From 2d7f81b809ec469b82ac724c31e5c1cc4f444b9b Mon Sep 17 00:00:00 2001
From: Willy Tarreau <w@1wt.eu>
Date: Thu, 21 Feb 2019 22:19:17 +0100
Subject: [PATCH] MINOR: fd: add a new my_closefrom() function to close all FDs

This is a naive implementation of closefrom() which closes all FDs
starting from the one passed in argument. closefrom() is not provided
on all operating systems, and other versions will follow.
---
 include/proto/fd.h |  3 +++
 src/fd.c           | 22 ++++++++++++++++++++++
 2 files changed, 25 insertions(+)

diff --git a/include/proto/fd.h b/include/proto/fd.h
index 81aea87bc..14c22201c 100644
--- a/include/proto/fd.h
+++ b/include/proto/fd.h
@@ -61,6 +61,9 @@ void fd_delete(int fd);
  */
 void fd_remove(int fd);
 
+/* close all FDs starting from <start> */
+void my_closefrom(int start);
+
 /* disable the specified poller */
 void disable_poller(const char *poller_name);
 
diff --git a/src/fd.c b/src/fd.c
index 9434c6300..92d093cb6 100644
--- a/src/fd.c
+++ b/src/fd.c
@@ -149,6 +149,7 @@
 #include <unistd.h>
 #include <fcntl.h>
 #include <sys/types.h>
+#include <sys/resource.h>
 
 #include <common/compat.h>
 #include <common/config.h>
@@ -460,6 +461,27 @@ void fd_process_cached_events()
 	fdlist_process_cached_events(&fd_cache);
 }
 
+/* This is a portable implementation of closefrom(). It closes all open file
+ * descriptors starting at <start> and above. This is a naive version for use
+ * when the operating system provides no alternative.
+ */
+void my_closefrom(int start)
+{
+	struct rlimit limit;
+	int nbfds;
+
+	if (getrlimit(RLIMIT_NOFILE, &limit) == 0)
+		nbfds = limit.rlim_cur;
+	else
+		nbfds = 0;
+
+	if (nbfds <= 0)
+		nbfds = 1024; /* safe limit */
+
+	while (start < nbfds)
+		close(start++);
+}
+
 /* disable the specified poller */
 void disable_poller(const char *poller_name)
 {