Artifact [3075e9e743]

Artifact 3075e9e7438d27c4af6564673a3014ba12bacf058fcf8ddf992ef875a03a5a9b:

• File internal/blob/blob.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: 6873) [annotate] [blame] [check-ins using]

package blob

import (
	"fmt"

	libfossil "github.com/danmestas/libfossil/internal/fsltype"
	"github.com/danmestas/libfossil/db"
	"github.com/danmestas/libfossil/internal/delta"
	"github.com/danmestas/libfossil/internal/hash"
)

func Store(q db.Querier, content []byte) (rid libfossil.FslID, uuid string, err error) {
	if q == nil {
		panic("blob.Store: q must not be nil")
	}
	if len(content) == 0 {
		panic("blob.Store: content length must be > 0")
	}
	defer func() {
		if err == nil && rid <= 0 {
			panic("blob.Store: postcondition violated: rid <= 0 with no error")
		}
	}()

	uuid = hash.SHA1(content)

	if rid, ok := Exists(q, uuid); ok {
		return rid, uuid, nil
	}

	compressed, err := Compress(content)
	if err != nil {
		return 0, "", fmt.Errorf("blob.Store compress: %w", err)
	}

	result, err := q.Exec(
		"INSERT INTO blob(uuid, size, content, rcvid) VALUES(?, ?, ?, 1)",
		uuid, len(content), compressed,
	)
	if err != nil {
		return 0, "", fmt.Errorf("blob.Store insert: %w", err)
	}

	ridInt, err := result.LastInsertId()
	if err != nil {
		return 0, "", fmt.Errorf("blob.Store lastid: %w", err)
	}

	rid = libfossil.FslID(ridInt)

	// Verify round-trip: re-read, decompress, re-hash.
	// Matches Fossil's content_put_pk() post-write verification.
	readBack, err := Load(q, rid)
	if err != nil {
		return 0, "", fmt.Errorf("blob.Store verify read-back: %w", err)
	}
	if got := hash.SHA1(readBack); got != uuid {
		return 0, "", fmt.Errorf("blob.Store verify: hash mismatch after round-trip: stored %s, got %s", uuid, got)
	}

	// Mark as unclustered — matches Fossil's content_put_ex (content.c:633).
	// Only new blobs reach here; Exists early-return skips this.
	if _, err := q.Exec("INSERT OR IGNORE INTO unclustered(rid) VALUES(?)", rid); err != nil {
		return 0, "", fmt.Errorf("blob.Store unclustered: %w", err)
	}

	return rid, uuid, nil
}

func StoreDelta(q db.Querier, content []byte, srcRid libfossil.FslID) (rid libfossil.FslID, uuid string, err error) {
	if q == nil {
		panic("blob.StoreDelta: q must not be nil")
	}
	if len(content) == 0 {
		panic("blob.StoreDelta: content length must be > 0")
	}
	if srcRid <= 0 {
		panic("blob.StoreDelta: srcRid must be > 0")
	}
	defer func() {
		if err == nil && rid <= 0 {
			panic("blob.StoreDelta: postcondition violated: rid <= 0 with no error")
		}
	}()

	uuid = hash.SHA1(content)

	if rid, ok := Exists(q, uuid); ok {
		return rid, uuid, nil
	}

	srcContent, err := Load(q, srcRid)
	if err != nil {
		return 0, "", fmt.Errorf("blob.StoreDelta load source: %w", err)
	}

	deltaBytes := delta.Create(srcContent, content)
	compressed, err := Compress(deltaBytes)
	if err != nil {
		return 0, "", fmt.Errorf("blob.StoreDelta compress: %w", err)
	}

	result, err := q.Exec(
		"INSERT INTO blob(uuid, size, content, rcvid) VALUES(?, ?, ?, 1)",
		uuid, len(content), compressed,
	)
	if err != nil {
		return 0, "", fmt.Errorf("blob.StoreDelta insert blob: %w", err)
	}

	ridInt, err := result.LastInsertId()
	if err != nil {
		return 0, "", fmt.Errorf("blob.StoreDelta lastid: %w", err)
	}

	rid = libfossil.FslID(ridInt)
	_, err = q.Exec("INSERT INTO delta(rid, srcid) VALUES(?, ?)", rid, srcRid)
	if err != nil {
		return 0, "", fmt.Errorf("blob.StoreDelta insert delta: %w", err)
	}

