fix: #251 #252 #253 #255 #256 #257 receiver & remove-source correctness

#251 --remove-source-files deletes sources that were skipped receiver-side
     (--existing/--ignore-existing/--update). The receiver now reports a
     per-file outcome for every processed data file when the sender requests
     removal; the client only unlinks sources the receiver actually wrote.
     add remove_source_files to the wire config and bump the protocol to 2.5.0.
#252 --backup/--suffix/--backup-dir broken by NULL-vs-empty wire loss. Receivers
     canonicalize the empty wire string back to NULL for backup_dir, temp_dir,
     partial_dir and suffix, and --suffix is received unconditionally.
#253 --partial --partial-dir never installed completed files. file_save_to_disk
     now renames a fully written partial-dir file into the real destination.
#255 STATUS_CHECK read the entire old file before the size/mtime quick check.
     Old contents are only read when a checksum compare or delta needs them.
#256 receive_delta_file failure paths did not set *failed, so the caller sent
     STATUS_NEXT and waited for a body that never came. Every NULL return now
     marks the transfer failed.
#257 files >64 MiB could not transfer. Whole-file receive caps raised to the
     256 MiB connection/allocation ceiling (chunk caps stay 64 MiB) and the
     client ignores SIGPIPE so a server-side close surfaces as a clean error.

Unit tests added: config NULL-vs-empty round trip, incremental quick-check
skip/NEXT paths, delta oversize failure, partial-dir install, save-result
skip reporting.

src/client/client_cli.c

@@ -12,6 +12,7 @@
 #include "utils.h"
 #include <errno.h>
 #include <limits.h>
+#include <signal.h>
 #include <stdbool.h>
 #include <stddef.h>
 #include <stdio.h>
@@ -903,6 +904,10 @@ static int read_patterns_from_file(const char* filepath, char*** patterns, int*
 
 #ifndef FASTSYNC_TEST_BUILD
 int main(int argc, char* argv[]) {
+  /* The server may close a connection mid-stream (e.g. when it rejects an
+     oversized delta).  Ignore SIGPIPE so that a broken TCP connection
+     surfaces as a clean write error instead of killing the client. */
+  signal(SIGPIPE, SIG_IGN);
   const char* env_source = NULL;
   const char* env_dest = NULL;
   bool save_to_disk = false;

src/client/client_send.c

@@ -109,16 +109,13 @@ static bool add_chunk_to_manifest(ArrayList* manifest, const Chunk* chunk) {
   return true;
 }
 
-static bool finalize_transfer(Client* client) {
-  Status status;
-  return send_status(client->file_descriptor, STATUS_FINISHED) &&
-         receive_status(client->file_descriptor, &status) && status == STATUS_OK;
-}
+/* (finalize_transfer is defined after the SourceFile helpers below.) */
 
-typedef struct {
+typedef struct SourceFile {
   char* path;
   dev_t device;
   ino_t inode;
+  bool skipped; /* receiver reported the file was not written */
 } SourceFile;
 
 static void source_file_destroy(void* item) {
@@ -135,6 +132,8 @@ static void remove_transferred_sources(const Config* config, ArrayList* paths) {
     return;
   for (int i = 0; i < paths->size; i++) {
     SourceFile* source = paths->items[i];
+    if (source->skipped)
+      continue;
     const char* slash = strrchr(source->path, '/');
     const char* leaf = slash ? slash + 1 : source->path;
     char parent[PATH_MAX];
@@ -177,6 +176,7 @@ static SourceFile* source_file_create(const File* file) {
   source->path = str_dup(file->path);
   source->device = st.st_dev;
   source->inode = st.st_ino;
+  source->skipped = false;
   if (!source->path) {
     source_file_destroy(source);
     return NULL;
@@ -203,6 +203,33 @@ static void mark_sender_done(PipelineContextSender* context) {
   mtx_unlock(&context->mutex_progress);
 }
 
+/* Send the final STATUS_FINISHED frame and await the receiver's verdict.
+   When --remove-source-files is active the receiver acknowledges each data
+   file it processed, in send order: STATUS_NEXT means the file was written,
+   STATUS_OK means the file was skipped/unchanged.  Skipped sources are marked
+   so the later removal pass keeps them. */
+static bool finalize_transfer(Client* client, const Config* config, ArrayList* remove_sources) {
+  if (!send_status(client->file_descriptor, STATUS_FINISHED))
+    return false;
+  if (config->remove_source_files && remove_sources) {
+    for (int i = 0; i < remove_sources->size; i++) {
+      Status per_file;
+      if (!receive_status(client->file_descriptor, &per_file))
+        return false;
+      if (per_file == STATUS_ERROR)
+        return false;
+      if (per_file == STATUS_OK) {
+        ((SourceFile*)remove_sources->items[i])->skipped = true;
+      } else if (per_file != STATUS_NEXT) {
+        log_message(LOG_LEVEL_ERROR, "Unexpected per-file status from receiver");
+        return false;
+      }
+    }
+  }
+  Status status;
+  return receive_status(client->file_descriptor, &status) && status == STATUS_OK;
+}
+
 static void pipeline_cancel(PipelineContextSender* context) {
   mtx_lock(&context->mutex_scanner);
   mtx_lock(&context->mutex_loader);
@@ -575,7 +602,7 @@ static int send_chunks_multithreaded(void* pipeline_context) {
         if (send_delete_manifest(client->file_descriptor, context->manifest) != 0)
           goto send_fail;
       }
-      bool ok = finalize_transfer(client);
+      bool ok = finalize_transfer(client, context->config, context->remove_source_files);
       if (ok)
         remove_transferred_sources(context->config, context->remove_source_files);
       mtx_lock(&context->mutex_progress);
@@ -866,7 +893,7 @@ int send_files(Config* config) {
     array_list_delete(manifest);
     manifest = NULL;
   }
-  bool ok = finalize_transfer(client);
+  bool ok = finalize_transfer(client, config, remove_sources);
   if (ok)
     remove_transferred_sources(config, remove_sources);
   if (config->show_progress && !config->quiet)

src/server/receiver.c

@@ -1,6 +1,7 @@
 #include "receiver.h"
 
