lib: Support empty header values in database

[notmuch] / lib / message.cc

diff --git a/lib/message.cc b/lib/message.cc
index 3f934265a73727feceb0f5dfa26bc70f55669dbe..ed8c59e9b072795aec252b99def49a5d4b14e20e 100644 (file)
--- a/lib/message.cc
+++ b/lib/message.cc
@@ -414,26 +414,35 @@ _notmuch_message_ensure_message_file (notmuch_message_t *message)
 const char *
 notmuch_message_get_header (notmuch_message_t *message, const char *header)
 {
-    try {
-           std::string value;
-
-           /* Fetch header from the appropriate xapian value field if
-            * available */
-           if (strcasecmp (header, "from") == 0)
-               value = message->doc.get_value (NOTMUCH_VALUE_FROM);
-           else if (strcasecmp (header, "subject") == 0)
-               value = message->doc.get_value (NOTMUCH_VALUE_SUBJECT);
-           else if (strcasecmp (header, "message-id") == 0)
-               value = message->doc.get_value (NOTMUCH_VALUE_MESSAGE_ID);
-
-           if (!value.empty())
+    Xapian::valueno slot = Xapian::BAD_VALUENO;
+
+    /* Fetch header from the appropriate xapian value field if
+     * available */
+    if (strcasecmp (header, "from") == 0)
+       slot = NOTMUCH_VALUE_FROM;
+    else if (strcasecmp (header, "subject") == 0)
+       slot = NOTMUCH_VALUE_SUBJECT;
+    else if (strcasecmp (header, "message-id") == 0)
+       slot = NOTMUCH_VALUE_MESSAGE_ID;
+
+    if (slot != Xapian::BAD_VALUENO) {
+       try {
+           std::string value = message->doc.get_value (slot);
+
+           /* If we have NOTMUCH_FEATURE_FROM_SUBJECT_ID_VALUES, then
+            * empty values indicate empty headers.  If we don't, then
+            * it could just mean we didn't record the header. */
+           if ((message->notmuch->features &
+                NOTMUCH_FEATURE_FROM_SUBJECT_ID_VALUES) ||
+               ! value.empty())
                return talloc_strdup (message, value.c_str ());
 
-    } catch (Xapian::Error &error) {
-       fprintf (stderr, "A Xapian exception occurred when reading header: %s\n",
-                error.get_msg().c_str());
-       message->notmuch->exception_reported = TRUE;
-       return NULL;
+       } catch (Xapian::Error &error) {
+           fprintf (stderr, "A Xapian exception occurred when reading header: %s\n",
+                    error.get_msg().c_str());
+           message->notmuch->exception_reported = TRUE;
+           return NULL;
+       }
     }
 
     /* Otherwise fall back to parsing the file */