Artifact [8ebaed0f2b]

Artifact 8ebaed0f2b40dabb4710223aa9e5549f589eca6cae889b23bebc1e4bc19f7251:

• File internal/checkout/extract.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: 5732) [annotate] [blame] [check-ins using]

package checkout

import (
	"context"
	"fmt"
	"os"
	"path/filepath"
	"strconv"
	"time"

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

// extractSingleFile expands a blob and writes it to the checkout directory.
// Skips writing if dryRun is true.
func (c *Checkout) extractSingleFile(
	pathname string, blobRid int64, isexe int64, dryRun bool,
) error {
	if dryRun {
		return nil
	}

	data, err := content.Expand(c.repo.DB(), libfossil.FslID(blobRid))
	if err != nil {
		return fmt.Errorf("checkout.Extract: expand blob for %s: %w", pathname, err)
	}

	fullPath, err := c.safePath(pathname)
	if err != nil {
		return fmt.Errorf("checkout.Extract: path traversal in %s: %w", pathname, err)
	}

	parentDir := filepath.Dir(fullPath)
	if err := c.env.Storage.MkdirAll(parentDir, 0o755); err != nil {
		return fmt.Errorf("checkout.Extract: mkdir %s: %w", parentDir, err)
	}

	perm := os.FileMode(0o644)
	if isexe != 0 {
		perm = 0o755
	}

	if err := c.env.Storage.WriteFile(fullPath, data, perm); err != nil {
		return fmt.Errorf("checkout.Extract: write %s: %w", fullPath, err)
	}

	return nil
}

// Extract writes files from the specified checkin to disk via simio.Storage.
// Populates vfile, updates vvar checkout/checkout-hash to rid.
//
// If opts.DryRun is true, skips writing files but still calls observer and callback.
// If opts.Force is false (default), fails if locally modified files would be overwritten.
//
// Panics if c is nil (TigerStyle precondition).
func (c *Checkout) Extract(rid libfossil.FslID, opts ExtractOpts) error {
	if c == nil {
		panic("checkout.Extract: nil *Checkout")
	}

	// Start observer
	ctx := c.obs.ExtractStarted(context.Background(), ExtractStart{
		Operation: "extract",
		TargetRID: rid,
	})

	var filesWritten int
	var extractErr error
	defer func() {
		c.obs.ExtractCompleted(ctx, ExtractEnd{
			Operation:    "extract",
			TargetRID:    rid,
			FilesWritten: filesWritten,
			Err:          extractErr,
		})
	}()

	if _, err := c.LoadVFile(rid, true); err != nil {
		extractErr = fmt.Errorf("checkout.Extract: %w", err)
		return extractErr
	}

	// Collect all rows before processing to avoid holding the cursor
	// open during I/O and DB writes.
	type vfileRow struct {
		id       int64
		pathname string
		blobRid  int64
		isexe    int64
	}
	var vfRows []vfileRow

	rows, err := c.db.Query(
		"SELECT id, pathname, rid, isexe FROM vfile WHERE vid = ?",
		int64(rid),
	)
	if err != nil {
		extractErr = fmt.Errorf("checkout.Extract: query vfile: %w", err)
		return extractErr
	}
	for rows.Next() {
		var row vfileRow
		if err := rows.Scan(
			&row.id, &row.pathname, &row.blobRid, &row.isexe,
		); err != nil {
			rows.Close()
			extractErr = fmt.Errorf(
				"checkout.Extract: scan vfile row: %w", err,
			)
			return extractErr
		}
		vfRows = append(vfRows, row)
	}
	rows.Close()
	if err := rows.Err(); err != nil {
		extractErr = fmt.Errorf(
			"checkout.Extract: iterate vfile rows: %w", err,
		)
		return extractErr
	}

	// If Force is false, check for locally modified files before writing.
	if !opts.Force && !opts.DryRun {
		for _, row := range vfRows {
			var storedHash string
			_ = c.db.QueryRow(
				"SELECT mhash FROM vfile WHERE id = ?", row.id,
			).Scan(&storedHash)
			if storedHash == "" {
				continue // no hash to compare against
			}

			fullPath, pathErr := c.safePath(row.pathname)
			if pathErr != nil {
				continue // will be caught during extraction
			}
			data, readErr := c.env.Storage.ReadFile(fullPath)
			if readErr != nil {
				continue // file doesn't exist on disk, safe to write
			}
			diskHash := hash.ContentHash(data, storedHash)
			if diskHash != storedHash {
				extractErr = fmt.Errorf(
					"checkout.Extract: file %s has local changes; "+
						"use Force to overwrite",
					row.pathname,
				)
				return extractErr
			}
		}
	}

	// Look up checkin timestamp for SetMTime.
	var checkinTime time.Time
	if opts.SetMTime && !opts.DryRun {
		var mtimeRaw any
		if err := c.repo.DB().QueryRow(
			"SELECT mtime FROM event WHERE objid = ? AND type = 'ci'",
			int64(rid),
		).Scan(&mtimeRaw); err == nil {
			checkinTime, _ = db.ScanTime(mtimeRaw)
		}
	}

	for _, row := range vfRows {
		if err := c.extractSingleFile(
			row.pathname, row.blobRid, row.isexe, opts.DryRun,
		); err != nil {
			extractErr = err
			return extractErr
		}

		if opts.SetMTime && !opts.DryRun && !checkinTime.IsZero() {
			fullPath, _ := c.safePath(row.pathname)
			if fullPath != "" {
				_ = c.env.Storage.Chtimes(fullPath, checkinTime, checkinTime)
			}
		}

		c.obs.ExtractFileCompleted(ctx, row.pathname, UpdateAdded)

		if opts.Callback != nil {
			if err := opts.Callback(row.pathname, UpdateAdded); err != nil {
				extractErr = fmt.Errorf(
					"checkout.Extract: callback for %s: %w",
					row.pathname, err,
				)
				return extractErr
			}
		}

		filesWritten++
	}

	// Finalize: look up UUID and update vvar
	extractErr = c.finalizeExtract(rid)
	return extractErr
}

// finalizeExtract looks up the blob UUID for rid and updates the vvar
// checkout/checkout-hash entries.
func (c *Checkout) finalizeExtract(rid libfossil.FslID) error {
	var uuid string
	err := c.repo.DB().QueryRow("SELECT uuid FROM blob WHERE rid = ?", int64(rid)).Scan(&uuid)
	if err != nil {
		return fmt.Errorf("checkout.Extract: query blob uuid: %w", err)
	}

	if err := setVVar(c.db, "checkout", strconv.FormatInt(int64(rid), 10)); err != nil {
		return fmt.Errorf("checkout.Extract: %w", err)
	}
	if err := setVVar(c.db, "checkout-hash", uuid); err != nil {
		return fmt.Errorf("checkout.Extract: %w", err)
	}
	return nil
}