 #include "chunk.h"
+#include "file_receive.h"
 #include "log.h"
 #include "metadata.h"
 #include "protocol.h"
@@ -8,6 +9,48 @@
 #include <stdlib.h>
 #include <sys/stat.h>
 
+bool receiver_outcomes_append(ReceiverOutcomes* outcomes, unsigned char code) {
+  if (!outcomes)
+    return false;
+  if (outcomes->count == outcomes->capacity) {
+    size_t new_capacity = outcomes->capacity == 0 ? 64 : outcomes->capacity * 2;
+    if (new_capacity < outcomes->capacity)
+      return false;
+    unsigned char* grown = realloc(outcomes->entries, new_capacity);
+    if (!grown)
+      return false;
+    outcomes->entries = grown;
+    outcomes->capacity = new_capacity;
+  }
+  outcomes->entries[outcomes->count++] = code;
+  return true;
+}
+
+void receiver_outcomes_destroy(ReceiverOutcomes* outcomes) {
+  if (!outcomes)
+    return;
+  free(outcomes->entries);
+  outcomes->entries = NULL;
+  outcomes->count = 0;
+  outcomes->capacity = 0;
+}
+
+/* End-of-transfer success frame.  When --remove-source-files was negotiated
+   each processed data file is acknowledged first (STATUS_NEXT = written,
+   STATUS_OK = skipped) so the sender never removes a source the receiver did
+   not actually store.  The frame always ends with a plain STATUS_OK. */
+bool receiver_send_final_success(int fd, const Config* config, const ReceiverOutcomes* outcomes) {
+  if (!config->remove_source_files)
+    return send_status(fd, STATUS_OK);
+  size_t count = outcomes ? outcomes->count : 0;
+  for (size_t i = 0; i < count; i++) {
+    Status per_file = outcomes->entries[i] == FILE_SAVE_WRITTEN ? STATUS_NEXT : STATUS_OK;
+    if (!send_status(fd, per_file))
+      return false;
+  }
+  return send_status(fd, STATUS_OK);
+}
+
 static bool receiver_process_chunk(Chunk* chunk, const ReceiverSink* sink) {
   if (!chunk || !sink || !sink->store_file)
     return false;
@@ -52,7 +95,7 @@ static bool receiver_process_batch(Config* config, int file_descriptor) {
       send_status(file_descriptor, STATUS_ERROR);
       return false;
     }
-    if (check_size > MAX_RECEIVE_FILE_SIZE) {
+    if (check_size > MAX_RECEIVE_WHOLE_FILE_SIZE) {
       free(check_path);
       send_status(file_descriptor, STATUS_ERROR);
       return false;
@@ -130,8 +173,14 @@ int receiver_process(Config* config, int file_descriptor, const ReceiverSink* si
     log_message(LOG_LEVEL_ERROR, "Did not receive FINISHED Status");
     goto receive_error;
   }
-  if (sink->send_success && !send_status(file_descriptor, STATUS_OK))
-    return -1;
+  if (sink->send_success) {
+    if (sink->send_success_frame) {
+      if (!sink->send_success_frame(file_descriptor, sink->context))
+        return -1;
+    } else if (!send_status(file_descriptor, STATUS_OK)) {
+      return -1;
+    }
+  }
   return 0;
 
 receive_error:
@@ -140,15 +189,41 @@ receive_error:
   return -1;
 }
 
-static bool receiver_save_file(File* file, void* context) {
-  Config* config = context;
-  bool success =
-      !config->save_to_disk || file_save_to_disk(config->receive_root_directory, file, config);
+/* ---- Single-threaded sink (used by receiver_receive_files) ---- */
+
+typedef struct {
+  Config* config;
+  ReceiverOutcomes outcomes;
+} ReceiverSaveContext;
+
+static bool receiver_save_file(File* file, void* context_pointer) {
+  ReceiverSaveContext* context = context_pointer;
+  FileSaveResult result = FILE_SAVE_ERROR;
+  if (!context->config->save_to_disk) {
+    /* Nothing is stored; report the file as not-written so a
+       --remove-source-files sender keeps its source. */
+    result = FILE_SAVE_SKIPPED;
+  } else {
+    result = file_save_to_disk_full(context->config->receive_root_directory, file, context->config);
+  }
+  if (result != FILE_SAVE_ERROR && context->config->remove_source_files &&
+      !receiver_outcomes_append(&context->outcomes, (unsigned char)result)) {
+    file_destroy(file);
+    return false;
+  }
   file_destroy(file);
-  return success;
+  return result != FILE_SAVE_ERROR;
+}
+
+static bool receiver_send_success_frame(int fd, void* context_pointer) {
+  ReceiverSaveContext* context = context_pointer;
+  return receiver_send_final_success(fd, context->config, &context->outcomes);
 }
 
 int receiver_receive_files(Config* config, int file_descriptor) {
-  ReceiverSink sink = {receiver_save_file, config, true, true};
-  return receiver_process(config, file_descriptor, &sink);
+  ReceiverSaveContext context = {.config = config, .outcomes = {0}};
+  ReceiverSink sink = {receiver_save_file, &context, true, true, receiver_send_success_frame};
+  int ret = receiver_process(config, file_descriptor, &sink);
+  receiver_outcomes_destroy(&context.outcomes);
+  return ret;
 }

src/server/receiver.h

@@ -3,16 +3,37 @@
 
 #include "config.h"
 #include "file.h"
+#include "file_receive.h"
 
 typedef bool (*ReceiverFileSink)(File* file, void* context);
 
