[Xen-devel] [PATCH] libxl_qmp: Handle unexpected end-of-socket

[Anthony PERARD <anthony.perard@xxxxxxxxxx>]

When read() return 0, the current code just tries again. But this leads to an
infinite loop if QEMU died too soon.

Also, retry select if a signal was caught.

Signed-off-by: Anthony PERARD <anthony.perard@xxxxxxxxxx>

---
 tools/libxl/libxl_qmp.c |    6 +++++-
 1 files changed, 5 insertions(+), 1 deletions(-)

diff --git a/tools/libxl/libxl_qmp.c b/tools/libxl/libxl_qmp.c
index 1777e44..d3b1d53 100644
--- a/tools/libxl/libxl_qmp.c
+++ b/tools/libxl/libxl_qmp.c
@@ -385,18 +385,22 @@ static int qmp_next(libxl__gc *gc, libxl__qmp_handler 
*qmp)
         FD_ZERO(&rfds);
         FD_SET(qmp->qmp_fd, &rfds);
 
+do_select_again:
         ret = select(qmp->qmp_fd + 1, &rfds, NULL, NULL, &timeout);
         if (ret == 0) {
             LIBXL__LOG(qmp->ctx, LIBXL__LOG_ERROR, "timeout");
             return -1;
         } else if (ret < 0) {
+            if (errno == EINTR)
+                goto do_select_again;
             LIBXL__LOG_ERRNO(qmp->ctx, LIBXL__LOG_ERROR, "Select error");
             return -1;
         }
 
         rd = read(qmp->qmp_fd, qmp->buffer, QMP_RECEIVE_BUFFER_SIZE);
         if (rd == 0) {
-            continue;
+            LIBXL__LOG(qmp->ctx, LIBXL__LOG_ERROR, "Unexpected end of socket");
+            return -1;
         } else if (rd < 0) {
             LIBXL__LOG_ERRNO(qmp->ctx, LIBXL__LOG_ERROR, "Socket read error");
             return rd;
-- 
tg: (6674c38..) fix/qmp-end-of-socket (depends on: master)

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