* [PATCH] Clear fd after closing to avoid double-close error
@ 2013-10-22 12:10 Jens Lindström
2013-10-22 12:39 ` Duy Nguyen
0 siblings, 1 reply; 6+ messages in thread
From: Jens Lindström @ 2013-10-22 12:10 UTC (permalink / raw)
To: git; +Cc: Duy Nguyen
From: Jens Lindstrom <jl@opera.com>
In send_pack(), clear the fd passed to pack_objects() by setting
it to -1, since pack_objects() closes the fd (via a call to
run_command()).
Not doing so risks having git_transport_push(), caller of
send_pack(), closing the fd again, possibly incorrectly closing
some other open file.
Signed-off-by: Jens Lindström <jl@opera.com>
---
send-pack.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/send-pack.c b/send-pack.c
index 7d172ef..7def2af 100644
--- a/send-pack.c
+++ b/send-pack.c
@@ -302,6 +302,9 @@ int send_pack(struct send_pack_args *args,
finish_async(&demux);
return -1;
}
+ if (!args->stateless_rpc)
+ /* Closed by pack_objects() via start_command() */
+ fd[1] = -1;
}
if (args->stateless_rpc && cmds_sent)
packet_flush(out);
--
1.8.1.2
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH] Clear fd after closing to avoid double-close error
2013-10-22 12:10 [PATCH] Clear fd after closing to avoid double-close error Jens Lindström
@ 2013-10-22 12:39 ` Duy Nguyen
2013-10-22 13:15 ` Jens Lindström
2013-10-22 18:42 ` Junio C Hamano
0 siblings, 2 replies; 6+ messages in thread
From: Duy Nguyen @ 2013-10-22 12:39 UTC (permalink / raw)
To: Jens Lindström; +Cc: Git Mailing List
On Tue, Oct 22, 2013 at 7:10 PM, Jens Lindström <jl@opera.com> wrote:
> From: Jens Lindstrom <jl@opera.com>
>
> In send_pack(), clear the fd passed to pack_objects() by setting
> it to -1, since pack_objects() closes the fd (via a call to
> run_command()).
>
> Not doing so risks having git_transport_push(), caller of
> send_pack(), closing the fd again, possibly incorrectly closing
> some other open file.
Not your itch. But if you have time you may want to fix fetch-pack
too. It has the same problem. fetch-pack.c:get_pack() with
use_sideband == 0 passes fd[0] to start_command(), then later its
caller transport.c:fetch_refs_via_pack() closes the handle again.
> Signed-off-by: Jens Lindström <jl@opera.com>
> ---
> send-pack.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/send-pack.c b/send-pack.c
> index 7d172ef..7def2af 100644
> --- a/send-pack.c
> +++ b/send-pack.c
> @@ -302,6 +302,9 @@ int send_pack(struct send_pack_args *args,
> finish_async(&demux);
> return -1;
In this code block, there is "close(out);", we may need to set fd[1] = -1 too.
> }
> + if (!args->stateless_rpc)
> + /* Closed by pack_objects() via start_command() */
> + fd[1] = -1;
> }
> if (args->stateless_rpc && cmds_sent)
> packet_flush(out);
I was puzzled by this packet_flush(out) for a while because I thought
"out" was already closed. Turns out when stateless_rpc is true, a new
pipe is created in pack_objects() and "out" is not closed. So
everything is still good (and messy).
Life would have been simpler if fd[1] was _always_ closed by
send_pack(), like in c20181e (start_command(), if .in/.out > 0, closes
file descriptors, not the callers - 2008-02-21).
--
Duy
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] Clear fd after closing to avoid double-close error
2013-10-22 12:39 ` Duy Nguyen
@ 2013-10-22 13:15 ` Jens Lindström
2013-10-22 18:42 ` Junio C Hamano
1 sibling, 0 replies; 6+ messages in thread
From: Jens Lindström @ 2013-10-22 13:15 UTC (permalink / raw)
To: Duy Nguyen; +Cc: Git Mailing List
On Tue, Oct 22, 2013 at 2:39 PM, Duy Nguyen <pclouds@gmail.com> wrote:
> Not your itch. But if you have time you may want to fix fetch-pack
> too. It has the same problem. fetch-pack.c:get_pack() with
> use_sideband == 0 passes fd[0] to start_command(), then later its
> caller transport.c:fetch_refs_via_pack() closes the handle again.
I'll update the patch to clear that fd as well.
>> Signed-off-by: Jens Lindström <jl@opera.com>
>> ---
>> send-pack.c | 3 +++
>> 1 file changed, 3 insertions(+)
>>
>> diff --git a/send-pack.c b/send-pack.c
>> index 7d172ef..7def2af 100644
>> --- a/send-pack.c
>> +++ b/send-pack.c
>> @@ -302,6 +302,9 @@ int send_pack(struct send_pack_args *args,
>> finish_async(&demux);
>> return -1;
>
> In this code block, there is "close(out);", we may need to set fd[1] = -1 too.
This block closes the fd unconditionally, I think. Either via
pack_objects() (if !args->stateless_rpc) or directly (otherwise.) So I
guess it should always clear the fd before returning to be safe.
