search: Add a readme for search helpers, move third-party helpers

into the search-helpers directory, clean up search logging a bit.

Author: mtwebster

libnemo-private/nemo-search-engine-advanced.c

@@ -122,6 +122,7 @@ get_cat_helper_directories (void)
     }
 
     helper_dirs = g_list_prepend (helper_dirs, path);
+    helper_dirs = g_list_reverse (helper_dirs);
 
     return helper_dirs;
 }
@@ -160,7 +161,7 @@ process_search_helper_file (const gchar *path)
     try_exec = g_key_file_get_string (key_file, SEARCH_HELPER_GROUP, "TryExec", NULL);
     abs_try_path = g_find_program_in_path (try_exec);
     if (!abs_try_path) {
-        g_message ("Skipping search helper '%s' - program is not available (%s)", path, try_exec);
+        DEBUG ("Skipping search helper '%s' - program is not available (%s)", path, try_exec);
         goto done;
     }
 
@@ -198,10 +199,10 @@ process_search_helper_file (const gchar *path)
 
         existing = g_hash_table_lookup (search_helpers, mime_type);
         if (existing && existing->priority > priority) {
-            g_message ("Existing nemo search_helper for '%s' has higher priority than a new one (%s), ignoring the new one.", mime_type, path);
+            DEBUG ("Existing nemo search_helper for '%s' has higher priority than a new one (%s), ignoring the new one.", mime_type, path);
             continue;
         } else if (existing) {
-            g_message ("Replacing existing nemo search_helper for '%s' with %s based on priority.", mime_type, path);
+            DEBUG ("Replacing existing nemo search_helper for '%s' with %s based on priority.", mime_type, path);
         }
 
         helper = g_slice_new0 (SearchHelper);
@@ -239,6 +240,8 @@ initialize_search_helpers (NemoSearchEngineAdvanced *engine)
         const gchar *path;
 
         path = (const gchar *) d_iter->data;
+        DEBUG ("Checking location '%s' for search helpers", path);
+
         error = NULL;
 
         dir = g_dir_open (path, 0, &error);
@@ -256,6 +259,7 @@ initialize_search_helpers (NemoSearchEngineAdvanced *engine)
             }
 
             file_path = g_build_filename (path, filename, NULL);
+            DEBUG ("Processing '%s'", path);
             process_search_helper_file (file_path);
             g_free (file_path);
         }

search-helpers/README.md

@@ -0,0 +1,39 @@
+### Search Helpers
+
+Nemo's file and content search utilizes a plugin-type system to allow content search for additional file types.
+
+The only requirements for a helper is the ability to extract text from a given file type and print it to stdout. A definition file provides details necessary to use the helper.
+
+##### Example definition file:
+
+```
+[Nemo Search Cat Helper]
+TryExec=pdftotext
+Exec=pdftotext %s -
+MimeType=application/pdf;
+Priority=200
+
+```
+The `Nemo Search Cat Helper` group name is mandatory.
+
+- The filename must end in `.nemo_search_helper`.
+- `TryExec` should be set to the name of the executable (without any arguments). When the helpers are loaded, Nemo will
+  check that the program a) exists and b) is executable. If these checks fail, the helper will be skipped. If only a
+  program name is provided, it must exist in the user's path. This can also be an absolute path. 
+- `Exec` should provide the full command line necessary to extract the text from the file. The `%s` argument will be replaced by
+  the file name being processed during content search. Note, uris are not supported, only paths (local files).
+- `MimeType`is a semicolon (`;`)-separated list of mimetypes that this search helper should be used with. It must be
+  semicolon-terminated (even if there's only a single item).
+- `Priority` is a value used to break a tie when multiple helpers support the same mimetype. The higher value wins. In the
+  event of a tie, the last helper processed is used (the order is currently undefined). If the `Priority` entry is missing,
+  the value is assumed to be 100.
+- The `TryExec`, `Exec` and `MimeType` keys are mandatory.
+
+These definition files can be placed in `<datadir>/nemo/search-helpers` where `<datadir>` can be some directory in XDG_DATA_DIRS or under the user's data directory (`~/.local/share/namo/search-helpers`). The user directory is processed last, and takes precedence over the system dirs.
+
+##### Debugging:
+If something doesn't seem to be working, you can run nemo with debugging enabled:
+```
+NEMO_DEBUG=Search nemo --debug
+```
+This will print out a bit of extra information related to searches.

search-helpers/meson.build

@@ -1,4 +1,3 @@
-
 libgsf = dependency('libgsf-1', required: true)
 
 mso_to_txt_sources = [
@@ -15,3 +14,5 @@ install_data(
     'mso.nemo_search_helper',
     install_dir: join_paths(nemoDataPath, 'search-helpers')
 )
+
+subdir('third-party')

files/usr/share/nemo/search-helpers/exif.nemo_search_helper renamed to search-helpers/third-party/exif.nemo_search_helper

@@ -0,0 +1,14 @@
+helpers = [
+  'exif.nemo_search_helper',
+  'id3.nemo_search_helper',
+  'libreoffice.nemo_search_helper',
+  'pdf2txt.nemo_search_helper',
+  'pdftotext.nemo_search_helper',
+  'ps2ascii.nemo_search_helper'
+]
+
+install_data(
+    helpers,
+    install_dir: join_paths(nemoDataPath, 'search-helpers')
+)
+