Re: [Minios-devel] [UNIKRAFT/MUSL PATCH V2 2/5] Update __stdout_write to allow flushing on stdout

[Simon Kuenzer <simon.kuenzer@xxxxxxxxx>]

Hi Gaulthier,

I think this is a reasonable solution to the problem. Hopefully, we can 
remove it when ioctl systemcall support is there. Do you know if stderr 
is handled separately and do we need a similar patch for it?
Thanks,

Simon

Reviewed-by: Simon Kuenzer <simon.kuenzer@xxxxxxxxx>

On 03.03.20 11:23, gaulthier.gain@xxxxxxxxx wrote:
> From: gaulthier gain <gaulthier.gain@xxxxxxxxx>
>
> This patch fixes the issue where printing on stdout does nothing
> since stdout was not flushed. In that case, we found that the problem
> was related to __stdout_write. Indeed f->lbf must be set to '\n' for
> line-buffered mode nevertheless, the condition "(!(f->flags & F_SVB)
> && __syscall(SYS_ioctl, f->fd, TIOCGWINSZ, &wsz))" fails on Unikraft.
> The variable f->lbf is thus reset to -1 which prevents a correct
> display on stdout. With this patch, we "force" f->lbf to be set in
> line-buffered mode.
>
> Signed-off-by: gaulthier gain <gaulthier.gain@xxxxxxxxx>
> ---
>   ...09-update__stdout_write_for_flushing.patch | 25 +++++++++++++++++++
>   1 file changed, 25 insertions(+)
>   create mode 100644 patches/0009-update__stdout_write_for_flushing.patch
>
> diff --git a/patches/0009-update__stdout_write_for_flushing.patch 
> b/patches/0009-update__stdout_write_for_flushing.patch
> new file mode 100644
> index 0000000..2653104
> --- /dev/null
> +++ b/patches/0009-update__stdout_write_for_flushing.patch
> @@ -0,0 +1,25 @@
> +From 235b3d8240fbc99782f2fb8449786f519fcb3bde Mon Sep 17 00:00:00 2001
> +From: gaulthier gain <gaulthier.gain@xxxxxxxxx>
> +Date: Fri, 28 Feb 2020 17:05:28 +0000
> +Subject: [UNIKRAFT/MUSL] Update __stdout_write to allow flushing on stdout
> +
> +Signed-off-by: gaulthier gain <gaulthier.gain@xxxxxxxxx>
> +---
> + src/stdio/__stdout_write.c | 2 +-
> + 1 file changed, 1 insertion(+), 1 deletion(-)
> +
> +diff --git a/src/stdio/__stdout_write.c b/src/stdio/__stdout_write.c
> +index dd1ec60..f9c9489 100644
> +--- a/src/stdio/__stdout_write.c
> ++++ b/src/stdio/__stdout_write.c
> +@@ -6,6 +6,6 @@ size_t __stdout_write(FILE *f, const unsigned char *buf, 
> size_t len)
> +       struct winsize wsz;
> +       f->write = __stdio_write;
> +       if (!(f->flags & F_SVB) && __syscall(SYS_ioctl, f->fd, TIOCGWINSZ, 
> &wsz))
> +-              f->lbf = -1;
> ++              f->lbf = '\n';
> +       return __stdio_write(f, buf, len);
> + }
> +--
> +2.17.1
> +
> --
> 2.17.1
>
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