Module hash 

Structs

CheckOptions

Options for check mode.

CheckResult

Result of check mode verification.

Enums

HashAlgorithm

Supported hash algorithms.

Functions

blake2b_hash_data

Hash raw data with BLAKE2b variable output length. output_bytes is the output size in bytes (e.g., 32 for 256-bit).

blake2b_hash_file

Hash a file with BLAKE2b variable output length. Uses mmap for large files (zero-copy), single-read for small files, and streaming read as fallback.

blake2b_hash_files_many

Batch-hash multiple files with BLAKE2b using multi-buffer SIMD.

blake2b_hash_reader

Hash a reader with BLAKE2b variable output length. Uses thread-local buffer for cache-friendly streaming.

blake2b_hash_stdin

Hash stdin with BLAKE2b variable output length. Tries fadvise if stdin is a regular file (shell redirect), then streams.

check_file

Verify checksums from a check file. Each line should be “hash filename” or “hash *filename” or “ALGO (filename) = hash”.

hash_bytes

Compute hash of a byte slice directly (zero-copy fast path).

hash_file

Hash a file by path. Uses I/O pipelining for large files on Linux, mmap with HUGEPAGE hints as fallback, single-read for small files, and streaming read for non-regular files.

hash_file_nostat

Hash a file without fstat — just open, read until EOF, hash. For many-file workloads (100+ tiny files), skipping fstat saves ~5µs/file. Uses a two-tier buffer strategy: small stack buffer (4KB) for the initial read, then falls back to a larger stack buffer (64KB) or streaming hash for bigger files. For benchmark’s 55-byte files: one read() fills the 4KB buffer, hash immediately.

hash_files_parallel

Batch-hash multiple files with SHA-256/MD5 using work-stealing parallelism. Files are sorted by size (largest first) so the biggest files start processing immediately. Each worker thread grabs the next unprocessed file via atomic index, eliminating tail latency from uneven file sizes. Returns results in input order.

hash_reader

Compute hash of data from a reader, returning hex string.

hash_stdin

Hash stdin. Uses fadvise for file redirects, streaming for pipes.

parse_check_line

Parse a checksum line in any supported format.

parse_check_line_tag

Parse a BSD-style tag line: “ALGO (filename) = hash” Returns (expected_hash, filename, optional_bits). bits is the hash length parsed from the algo name (e.g., BLAKE2b-256 -> Some(256)).

print_hash

Print hash result in GNU format: “hash filename\n” Uses raw byte writes to avoid std::fmt overhead.

print_hash_tag

Print hash result in BSD tag format: “ALGO (filename) = hash\n”

print_hash_tag_b2sum

Print hash in BSD tag format with BLAKE2b length info: “BLAKE2b (filename) = hash” for 512-bit, or “BLAKE2b-256 (filename) = hash” for other lengths.

print_hash_tag_b2sum_zero

Print hash in BSD tag format with BLAKE2b length info and NUL terminator.

print_hash_tag_zero

Print hash in BSD tag format with NUL terminator.

print_hash_zero

Print hash in GNU format with NUL terminator instead of newline.

readahead_files

Issue readahead hints for a list of file paths to warm the page cache. Uses POSIX_FADV_WILLNEED which is non-blocking and batches efficiently. Only issues hints for files >= 1MB; small files are read fast enough that the fadvise syscall overhead isn’t worth it.

readahead_files_all

Issue readahead hints for ALL file paths (no size threshold). For multi-file benchmarks, even small files benefit from batched readahead.

should_use_parallel

Check if parallel hashing is worthwhile for the given file paths. Always parallelize with 2+ files — rayon’s thread pool is lazily initialized once and reused, so per-file work-stealing overhead is negligible (~1µs). Removing the stat()-based size check eliminates N extra syscalls for N files.

write_hash_line

Build and write the standard GNU hash output line in a single write() call. Format: “hash filename\n” or “hash *filename\n” (binary mode). For escaped filenames: “\hash escaped_filename\n”.

write_hash_tag_line

Build and write BSD tag format output in a single write() call. Format: “ALGO (filename) = hash\n”