[Libguestfs] [PATCH nbdkit v2 6/9] retry-request: Allow get_size operation to be retried

[Richard W.M. Jones]

This plugin operation might need to do some real work (instead of just
fetching a number from memory), and so it might have to be retried.

In particular, changes to the curl plugin make .get_size into a
heavyweight operation, where previously it was done as a side-effect
of .open.  And so we must allow .get_size to be retried independent of
.open.
---
 filters/retry-request/retry-request.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/filters/retry-request/retry-request.c b/filters/retry-request/retry-request.c
index e5b8344cd..8e3dd8246 100644
--- a/filters/retry-request/retry-request.c
+++ b/filters/retry-request/retry-request.c
@@ -141,6 +141,18 @@ retry_request_open (nbdkit_next_open *next, nbdkit_context *nxdata,
   return r == 0 ? NBDKIT_HANDLE_NOT_NEEDED : NULL;
 }
 
+static int64_t
+retry_request_get_size (nbdkit_next *next, void *handle)
+{
+  int64_t r;
+  int *err = &errno;          /* used by the RETRY_* macros */
+
+  RETRY_START("get_size")
+    r = next->get_size (next);
+  RETRY_END;
+  return r;
+}
+
 static int
 retry_request_pread (nbdkit_next *next,
                      void *handle, void *buf, uint32_t count, uint64_t offset,
@@ -267,6 +279,7 @@ static struct nbdkit_filter filter = {
   .config            = retry_request_config,
   .config_help       = retry_request_config_help,
   .open              = retry_request_open,
+  .get_size          = retry_request_get_size,
   .pread             = retry_request_pread,
   .pwrite            = retry_request_pwrite,
   .trim              = retry_request_trim,
-- 
2.41.0