Flush existing debug messages before writing an error to stderr.  stderr
is usually unbuffered and stdout is usually buffered. This results in
odd looking output when an error occurs and both stderr/stdout are
printed on the same console/file. More precisely, the error message is
printed in the middle of previously emitted debug messages.

Signed-off-by: Michael Kurth <mku@amazon.com>
---
 common.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/common.h b/common.h
index 02c9b7b..9a9da79 100644
--- a/common.h
+++ b/common.h
@@ -10,6 +10,7 @@ extern char *childobj;
 
 #define DIFF_FATAL(format, ...) \
 ({ \
+	fflush(stdout); \
 	fprintf(stderr, "ERROR: %s: " format "\n", childobj, ##__VA_ARGS__); \
 	error(2, 0, "unreconcilable difference"); \
 })
-- 
2.38.1




Amazon Development Center Germany GmbH
Krausenstr. 38
10117 Berlin
Geschaeftsfuehrung: Christian Schlaeger, Jonathan Weiss
Eingetragen am Amtsgericht Charlottenburg unter HRB 149173 B
Sitz: Berlin
Ust-ID: DE 289 237 879

> From: Xen-devel <xen-devel-bounces@lists.xenproject.org> on behalf of Mihails Strasuns <mstrasun@amazon.com>
> Sent: Thursday, January 19, 2023 10:13 AM
> To: xen-devel@lists.xenproject.org <xen-devel@lists.xenproject.org>
> Cc: mstrasun@amazon.com <mstrasun@amazon.com>; Michael Kurth <mku@amazon.com>
> Subject: [PATCH v1 1/4] common.h: Flush stdout before writing to stderr 
>  
> Flush existing debug messages before writing an error to stderr.  stderr
> is usually unbuffered and stdout is usually buffered. This results in
> odd looking output when an error occurs and both stderr/stdout are
> printed on the same console/file. More precisely, the error message is
> printed in the middle of previously emitted debug messages.
> 
> Signed-off-by: Michael Kurth <mku@amazon.com>
> ---
>  common.h | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/common.h b/common.h
> index 02c9b7b..9a9da79 100644
> --- a/common.h
> +++ b/common.h
> @@ -10,6 +10,7 @@ extern char *childobj;
>  
>  #define DIFF_FATAL(format, ...) \
>  ({ \
> +       fflush(stdout); \
>          fprintf(stderr, "ERROR: %s: " format "\n", childobj, ##__VA_ARGS__); \
>          error(2, 0, "unreconcilable difference"); \
>  })
> -- 
> 2.38.1

Reviewed-by: Ross Lagerwall <ross.lagerwall@citrix.com>