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use gix_error::{Result, corruption};
use std::sync::atomic::AtomicBool;
use gix_error::{ErrorExt, ResultExt, bail, message};
use gix_parallel as parallel;
use gix_utils::progress::Progress;
use crate::index;
mod reduce;
///
pub mod with_index;
///
pub mod with_lookup;
use reduce::Reducer;
use gix_utils::progress::DynNestedProgress;
mod types;
pub use types::{Algorithm, ProgressId, SafetyCheck, Statistics};
/// Traversal options for [`index::File::traverse()`].
#[derive(Debug, Clone)]
pub struct Options<F> {
/// The algorithm to employ.
pub traversal: Algorithm,
/// If `Some`, only use the given number of threads. Otherwise, the number of threads to use will be selected based on
/// the number of available logical cores.
pub thread_limit: Option<usize>,
/// The kinds of safety checks to perform.
pub check: SafetyCheck,
/// If `Some`, rejects individual allocations above the given number of bytes while resolving decoded object and
/// delta result buffers during delta-tree traversal. `Some(0)` rejects all non-empty allocations.
pub alloc_limit_bytes: Option<usize>,
/// A function to create a pack cache
pub make_pack_lookup_cache: F,
}
impl Default for Options<fn() -> crate::cache::Never> {
fn default() -> Self {
Options {
check: Default::default(),
traversal: Default::default(),
thread_limit: None,
alloc_limit_bytes: None,
make_pack_lookup_cache: || crate::cache::Never,
}
}
}
/// The outcome of the [`traverse()`][index::File::traverse()] method.
pub struct Outcome {
/// The checksum obtained when hashing the file, which matched the checksum contained within the file.
pub actual_index_checksum: gix_hash::ObjectId,
/// The statistics obtained during traversal.
pub statistics: Statistics,
}
/// Traversal of pack data files using an index file
impl<T> index::File<T>
where
T: crate::FileData + Sync,
{
/// Iterate through all _decoded objects_ in the given `pack` and handle them with a `Processor`.
/// The return value is (pack-checksum, [`Outcome`], `progress`), thus the pack traversal will always verify
/// the whole packs checksum to assure it was correct. In case of bit-rod, the operation will abort early without
/// verifying all objects using the [interrupt mechanism][gix_utils::interrupt] mechanism.
///
/// # Algorithms
///
/// Using the [`Options::traversal`] field one can chose between two algorithms providing different tradeoffs. Both invoke
/// `new_processor()` to create functions receiving decoded objects, their object kind, index entry and a progress instance to provide
/// progress information.
///
/// * [`Algorithm::DeltaTreeLookup`] builds an index to avoid any unnecessary computation while resolving objects, avoiding
/// the need for a cache entirely, rendering `new_cache()` unused.
/// One could also call [`traverse_with_index()`][index::File::traverse_with_index()] directly.
/// * [`Algorithm::Lookup`] uses a cache created by `new_cache()` to avoid having to re-compute all bases of a delta-chain while
/// decoding objects.
/// One could also call [`traverse_with_lookup()`][index::File::traverse_with_lookup()] directly.
///
/// Use [`thread_limit`][Options::thread_limit] to further control parallelism and [`check`][SafetyCheck] to define how much the passed
/// objects shall be verified beforehand.
