From 4fb0f88d53fc60395a4a87b7a9ca1245ba033ee7 Mon Sep 17 00:00:00 2001
From: Ian Jackson <ijackson@chiark.greenend.org.uk>
Date: Mon, 22 Sep 2014 15:51:30 +0100
Subject: [PATCH] fds: Provide cloexec() and use it in udp.c and tun.c

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>
---
 secnet.h | 4 ++++
 tun.c    | 4 ++++
 udp.c    | 5 +----
 util.c   | 7 +++++++
 4 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/secnet.h b/secnet.h
index 194341c..ce01d24 100644
--- a/secnet.h
+++ b/secnet.h
@@ -9,6 +9,8 @@
 #include <stdio.h>
 #include <string.h>
 #include <assert.h>
+#include <fcntl.h>
+#include <unistd.h>
 #include <sys/poll.h>
 #include <sys/types.h>
 #include <sys/time.h>
@@ -136,6 +138,8 @@ extern char *safe_strdup(const char *string, const char *message);
 extern void *safe_malloc(size_t size, const char *message);
 extern void *safe_malloc_ary(size_t size, size_t count, const char *message);
 
+void setcloexec(int fd); /* cannot fail */
+
 extern int sys_cmd(const char *file, const char *argc, ...);
 
 extern uint64_t now_global;
diff --git a/tun.c b/tun.c
index d4070f2..ffc195c 100644
--- a/tun.c
+++ b/tun.c
@@ -340,6 +340,8 @@ static void tun_phase_hook(void *sst, uint32_t newphase)
 	st->interface_name=safe_malloc(10,"tun_apply");
 	sprintf(st->interface_name,"tun%d",ppa);
 	st->fd=tun_fd;
+	setcloexec(if_ifd);
+	setcloexec(ip_ifd);
 #else
 	fatal("tun_phase_hook: TUN_FLAVOUR_STREAMS unexpected");
 #endif /* HAVE_TUN_STREAMS */
@@ -350,6 +352,8 @@ static void tun_phase_hook(void *sst, uint32_t newphase)
        to set the TUN device's address, and route to add routes to all
        our networks. */
 
+    setcloexec(st->fd);
+
     hostaddr=ipaddr_to_string(st->nl.local_address);
     secnetaddr=ipaddr_to_string(st->nl.secnet_address);
     snprintf(mtu,sizeof(mtu),"%d",st->nl.mtu);
diff --git a/udp.c b/udp.c
index 552a58e..bb82026 100644
--- a/udp.c
+++ b/udp.c
@@ -224,10 +224,7 @@ static void udp_phase_hook(void *sst, uint32_t new_phase)
 	fatal_perror("udp (%s:%d): fcntl(set O_NONBLOCK)",
 		     st->loc.file,st->loc.line);
     }
-    if (fcntl(st->fd, F_SETFD, FD_CLOEXEC)==-1) {
-	fatal_perror("udp (%s:%d): fcntl(set FD_CLOEXEC)",
-		     st->loc.file,st->loc.line);
-    }
+    setcloexec(st->fd);
 
     FILLZERO(addr);
     addr.sin_family=AF_INET;
diff --git a/util.c b/util.c
index 094870f..fc6f626 100644
--- a/util.c
+++ b/util.c
@@ -162,6 +162,13 @@ int32_t write_mpbin(MP_INT *a, uint8_t *buffer, int32_t buflen)
     return i;
 }
 
+void setcloexec(int fd) {
+    int r=fcntl(fd, F_GETFD);
+    if (r<0) fatal_perror("fcntl(,F_GETFD) failed");
+    r=fcntl(fd, F_SETFD, r|FD_CLOEXEC);
+    if (r<0) fatal_perror("fcntl(,F_SETFD,|FD_CLOEXEC) failed");
+}
+
 static const char *phases[NR_PHASES]={
     "PHASE_INIT",
     "PHASE_GETOPTS",
-- 
2.30.2