Implemtn getdtablecount() to count open file descriptors for current process.

Use underlying sysctl implemented by mjg in r290473.

PR:                    194985
Reviewed by:           bapt, mjg
Differential Revision: https://reviews.freebsd.org/D4084

1 files changed, 58 insertions, 0 deletions

diff --git a/lib/libopenbsd/getdtablecount.c b/lib/libopenbsd/getdtablecount.c
new file mode 100644
index 0000000..9d2ba25
--- /dev/null
+++ b/lib/libopenbsd/getdtablecount.c
@@ -0,0 +1,58 @@
+/*-
+ * Copyright (c) 2015 Craig Rodrigues
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/types.h>
+#include <sys/sysctl.h>
+#include <stddef.h>
+
+int getdtablecount(void);
+
+/* 
+ * Return the count of open file descriptors for this process.
+ *
+ */
+int
+getdtablecount(void)
+{
+	int mib[4];
+	int error;
+	int nfds;
+	size_t len;
+
+	len = sizeof(nfds);
+	mib[0] = CTL_KERN;
+	mib[1] = KERN_PROC;
+	mib[2] = KERN_PROC_NFDS;
+	mib[3] = 0;
+
+	error = sysctl(mib, 4, &nfds, &len, NULL, 0);
+	if (error)
+		return (-1);
+	return (nfds);
+}