: &str) -> Result<(u32, u32, u32)> {
    let sig_bytes = signature.as_bytes();
    if sig_bytes.len() != 4 {
        bail!("Signature must be 4 bytes long, but got '{signature}'");
    }

    let mut offset = 0;
    while offset < tables.len() {
        // Ensure there's enough space for a table header
        if offset + 8 > tables.len() {
            bail!("Table not found: {signature}");
        }

        let header = AcpiTableHeader::decode(&mut &tables[offset..])
            .context("failed to decode ACPI table header")?;

        if header.signature == sig_bytes {
            // Found the table
            return Ok((offset as u32, (offset + 9) as u32, header.length));
        }

        if header.length == 0 {
            // Invalid table length, stop searching
            bail!("found table with zero length at offset {offset}");
        }
        // Move to the next table
        offset += header.length as usize;
    }

    bail!("table not found: {signature}");
}