dl: Fix download of 0-byte files + resume finalize on priority change

The latter is required to recover from errors in download finalization.
(Errors will be properly handled in next commit)

0-byte files also take a shorter route, no attempt to open a connection
to the user is made.

2 files changed, 52 insertions, 42 deletions

diff --git a/src/dl.c b/src/dl.c
index 4b1f1ec..e546462 100644
--- a/src/dl.c
+++ b/src/dl.c
@@ -586,6 +586,9 @@ static gboolean dl_queue_addfile(guint64 uid, char *hash, guint64 size, char *fn
   dl_queue_insert(dl, FALSE);
   dl_user_add(dl, uid, 0, NULL);
   db_dl_adduser(dl->hash, uid, 0, NULL);
+  // Empty files get a shortcut here
+  if(!size)
+    dlfile_finished(dl);
   return TRUE;
 }
 
@@ -715,9 +718,13 @@ void dl_queue_setprio(dl_t *dl, signed char prio) {
   int i;
   for(i=0; i<dl->u->len; i++)
     g_sequence_sort_changed(g_ptr_array_index(dl->u, i), dl_user_dl_sort, NULL);
-  // Start the download if it is enabled
-  if(enabled)
-    dl_queue_start();
+  // Start downloading or re-attempt finalization if it is enabled
+  if(enabled) {
+    if(!dl->active_threads && (dl->hassize || !dl->islist) && dl->have == dl->size)
+      dlfile_finished(dl);
+    else
+      dl_queue_start();
+  }
   /* TODO: Disconnect active users if the dl item is disabled */
 }
 
diff --git a/src/dlfile.c b/src/dlfile.c
index ce9dcdf..f942ad9 100644
--- a/src/dlfile.c
+++ b/src/dlfile.c
@@ -341,8 +341,49 @@ void dlfile_rm(dl_t *dl) {
 }
 
 
+/* Create the inc file and initialize the necessary structs to prepare for
+ * handling downloaded data. */
+static gboolean dlfile_open(dl_t *dl) {
+  if(dl->incfd <= 0)
+    dl->incfd = open(dl->inc, O_WRONLY|O_CREAT, 0666);
+  if(dl->incfd < 0) {
+    g_warning("Error opening %s: %s", dl->inc, g_strerror(errno));
+    dl_queue_seterr(dl, DLE_IO_INC, g_strerror(errno));
+    return FALSE;
+  }
+
+  /* Everything else has already been initialized if we have a thread */
+  if(dl->threads)
+    return TRUE;
+
+  if(!dl->islist) {
+    dl->bitmap = bita_new(dlfile_chunks(dl->size));
+    if(!dlfile_save_bitmap(dl, dl->incfd)) {
+      g_warning("Error writing bitmap for `%s': %s.", dl->dest, g_strerror(errno));
+      dl_queue_seterr(dl, DLE_IO_INC, g_strerror(errno));
+      free(dl->bitmap);
+      dl->bitmap = NULL;
+      return FALSE;
+    }
+  }
+
+  dlfile_thread_t *t = g_slice_new0(dlfile_thread_t);
+  t->dl = dl;
+  t->chunk = 0;
+  t->allocated = 0;
+  if(!dl->islist)
+    t->avail = dlfile_chunks(dl->size);
+  tth_init(&t->hash_tth);
+  dl->threads = g_slist_prepend(dl->threads, t);
+  return TRUE;
+}
+
+
 /* XXX: This function may block in the main thread for a while. Perhaps do it in a threadpool? */
-static void dlfile_finished(dl_t *dl) {
+void dlfile_finished(dl_t *dl) {
+  if(dl->incfd <= 0 && !dlfile_open(dl))
+    return;
+
   /* Regular files: Remove bitmap from the file
    * File lists: Ensure that the file size is correct after we've downloaded a
    *   longer file list before that got interrupted. */
@@ -386,44 +427,6 @@ static void dlfile_finished(dl_t *dl) {
 }
 
 
-/* Create the inc file and initialize the necessary structs to prepare for
- * handling downloaded data. */
-static gboolean dlfile_open(dl_t *dl) {
-  if(dl->incfd <= 0)
-    dl->incfd = open(dl->inc, O_WRONLY|O_CREAT, 0666);
-  if(dl->incfd < 0) {
-    g_warning("Error opening %s: %s", dl->inc, g_strerror(errno));
-    dl_queue_seterr(dl, DLE_IO_INC, g_strerror(errno));
-    return FALSE;
-  }
-
-  /* Everything else has already been initialized if we have a thread */
-  if(dl->threads)
-    return TRUE;
-
-  if(!dl->islist) {
-    dl->bitmap = bita_new(dlfile_chunks(dl->size));
-    if(!dlfile_save_bitmap(dl, dl->incfd)) {
-      g_warning("Error writing bitmap for `%s': %s.", dl->dest, g_strerror(errno));
-      dl_queue_seterr(dl, DLE_IO_INC, g_strerror(errno));
-      free(dl->bitmap);
-      dl->bitmap = NULL;
-      return FALSE;
-    }
-  }
-
-  dlfile_thread_t *t = g_slice_new0(dlfile_thread_t);
-  t->dl = dl;
-  t->chunk = 0;
-  t->allocated = 0;
-  if(!dl->islist)
-    t->avail = dlfile_chunks(dl->size);
-  tth_init(&t->hash_tth);
-  dl->threads = g_slist_prepend(dl->threads, t);
-  return TRUE;
-}
-
-
 /* The 'speed' argument should be a pessimistic estimate of the peers' speed,
  * in bytes/s. I think this is best obtained from a 30 second average.
  * Returns the thread pointer. */