Re: [bug report] git-am applying maildir patches in reverse
On Fri, Mar 01, 2013 at 03:24:42PM -0800, Junio C Hamano wrote:
Show 21 quoted lines
> Jeff King <peff@peff.net> writes:
>
> > On Fri, Mar 01, 2013 at 05:52:31PM -0500, Jeff King wrote:
> > ...
> >> The maildir spec explicitly says that readers should not make
> >> assumptions about the content of the filenames. Mutt happens to write
> >> them as:
> >>
> >> ${epoch_seconds}.${pid}_${seq}.${host}
> >>
> >> so in practice, sorting them kind of works. Except that ...
> >> << it does not work >> ...
> > That ordering is not necessarily useful.
> > ...
> > So it is somewhat against the maildir spec, but I think in practice it
> > would help.
>
> I do not think it would help, unless these epoch_seconds are the
> sender timestamps. And the number of digits in epoch-seconds for
> recent messages would be the same, so ordering textually would be
> sufficient if ordering by timestamp were.The epoch_seconds are the time of writing into the maildir. They will typically all be the same, unless your system is very slow, or you are writing a really long patch series. The PID likewise should be the same for a given series. It's the sequence number that is the interesting bit to sort numerically (for mutt, anyway; ditto for dovecot).
The patch below seems to fix the issue for me with mutt. It's possible that it regresses another case (which has numbers, but really wants them sorted as byte strings), but I find that unlikely. If you're zero-padding your numbers this will still work, and if you're not, then you likely have no meaningful sort order at all.
-- >8 --
Subject: [PATCH] mailsplit: sort maildir filenames more cleverly
A maildir does not technically record the order in which items were placed into it. That means that when applying a patch series from a maildir, we may get the patches in the wrong order. We try to work around this by sorting the filenames. Unfortunately, this may or may not work depending on the naming scheme used by the writer of the maildir.
For instance, mutt will write:
${epoch_seconds}.${pid}_${seq}.${host}where we have:
- epoch_seconds: timestamp at which entry was written
- pid: PID of writing process
- seq: a sequence number to ensure uniqueness of filenames
- host: hostname
None of the numbers are zero-padded. Therefore, when we sort the names as byte strings, entries that cross a digit boundary (e.g., 10) will sort out of order. In the case of timestamps, it almost never matters (because we do not cross a digit boundary in the epoch time very often these days). But for the sequence number, a 10-patch series would be ordered as 1, 10, 2, 3, etc.
To fix this, we can use a custom sort comparison function which traverses each string, comparing chunks of digits numerically, and otherwise doing a byte-for-byte comparison. That would sort:
123.456_1.bar
123.456_2.bar
...
123.456_10.bar
according to the sequence number. Since maildir does not define a filename format, this is really just a heuristic. But it happens to work for mutt, and there is a reasonable chance that it will work for other writers, too (at least as well as a straight sort).
Signed-off-by: Jeff King <peff@peff.net>
---
builtin/mailsplit.c | 22 ++++++++++++++++++++++
1 file changed, 22 insertions(+)
diff --git a/builtin/mailsplit.c b/builtin/mailsplit.c
index 2d43278..772c668 100644
--- a/builtin/mailsplit.c
+++ b/builtin/mailsplit.c
@@ -130,6 +130,26 @@ static int populate_maildir_list(struct string_list *list, const char *path)
return 0;
}
+static int maildir_filename_cmp(const char *a, const char *b)
+{
+ while (1) {
+ if (isdigit(*a) && isdigit(*b)) {
+ long int na, nb;
+ na = strtol(a, (char **)&a, 10);
+ nb = strtol(b, (char **)&b, 10);
+ if (na != nb)
+ return na - nb;
+ /* strtol advanced our pointers */
+ }
+ else {
+ if (*a != *b)
+ return *a - *b;
+ a++;
+ b++;
+ }
+ }
+}
+
static int split_maildir(const char *maildir, const char *dir,
int nr_prec, int skip)
{
@@ -139,6 +159,8 @@ static int split_maildir(const char *maildir, const char *dir,
int i;
struct string_list list = STRING_LIST_INIT_DUP;
+ list.cmp = maildir_filename_cmp;
+
if (populate_maildir_list(&list, maildir) < 0)
goto out;
--
1.8.1.39.gbb3bf60
William Giokas
