Files
FastSync/src/shared/file.h
T
TapTap d38920c972 feat: receiver-side basis matching with link/copy materialization
The receiver's per-file incremental check now consults the ordered basis-dir
list whenever the destination is not already up to date.  An exact basis match
requires equal size, equal mtime (unless --size-only; --ignore-times disables
basis matching like rsync), and an equal content xxHash64 -- the sender sends
its xxHash for every file whenever basis dirs are configured (not only under
--checksum), so a hard link or local copy is only ever made from byte-identical
content.

On a match:
  - compare-dest: reply STATUS_OK and skip data only when the destination does
    not already hold the file (sparse, rsync parity).  A destination that holds
    a DIFFERENT version falls back to a normal transfer instead of rsync's
    delete, keeping the mirror complete.
  - copy-dest: reply STATUS_OK and hand a synthetic File (bytes read from the
    basis file, basis metadata) to the normal store sink, so the file is
    installed as a real local copy through the existing atomic temp+rename
    engine and honors --existing/--ignore-existing/--update/--backup/
    --delay-updates/--partial-dir unchanged.
  - link-dest: same, but File.basis_link records the basis path and the store
    engine calls the new file_to_disk_secure_link(): an atomic temp hard link +
    rename.  Cross-filesystem/refused links fall back to a byte-identical local
    copy (never a corrupt or partial file); the copy fallback applies metadata,
    while a successful link keeps the basis inode's own attributes so the basis
    file is never mutated.

Basis-materialized files carry File.skip so they are not acknowledged to a
--remove-source-files sender (the sender already saw STATUS_OK and keeps the
source).  The no-match path is byte-for-byte identical to the existing delta /
full-data transfer.
2026-09-06 18:47:26 +02:00

75 lines
4.2 KiB
C

#ifndef FILE_H
#define FILE_H
#include "file_send.h"
#include "file_receive.h"
#include "file_types.h"
#include <stdbool.h>
#include <stdint.h>
#include <sys/stat.h>
/* File/FileMetadata lifecycle, local disk helpers, and secure filesystem
primitives shared by the send/receive pipelines. */
File* file_create(const char* path);
void file_destroy(void* item);
bool file_load_data(File* file);
bool file_checksum(File* file, uint64_t* checksum);
size_t file_content_to_buffer(File* file);
FileMetadata* file_metadata_create(const struct stat* stats);
void file_metadata_destroy(void* metadata);
bool file_write_to_disk(const char* path, const void* data, unsigned long long data_size,
bool inplace, bool sparse);
/* A configured fd without a canonical identity deliberately rejects paths. */
bool file_set_authorized_root(int fd, const char* canonical_path);
/* Secure path/filesystem primitives (symlink-safe, O_NOFOLLOW, root-confined). */
bool file_path_exists_secure(const char* path);
bool file_stat_secure(const char* path, struct stat* st);
bool file_destination_is_newer_secure(const char* path, const FileMetadata* metadata);
int file_open_secure_parent(const char* path, char** leaf_out, bool create_dirs);
bool file_ensure_directory_secure(const char* path);
bool file_directory_exists_secure(const char* path);
bool file_rename_secure(const char* old_path, const char* new_path);
/* Open a private 0700 directory (creating it on demand) that must live below
the authorized root. Used for the --temp-dir scratch directory and the
--delay-updates staging directory. */
int file_open_private_dir(const char* dir_path);
/* The file_to_disk_secure* variants write a temporary copy in the destination
directory and atomically rename it over `path`. temp_dir is an absolute,
root-confined scratch directory (already validated by the caller): when it
is non-NULL the temporary copy is instead created there (with a name unique
across the whole scratch directory) and atomically renamed into the
destination directory once fully written and fsynced. A rename across
filesystems (EXDEV) fails the write with an error; the file is never
silently copied into place. Pass NULL for the historical same-directory
behavior. --inplace writes never use temp_dir. */
bool file_to_disk_secure(const char* path, const void* data, unsigned long long data_size,
bool inplace, bool sparse, const FileMetadata* metadata,
bool preserve_executability, const char* temp_dir);
bool file_to_disk_secure_with_fsync(const char* path, const void* data,
unsigned long long data_size, bool inplace, bool sparse,
const FileMetadata* metadata, bool preserve_executability,
bool use_fsync, const char* temp_dir);
/* With update enabled, an existing newer destination is left untouched. The
check is descriptor-based for inplace writes; atomic replacement still has
an unavoidable final rename race without filesystem locking. */
bool file_to_disk_secure_update(const char* path, const void* data, unsigned long long data_size,
bool inplace, bool sparse, const FileMetadata* metadata,
bool preserve_executability, const char* temp_dir);
bool file_to_disk_secure_no_replace(const char* path, const void* data,
unsigned long long data_size, bool sparse,
const FileMetadata* metadata, bool preserve_executability,
const char* temp_dir);
/* Atomic --link-dest install: replace `path` with a hard link to `basis_path`
(via a temp name + rename); fall back to a byte-identical local copy from
`data` when the link is impossible (EXDEV/EPERM/unsupported filesystem).
`metadata` is applied only on the copy fallback. */
bool file_to_disk_secure_link(const char* path, const char* basis_path, const void* data,
unsigned long long data_size, const FileMetadata* metadata,
bool preserve_executability, bool use_fsync, const char* temp_dir);
#endif