Allow user to trigger full rescan with a .force-rescan file

README

@@ -257,6 +257,12 @@ be offered until they've been scanned.
 Changes to the library are reflected in real time after the initial scan. The
 directories are monitored for changes and rescanned on the fly.
 
+If you place a file with the filename ending .force-rescan in your library,
+you can trigger a full rescan of your library. This will clear all music and
+playlists from forked-daapd's database and initiate a fresh bulk scan. Pairing
+and speaker information will be kept. Only use this for troubleshooting, it is
+not necessary during normal operation.
+
 Symlinks are supported and dereferenced. This does interact in tricky ways
 with the above monitoring and rescanning, so you've been warned. Changes to
 symlinks themselves won't be taken into account, or not the way you'd expect.

src/db.c

@@ -651,6 +651,36 @@ db_purge_cruft(time_t ref)
 
 }
 
+void
+db_purge_all(void)
+{
+  char *queries[4] =
+    {
+      "DELETE FROM inotify;",
+      "DELETE FROM playlistitems;",
+      "DELETE FROM playlists WHERE type <> 1;",
+      "DELETE FROM files;"
+    };
+  char *errmsg;
+  int i;
+  int ret;
+
+  for (i = 0; i < (sizeof(queries) / sizeof(queries[0])); i++)
+    {
+      DPRINTF(E_DBG, L_DB, "Running purge query '%s'\n", queries[i]);
+
+      ret = db_exec(queries[i], &errmsg);
+      if (ret != SQLITE_OK)
+	{
+	  DPRINTF(E_LOG, L_DB, "Purge query %d error: %s\n", i, errmsg);
+
+	  sqlite3_free(errmsg);
+	}
+      else
+	DPRINTF(E_DBG, L_DB, "Purged %d rows\n", sqlite3_changes(hdl));
+    }
+}
+
 static int
 db_get_count(char *query)
 {

src/db.h

@@ -295,6 +295,9 @@ db_hook_post_scan(void);
 void
 db_purge_cruft(time_t ref);
 
+void
+db_purge_all(void);
+
 /* Queries */
 int
 db_query_start(struct query_params *qp);

src/filescanner.c

@@ -90,6 +90,9 @@ static pthread_t tid_scan;
 static struct deferred_pl *playlists;
 static struct stacked_dir *dirstack;
 
+/* Forward */
+static void
+bulk_scan(void);
 
 static int
 push_dir(struct stacked_dir **s, char *path)
@@ -560,6 +563,19 @@ process_file(char *file, time_t mtime, off_t size, int type, int flags)
 
 	  return;
 	}
+      else if (strcmp(ext, ".force-rescan") == 0)
+	{
+	  if (flags & F_SCAN_BULK)
+	    return;
+	  else
+	    {
+	      DPRINTF(E_LOG, L_SCAN, "Forcing full rescan, found force-rescan file: %s\n", file);
+	      db_purge_all();
+	      bulk_scan();
+
+	      return;
+	    }
+	}
     }
 
   /* Not any kind of special file, so let's see if it's a media file */