Files
FastSync/src/shared/delay_updates.h
T
TapTap 4295fefaa3 fix: --delay-updates delete/backup collisions, publish-failure test, staging lock
Review fixes for --delay-updates:

- --delete no longer deletes the staged files: the delete walker gains a
  skip_root_child parameter and receive_manifest passes DELAY_UPDATES_STAGING_DIR
  when delay_updates is active, so deletion removes genuine extras while the
  staging dir (a direct child of the receive root) is left for publication in
  both single and -m modes.
- --backup-dir is rejected when it collides with the reserved internal staging
  name .fastsync-stage (trailing slash normalized), in client validation and in
  the received-config wire validation, preventing old backups from being
  silently installed as new files.
- Staging dir is now held under an exclusive advisory flock for the whole
  transfer (context lifetime): two simultaneous delayed transfers to one
  destination root no longer share/destroy each other's staged data - the
  second fails cleanly.  Cleanup only touches the staging dir when this context
  owns the lock, so a lock-contention failure cannot wipe a live session.
- Post-publish staging cleanup now returns/logs instead of discarding failures
  (warning when the staging dir cannot be fully removed).
- Reworked the publish-failure integration test to exercise real mid-publish
  semantics (top-level file published, nested rename fails, no rollback,
  sources retained under --remove-source-files) and added integration tests for
  --delete + --delay-updates ordering and reserved --backup-dir rejection.
- RSYNC_COMPAT note documents delete ordering, the reserved-name hazard, and
  the concurrency guard.
2026-09-06 14:19:18 +02:00

69 lines
3.1 KiB
C

#ifndef DELAY_UPDATES_H
#define DELAY_UPDATES_H
#include <stdbool.h>
#include <stddef.h>
#include <threads.h>
/* Forward-declared in config.h; full type needed by file_save_to_disk. */
typedef struct Config Config;
/* One staged file awaiting publication. */
typedef struct {
char* staged_path; /* full path inside the staging tree */
char* final_path; /* full final destination path */
char* file_path; /* the file path as received on the wire */
} StagedFileEntry;
/* Receiver-side --delay-updates staging registry. All successfully written
files land under a private staging directory inside the receive root and are
atomically renamed into their final destination only at the very end of the
transfer. A single PipelineContextReceiver has exactly one writer thread,
but the registry is still mutex-protected so the same object can be safely
shared with the publish/cleanup phase that runs after the threads join. */
typedef struct DelayUpdatesContext {
char* root_directory; /* receive root the staging dir lives under */
char* staging_root; /* root_directory/<staging dir name> */
mtx_t mutex;
StagedFileEntry* entries;
size_t count;
size_t capacity;
bool prepared; /* staging dir created, wiped, and exclusively locked */
int lock_fd; /* advisory exclusive flock held on the staging dir, or -1 */
} DelayUpdatesContext;
/* Name of the private staging subdirectory created under the receive root. */
#define DELAY_UPDATES_STAGING_DIR ".fastsync-stage"
/* True when `dir` (ignoring a trailing "/") is the reserved staging directory
name. Used to reject a --backup-dir that would collide with the internal
staging area. */
bool delay_updates_staging_name_conflict(const char* dir);
/* Create an empty staging context rooted below root_directory. Does not touch
the filesystem yet. */
DelayUpdatesContext* delay_updates_context_create(const char* root_directory);
void delay_updates_context_destroy(DelayUpdatesContext* context);
/* Create the private 0700 staging directory (on first call) and wipe any
leftovers from a previously interrupted delayed transfer. Idempotent. */
bool delay_updates_prepare(DelayUpdatesContext* context);
/* Record a fully-written staged file for later publication. Copies all three
paths. Returns false on allocation failure. */
bool delay_updates_record(DelayUpdatesContext* context, const char* staged_path,
const char* final_path, const char* file_path);
/* Atomically rename every staged file into its final destination. Deferred
--backup handling runs immediately before each rename. On any failure the
remaining staged files are removed (best effort); already-published files
are not rolled back. Afterwards the staging tree is removed so a successful
or failed publish leaves no staging leftovers. */
bool delay_updates_publish(DelayUpdatesContext* context, const Config* config);
/* Best-effort removal of every staged file and the staging directory itself.
Safe to call when nothing was staged or after a successful publish. */
void delay_updates_cleanup(DelayUpdatesContext* context);
#endif