	// Verify round-trip: re-read delta, apply to source, re-hash.
	// Matches Fossil's content_put_pk() post-write verification.
	storedDelta, err := Load(q, rid)
	if err != nil {
		return 0, "", fmt.Errorf("blob.StoreDelta verify read-back: %w", err)
	}
	rebuilt, err := delta.Apply(srcContent, storedDelta)
	if err != nil {
		return 0, "", fmt.Errorf("blob.StoreDelta verify apply: %w", err)
	}
	if got := hash.SHA1(rebuilt); got != uuid {
		return 0, "", fmt.Errorf("blob.StoreDelta verify: hash mismatch after round-trip: stored %s, got %s", uuid, got)
	}

	// Mark as unclustered — matches Fossil's content_put_ex (content.c:633).
	if _, err := q.Exec("INSERT OR IGNORE INTO unclustered(rid) VALUES(?)", rid); err != nil {
		return 0, "", fmt.Errorf("blob.StoreDelta unclustered: %w", err)
	}

	return rid, uuid, nil
}

func StorePhantom(q db.Querier, uuid string) (rid libfossil.FslID, err error) {
	if q == nil {
		panic("blob.StorePhantom: q must not be nil")
	}
	if uuid == "" {
		panic("blob.StorePhantom: uuid must not be empty")
	}
	defer func() {
		if err == nil && rid <= 0 {
			panic("blob.StorePhantom: postcondition violated: rid <= 0 with no error")
		}
	}()

	if rid, ok := Exists(q, uuid); ok {
		return rid, nil
	}

	result, err := q.Exec(
		"INSERT INTO blob(uuid, size, content, rcvid) VALUES(?, -1, NULL, 0)",
		uuid,
	)
	if err != nil {
		return 0, fmt.Errorf("blob.StorePhantom: %w", err)
	}

	ridInt, err := result.LastInsertId()
	if err != nil {
		return 0, fmt.Errorf("blob.StorePhantom lastid: %w", err)
	}

	rid = libfossil.FslID(ridInt)
	_, err = q.Exec("INSERT INTO phantom(rid) VALUES(?)", rid)
	if err != nil {
		return 0, fmt.Errorf("blob.StorePhantom phantom table: %w", err)
	}

	return rid, nil
}

func Load(q db.Querier, rid libfossil.FslID) (result []byte, err error) {
	if q == nil {
		panic("blob.Load: q must not be nil")
	}
	if rid <= 0 {
		panic("blob.Load: rid must be > 0")
	}
	defer func() {
		if err == nil && result == nil {
			panic("blob.Load: postcondition violated: result is nil with no error")
		}
	}()

	var content []byte
	var size int64
	err = q.QueryRow("SELECT content, size FROM blob WHERE rid=?", rid).Scan(&content, &size)
	if err != nil {
		return nil, fmt.Errorf("blob.Load query: %w", err)
	}

	if size == -1 {
		return nil, fmt.Errorf("blob.Load: rid %d is a phantom", rid)
	}

	if content == nil || len(content) == 0 {
		return nil, fmt.Errorf("blob.Load: rid %d has NULL or empty content", rid)
	}

	// Fossil stores blobs as [4-byte BE uncompressed-size][zlib data].
	// When the compressed form happens to be the same length as the
	// uncompressed content (rare but real — ~2 in 66K in the Fossil SCM
	// repo), we must still decompress. Detect compressed content by
	// checking for the 4-byte BE prefix matching the declared size
	// followed by a zlib header (0x78).
	if len(content) >= 6 {
		prefixSize := int64(content[0])<<24 | int64(content[1])<<16 | int64(content[2])<<8 | int64(content[3])
		if prefixSize == size && content[4] == 0x78 {
			return Decompress(content)
		}
	}
	// No compression prefix — content is stored uncompressed.
	if int64(len(content)) == size {
		return content, nil
	}
	// Stored bytes < declared size — compressed.
	return Decompress(content)
}

func Exists(q db.Querier, uuid string) (libfossil.FslID, bool) {
	if q == nil {
		panic("blob.Exists: q must not be nil")
	}
	if uuid == "" {
		panic("blob.Exists: uuid must not be empty")
	}
	var rid int64
	err := q.QueryRow("SELECT rid FROM blob WHERE uuid=?", uuid).Scan(&rid)
	if err != nil {
		return 0, false
	}
	return libfossil.FslID(rid), true
}