1 files changed, 25 insertions, 0 deletions
diff --git a/src/libstddjb/fd_ensure_open.c b/src/libstddjb/fd_ensure_open.c
new file mode 100644
index 0000000..b399af2
--- /dev/null
+++ b/src/libstddjb/fd_ensure_open.c
@@ -0,0 +1,25 @@
+/* ISC license. */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <skalibs/djbunix.h>
+
+int fd_ensure_open (int fd, int w)
+{
+  int dummy ;
+  if (fcntl(fd, F_GETFD, &dummy) < 0)
+  {
+    int newfd ;
+    if (errno != EBADF) return 0 ;
+    newfd = open2("/dev/null", w ? O_WRONLY : O_RDONLY) ;
+    if (newfd < 0) return 0 ;
+    if (fd_move(fd, newfd) < 0)
+    {
+      register int e = errno ;
+      fd_close(newfd) ;
+      errno = e ;
+      return 0 ;
+    }
+  }
+  return 1 ;
+}