TapTap
0e33f84f38
Add real implementations for the rsync 3.4.1 checksum and compression breadth: a self-contained MD4 (RFC 1320), OpenSSL-backed SHA1, a no-digest mode, and LZ4/zlib codecs alongside zstd. Compressed buffers are now self-describing (a leading codec id), so every existing decompression call site keeps working through a process-global codec selection. zlibx shares the zlib codec because FastSync compresses only delta/token bytes (never matched file data), matching the 'x' intent.
70 lines
3.0 KiB
C
70 lines
3.0 KiB
C
#ifndef CHECKSUM_H
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#define CHECKSUM_H
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#include <stdbool.h>
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#include <stddef.h>
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#include <stdint.h>
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/* Whole-file content-digest algorithms selectable with --checksum-choice and
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* seeded with --checksum-seed. The ids are the values actually placed on the
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* wire (config frame), so they must be kept stable and validated on receive.
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* CHECKSUM_ALGO_XXH64 == 0 is the historical FastSync default and its numeric
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* value is preserved. The full set mirrors the algorithms rsync 3.4.1 can be
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* built with; every one of them is implemented here. */
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typedef enum {
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CHECKSUM_ALGO_XXH64 = 0,
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CHECKSUM_ALGO_MD5 = 1,
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CHECKSUM_ALGO_XXH3 = 2,
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CHECKSUM_ALGO_XXH128 = 3,
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CHECKSUM_ALGO_MD4 = 4,
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CHECKSUM_ALGO_SHA1 = 5,
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CHECKSUM_ALGO_NONE = 6
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} ChecksumAlgo;
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/* FastSync's negotiated default (rsync 3.4.1 auto-negotiates xxh128 first).
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* The wire default for Config->checksum_algo is this value. */
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#define CHECKSUM_ALGO_DEFAULT CHECKSUM_ALGO_XXH128
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/* sha1 digest is 20 bytes, the longest supported. */
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#define CHECKSUM_MAX_DIGEST_LEN 20
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/* Compute the whole-file digest of the first `size` bytes of `data`.
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*
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* - CHECKSUM_ALGO_XXH64: xxHash64(data, size, seed) (full 64-bit seed).
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* - CHECKSUM_ALGO_XXH3: XXH3_64bits_withSeed(data, size, seed).
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* - CHECKSUM_ALGO_XXH128: XXH3_128bits_withSeed(data, size, seed).
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* - CHECKSUM_ALGO_MD5: md5(data, size) via OpenSSL EVP (seed ignored).
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* - CHECKSUM_ALGO_MD4: md4(data, size), self-contained RFC 1320 (seed ignored).
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* - CHECKSUM_ALGO_SHA1: sha1(data, size) via OpenSSL EVP (seed ignored).
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* - CHECKSUM_ALGO_NONE: no digest; *out_len is 0 and nothing is written.
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* - `size == 0` hashes the empty input (plus its seed), not a NULL input.
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*
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* Writes up to `out_capacity` bytes into `out`, storing the digest length in
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* *out_len. Returns false on NULL out* or when the digest would not fit.
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* Never writes more than CHECKSUM_MAX_DIGEST_LEN bytes. */
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bool checksum_digest(ChecksumAlgo algo, uint64_t seed, const void* data, size_t size, uint8_t* out,
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size_t out_capacity, size_t* out_len);
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/* Resolve a --checksum-choice string (case-insensitive) to an algorithm id.
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* Accepts "xxh64"/"xxhash", "xxh3", "xxh128", "md5", "md4", "sha1", "none".
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* "auto" is not an algorithm here; the caller resolves it to the negotiated
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* default. Returns -1 for any unrecognized name. */
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int checksum_algo_from_name(const char* name);
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/* Canonical name of an algorithm (used in CLI error messages). */
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const char* checksum_algo_name(ChecksumAlgo algo);
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/* True when `algo` is a supported id (used by config receive validation). */
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bool checksum_algo_valid(int algo);
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/* Digest length in bytes for an algorithm (xxh64/xxh3 = 8,
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* md5/md4/xxh128 = 16, sha1 = 20, none = 0). */
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uint8_t checksum_digest_len(ChecksumAlgo algo);
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/* Pick the first algorithm from FastSync's compiled-in preference list that is
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* supported on this build (rsync 3.4.1's `--version` order:
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* xxh128 xxh3 xxh64 md5 md4 sha1 none). Used to resolve "auto". */
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ChecksumAlgo checksum_negotiate_default(void);
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#endif /* CHECKSUM_H */
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