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make window size assertions much less complex with Magic

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Danny McClanahan 2024-05-18 04:04:32 -04:00
parent 7eb5907622
commit 83cdbadae8
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GPG key ID: 6105C10F1A199CC7
1 changed files with 6 additions and 6 deletions
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12
src/spec.rs
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@ -278,6 +278,8 @@ impl Zip32CentralDirectoryEnd {
let search_upper_bound = 0;
const END_WINDOW_SIZE: usize = 512;
/* TODO: use static_assertions!() */
assert!(END_WINDOW_SIZE > mem::size_of::<Magic>());
let sig_bytes = CENTRAL_DIRECTORY_END_SIGNATURE.to_le_bytes();
let finder = FinderRev::new(&sig_bytes);
@ -314,13 +316,12 @@ impl Zip32CentralDirectoryEnd {
if window_start == search_upper_bound {
break;
}
debug_assert!(END_WINDOW_SIZE > mem::size_of_val(&CENTRAL_DIRECTORY_END_SIGNATURE));
/* Shift the window by END_WINDOW_SIZE bytes, but make sure to cover matches that
* overlap our nice neat window boundaries! */
window_start = (window_start
/* NB: To catch matches across window boundaries, we need to make our blocks overlap
* by the width of the pattern to match. */
+ mem::size_of_val(&CENTRAL_DIRECTORY_END_SIGNATURE) as u64)
+ mem::size_of::<Magic>() as u64)
/* This should never happen, but make sure we don't go past the end of the file. */
.min(file_length);
window_start = window_start
@ -549,6 +550,8 @@ impl Zip64CentralDirectoryEnd {
let mut results = Vec::new();
const END_WINDOW_SIZE: usize = 2048;
/* TODO: use static_assertions!() */
assert!(END_WINDOW_SIZE > mem::size_of::<Magic>());
let sig_bytes = ZIP64_CENTRAL_DIRECTORY_END_SIGNATURE.to_le_bytes();
let finder = FinderRev::new(&sig_bytes);
@ -592,15 +595,12 @@ impl Zip64CentralDirectoryEnd {
if window_start == nominal_offset {
break;
}
debug_assert!(
END_WINDOW_SIZE > mem::size_of_val(&ZIP64_CENTRAL_DIRECTORY_END_SIGNATURE)
);
/* Shift the window by END_WINDOW_SIZE bytes, but make sure to cover matches that
* overlap our nice neat window boundaries! */
window_start = (window_start
/* NB: To catch matches across window boundaries, we need to make our blocks overlap
* by the width of the pattern to match. */
+ mem::size_of_val(&ZIP64_CENTRAL_DIRECTORY_END_SIGNATURE) as u64)
+ mem::size_of::<Magic>() as u64)
/* This may never happen, but make sure we don't go past the end of the specified
* range. */
.min(search_upper_bound);