Austin Clements yazmış:
>Quoth Ali Polatel on Sep 28 at 10:53 am:
>> On Tue, 27 Sep 2011 18:46:22 -0400, Austin Clements <amdragon@MIT.EDU> wrote:
>> > Quoth David Bremner on Sep 27 at 1:59 pm:
>> > > On Tue, 27 Sep 2011 16:25:58 +0300, Ali Polatel <polatel@gmail.com> wrote:
>> > >
>> > > > The problem with their design is NULL return may both mean an error
>> > > > condition and "message not found". However, we already have a similar
>> > > > function which does not have such a flaw, namely notmuch_database_add_message().
>> > >
>> > > So, I take there is no way to distinguish those two outcomes? That does
>> > > sound bad. Looking at the code for notmuch-new, it looks like the return
>> > > value of notmuch_database_find_message_by_filename is used without
>> > > checking it for NULL. Austin, can you comment on that at all?
>> >
>> > I'd be happy to distinguish these outcomes. I did
>> > notmuch_database_find_message_by_filename the way I did only to be
>> > consistent with notmuch_database_find_message. Since ndfmbf isn't
>> > entrenched yet, now is a good time to change it.
>>
>> What about notmuch_database_find_message()? If we leave it as it is,
>> this will lead to inconsistency and if we change it, we need to think
>> about API breakage issues.
>
>Yes. We could just deal with that (there aren't *that* many API
>consumers). For binary compatibility, I suppose we could even use
>symbol versioning.
>
>> > The call in notmuch-new should check the return, though if it can't
>> > find the message at that point, something has gone terribly wrong.
>> > Segfaulting is never the answer, though.
>>
>> Indeed, just not to step on each other's feet, are you going to write a
>> patch or shall I start writing one?
>
>Please feel free to write a patch.
Below is a quick patch, which compiles and passes tests.
Please comment.
-alip
-- >8 --
Subject: [PATCH] lib: make find_message{,by_filename) report errors
Previously, the functions notmuch_database_find_message() and
notmuch_database_find_message_by_filename() functions did not properly
report error condition to the library user.
For more information, read the thread on the notmuch mailing list
starting with my mail "id:871uv2unfd.fsf@gmail.com"
Make these functions accept a pointer to 'notmuch_message_t' as argument
and return notmuch_status_t which may be used to check for any error
condition.
restore: Modify for the new notmuch_database_find_message()
new: Modify for the new notmuch_database_find_message_by_filename()
---
lib/database.cc | 89 ++++++++++++++++++++++++++++++++++------------------
lib/message.cc | 6 ++--
lib/notmuch.h | 61 +++++++++++++++++++++++++-----------
notmuch-new.c | 4 ++-
notmuch-restore.c | 11 ++++--
5 files changed, 114 insertions(+), 57 deletions(-)
diff --git a/lib/database.cc b/lib/database.cc
index 9299c8d..6641aa5 100644
--- a/lib/database.cc
+++ b/lib/database.cc
@@ -360,13 +360,17 @@ _message_id_compressed (void *ctx, const char *message_id)
return compressed;
}
-notmuch_message_t *
+notmuch_status_t
notmuch_database_find_message (notmuch_database_t *notmuch,
- const char *message_id)
+ const char *message_id,
+ notmuch_message_t **message)
{
notmuch_private_status_t status;
unsigned int doc_id;
+ if (message == NULL)
+ return NOTMUCH_STATUS_NULL_POINTER;
+
if (strlen (message_id) > NOTMUCH_MESSAGE_ID_MAX)
message_id = _message_id_compressed (notmuch, message_id);
@@ -375,14 +379,20 @@ notmuch_database_find_message (notmuch_database_t *notmuch,
message_id, &doc_id);
if (status == NOTMUCH_PRIVATE_STATUS_NO_DOCUMENT_FOUND)
- return NULL;
+ *message = NULL;
+ else {
+ *message = _notmuch_message_create (notmuch, notmuch, doc_id, NULL);
+ if (*message == NULL)
+ return NOTMUCH_STATUS_OUT_OF_MEMORY;
+ }
- return _notmuch_message_create (notmuch, notmuch, doc_id, NULL);
+ return NOTMUCH_STATUS_SUCCESS;
} catch (const Xapian::Error &error) {
fprintf (stderr, "A Xapian exception occurred finding message: %s.\n",
error.get_msg().c_str());
notmuch->exception_reported = TRUE;
- return NULL;
+ *message = NULL;
+ return NOTMUCH_STATUS_XAPIAN_EXCEPTION;
}
}
@@ -1311,7 +1321,8 @@ _get_metadata_thread_id_key (void *ctx, const char *message_id)
/* Find the thread ID to which the message with 'message_id' belongs.
