support: Add support_open_dev_null_range

It returns a range of file descriptor referring to the '/dev/null'
pathname.  The function takes care of restarting the open range
if a file descriptor is found within the specified range and
also increases RLIMIT_NOFILE if required.

Checked on x86_64-linux-gnu.

1 files changed, 8 insertions, 0 deletions

diff --git a/support/support.h b/support/support.h
index 834dba9097..e6911e193a 100644
--- a/support/support.h
+++ b/support/support.h
@@ -193,6 +193,14 @@ struct support_stack support_stack_alloc (size_t size);
 /* Deallocate the STACK.  */
 void support_stack_free (struct support_stack *stack);
 
+
+/* Create a range of NUM opened '/dev/null' file descriptors using FLAGS and
+   MODE.  The function takes care of restarting the open range if a file
+   descriptor is found within the specified range and also increases
+   RLIMIT_NOFILE if required.
+   The returned value is the lowest file descriptor number.  */
+int support_open_dev_null_range (int num, int flags, mode_t mode);
+
 __END_DECLS
 
 #endif /* SUPPORT_H */