>> }
>> + if (!args->stateless_rpc)
>> + /* Closed by pack_objects() via start_command() */
>> + fd[1] = -1;
>> }
>> if (args->stateless_rpc && cmds_sent)
>> packet_flush(out);
>
> I was puzzled by this packet_flush(out) for a while because I thought
> "out" was already closed. Turns out when stateless_rpc is true, a new
> pipe is created in pack_objects() and "out" is not closed. So
> everything is still good (and messy).
>
> Life would have been simpler if fd[1] was _always_ closed by
> send_pack(), like in c20181e (start_command(), if .in/.out > 0, closes
> file descriptors, not the callers - 2008-02-21).
It did strike me as a bit unclear who exactly "owned" these file
descriptors. But I'm of course wholly unfamiliar with this code.
/ Jens
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] Clear fd after closing to avoid double-close error
2013-10-22 12:39 ` Duy Nguyen
2013-10-22 13:15 ` Jens Lindström
@ 2013-10-22 18:42 ` Junio C Hamano
2013-10-23 7:52 ` Jens Lindström
1 sibling, 1 reply; 6+ messages in thread
From: Junio C Hamano @ 2013-10-22 18:42 UTC (permalink / raw)
To: Duy Nguyen; +Cc: Jens Lindström, Git Mailing List
Duy Nguyen <pclouds@gmail.com> writes:
> On Tue, Oct 22, 2013 at 7:10 PM, Jens Lindström <jl@opera.com> wrote:
> ...
>> + if (!args->stateless_rpc)
>> + /* Closed by pack_objects() via start_command() */
>> + fd[1] = -1;
>> }
> ...
> Life would have been simpler if fd[1] was _always_ closed by
> send_pack(), like in c20181e (start_command(), if .in/.out > 0, closes
> file descriptors, not the callers - 2008-02-21).
Yeah, that was also my first reaction when I saw the above three
lines after reading the discussion that led to the diagnosis.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] Clear fd after closing to avoid double-close error
2013-10-22 18:42 ` Junio C Hamano
@ 2013-10-23 7:52 ` Jens Lindström
2013-10-23 16:06 ` Junio C Hamano
0 siblings, 1 reply; 6+ messages in thread
From: Jens Lindström @ 2013-10-23 7:52 UTC (permalink / raw)
To: Junio C Hamano; +Cc: Duy Nguyen, Git Mailing List
On Tue, Oct 22, 2013 at 8:42 PM, Junio C Hamano <gitster@pobox.com> wrote:
> Duy Nguyen <pclouds@gmail.com> writes:
>> Life would have been simpler if fd[1] was _always_ closed by
>> send_pack(), like in c20181e (start_command(), if .in/.out > 0, closes
>> file descriptors, not the callers - 2008-02-21).
>
> Yeah, that was also my first reaction when I saw the above three
> lines after reading the discussion that led to the diagnosis.
If send_pack() always closes fd[1], then I believe "git send-pack
--stateless-rpc --helper-status" would die in print_helper_status(),
called after send_pack(), since fd[1] would be 1, to which
print_helper_status() will try to write. (I don't know what either
--stateless-rpc or --helper-status mean, other than what's obvious
from the code, or if the combination of them makes any sense.)
I don't really have any more time to spend on this issue, so if a more
thorough fix is required, I'm afraid someone else will have to work on
it.
/ Jens
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] Clear fd after closing to avoid double-close error
2013-10-23 7:52 ` Jens Lindström
@ 2013-10-23 16:06 ` Junio C Hamano
0 siblings, 0 replies; 6+ messages in thread
From: Junio C Hamano @ 2013-10-23 16:06 UTC (permalink / raw)
To: Jens Lindström; +Cc: Duy Nguyen, Git Mailing List
Jens Lindström <jl@opera.com> writes:
> On Tue, Oct 22, 2013 at 8:42 PM, Junio C Hamano <gitster@pobox.com> wrote:
>> Duy Nguyen <pclouds@gmail.com> writes:
>
>>> Life would have been simpler if fd[1] was _always_ closed by
>>> send_pack(), like in c20181e (start_command(), if .in/.out > 0, closes
>>> file descriptors, not the callers - 2008-02-21).
>>
>> Yeah, that was also my first reaction when I saw the above three
>> lines after reading the discussion that led to the diagnosis.
>
> If send_pack() always closes fd[1], then I believe "git send-pack
> --stateless-rpc --helper-status" would die in print_helper_status(),
> called after send_pack(), since fd[1] would be 1, to which
> print_helper_status() will try to write.
Ah, I obviously did not look far enough. Of course we could dup(2)
the fd=1 to code it around, but it is not clear to me if it is worth
it---your solution (v2) is clearer, so let's queue it with Acks we
saw from Peff and Duy.
Thanks.
^ permalink raw reply [flat|nested] 6+ messages in thread
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2013-10-22 12:10 [PATCH] Clear fd after closing to avoid double-close error Jens Lindström
2013-10-22 12:39 ` Duy Nguyen
2013-10-22 13:15 ` Jens Lindström
2013-10-22 18:42 ` Junio C Hamano
2013-10-23 7:52 ` Jens Lindström
2013-10-23 16:06 ` Junio C Hamano
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