+/* Ordered per-file save outcomes for one connection.  One entry is appended
+   for every data-bearing file the receiver processes (in the order the files
+   were sent) so the sender of a --remove-source-files transfer can be told
+   which sources were actually written versus skipped on the receiver. */
+typedef struct {
+  unsigned char* entries; /* FILE_SAVE_WRITTEN or FILE_SAVE_SKIPPED */
+  size_t count;
+  size_t capacity;
+} ReceiverOutcomes;
+
+typedef bool (*ReceiverSuccessFrame)(int fd, void* context);
+
 typedef struct {
   ReceiverFileSink store_file;
   void* context;
   bool send_error;
   bool send_success;
+  /* Emits the end-of-transfer success frame.  When the sender requested
+     --remove-source-files this includes one per-file status per processed
+     data file followed by the final STATUS_OK; otherwise just STATUS_OK. */
+  ReceiverSuccessFrame send_success_frame;
 } ReceiverSink;
 
+bool receiver_outcomes_append(ReceiverOutcomes* outcomes, unsigned char code);
+void receiver_outcomes_destroy(ReceiverOutcomes* outcomes);
+bool receiver_send_final_success(int fd, const Config* config, const ReceiverOutcomes* outcomes);
+
 int receiver_process(Config* config, int file_descriptor, const ReceiverSink* sink);
 int receiver_receive_files(Config* config, int file_descriptor);
 

src/server/server.c

@@ -342,9 +342,15 @@ void handler(int file_descriptor) {
     int writer_result;
     thrd_join(receiver, &receiver_result);
     thrd_join(writer, &writer_result);
-    send_status(file_descriptor, receiver_result == thrd_success && writer_result == thrd_success
-                                     ? STATUS_OK
-                                     : STATUS_ERROR);
+    bool transfer_ok = receiver_result == thrd_success && writer_result == thrd_success;
+    if (transfer_ok) {
+      if (!receiver_send_final_success(file_descriptor, config, &context->outcomes))
+        transfer_ok = false;
+    } else {
+      send_status(file_descriptor, STATUS_ERROR);
+    }
+    if (!transfer_ok)
+      log_message(LOG_LEVEL_ERROR, "Transfer failed");
     pipeline_context_receiver_destroy(context);
   } else {
     if (receiver_receive_files(config, file_descriptor) != 0)

src/shared/config.c

@@ -139,8 +139,9 @@ static bool validate_received_config(const Config* config) {
          valid_wire_bool(config->use_delete) && valid_wire_bool(config->use_incremental) &&
          valid_wire_bool(config->size_only) && valid_wire_bool(config->ignore_times) &&
          valid_wire_bool(config->use_delta) && valid_wire_bool(config->backup) &&
-         valid_wire_bool(config->follow_symlinks) && valid_wire_bool(config->copy_links) &&
-         valid_wire_bool(config->safe_links) && valid_wire_bool(config->copy_unsafe_links) &&
+         valid_wire_bool(config->remove_source_files) && valid_wire_bool(config->follow_symlinks) &&
+         valid_wire_bool(config->copy_links) && valid_wire_bool(config->safe_links) &&
+         valid_wire_bool(config->copy_unsafe_links) &&
          valid_wire_bool(config->preserve_hard_links) && valid_wire_bool(config->preserve_acls) &&
          valid_wire_bool(config->preserve_xattrs) && valid_wire_bool(config->preserve_devices) &&
          valid_wire_bool(config->preserve_sparse) && valid_wire_bool(config->ignore_existing) &&
@@ -274,11 +275,11 @@ static bool send_delta_fields(int fd, const Config* c) {
 
 static bool send_file_options(int fd, const Config* c) {
   return send_int(fd, c->backup) && send_str(fd, c->backup_dir ? c->backup_dir : "") &&
-         send_int(fd, c->follow_symlinks) && send_int(fd, c->copy_links) &&
-         send_int(fd, c->safe_links) && send_int(fd, c->copy_unsafe_links) &&
-         send_int(fd, c->preserve_hard_links) && send_int(fd, c->preserve_acls) &&
-         send_int(fd, c->preserve_xattrs) && send_int(fd, c->preserve_devices) &&
-         send_int(fd, c->preserve_sparse);
+         send_int(fd, c->remove_source_files) && send_int(fd, c->follow_symlinks) &&
+         send_int(fd, c->copy_links) && send_int(fd, c->safe_links) &&
+         send_int(fd, c->copy_unsafe_links) && send_int(fd, c->preserve_hard_links) &&
+         send_int(fd, c->preserve_acls) && send_int(fd, c->preserve_xattrs) &&
+         send_int(fd, c->preserve_devices) && send_int(fd, c->preserve_sparse);
 }
 
