[notmuch] [PATCH] [RFC] notmuch search: Return a non-zero exitcode if the search returns no hits.

[Chris Wilson]

If the user is explicitly searching for a message, then if notmuch
fails to find it, it is useful to set a failure exit code. This makes it
easier for scripting. However, we will want to then distinguish between
fatal errors (such as out-of-memory, invalid arguments, corrupt db, etc)
from the simple no message. To that end, we introduce a set of
enumerated exit-codes which may prove useful to use consistently across
notmuch. (I'm not that convinced highly differentiated errors is
particularly useful, though separate CONFIG_ERROR and DATABASE_ERROR
would seem to have value for scripts.)
---
 notmuch-search.c |   34 ++++++++++++++++++++++++----------
 1 files changed, 24 insertions(+), 10 deletions(-)

diff --git a/notmuch-search.c b/notmuch-search.c
index dc44eb6..6ca903b 100644
--- a/notmuch-search.c
+++ b/notmuch-search.c
@@ -20,7 +20,17 @@
 
 #include "notmuch-client.h"
 
-static void
+/* XXX After some review, make these universal? */
+enum {
+    NOTMUCH_EXIT_SUCCESS = 0,
+    NOTMUCH_EXIT_NOT_FOUND,
+    NOTMUCH_EXIT_INVALID_ARGUMENT,
+    NOTMUCH_EXIT_SYSTEM_ERROR, /* XXX just out-of-memory? */
+    NOTMUCH_EXIT_CONFIG_ERROR,
+    NOTMUCH_EXIT_DATABASE_ERROR,
+};
+
+static int
 do_search_threads (const void *ctx,
 		   notmuch_query_t *query,
 		   notmuch_sort_t sort)
@@ -30,6 +40,7 @@ do_search_threads (const void *ctx,
     notmuch_tags_t *tags;
     time_t date;
     const char *relative_date;
+    int count = 0;
 
     for (threads = notmuch_query_search_threads (query);
 	 notmuch_threads_has_more (threads);
@@ -67,7 +78,10 @@ do_search_threads (const void *ctx,
 	printf (")\n");
 
 	notmuch_thread_destroy (thread);
+	count++;
     }
+
+    return count;
 }
 
 int
@@ -94,11 +108,11 @@ notmuch_search_command (void *ctx, int argc, char *argv[])
 		sort = NOTMUCH_SORT_NEWEST_FIRST;
 	    } else {
 		fprintf (stderr, "Invalid value for --sort: %s\n", opt);
-		return 1;
+		return NOTMUCH_EXIT_INVALID_ARGUMENT;
 	    }
 	} else {
 	    fprintf (stderr, "Unrecognized option: %s\n", argv[i]);
-	    return 1;
+	    return NOTMUCH_EXIT_INVALID_ARGUMENT;
 	}
     }
 
@@ -107,35 +121,35 @@ notmuch_search_command (void *ctx, int argc, char *argv[])
 
     config = notmuch_config_open (ctx, NULL, NULL);
     if (config == NULL)
-	return 1;
+	return NOTMUCH_EXIT_CONFIG_ERROR;
 
     notmuch = notmuch_database_open (notmuch_config_get_database_path (config),
 				     NOTMUCH_DATABASE_MODE_READ_ONLY);
     if (notmuch == NULL)
-	return 1;
+	return NOTMUCH_EXIT_DATABASE_ERROR;
 
     query_str = query_string_from_args (ctx, argc, argv);
     if (query_str == NULL) {
 	fprintf (stderr, "Out of memory.\n");
-	return 1;
+	return NOTMUCH_EXIT_SYSTEM_ERROR;
     }
     if (*query_str == '\0') {
 	fprintf (stderr, "Error: notmuch search requires at least one search term.\n");
-	return 1;
+	return NOTMUCH_EXIT_INVALID_ARGUMENT;
     }
 
     query = notmuch_query_create (notmuch, query_str);
     if (query == NULL) {
 	fprintf (stderr, "Out of memory\n");
-	return 1;
+	return NOTMUCH_EXIT_SYSTEM_ERROR;
     }
 
     notmuch_query_set_sort (query, sort);
 
-    do_search_threads (ctx, query, sort);
+    i = do_search_threads (ctx, query, sort);
 
     notmuch_query_destroy (query);
     notmuch_database_close (notmuch);
 
-    return 0;
+    return i ? NOTMUCH_EXIT_SUCCESS : NOTMUCH_EXIT_NOT_FOUND;
 }
-- 
1.6.6