*
- * Always returns a newly talloced string belonging to 'ctx'.
+ * Note: 'thread_id' must not be NULL!
+ * On success '*thread_id' is set to a newly talloced string belonging to 'ctx'.
*
* Note: If there is no message in the database with the given
* 'message_id' then a new thread_id will be allocated for this
@@ -1319,25 +1330,29 @@ _get_metadata_thread_id_key (void *ctx, const char *message_id)
* thread ID can be looked up if the message is added to the database
* later).
*/
-static const char *
+static notmuch_status_t
_resolve_message_id_to_thread_id (notmuch_database_t *notmuch,
void *ctx,
- const char *message_id)
+ const char *message_id,
+ const char **thread_id)
{
+ notmuch_status_t status;
notmuch_message_t *message;
string thread_id_string;
- const char *thread_id;
char *metadata_key;
Xapian::WritableDatabase *db;
- message = notmuch_database_find_message (notmuch, message_id);
+ status = notmuch_database_find_message (notmuch, message_id, &message);
+
+ if (status)
+ return status;
if (message) {
- thread_id = talloc_steal (ctx, notmuch_message_get_thread_id (message));
+ *thread_id = talloc_steal (ctx, notmuch_message_get_thread_id (message));
notmuch_message_destroy (message);
- return thread_id;
+ return NOTMUCH_STATUS_SUCCESS;
}
/* Message has not been seen yet.
@@ -1351,15 +1366,15 @@ _resolve_message_id_to_thread_id (notmuch_database_t *notmuch,
thread_id_string = notmuch->xapian_db->get_metadata (metadata_key);
if (thread_id_string.empty()) {
- thread_id = _notmuch_database_generate_thread_id (notmuch);
- db->set_metadata (metadata_key, thread_id);
+ *thread_id = talloc_strdup(ctx, _notmuch_database_generate_thread_id (notmuch));
+ db->set_metadata (metadata_key, *thread_id);
} else {
- thread_id = thread_id_string.c_str();
+ *thread_id = talloc_strdup(ctx, thread_id_string.c_str());
}
talloc_free (metadata_key);
- return talloc_strdup (ctx, thread_id);
+ return NOTMUCH_STATUS_SUCCESS;
}
static notmuch_status_t
@@ -1446,9 +1461,12 @@ _notmuch_database_link_message_to_parents (notmuch_database_t *notmuch,
_notmuch_message_add_term (message, "reference",
parent_message_id);
- parent_thread_id = _resolve_message_id_to_thread_id (notmuch,
- message,
- parent_message_id);
+ ret = _resolve_message_id_to_thread_id (notmuch,
+ message,
+ parent_message_id,
+ &parent_thread_id);
+ if (ret)
+ goto DONE;
if (*thread_id == NULL) {
*thread_id = talloc_strdup (message, parent_thread_id);
@@ -1759,11 +1777,12 @@ notmuch_status_t
notmuch_database_remove_message (notmuch_database_t *notmuch,
const char *filename)
{
- notmuch_message_t *message =
- notmuch_database_find_message_by_filename (notmuch, filename);
- notmuch_status_t status = NOTMUCH_STATUS_SUCCESS;
+ notmuch_status_t status;
+ notmuch_message_t *message;
- if (message) {
+ status = notmuch_database_find_message_by_filename (notmuch, filename, &message);
+
+ if (status == NOTMUCH_STATUS_SUCCESS && message) {
status = _notmuch_message_remove_filename (message, filename);
if (status == NOTMUCH_STATUS_SUCCESS)
_notmuch_message_delete (message);
@@ -1774,24 +1793,27 @@ notmuch_database_remove_message (notmuch_database_t *notmuch,
return status;
}
-notmuch_message_t *
+notmuch_status_t