 static bool send_selection_options(int fd, const Config* c) {
@@ -355,8 +356,17 @@ static bool receive_delta_fields(int fd, Config* c) {
 static bool receive_file_options(int fd, Config* c) {
   if (!receive_wire_bool(fd, &c->backup))
     return false;
-  c->backup_dir = receive_str(fd);
-  if (!c->backup_dir)
+  char* backup_dir = receive_str(fd);
+  if (!backup_dir)
+    return false;
+  if (*backup_dir != '\0') {
+    c->backup_dir = backup_dir;
+  } else {
+    /* The sender serializes an unset (NULL) string as "", so canonicalize the
+       empty wire value back to NULL to preserve NULL-vs-empty semantics. */
+    free(backup_dir);
+  }
+  if (!receive_wire_bool(fd, &c->remove_source_files))
     return false;
   bool* flags[] = {&c->follow_symlinks,   &c->copy_links,          &c->safe_links,
                    &c->copy_unsafe_links, &c->preserve_hard_links, &c->preserve_acls,
@@ -386,12 +396,37 @@ static bool receive_selection_options(int fd, Config* c) {
 }
 
 static bool receive_resume_options(int fd, Config* c) {
-  c->temp_dir = receive_str(fd);
-  if (!c->temp_dir || !receive_wire_bool(fd, &c->partial))
+  char* temp_dir = receive_str(fd);
+  if (!temp_dir)
     return false;
-  c->partial_dir = receive_str(fd);
-  c->suffix = c->partial_dir ? receive_str(fd) : NULL;
-  if (!c->partial_dir || !c->suffix || !receive_wire_bool(fd, &c->delete_before))
+  if (*temp_dir != '\0') {
+    c->temp_dir = temp_dir;
+  } else {
+    free(temp_dir);
+  }
+  if (!receive_wire_bool(fd, &c->partial))
+    return false;
+  /* These options have NULL client defaults, so the sender transmits an empty
+     string for "unset".  Canonicalize the empty wire value back to NULL so
+     receivers observe exactly what the client configured (plain --backup, for
+     example, must not look like --backup-dir ""). */
+  char* partial_dir = receive_str(fd);
+  if (!partial_dir)
+    return false;
+  if (*partial_dir != '\0') {
+    c->partial_dir = partial_dir;
+  } else {
+    free(partial_dir);
+  }
+  char* suffix = receive_str(fd);
+  if (!suffix)
+    return false;
+  if (*suffix != '\0') {
+    c->suffix = suffix;
+  } else {
+    free(suffix);
+  }
+  if (!receive_wire_bool(fd, &c->delete_before))
     return false;
   if (!receive_wire_bool(fd, &c->checksum))
     return false;

src/shared/config.h

@@ -147,7 +147,7 @@ typedef struct Config {
   bool skip_compress_set;
 } Config;
 
-#define PROTOCOL_VERSION "2.4.0"
+#define PROTOCOL_VERSION "2.5.0"
 #define DEFAULT_CHUNK_SIZE (10 * 1024 * 1024)
 
 Config* config_create(void);

src/shared/file_receive.c

@@ -20,9 +20,14 @@
 #include "utils.h"
 
 #define MAX_SERVER_DELETE_COUNT 100000U
-#define MAX_FILE_DATA_SIZE MAX_RECEIVE_FILE_SIZE
+#define MAX_FILE_DATA_SIZE MAX_RECEIVE_WHOLE_FILE_SIZE
 
 bool file_save_to_disk(const char* root_directory, const File* file, const Config* config) {
+  return file_save_to_disk_full(root_directory, file, config) != FILE_SAVE_ERROR;
+}
+
+FileSaveResult file_save_to_disk_full(const char* root_directory, const File* file,
+                                      const Config* config) {
   /* Backups are incompatible with ignore-existing: moving the entry first
      would make a concurrent no-replace commit overwrite its old name. */
   bool backup_enabled = config && config->backup && !config->ignore_existing;
@@ -32,6 +37,7 @@ bool file_save_to_disk(const char* root_directory, const File* file, const Confi
   const char* backup_suffix = (config && config->suffix) ? config->suffix : "~";
   const char* backup_dir = (config && config->backup_dir) ? config->backup_dir : NULL;
   const char* partial_dir = (config && config->partial_dir) ? config->partial_dir : NULL;
+  bool use_partial_root = partial_dir && config && config->partial;
   char *confined_backup = NULL, *confined_partial = NULL, *disk_path = NULL;
   char* destination_path = NULL;
   char *backup_path = NULL, *parent_copy = NULL;
@@ -42,23 +48,22 @@ bool file_save_to_disk(const char* root_directory, const File* file, const Confi
        (!backup_suffix || backup_suffix[0] == '\0' || strchr(backup_suffix, '/') != NULL ||
         strcmp(backup_suffix, ".") == 0 || strcmp(backup_suffix, "..") == 0))) {
     log_message(LOG_LEVEL_ERROR, "Invalid file or path received");
-    return false;
+    return FILE_SAVE_ERROR;
   }
 
   /* These options arrive from the client.  They are names below the server
      root, never independent filesystem roots. */
   if ((backup_dir && (backup_dir[0] == '/' || has_path_traversal(backup_dir))) ||
       (partial_dir && (partial_dir[0] == '/' || has_path_traversal(partial_dir))))
-    return false;
+    return FILE_SAVE_ERROR;
   if (backup_dir && !(confined_backup = path_cat(root_directory, backup_dir)))
-    return false;
+    return FILE_SAVE_ERROR;
   if (partial_dir && !(confined_partial = path_cat(root_directory, partial_dir))) {
     free(confined_backup);
-    return false;
+    return FILE_SAVE_ERROR;
   }
 
