* [PATCH ucspi-vsock] vsockserver: use fclose instead of close
@ 2021-03-09 15:40 Alyssa Ross
2021-03-10 17:41 ` Cole Helbling
0 siblings, 1 reply; 3+ messages in thread
From: Alyssa Ross @ 2021-03-09 15:40 UTC (permalink / raw)
To: devel
stdio can buffer output, so if we close stdout without going through
stdio, there might be buffered output that is never written.
---
vsockserver.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/vsockserver.c b/vsockserver.c
index dd9a74a..196056a 100644
--- a/vsockserver.c
+++ b/vsockserver.c
@@ -90,7 +90,7 @@ int main(int argc, char *argv[])
if (notify) {
printf("%" PRIu32 "\n", lport);
- close(STDOUT_FILENO);
+ fclose(stdout);
}
setenvf("VSOCKLOCALCID", 1, "%" PRIu32, lcid);
--
2.30.0
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH ucspi-vsock] vsockserver: use fclose instead of close
2021-03-09 15:40 [PATCH ucspi-vsock] vsockserver: use fclose instead of close Alyssa Ross
@ 2021-03-10 17:41 ` Cole Helbling
2021-03-10 22:43 ` Alyssa Ross
0 siblings, 1 reply; 3+ messages in thread
From: Cole Helbling @ 2021-03-10 17:41 UTC (permalink / raw)
To: Alyssa Ross, devel
On Tue Mar 9, 2021 at 7:40 AM PST, Alyssa Ross wrote:
> stdio can buffer output, so if we close stdout without going through
> stdio, there might be buffered output that is never written.
> ---
> vsockserver.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/vsockserver.c b/vsockserver.c
> index dd9a74a..196056a 100644
> --- a/vsockserver.c
> +++ b/vsockserver.c
> @@ -90,7 +90,7 @@ int main(int argc, char *argv[])
>
> if (notify) {
> printf("%" PRIu32 "\n", lport);
> - close(STDOUT_FILENO);
> + fclose(stdout);
> }
>
> setenvf("VSOCKLOCALCID", 1, "%" PRIu32, lcid);
> --
> 2.30.0
I don't write much (if any) C, so I never knew there was both
STDOUT_FILENO (as an int) _and_ stdout (as a FILE*). I suppose the most
important part is that fclose() uses fflush(3) under the hood to make
sure we actually write everything.
Reviewed-by: Cole Helbling <cole.e.helbling@outlook.com>
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH ucspi-vsock] vsockserver: use fclose instead of close
2021-03-10 17:41 ` Cole Helbling
@ 2021-03-10 22:43 ` Alyssa Ross
0 siblings, 0 replies; 3+ messages in thread
From: Alyssa Ross @ 2021-03-10 22:43 UTC (permalink / raw)
To: Cole Helbling; +Cc: devel
[-- Attachment #1: Type: text/plain, Size: 1309 bytes --]
On Wed, Mar 10, 2021 at 09:41:01AM -0800, Cole Helbling wrote:
> On Tue Mar 9, 2021 at 7:40 AM PST, Alyssa Ross wrote:
> > stdio can buffer output, so if we close stdout without going through
> > stdio, there might be buffered output that is never written.
> > ---
> > vsockserver.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/vsockserver.c b/vsockserver.c
> > index dd9a74a..196056a 100644
> > --- a/vsockserver.c
> > +++ b/vsockserver.c
> > @@ -90,7 +90,7 @@ int main(int argc, char *argv[])
> >
> > if (notify) {
> > printf("%" PRIu32 "\n", lport);
> > - close(STDOUT_FILENO);
> > + fclose(stdout);
> > }
> >
> > setenvf("VSOCKLOCALCID", 1, "%" PRIu32, lcid);
> > --
> > 2.30.0
>
> I don't write much (if any) C, so I never knew there was both
> STDOUT_FILENO (as an int) _and_ stdout (as a FILE*). I suppose the most
> important part is that fclose() uses fflush(3) under the hood to make
> sure we actually write everything.
Yeah, C on UNIX essentially gives you two different IO interfaces
(open/write/close/etc. from POSIX, and fopen/fprintf/fclose/etc. from
stdio in the C standard library). The POSIX stuff doesn't know
anything about the buffering that stdio does on top of it. Mixing them
is probably never a good idea if you're not doing it very deliberately.
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^ permalink raw reply [flat|nested] 3+ messages in thread
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2021-03-09 15:40 [PATCH ucspi-vsock] vsockserver: use fclose instead of close Alyssa Ross
2021-03-10 17:41 ` Cole Helbling
2021-03-10 22:43 ` Alyssa Ross
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