notmuch_database_find_message_by_filename (notmuch_database_t *notmuch,
- const char *filename)
+ const char *filename,
+ notmuch_message_t **message)
{
void *local;
const char *prefix = _find_prefix ("file-direntry");
char *direntry, *term;
Xapian::PostingIterator i, end;
- notmuch_message_t *message = NULL;
notmuch_status_t status;
+ if (message == NULL)
+ return NOTMUCH_STATUS_NULL_POINTER;
+
local = talloc_new (notmuch);
try {
status = _notmuch_database_filename_to_direntry (local, notmuch,
filename, &direntry);
if (status)
- return NULL;
+ goto DONE;
term = talloc_asprintf (local, "%s%s", prefix, direntry);
@@ -1800,19 +1822,24 @@ notmuch_database_find_message_by_filename (notmuch_database_t *notmuch,
if (i != end) {
notmuch_private_status_t private_status;
- message = _notmuch_message_create (notmuch, notmuch,
- *i, &private_status);
+ *message = _notmuch_message_create (notmuch, notmuch,
+ *i, &private_status);
+ if (*message == NULL)
+ status = NOTMUCH_STATUS_OUT_OF_MEMORY;
}
} catch (const Xapian::Error &error) {
fprintf (stderr, "Error: A Xapian exception occurred finding message by filename: %s\n",
error.get_msg().c_str());
notmuch->exception_reported = TRUE;
- message = NULL;
+ status = NOTMUCH_STATUS_OUT_OF_MEMORY;
}
+ DONE:
talloc_free (local);
- return message;
+ if (status)
+ *message = NULL;
+ return status;
}
notmuch_string_list_t *
diff --git a/lib/message.cc b/lib/message.cc
index 531d304..2a85744 100644
--- a/lib/message.cc
+++ b/lib/message.cc
@@ -216,11 +216,11 @@ _notmuch_message_create_for_message_id (notmuch_database_t *notmuch,
unsigned int doc_id;
char *term;
- *status_ret = NOTMUCH_PRIVATE_STATUS_SUCCESS;
-
- message = notmuch_database_find_message (notmuch, message_id);
+ *status_ret = (notmuch_private_status_t) notmuch_database_find_message (notmuch, message_id, &message);
if (message)
return talloc_steal (notmuch, message);
+ else if (*status_ret)
+ return NULL;
term = talloc_asprintf (NULL, "%s%s",
_find_prefix ("id"), message_id);
diff --git a/lib/notmuch.h b/lib/notmuch.h
index 6d7a99f..08b4ce2 100644
--- a/lib/notmuch.h
+++ b/lib/notmuch.h
@@ -347,35 +347,60 @@ notmuch_database_remove_message (notmuch_database_t *database,
/* Find a message with the given message_id.
*
- * If the database contains a message with the given message_id, then
- * a new notmuch_message_t object is returned. The caller should call
- * notmuch_message_destroy when done with the message.
+ * If message with the given message_id is found then, on successful return
+ * (NOTMUCH_STATUS_SUCCESS) '*message' will be initialized to a message object.
+ * The user should call notmuch_message_destroy when done with the message.
*
- * This function returns NULL in the following situations:
+ * On any failure or when the message is not found, this function initializes
+ * '*message' to NULL. This means, when NOTMUCH_STATUS_SUCCESS is returned, the
+ * user is supposed to check '*message' for NULL to find out whether the
+ * message with the given message_id was found.
*
- * * No message is found with the given message_id
- * * An out-of-memory situation occurs
- * * A Xapian exception occurs
+ * Note: The argument 'message' must not be NULL!
