lib: add and use set_cloexec()

watchquagga is already leaking an open file descriptor on its pid file
on fork+exec() invocations; next up is adding vtysh support with even
more fds.  Mark things CLOEXEC before going there.

Signed-off-by: David Lamparter <equinox@opensourcerouting.org>

lib/network.c

@@ -94,6 +94,20 @@ set_nonblocking(int fd)
   return 0;
 }
 
+int
+set_cloexec(int fd)
+{
+  int flags;
+  flags = fcntl(fd, F_GETFD, 0);
+  if (flags == -1)
+    return -1;
+
+  flags |= FD_CLOEXEC;
+  if (fcntl(fd, F_SETFD, flags) == -1)
+    return -1;
+  return 0;
+}
+
 float
 htonf (float host)
 {

lib/network.h

@@ -33,6 +33,8 @@ extern int writen (int, const u_char *, int);
    -1 on error. */
 extern int set_nonblocking(int fd);
 
+extern int set_cloexec(int fd);
+
 /* Does the I/O error indicate that the operation should be retried later? */
 #define ERRNO_IO_RETRY(EN) \
 	(((EN) == EAGAIN) || ((EN) == EWOULDBLOCK) || ((EN) == EINTR))

lib/pid_output.c

@@ -24,6 +24,7 @@
 #include <fcntl.h>
 #include <log.h>
 #include "version.h"
+#include "network.h"
 
 #define PIDFILE_MASK 0644
 #ifndef HAVE_FCNTL
@@ -84,6 +85,8 @@ pid_output (const char *path)
       umask(oldumask);
       memset (&lock, 0, sizeof(lock));
 
+      set_cloexec(fd);
+
       lock.l_type = F_WRLCK;
       lock.l_whence = SEEK_SET;
 

lib/vty.c

@@ -1841,6 +1841,7 @@ vty_accept (struct thread *thread)
       return -1;
     }
   set_nonblocking(vty_sock);
+  set_cloexec(vty_sock);
 
   sockunion2hostprefix (&su, &p);
 
@@ -1939,6 +1940,7 @@ vty_serv_sock_addrinfo (const char *hostname, unsigned short port)
       sockopt_v6only (ainfo->ai_family, sock);
       sockopt_reuseaddr (sock);
       sockopt_reuseport (sock);
+      set_cloexec (sock);
 
       ret = bind (sock, ainfo->ai_addr, ainfo->ai_addrlen);
       if (ret < 0)
@@ -2006,6 +2008,7 @@ vty_serv_sock_family (const char* addr, unsigned short port, int family)
   /* This is server, so reuse address. */
   sockopt_reuseaddr (accept_sock);
   sockopt_reuseport (accept_sock);
+  set_cloexec (accept_sock);
 
   /* Bind socket to universal address and given port. */
   ret = sockunion_bind (accept_sock, &su, port, naddr);
@@ -2068,6 +2071,8 @@ vty_serv_un (const char *path)
   len = sizeof (serv.sun_family) + strlen (serv.sun_path);
 #endif /* HAVE_STRUCT_SOCKADDR_UN_SUN_LEN */
 
+  set_cloexec (sock);
+
   ret = bind (sock, (struct sockaddr *) &serv, len);
   if (ret < 0)
     {
@@ -2135,6 +2140,7 @@ vtysh_accept (struct thread *thread)
       close (sock);
       return -1;
     }
+  set_cloexec(sock);
 
 #ifdef VTYSH_DEBUG
   printf ("VTY shell accept\n");