Update __stdout_write to allow flushing on stdout

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@uliege.be>
Reviewed-by: Simon Kuenzer <simon.kuenzer@neclab.eu>

diff --git a/patches/0009-update__stdout_write_for_flushing.patch b/patches/0009-update__stdout_write_for_flushing.patch
new file mode 100644 (file)
index 0000000..bda423f
--- /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@uliege.be>
+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@uliege.be>
+---
+ 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
+