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//! Shared module image-base representation.
/// The image-wide base addresses for one loaded object.
///
/// `avma` is the runtime address that corresponds to the object's `svma`.
/// Every mapping of the same loaded image shares this pair when correlation
/// against the object file succeeds.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
pub struct ModuleImageBase {
/// Process-absolute virtual memory address (AVMA) where the image's
/// base SVMA is mapped.
pub avma: u64,
/// Static virtual memory address (SVMA) from the object file that
/// corresponds to [`Self::avma`] at runtime.
pub svma: u64,
}
impl ModuleImageBase {
/// Build a base anchor from a matched (AVMA, SVMA) pair.
#[must_use]
pub const fn new(avma: u64, svma: u64) -> Self {
Self { avma, svma }
}
/// Returns `None` when `avma` lies below the image base.
#[must_use]
pub const fn relative_address(self, avma: u64) -> Option<u64> {
avma.checked_sub(self.avma)
}
/// Translate a runtime AVMA into the SVMA used by the object's symbol
/// tables, debug info, and unwind sections.
/// Returns `None` when the AVMA is below the image base or when adding the
/// image-relative offset to the static base would overflow.
#[must_use]
pub const fn svma_for_avma(self, avma: u64) -> Option<u64> {
let relative = match self.relative_address(avma) {
Some(relative) => relative,
None => return None,
};
self.svma.checked_add(relative)
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn checked_translation_rejects_avma_below_base() {
let base = ModuleImageBase::new(0x2000, 0x1000);
assert_eq!(base.relative_address(0x1fff), None);
assert_eq!(base.svma_for_avma(0x1fff), None);
}
#[test]
fn checked_translation_rejects_svma_overflow() {
let base = ModuleImageBase::new(0x1000, u64::MAX - 1);
assert_eq!(base.svma_for_avma(0x1002), None);
}
#[test]
fn checked_translation_preserves_valid_addresses() {
let base = ModuleImageBase::new(0x2000, 0x1000);
assert_eq!(base.relative_address(0x2123), Some(0x123));
assert_eq!(base.svma_for_avma(0x2123), Some(0x1123));
}
}