Artifact [adde80f561]

Artifact adde80f5613398e8368a081c4b782c2314b48eed0e8cd16562354e6983fdee20:

• File internal/hash/hash.go — part of check-in [f5744359d3] at 2026-04-19 16:30:54 on branch trunk — Initial open source release

  libfossil is a pure-Go implementation of the Fossil SCM, reading and writing the same .fossil SQLite repository format as upstream Fossil.

  This is the first public release of code that previously lived in a private repository. The module path is github.com/danmestas/libfossil and the binary is named libfossil to avoid $PATH collisions with upstream fossil.

  Included: - Repo lifecycle (create, clone), checkout/checkin, timeline, merge, diff, annotate, shun, tag, branch, bisect, stash, undo/redo - Sync-over-HTTP protocol (client and handler) - Two SQLite drivers: modernc (pure Go, default) and ncruces (wasm-capable) - Observer interfaces (SyncObserver, CheckoutObserver) with an optional OpenTelemetry implementation in observer/otel (separate submodule) - Deterministic simulation testing harness with BUGGIFY fault injection - Kong-based embeddable CLI under cli/ and a standalone binary under cmd/libfossil/ (user: [email protected], size: 1368) [annotate] [blame] [check-ins using]

package hash

import (
	"crypto/sha1"
	"encoding/hex"

	"golang.org/x/crypto/sha3"
)

func SHA1(data []byte) string {
	if data == nil {
		panic("hash.SHA1: data must not be nil")
	}
	h := sha1.Sum(data)
	return hex.EncodeToString(h[:])
}

func SHA3(data []byte) string {
	if data == nil {
		panic("hash.SHA3: data must not be nil")
	}
	h := sha3.Sum256(data)
	return hex.EncodeToString(h[:])
}

func HashSize(hashType string) int {
	if hashType == "" {
		panic("hash.HashSize: hashType must not be empty")
	}
	switch hashType {
	case "sha1":
		return sha1.Size * 2
	case "sha3":
		return 64
	default:
		return 0
	}
}

// ContentHash hashes content using the algorithm implied by referenceHash length.
// 64-char reference = SHA3-256, otherwise SHA1. referenceHash must not be empty.
func ContentHash(content []byte, referenceHash string) string {
	if content == nil {
		panic("hash.ContentHash: content must not be nil")
	}
	if referenceHash == "" {
		panic("hash.ContentHash: referenceHash must not be empty")
	}
	if len(referenceHash) > 40 {
		return SHA3(content)
	}
	return SHA1(content)
}

func IsValidHash(h string) bool {
	if h == "" {
		panic("hash.IsValidHash: h must not be empty")
	}
	if len(h) != 40 && len(h) != 64 {
		return false
	}
	for _, c := range h {
		if !((c >= '0' && c <= '9') || (c >= 'a' && c <= 'f')) {
			return false
		}
	}
	return true
}