test-helpers: use sysctl() to count open fds on FreeBSD

This allows running the tests on FreeBSD without mounting fdescfs.
Previously you had to run `mount -t fdescfs -o linrdlnk null /dev/fd` to
get file descriptors >=3 listed in /dev/fd.

Signed-off-by: Alex Richardson <Alexander.Richardson@cl.cam.ac.uk>

1 files changed, 22 insertions, 0 deletions

diff --git a/tests/test-helpers.c b/tests/test-helpers.c
index 4cdd1fc..3535744 100644
--- a/tests/test-helpers.c
+++ b/tests/test-helpers.c
@@ -41,6 +41,27 @@
 
 #include "test-runner.h"
 
+#if defined(__FreeBSD__)
+#include <sys/sysctl.h>
+
+/*
+ * On FreeBSD, get file descriptor information using sysctl() since that does
+ * not depend on a mounted fdescfs (which provides /dev/fd/N for N > 2).
+ */
+int
+count_open_fds(void)
+{
+	int error;
+	int nfds;
+	int mib[4] = {CTL_KERN, KERN_PROC, KERN_PROC_NFDS, 0 };
+	size_t len;
+
+	len = sizeof(nfds);
+	error = sysctl(mib, 4, &nfds, &len, NULL, 0);
+	assert(error == 0 && "sysctl KERN_PROC_NFDS failed.");
+	return nfds;
+}
+#else
 int
 count_open_fds(void)
 {
@@ -68,6 +89,7 @@ count_open_fds(void)
 
 	return count;
 }
+#endif
 
 void
 exec_fd_leak_check(int nr_expected_fds)