[PATCH 00/12] Add ghost messages and fix thread linking

[Austin Clements]

This is v2 of the
id:1412345958-8278-1-git-send-email-aclements at csail.mit.edu.  This
adds some comments and clarifies some code as suggested by David.
Patch 6 is new in v2 and adds some bit-twiddling macros for clarity
and robustness in later patches.

The diff from v1 is below.

diff --git a/lib/database.cc b/lib/database.cc
index 4655f59..6e51a72 100644
--- a/lib/database.cc
+++ b/lib/database.cc
@@ -1277,6 +1277,8 @@ notmuch_database_upgrade (notmuch_database_t *notmuch,
 	    ++total;
     }
     if (new_features & NOTMUCH_FEATURE_GHOSTS) {
+	/* The ghost message upgrade converts all thread_id_*
+	 * metadata values into ghost message documents. */
 	t_end = db->metadata_keys_end ("thread_id_");
 	for (t = db->metadata_keys_begin ("thread_id_"); t != t_end; ++t)
 	    ++total;
diff --git a/lib/message.cc b/lib/message.cc
index ad832cf..a7a13cc 100644
--- a/lib/message.cc
+++ b/lib/message.cc
@@ -344,15 +344,17 @@ _notmuch_message_ensure_metadata (notmuch_message_t *message)
 
     /* Get document type */
     assert (strcmp (id_prefix, type_prefix) < 0);
-    if (! (message->lazy_flags & (1 << NOTMUCH_MESSAGE_FLAG_GHOST))) {
+    if (! NOTMUCH_TEST_BIT (message->lazy_flags, NOTMUCH_MESSAGE_FLAG_GHOST)) {
 	i.skip_to (type_prefix);
+	/* "T" is the prefix "type" fields.  See
+	 * BOOLEAN_PREFIX_INTERNAL. */
 	if (*i == "Tmail")
-	    message->flags &= ~(1 << NOTMUCH_MESSAGE_FLAG_GHOST);
+	    NOTMUCH_CLEAR_BIT (&message->flags, NOTMUCH_MESSAGE_FLAG_GHOST);
 	else if (*i == "Tghost")
-	    message->flags |= (1 << NOTMUCH_MESSAGE_FLAG_GHOST);
+	    NOTMUCH_SET_BIT (&message->flags, NOTMUCH_MESSAGE_FLAG_GHOST);
 	else
 	    INTERNAL_ERROR ("Message without type term");
-	message->lazy_flags |= (1 << NOTMUCH_MESSAGE_FLAG_GHOST);
+	NOTMUCH_SET_BIT (&message->lazy_flags, NOTMUCH_MESSAGE_FLAG_GHOST);
     }
 
     /* Get filename list.  Here we get only the terms.  We lazily
@@ -390,8 +392,8 @@ _notmuch_message_invalidate_metadata (notmuch_message_t *message,
     }
 
     if (strcmp ("type", prefix_name) == 0) {
-	message->flags &= ~(1 << NOTMUCH_MESSAGE_FLAG_GHOST);
-	message->lazy_flags &= ~(1 << NOTMUCH_MESSAGE_FLAG_GHOST);
+	NOTMUCH_CLEAR_BIT (&message->flags, NOTMUCH_MESSAGE_FLAG_GHOST);
+	NOTMUCH_CLEAR_BIT (&message->lazy_flags, NOTMUCH_MESSAGE_FLAG_GHOST);
     }
 
     if (strcmp ("file-direntry", prefix_name) == 0) {
@@ -893,10 +895,10 @@ notmuch_message_get_flag (notmuch_message_t *message,
 			  notmuch_message_flag_t flag)
 {
     if (flag == NOTMUCH_MESSAGE_FLAG_GHOST &&
-	! (message->lazy_flags & (1 << flag)))
+	! NOTMUCH_TEST_BIT (message->lazy_flags, flag))
 	_notmuch_message_ensure_metadata (message);
 
-    return message->flags & (1 << flag);
+    return NOTMUCH_TEST_BIT (message->flags, flag);
 }
 
 void
@@ -904,10 +906,10 @@ notmuch_message_set_flag (notmuch_message_t *message,
 			  notmuch_message_flag_t flag, notmuch_bool_t enable)
 {
     if (enable)
-	message->flags |= (1 << flag);
+	NOTMUCH_SET_BIT (&message->flags, flag);
     else
-	message->flags &= ~(1 << flag);
-    message->lazy_flags |= (1 << flag);
+	NOTMUCH_CLEAR_BIT (&message->flags, flag);
+    NOTMUCH_SET_BIT (&message->lazy_flags, flag);
 }
 
 time_t
diff --git a/lib/notmuch-private.h b/lib/notmuch-private.h
index 2fbd38e..2f43c1d 100644
--- a/lib/notmuch-private.h
+++ b/lib/notmuch-private.h
@@ -63,6 +63,17 @@ NOTMUCH_BEGIN_DECLS
 #define STRNCMP_LITERAL(var, literal) \
     strncmp ((var), (literal), sizeof (literal) - 1)
 
+/* Robust bit test/set/reset macros */
+#define NOTMUCH_TEST_BIT(val, bit) \
+    ((bit < 0 || bit >= CHAR_BIT * sizeof (unsigned long long)) ? 0	\
+     : !!((val) & (1ull << bit)))
+#define NOTMUCH_SET_BIT(valp, bit) \
+    ((bit < 0 || bit >= CHAR_BIT * sizeof (unsigned long long)) ? *(valp) \
+     : (*(valp) |= (1ull << bit)))
+#define NOTMUCH_CLEAR_BIT(valp,  bit) \
+    ((bit < 0 || bit >= CHAR_BIT * sizeof (unsigned long long)) ? *(valp) \
+     : (*(valp) &= ~(1ull << bit)))
+
 #define unused(x) x __attribute__ ((unused))
 
 #ifdef __cplusplus