Re: cat-file timing window on Cygwin

On Sat, Aug 26, 2017 at 11:53:37AM -0700, Jeff King wrote:

On Sat, Aug 26, 2017 at 01:57:18AM +0100, Ramsay Jones wrote:

quoted

quoted

diff --git a/run-command.c b/run-command.c
index 98621faca8..064ebd1995 100644
--- a/run-command.c
+++ b/run-command.c

@@ -641,7 +641,6 @@ int start_command(struct child_process *cmd)
 	}
 
 	trace_argv_printf(cmd->argv, "trace: run_command:");
-	fflush(NULL);
 
 #ifndef GIT_WINDOWS_NATIVE
 {

I suspect not, but I can give it a try ...

... oh, wow, that works! Ahem. (Hmm, so it's flushing stdin?!)

Interesting. I find it a little hard to believe there's so obvious a bug
as "fflush(NULL) flushes stdin", but well...that's what it seems like.

If that's truly what it is, this is the minimal reproduction I came up
with:

-- >8 --
#include <stdio.h>

int main(void)
{
	char buf[256];
	while (fgets(buf, sizeof(buf), stdin)) {
		fprintf(stdout, "got: %s", buf);
		fflush(NULL);
	}
	return 0;
}
-- 8< --

If this really is the bug, then doing something like "seq 10 | ./a.out"
would drop some of the input lines.

...yep.  It does.  Specifically, I consistently only get the firsts
line:

    $ seq 10 | ./a.exe
    got: 1
    
    $ 

If I introduce a delay between the lines of stdin (which I tested by
just typing stdin from the keyboard), it works as expected.

Looks like this one will need to go to the Cygwin mailing list; I'll
take it there shortly.  Thank you all for your help getting this far!