+ *
+ * Return value:
+ *
+ * NOTMUCH_STATUS_SUCCESS: Successful return, check '*message'.
+ *
+ * NOTMUCH_STATUS_NULL_POINTER: The given 'message' argument is NULL
+ *
+ * NOTMUCH_STATUS_OUT_OF_MEMORY: Out of memory, creating message object
+ *
+ * NOTMUCH_STATUS_XAPIAN_EXCEPTION: A Xapian exception occurred
*/
-notmuch_message_t *
+notmuch_status_t
notmuch_database_find_message (notmuch_database_t *database,
- const char *message_id);
+ const char *message_id,
+ notmuch_message_t **message);
/* Find a message with the given filename.
*
- * If the database contains a message with the given filename, then a
- * new notmuch_message_t object is returned. The caller should call
- * notmuch_message_destroy when done with the message.
+ * If the database contains a message with the given filename then, on
+ * successful return (NOTMUCH_STATUS_SUCCESS) '*message' will be initialized to
+ * a message object. The user should call notmuch_message_destroy when done
+ * with the message.
*
- * This function returns NULL in the following situations:
+ * On any failure or when the message is not found, this function initializes
+ * '*message' to NULL. This means, when NOTMUCH_STATUS_SUCCESS is returned, the
+ * user is supposed to check '*message' for NULL to find out whether the
+ * message with the given filename is found.
*
- * * No message is found with the given filename
- * * An out-of-memory situation occurs
- * * A Xapian exception occurs
+ * Note: The argument 'message' must not be NULL!
+ *
+ * Return value:
+ *
+ * NOTMUCH_STATUS_SUCCESS: Successful return, check '*message'
+ *
+ * NOTMUCH_STATUS_NULL_POINTER: The given 'message' argument is NULL
+ *
+ * NOTMUCH_STATUS_OUT_OF_MEMORY: Out of memory, creating the message object
+ *
+ * NOTMUCH_STATUS_XAPIAN_EXCEPTION: A Xapian exception occurred
*/
-notmuch_message_t *
+notmuch_status_t
notmuch_database_find_message_by_filename (notmuch_database_t *notmuch,
- const char *filename);
+ const char *filename,
+ notmuch_message_t **message);
/* Return a list of all tags found in the database.
*
diff --git a/notmuch-new.c b/notmuch-new.c
index e79593c..96a1e31 100644
--- a/notmuch-new.c
+++ b/notmuch-new.c
@@ -743,7 +743,9 @@ remove_filename (notmuch_database_t *notmuch,
status = notmuch_database_begin_atomic (notmuch);
if (status)
return status;
- message = notmuch_database_find_message_by_filename (notmuch, path);
+ status = notmuch_database_find_message_by_filename (notmuch, path, &message);
+ if (status || message == NULL)
+ return status;
status = notmuch_database_remove_message (notmuch, path);
if (status == NOTMUCH_STATUS_DUPLICATE_MESSAGE_ID) {
add_files_state->renamed_messages++;
diff --git a/notmuch-restore.c b/notmuch-restore.c
index f095f64..3b0ae71 100644
--- a/notmuch-restore.c
+++ b/notmuch-restore.c
@@ -87,10 +87,13 @@ notmuch_restore_command (unused (void *ctx), int argc, char *argv[])
file_tags = xstrndup (line + match[2].rm_so,
match[2].rm_eo - match[2].rm_so);
- message = notmuch_database_find_message (notmuch, message_id);
- if (message == NULL) {
- fprintf (stderr, "Warning: Cannot apply tags to missing message: %s\n",
- message_id);
+ status = notmuch_database_find_message (notmuch, message_id, &message);
+ if (status || message == NULL) {
+ fprintf (stderr, "Warning: Cannot apply tags to %smessage: %s\n",
+ message ? "" : "missing ", message_id);
+ if (status)
+ fprintf (stderr, "%s\n",
+ notmuch_status_to_string(status));
goto NEXT_LINE;
}
--
1.7.6.1