-  const char* actual_root =
-      (partial_dir && config && config->partial) ? confined_partial : root_directory;
+  const char* actual_root = use_partial_root ? confined_partial : root_directory;
   destination_path = path_cat(root_directory, file->path);
   disk_path = path_cat(actual_root, file->path);
   if (destination_path == NULL || disk_path == NULL) {
@@ -66,7 +71,7 @@ bool file_save_to_disk(const char* root_directory, const File* file, const Confi
     free(confined_partial);
     free(destination_path);
     free(disk_path);
-    return false;
+    return FILE_SAVE_ERROR;
   }
 
   /* --existing checks the final destination, not a temporary partial path. */
@@ -75,7 +80,7 @@ bool file_save_to_disk(const char* root_directory, const File* file, const Confi
     free(confined_partial);
     free(destination_path);
     free(disk_path);
-    return true;
+    return FILE_SAVE_SKIPPED;
   }
 
   /* --ignore-existing checks the final destination before partial files or
@@ -87,34 +92,40 @@ bool file_save_to_disk(const char* root_directory, const File* file, const Confi
       free(confined_partial);
       free(destination_path);
       free(disk_path);
-      return true;
+      return FILE_SAVE_SKIPPED;
     }
   }
-  free(destination_path);
-  destination_path = NULL;
 
   /* --update is receiver-side policy: never replace a newer destination.
-     The secure stat does not require read permission on the destination. */
-  if (config && config->update && file_destination_is_newer_secure(disk_path, file->metadata)) {
+     In partial-dir mode the entry that would be replaced is the real
+     destination, not the temporary partial file.  The secure stat does not
+     require read permission on the destination. */
+  const char* update_target = use_partial_root ? destination_path : disk_path;
+  if (config && config->update && file_destination_is_newer_secure(update_target, file->metadata)) {
     free(confined_backup);
     free(confined_partial);
+    free(destination_path);
     free(disk_path);
-    return true;
+    return FILE_SAVE_SKIPPED;
   }
 
   if (backup_enabled) {
+    /* Back up the entry that the incoming write will replace.  When writing
+       through a partial dir the pre-existing destination file is the one to
+       preserve; any stale partial file is overwritten without a backup. */
+    const char* replace_target = use_partial_root ? destination_path : disk_path;
     struct stat backup_stat;
-    if (file_stat_secure(disk_path, &backup_stat)) {
+    if (file_stat_secure(replace_target, &backup_stat)) {
       if (backup_dir) {
         backup_path = path_cat(confined_backup, file->path);
       } else {
-        size_t path_len = strlen(disk_path);
+        size_t path_len = strlen(replace_target);
         size_t suffix_len = strlen(backup_suffix);
         if (path_len > SIZE_MAX - suffix_len - 1)
           goto fail;
         backup_path = malloc(path_len + suffix_len + 1);
         if (backup_path) {
-          memcpy(backup_path, disk_path, path_len);
+          memcpy(backup_path, replace_target, path_len);
           memcpy(backup_path + path_len, backup_suffix, suffix_len + 1);
         }
       }
@@ -125,7 +136,7 @@ bool file_save_to_disk(const char* root_directory, const File* file, const Confi
         goto fail;
       free(parent_copy);
       parent_copy = NULL;
-      if (!file_rename_secure(disk_path, backup_path))
+      if (!file_rename_secure(replace_target, backup_path))
         goto fail;
       free(backup_path);
       backup_path = NULL;
@@ -149,13 +160,25 @@ bool file_save_to_disk(const char* root_directory, const File* file, const Confi
                 : file_to_disk_secure_with_fsync(disk_path, file->data->data, file->data->size,
                                                  inplace, sparse, metadata, preserve_executability,
                                                  config && config->use_fsync);
+  if (!ok)
+    goto fail;
+
+  /* --partial --partial-dir writes the complete file under the partial dir so
+     interrupted transfers leave a resumable copy there.  Once the file is
+     fully written it must be atomically installed at the real destination;
+     otherwise completed transfers would linger under the partial dir. */
+  if (use_partial_root) {
+    if (!file_rename_secure(disk_path, destination_path))
+      goto fail;
+  }
+
   free(parent_copy);
   free(backup_path);
   free(confined_backup);
   free(confined_partial);
   free(destination_path);
   free(disk_path);
-  return ok;
+  return FILE_SAVE_WRITTEN;
 
 fail:
   free(parent_copy);
@@ -164,13 +187,15 @@ fail:
   free(confined_partial);
   free(destination_path);
   free(disk_path);
-  return false;
+  return FILE_SAVE_ERROR;
 }
 
 static File* receive_delta_file(int fd, const Config* config, const char* check_path,
                                 void* old_data, unsigned long long old_size, bool* failed) {
-  if (!old_data)
+  if (!old_data) {
+    *failed = true;
     return NULL;
+  }
 
