[PATCH] Before clearing the capability bounding set, check if we have the cap

From: Harald Hoyer <harald@...>

PR_CAPBSET_DROP can return EINVAL, if an older kernel does support
some capabilities, which are defined by CAP_LAST_CAP, which results in
a failure of the service.

For example kernel 3.4 errors on CAP_EPOLLWAKEUP, which was newly
introduced in 3.5.

So, for future capabilities, we clear until we get an EINVAL for
PR_CAPBSET_READ.
---
 support/nsm/file.c      |    2 +-
 utils/nfsdcld/nfsdcld.c |    4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/support/nsm/file.c b/support/nsm/file.c
index 5476446..4711c2c 100644
--- a/support/nsm/file.c
+++ b/support/nsm/file.c
 <at>  <at>  -386,7 +386,7  <at>  <at>  prune_bounding_set(void)
 	}

 	/* prune the bounding set to nothing */
-	for (i = 0; i <= CAP_LAST_CAP; ++i) {
+	for (i = 0; prctl(PR_CAPBSET_READ, i, 0, 0, 0) >=0 ; ++i) {
 		ret = prctl(PR_CAPBSET_DROP, i, 0, 0, 0);
 		if (ret) {
 			xlog(L_ERROR, "Unable to prune capability %lu from "
diff --git a/utils/nfsdcld/nfsdcld.c b/utils/nfsdcld/nfsdcld.c