[PATCH 1/6] fds: Provide cloexec() and use it in udp.c

[Ian Jackson]

Signed-off-by: Ian Jackson <ijackson at chiark.greenend.org.uk>
---
 secnet.h |    4 ++++
 udp.c    |    5 +----
 util.c   |    8 ++++++++
 3 files changed, 13 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/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..cfa6b4c 100644
--- a/util.c
+++ b/util.c
@@ -162,6 +162,14 @@ 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 |= FD_CLOEXEC;
+    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",
-- 
1.7.10.4