   DeltaSignature* sig = delta_signature_create(old_data, old_size, config->delta_block_size);
   if (!sig) {
@@ -206,7 +231,7 @@ static File* receive_delta_file(int fd, const Config* config, const char* check_
   }
 
   if (resp == STATUS_DELTA_DATA) {
-    Data* delta_data = receive_data_limited(fd, MAX_RECEIVE_FILE_SIZE);
+    Data* delta_data = receive_data_limited(fd, MAX_RECEIVE_WHOLE_FILE_SIZE);
     if (!delta_data) {
       delta_signature_destroy(sig);
       free(old_data);
@@ -219,7 +244,7 @@ static File* receive_delta_file(int fd, const Config* config, const char* check_
         !compression_should_skip_with_suffixes(
             check_path, config->skip_compress_suffixes,
             config->skip_compress_set ? config->skip_compress_count : -1)) {
-      raw_delta = data_decompress_limited(delta_data, MAX_RECEIVE_FILE_SIZE);
+      raw_delta = data_decompress_limited(delta_data, MAX_RECEIVE_WHOLE_FILE_SIZE);
       data_destroy(delta_data);
       if (!raw_delta) {
         free(old_data);
@@ -239,11 +264,12 @@ static File* receive_delta_file(int fd, const Config* config, const char* check_
     }
 
     uint64_t new_size = delta->new_file_size;
-    if (new_size > MAX_RECEIVE_FILE_SIZE || new_size > SIZE_MAX) {
+    if (new_size > MAX_RECEIVE_WHOLE_FILE_SIZE || new_size > SIZE_MAX) {
       delta_destroy(delta);
       free(old_data);
       delta_signature_destroy(sig);
       send_status(fd, STATUS_ERROR);
+      *failed = true;
       return NULL;
     }
     void* new_data = delta_apply(old_data, old_size, delta, config->delta_block_size);
@@ -284,6 +310,7 @@ static File* receive_delta_file(int fd, const Config* config, const char* check_
       free(old_data);
       delta_signature_destroy(sig);
       send_status(fd, STATUS_ERROR);
+      *failed = true;
       return NULL;
     }
     data_destroy(file->data);
@@ -314,7 +341,7 @@ static File* receive_delta_file(int fd, const Config* config, const char* check_
       }
     }
 
-    Data* file_data = receive_data_limited(fd, MAX_RECEIVE_FILE_SIZE);
+    Data* file_data = receive_data_limited(fd, MAX_RECEIVE_WHOLE_FILE_SIZE);
     if (file_data == NULL) {
       file_destroy(file);
       *failed = true;
@@ -325,7 +352,7 @@ static File* receive_delta_file(int fd, const Config* config, const char* check_
         !compression_should_skip_with_suffixes(
             file->path, config->skip_compress_suffixes,
             config->skip_compress_set ? config->skip_compress_count : -1)) {
-      Data* uncompressed = data_decompress_limited(file_data, MAX_RECEIVE_FILE_SIZE);
+      Data* uncompressed = data_decompress_limited(file_data, MAX_RECEIVE_WHOLE_FILE_SIZE);
       data_destroy(file_data);
       if (uncompressed == NULL) {
         file_destroy(file);
@@ -384,7 +411,7 @@ File* receive_incremental_check(int fd, const Config* config, bool* skipped) {
     return NULL;
   }
 
-  if (check_size > MAX_RECEIVE_FILE_SIZE) {
+  if (check_size > MAX_RECEIVE_WHOLE_FILE_SIZE) {
     free(check_path);
     send_status(fd, STATUS_ERROR);
     return NULL;
@@ -405,6 +432,9 @@ File* receive_incremental_check(int fd, const Config* config, bool* skipped) {
     send_status(fd, STATUS_ERROR);
     return NULL;
   }
+
+  /* Open the existing destination entry (if any) once and keep the descriptor
+     until the quick-check below decides whether the old contents are needed. */
   struct stat st;
   bool has_old_file = false;
   int old_fd = -1;
@@ -416,9 +446,34 @@ File* receive_incremental_check(int fd, const Config* config, bool* skipped) {
     close(parent_fd);
     has_old_file = old_fd >= 0 && fstat(old_fd, &st) == 0 && S_ISREG(st.st_mode);
   }
+  if (!has_old_file && old_fd >= 0) {
+    close(old_fd);
+    old_fd = -1;
+  }
   unsigned long long old_size = has_old_file ? (unsigned long long)st.st_size : 0;
+
+  /* Decide from metadata alone whether the receiver already holds the file
+     the sender is offering.  The old contents are only read into memory when
+     a checksum comparison or a delta transfer actually requires them. */
+  bool size_equal = has_old_file && old_size == check_size;
+  bool match_by_metadata = false;
+  if (size_equal && !config->ignore_times && !config->size_only) {
+    long long old_mtime_nsec = 0;
+#ifdef __linux__
+    old_mtime_nsec = st.st_mtim.tv_nsec;
+#endif
+    match_by_metadata = metadata_mtime_matches(st.st_mtime, old_mtime_nsec, (time_t)check_mtime,
+                                               (long)check_mtime_nsec, config->modify_window);
+  }
+
+  bool try_delta = config->use_delta && !config->whole_file && has_old_file &&
+                   delta_should_attempt(old_size, check_size, config->delta_max_file_size);
+  bool checksum_needs_read = size_equal && !config->ignore_times && config->checksum;
+  bool need_old_data = checksum_needs_read || try_delta;
+
   void* old_data = NULL;
-  if (has_old_file && old_size > 0 && old_size <= MAX_RECEIVE_FILE_SIZE && old_size <= SIZE_MAX) {
+  if (need_old_data && has_old_file && old_size > 0 && old_size <= MAX_RECEIVE_WHOLE_FILE_SIZE &&
+      old_size <= SIZE_MAX) {
     old_data = protocol_alloc((size_t)old_size);
     if (old_data) {
       size_t got = 0;
@@ -433,73 +488,63 @@ File* receive_incremental_check(int fd, const Config* config, bool* skipped) {
       }
     }
   }
-  if (old_fd >= 0) {
-    close(old_fd);
-  }
 
