Refactor the way we do the psx linkage in libcap.

Since we now have a serialized (linker trick) to initialize libcap
we can reliably compute the number of capabilities of the running
kernel in a race free way. Export the found number of capabilities
with the cap_max_bits() function. This is also what we now use in
both C and Go to define [all]=[eip]. In Go the equivalent function
is cap.MaxBits().

Signed-off-by: Andrew G. Morgan <morgan@kernel.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/pam_cap/pam_cap.c b/pam_cap/pam_cap.c
index d4c1e65..a800f58 100644
--- a/pam_cap/pam_cap.c
+++ b/pam_cap/pam_cap.c
@@ -242,6 +242,10 @@ static int set_capabilities(struct pam_cap_s *cs)
 	while (cap_get_bound(max_caps) >= 0) {
 	    max_caps++;
 	}
+	if (max_caps != cap_max_bits()) {
+	    D(("this vintage of libcap cannot be trusted; give up"));
+	    goto cleanup_caps;
+	}
 	has_bound = (max_caps != 0);
 	if (has_bound) {
 	    bound = calloc(max_caps, sizeof(int));