[tracker-miners/sam/text-extractor-errors] tracker-extract-text: Correctly report errors back to the caller

[Sam Thursfield <sthursfield src gnome org>]

commit 08f4af627fa01cdaca294cb1b346f22814ea2826
Author: Sam Thursfield <sam afuera me uk>
Date:   Wed May 1 15:54:39 2019 +0200

    tracker-extract-text: Correctly report errors back to the caller
    
    The tracker_extract_get_metadata() function should return FALSE if
    an error occurs reading the file. The tracker-extract-text module would
    return TRUE in all cases.
    
    This was causing intermittent failures in the functional-tests, as the
    following situation could occur:
    
      1. file2.txt is created
      2. tracker-miner-fs sees file2.txt and processes it
      3. file2.txt is deleted (or moved into an unmonitored directory)
      4. tracker-miner-fs sees the deletion and removes its resource from
         the store
      5. tracker-extract sees the created notification for file2.txt and
         tries to process it
      6. the tracker_extract_get_metadata() incorrectly returns TRUE
         (success), so tracker-extract recreates the deleted resource
    
    This problem was being detected in the functional tests and was
    causing intermittent failures.
    
    This hopefully fixes: https://gitlab.gnome.org/GNOME/tracker-miners/issues/56

 src/tracker-extract/tracker-extract-text.c | 19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)
---
diff --git a/src/tracker-extract/tracker-extract-text.c b/src/tracker-extract/tracker-extract-text.c
index 5f94d7309..a75909bfd 100644
--- a/src/tracker-extract/tracker-extract-text.c
+++ b/src/tracker-extract/tracker-extract-text.c
@@ -46,10 +46,7 @@ get_file_content (GFile *file,
        gchar *text, *uri, *path;
        int fd;
 
-       /* If no content requested, return */
-       if (n_bytes == 0) {
-               return NULL;
-       }
+       g_return_val_if_fail (n_bytes > 0, NULL);
 
        uri = g_file_get_uri (file);
 
@@ -85,12 +82,20 @@ tracker_extract_get_metadata (TrackerExtractInfo *info)
 {
        TrackerResource *metadata;
        TrackerConfig *config;
-       gchar *content;
+       gsize n_bytes;
+       gchar *content = NULL;
 
        config = tracker_main_get_config ();
 
-       content = get_file_content (tracker_extract_info_get_file (info),
-                                   tracker_config_get_max_bytes (config));
+       n_bytes = tracker_config_get_max_bytes (config);
+       if (n_bytes > 0) {
+               content = get_file_content (tracker_extract_info_get_file (info), n_bytes);
+
+               if (content == NULL) {
+                       /* An error occurred, perhaps the file was deleted. */
+                       return FALSE;
+               }
+       }
 
        metadata = tracker_resource_new (NULL);
        tracker_resource_add_uri (metadata, "rdf:type", "nfo:PlainTextDocument");