-  bool match =
-      !config->ignore_times && has_old_file && (unsigned long long)st.st_size == check_size;
-  if (match && config->checksum) {
-    uint64_t old_checksum = old_size == 0 ? delta_xxhash64("", 0) : 0;
-    if (old_data)
-      old_checksum = delta_xxhash64(old_data, (size_t)old_size);
-    match = (old_size == 0 || old_data) && old_checksum == check_checksum;
-    free(old_data);
-    old_data = NULL;
-  } else if (match && !config->size_only) {
-    long long old_mtime_nsec = 0;
-#ifdef __linux__
-    old_mtime_nsec = st.st_mtim.tv_nsec;
-#endif
-    match = metadata_mtime_matches(st.st_mtime, old_mtime_nsec, (time_t)check_mtime,
-                                   (long)check_mtime_nsec, config->modify_window);
+  /* Quick-skip decision.  If no content comparison is required this is final
+     and the old file was never read; if the read failed the file is not
+     skipped and the transfer proceeds with the full new contents. */
+  bool match = false;
+  if (checksum_needs_read) {
+    if (old_size == 0)
+      match = delta_xxhash64("", 0) == check_checksum;
+    else
+      match = old_data != NULL && delta_xxhash64(old_data, (size_t)old_size) == check_checksum;
+  } else if (size_equal && !config->ignore_times) {
+    match = config->size_only || match_by_metadata;
   }
 
   if (match) {
     free(old_data);
     if (!send_status(fd, STATUS_OK)) {
+      close(old_fd);
       free(full_path);
       free(check_path);
       return NULL;
     }
+    close(old_fd);
     free(full_path);
     free(check_path);
     *skipped = true;
     return NULL;
   }
 
-  bool try_delta = config->use_delta && !config->whole_file && has_old_file && old_data != NULL &&
-                   delta_should_attempt(old_size, check_size, config->delta_max_file_size);
-
-  if (try_delta) {
+  if (try_delta && old_data != NULL) {
     bool delta_failed = false;
     File* delta_file =
         receive_delta_file(fd, config, check_path, old_data, old_size, &delta_failed);
     old_data = NULL; /* receive_delta_file consumes the snapshot on every path */
     if (delta_file) {
+      close(old_fd);
       free(full_path);
       free(check_path);
       return delta_file;
     }
     if (delta_failed) {
+      close(old_fd);
       free(full_path);
       free(check_path);
       return NULL;
     }
-    free(old_data);
-    old_data = NULL;
-    try_delta = false;
   }
+  free(old_data);
+  old_data = NULL;
 
-  if (!try_delta) {
-    free(old_data);
-    old_data = NULL;
-    if (!send_status(fd, STATUS_NEXT)) {
-      free(full_path);
-      free(check_path);
-      return NULL;
-    }
+  if (!send_status(fd, STATUS_NEXT)) {
+    close(old_fd);
+    free(full_path);
+    free(check_path);
+    return NULL;
   }
+  close(old_fd);
 
   File* file = file_create(check_path);
   free(check_path);
@@ -517,7 +562,7 @@ File* receive_incremental_check(int fd, const Config* config, bool* skipped) {
     }
   }
 
-  Data* file_data = receive_data_limited(fd, MAX_RECEIVE_FILE_SIZE);
+  Data* file_data = receive_data_limited(fd, MAX_RECEIVE_WHOLE_FILE_SIZE);
   if (file_data == NULL) {
     file_destroy(file);
     return NULL;
@@ -527,7 +572,7 @@ File* receive_incremental_check(int fd, const Config* config, bool* skipped) {
       !compression_should_skip_with_suffixes(file->path, config->skip_compress_suffixes,
                                              config->skip_compress_set ? config->skip_compress_count
                                                                        : -1)) {
-    Data* uncompressed = data_decompress_limited(file_data, MAX_RECEIVE_FILE_SIZE);
+    Data* uncompressed = data_decompress_limited(file_data, MAX_RECEIVE_WHOLE_FILE_SIZE);
     data_destroy(file_data);
     if (uncompressed == NULL) {
       file_destroy(file);
@@ -571,7 +616,7 @@ File* file_receive(const Config* config, int file_descriptor) {
       return NULL;
     }
   }
-  Data* file_data = receive_data_limited(file_descriptor, MAX_RECEIVE_FILE_SIZE);
+  Data* file_data = receive_data_limited(file_descriptor, MAX_RECEIVE_WHOLE_FILE_SIZE);
   if (file_data == NULL) {
     file_destroy(file);
     return NULL;
@@ -580,7 +625,7 @@ File* file_receive(const Config* config, int file_descriptor) {
       !compression_should_skip_with_suffixes(file->path, config->skip_compress_suffixes,
                                              config->skip_compress_set ? config->skip_compress_count
                                                                        : -1)) {
-    Data* file_data_uncompressed = data_decompress_limited(file_data, MAX_RECEIVE_FILE_SIZE);
+    Data* file_data_uncompressed = data_decompress_limited(file_data, MAX_RECEIVE_WHOLE_FILE_SIZE);
     data_destroy(file_data);
     if (file_data_uncompressed == NULL) {
       file_destroy(file);

src/shared/file_receive.h

@@ -10,6 +10,14 @@
 File* file_receive(const Config* config, int file_descriptor);
 File* receive_incremental_check(int fd, const Config* config, bool* skipped);
 int receive_manifest(int fd, const Config* config, int* next_status);
+
+/* Outcome of a single file_save_to_disk operation.  The receiver needs to
+   distinguish "written" from "skipped" so --remove-source-files can be told
+   which sources were actually stored. */
+typedef enum { FILE_SAVE_ERROR = 0, FILE_SAVE_WRITTEN = 1, FILE_SAVE_SKIPPED = 2 } FileSaveResult;
+
+FileSaveResult file_save_to_disk_full(const char* root_directory, const File* file,
+                                      const Config* config);
 bool file_save_to_disk(const char* root_directory, const File* file, const Config* config);
 
