[Xen-devel] [PATCH v1 2/7] tools/livepatch: Set stdout and stderr unbuffered

[Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>]

Using both stdout and stderr interleaved without newlines can result in
strange output when using line buffered mode (e.g. a terminal) or when
fully buffered (e.g. redirected to a file). Set both to unbuffered mode
to fix this.

Signed-off-by: Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>
---
 tools/misc/xen-livepatch.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/tools/misc/xen-livepatch.c b/tools/misc/xen-livepatch.c
index f6c7c8a..2f6721b 100644
--- a/tools/misc/xen-livepatch.c
+++ b/tools/misc/xen-livepatch.c
@@ -330,7 +330,6 @@ int action_func(int argc, char *argv[], unsigned int idx)
         }
 
         printf(".");
-        fflush(stdout);
         usleep(DELAY);
     } while ( ++retry < RETRIES );
 
@@ -416,6 +415,13 @@ int main(int argc, char *argv[])
 {
     int i, j = 0, ret;
 
+    /*
+     * Set stdout and stderr to be unbuffered to avoid having to fflush
+     * when printing without a newline.
+     */
+    setvbuf(stdout, NULL, _IONBF, 0);
+    setvbuf(stderr, NULL, _IONBF, 0);
+
     if ( argc  <= 1 )
     {
         show_help();
-- 
2.7.4


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