ps | cat broken in newlib-cygwin git head (master)

ps | cat broken in newlib-cygwin git head (master)

[Takashi Yano]

I found that "ps | cat" outputs nothing with the current git head (master)
of newlib-cygwin. However, just "ps" and "ls | cat" works.

This happens after the commit:

commit 26747c47bc0a1137e02e0377306d721cc3478855
Author: Matt Joyce <matthew.joyce@embedded-brains.de>
Date:   Tue May 3 06:51:22 2022 +0200

    Add stdio_exit_handler()

    Add a dedicated stdio exit handler to avoid using _GLOBAL_REENT in exit().


Is this the problem of cygwin side? Or newlib?

I also found "stdbuf -o 0 ps | cat" works. It seems that this problem is
caused by buffering of stdout.

-- 
Takashi Yano <takashi.yano@nifty.ne.jp>

Re: ps | cat broken in newlib-cygwin git head (master)

[Takashi Yano]

On Tue, 17 May 2022 04:37:12 +0900
Takashi Yano wrote:
> I found that "ps | cat" outputs nothing with the current git head (master)
> of newlib-cygwin. However, just "ps" and "ls | cat" works.
> 
> This happens after the commit:
> 
> commit 26747c47bc0a1137e02e0377306d721cc3478855
> Author: Matt Joyce <matthew.joyce@embedded-brains.de>
> Date:   Tue May 3 06:51:22 2022 +0200
> 
>     Add stdio_exit_handler()
> 
>     Add a dedicated stdio exit handler to avoid using _GLOBAL_REENT in exit().
> 
> 
> Is this the problem of cygwin side? Or newlib?
> 
> I also found "stdbuf -o 0 ps | cat" works. It seems that this problem is
> caused by buffering of stdout.

I am not sure this is the right thing, however, I found the following
patch solves the issue. It seems that initializing __stdio_exit_handler
is missing.

diff --git a/newlib/libc/stdio/findfp.c b/newlib/libc/stdio/findfp.c
index 19952d4e0..e759b5402 100644
--- a/newlib/libc/stdio/findfp.c
+++ b/newlib/libc/stdio/findfp.c
@@ -63,6 +63,8 @@ struct _glue __sglue = {NULL, 3, &_GLOBAL_REENT->__sf[0]};
 #endif
 #endif
 
+static void stdio_exit_handler (void);
+
 #if (defined (__OPTIMIZE_SIZE__) || defined (PREFER_SIZE_OVER_SPEED))
 _NOINLINE_STATIC void
 #else
@@ -109,6 +111,11 @@ std (FILE *ptr,
   if (__stextmode (ptr->_file))
     ptr->_flags |= __SCLE;
 #endif
+
+  if (__stdio_exit_handler == NULL) {
+    __sinit (_GLOBAL_REENT);
+    __stdio_exit_handler = stdio_exit_handler;
+  }
 }
 
 static inline void

-- 
Takashi Yano <takashi.yano@nifty.ne.jp>

Re: ps | cat broken in newlib-cygwin git head (master)

[Corinna Vinschen]

Hi Takashi,

please send this to the newlib ML, ideally as a reply to the patch or
patchset, CCing Matt and Sebastian.


Thanks,
Corinna

On May 17 12:17, Takashi Yano wrote:
> On Tue, 17 May 2022 04:37:12 +0900
> Takashi Yano wrote:
> > I found that "ps | cat" outputs nothing with the current git head (master)
> > of newlib-cygwin. However, just "ps" and "ls | cat" works.
> > 
> > This happens after the commit:
> > 
> > commit 26747c47bc0a1137e02e0377306d721cc3478855
> > Author: Matt Joyce <matthew.joyce@embedded-brains.de>
> > Date:   Tue May 3 06:51:22 2022 +0200
> > 
> >     Add stdio_exit_handler()
> > 
> >     Add a dedicated stdio exit handler to avoid using _GLOBAL_REENT in exit().
> > 
> > 
> > Is this the problem of cygwin side? Or newlib?
> > 
> > I also found "stdbuf -o 0 ps | cat" works. It seems that this problem is
> > caused by buffering of stdout.
> 
> I am not sure this is the right thing, however, I found the following
> patch solves the issue. It seems that initializing __stdio_exit_handler
> is missing.
> 
> diff --git a/newlib/libc/stdio/findfp.c b/newlib/libc/stdio/findfp.c
> index 19952d4e0..e759b5402 100644
> --- a/newlib/libc/stdio/findfp.c
> +++ b/newlib/libc/stdio/findfp.c
> @@ -63,6 +63,8 @@ struct _glue __sglue = {NULL, 3, &_GLOBAL_REENT->__sf[0]};
>  #endif
>  #endif
>  
> +static void stdio_exit_handler (void);
> +
>  #if (defined (__OPTIMIZE_SIZE__) || defined (PREFER_SIZE_OVER_SPEED))
>  _NOINLINE_STATIC void
>  #else
> @@ -109,6 +111,11 @@ std (FILE *ptr,
>    if (__stextmode (ptr->_file))
>      ptr->_flags |= __SCLE;
>  #endif
> +
> +  if (__stdio_exit_handler == NULL) {
> +    __sinit (_GLOBAL_REENT);
> +    __stdio_exit_handler = stdio_exit_handler;
> +  }
>  }
>  
>  static inline void
> 
> -- 
> Takashi Yano <takashi.yano@nifty.ne.jp>
> 
> -- 
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