pub fn traverse<C, Processor, F, D>(
&self,
pack: &crate::data::File<D>,
progress: &mut dyn DynNestedProgress,
should_interrupt: &AtomicBool,
processor: Processor,
Options {
traversal,
thread_limit,
check,
alloc_limit_bytes,
make_pack_lookup_cache,
}: Options<F>,
) -> Result<Outcome>
where
C: crate::cache::DecodeEntry,
Processor: FnMut(gix_object::Kind, &[u8], &index::Entry, &dyn Progress) -> Result + Send + Clone,
F: Fn() -> C + Send + Clone,
D: crate::FileData + Send + Sync,
{
match traversal {
Algorithm::Lookup => self.traverse_with_lookup(
processor,
pack,
progress,
should_interrupt,
with_lookup::Options {
thread_limit,
check,
make_pack_lookup_cache,
},
),
Algorithm::DeltaTreeLookup => self.traverse_with_index(
pack,
processor,
progress,
should_interrupt,
with_index::Options {
check,
thread_limit,
alloc_limit_bytes,
},
),
}
}
fn possibly_verify<D>(
&self,
pack: &crate::data::File<D>,
check: SafetyCheck,
pack_progress: &mut dyn Progress,
index_progress: &mut dyn Progress,
should_interrupt: &AtomicBool,
) -> Result<gix_hash::ObjectId>
where
D: crate::FileData + Send + Sync,
{
Ok(if check.file_checksum() {
pack.checksum()
.verify(&self.pack_checksum())
.or_raise(|| corruption("Pack checksum differs from index"))?;
let (pack_res, id) = parallel::join(
move || pack.verify_checksum(pack_progress, should_interrupt),
move || self.verify_checksum(index_progress, should_interrupt),
);
pack_res?;
id?
} else {
self.index_checksum()
})
}
#[expect(clippy::too_many_arguments)]
fn decode_and_process_entry<C, D>(
&self,
check: SafetyCheck,
pack: &crate::data::File<D>,
cache: &mut C,
buf: &mut Vec<u8>,
inflate: &mut gix_zlib::Inflate,
progress: &mut dyn Progress,
index_entry: &index::Entry,
processor: &mut impl FnMut(gix_object::Kind, &[u8], &index::Entry, &dyn Progress) -> Result,
) -> Result<Option<crate::data::decode::entry::Outcome>>
where
C: crate::cache::DecodeEntry,
D: crate::FileData + Send + Sync,
{
let pack_entry = pack.entry(index_entry.pack_offset)?;
let pack_entry_data_offset = pack_entry.data_offset;
let entry_stats = match pack.decode_entry(
pack_entry,
buf,
inflate,
&|id, _| {
self.lookup(id)
.map(|index| {
pack.entry(self.pack_offset_at_index(index))
.map(crate::data::decode::entry::ResolvedBase::InPack)
})
.transpose()
},
cache,
) {
Ok(stats) => stats,
Err(err) if !check.fatal_decode_error() => {
progress.info(format!(
"Ignoring decode error for object {} at offset {}: {err}",
index_entry.oid, index_entry.pack_offset
));
return Ok(None);
}
Err(err) => {
return Err(err.and_raise(message!(
"Object {} at offset {} could not be decoded",
index_entry.oid,
index_entry.pack_offset
)));
}
};
let object_kind = entry_stats.kind;
let header_size = (pack_entry_data_offset - index_entry.pack_offset) as usize;
let entry_len = header_size + entry_stats.compressed_size;
process_entry(
check,
object_kind,
buf,
index_entry,
|| pack.entry_crc32(index_entry.pack_offset, entry_len),
progress,
processor,
)?;
Ok(Some(entry_stats))
}
}
fn process_entry(
check: SafetyCheck,
object_kind: gix_object::Kind,
decompressed: &[u8],
index_entry: &index::Entry,
pack_entry_crc32: impl FnOnce() -> u32,
progress: &dyn Progress,
processor: &mut impl FnMut(gix_object::Kind, &[u8], &index::Entry, &dyn Progress) -> Result,
) -> Result {
if check.object_checksum() {
gix_object::Data::new(decompressed, object_kind, index_entry.oid.kind())
.verify_checksum(&index_entry.oid)
.or_raise(|| {
corruption(format!(
"Error verifying object at offset {} against checksum in the index file",
index_entry.pack_offset
))
})?;
if let Some(desired_crc32) = index_entry.crc32 {
let actual_crc32 = pack_entry_crc32();
if actual_crc32 != desired_crc32 {
bail!(
"The CRC32 of {object_kind} object at offset {} didn't match the checksum in the index file: expected {desired_crc32}, got {actual_crc32}".corrupted(),
index_entry.pack_offset
);
}
}
}
processor(object_kind, decompressed, index_entry, progress)
}