 #endif

src/shared/multiprocessing.c

@@ -105,6 +105,9 @@ PipelineContextReceiver* pipeline_context_receiver_create(Config* config, Queue*
   context->queue = queue;
   context->file_descriptor = file_descriptor;
   context->ssl = ssl;
+  context->outcomes.entries = NULL;
+  context->outcomes.count = 0;
+  context->outcomes.capacity = 0;
   protocol_session_init(&context->session, file_descriptor, file_descriptor);
   protocol_session_set_ssl(&context->session, ssl);
   context->receiver_done = false;
@@ -137,6 +140,7 @@ fail:
 void pipeline_context_receiver_destroy(PipelineContextReceiver* context) {
   config_delete(context->config);
   queue_destroy(context->queue);
+  receiver_outcomes_destroy(&context->outcomes);
   mtx_destroy(&context->mutex);
   cnd_destroy(&context->condition_not_full);
   cnd_destroy(&context->condition_not_empty);
@@ -170,7 +174,7 @@ int receive_thread(void* pipeline_context) {
   const Config* config = context->config;
   mtx_unlock(&context->mutex);
 
-  ReceiverSink sink = {receiver_enqueue_file, context, false, false};
+  ReceiverSink sink = {receiver_enqueue_file, context, false, false, NULL};
   if (receiver_process((Config*)config, file_descriptor, &sink) != 0) {
     receiver_thread_fail(context);
     protocol_session_unbind();
@@ -211,7 +215,26 @@ int write_thread(void* pipeline_context) {
       protocol_session_unbind();
       return thrd_success;
     }
-    if (save_to_disk && !file_save_to_disk(root_directory, file, context->config)) {
+    FileSaveResult result = FILE_SAVE_SKIPPED;
+    if (save_to_disk) {
+      result = file_save_to_disk_full(root_directory, file, context->config);
+      if (result == FILE_SAVE_ERROR) {
+        file_destroy(file);
+        mtx_lock(&context->mutex);
+        atomic_store(&context->cancelled, true);
+        context->receiver_done = true;
+        cnd_broadcast(&context->condition_not_full);
+        cnd_broadcast(&context->condition_not_empty);
+        mtx_unlock(&context->mutex);
+        free(root_directory);
+        protocol_session_unbind();
+        return thrd_error;
+      }
+    }
+    /* Record the per-file outcome so a --remove-source-files sender learns
+       which sources were actually written versus skipped on the receiver. */
+    if (context->config->remove_source_files &&
+        !receiver_outcomes_append(&context->outcomes, (unsigned char)result)) {
       file_destroy(file);
       mtx_lock(&context->mutex);
       atomic_store(&context->cancelled, true);

src/shared/multiprocessing.h

@@ -9,6 +9,7 @@
 #include "file.h"
 #include "protocol.h"
 #include "queue.h"
+#include "receiver.h"
 #include <openssl/ssl.h>
 
 typedef struct {
@@ -40,6 +41,7 @@ typedef struct PipelineContextReceiver {
   int file_descriptor;
   SSL* ssl;
   ProtocolSession session;
+  ReceiverOutcomes outcomes;
   mtx_t mutex;
   cnd_t condition_not_full;
   cnd_t condition_not_empty;

src/shared/protocol.h

@@ -9,10 +9,16 @@
 /* Maximum allowed string size for receive_str (64 KB) */
 #define MAX_STRING_SIZE (64 * 1024)
 
-/* Maximum allowed data payload size for receive_data (100 MB) */
-#define MAX_DATA_PAYLOAD_SIZE (100ULL * 1024 * 1024)
-/* Maximum uncompressed file payload accepted by the receiver. */
-#define MAX_RECEIVE_FILE_SIZE (64ULL * 1024 * 1024)
+/* Maximum uncompressed file payload accepted by the receiver's whole-file
+ * paths.  A single whole file is charged against the per-connection memory
+ * reservation (MAX_CONNECTION_MEMORY) and against the server allocation
+ * ceiling (MAX_SERVER_ALLOC), so this mirrors those 256 MB bounds rather than
+ * the older 64 MB chunk-era cap.  Chunk-serialized payloads keep their own
+ * 64 MB cap (MAX_CHUNK_SIZE). */
+#define MAX_RECEIVE_WHOLE_FILE_SIZE (256ULL * 1024 * 1024)
+
+/* Maximum allowed data payload size for receive_data (whole-file bound) */
+#define MAX_DATA_PAYLOAD_SIZE MAX_RECEIVE_WHOLE_FILE_SIZE
 
 /* Maximum chunk size (64 MB) — prevents unbounded allocation from the wire */
 #define MAX_CHUNK_SIZE (64ULL * 1024 * 1024)