fd_util: add function dup_cloexec()

Unfortunately, there's no "optimized" implementation here.  We can't
use Linux's proprietary system call dup3(), because it would require
us to specify the new descriptor.

2 files changed, 17 insertions, 0 deletions

diff --git a/src/fd_util.c b/src/fd_util.c
index b9443b03..769823bc 100644
--- a/src/fd_util.c
+++ b/src/fd_util.c
@@ -104,6 +104,16 @@ fd_set_nonblock(int fd)
 }
 
 int
+dup_cloexec(int oldfd)
+{
+	int newfd = dup(oldfd);
+	if (newfd >= 0)
+		fd_set_nonblock(newfd);
+
+	return newfd;
+}
+
+int
 open_cloexec(const char *path_fs, int flags, int mode)
 {
 	int fd;
diff --git a/src/fd_util.h b/src/fd_util.h
index 80fb9870..5b80df2c 100644
--- a/src/fd_util.h
+++ b/src/fd_util.h
@@ -50,6 +50,13 @@
 struct sockaddr;
 
 /**
+ * Wrapper for dup(), which sets the CLOEXEC flag on the new
+ * descriptor.
+ */
+int
+dup_cloexec(int oldfd);
+
+/**
  * Wrapper for open(), which sets the CLOEXEC flag (atomically if
  * supported by the OS).
  */