[Qemu-devel] [PATCH] exec-migration: handle EINTR in popen_get_buffer()

[Uri Lublin <uril@redhat.com>]

Sometimes, upon interrupt, fread returns with no data, and
the (incoming exec) migration fails.

Fix by retrying on such a case.

Signed-off-by: Uri Lublin <uril@redhat.com>
---
 savevm.c |    9 ++++++++-
 1 files changed, 8 insertions(+), 1 deletions(-)

diff --git a/savevm.c b/savevm.c
index 248aea3..df2486d 100644
--- a/savevm.c
+++ b/savevm.c
@@ -215,7 +215,14 @@ static int popen_put_buffer(void *opaque, const uint8_t *buf, int64_t pos, int s
 static int popen_get_buffer(void *opaque, uint8_t *buf, int64_t pos, int size)
 {
     QEMUFilePopen *s = opaque;
-    return fread(buf, 1, size, s->popen_file);
+    FILE *fp = s->popen_file;
+    int bytes;
+
+    do {
+        clearerr(fp);
+        bytes = fread(buf, 1, size, fp);
+    } while ((bytes == 0) && ferror(fp) && (errno == EINTR));
+    return bytes;
 }

 static int popen_close(void *opaque)
-- 
1.6.2.2