Add renameat2 function [BZ #17662]

The implementation falls back to renameat if renameat2 is not available
in the kernel (or in the kernel headers) and the flags argument is zero.
Without kernel support, a non-zero argument returns EINVAL, not ENOSYS.
This mirrors what the kernel does for invalid renameat2 flags.

1 files changed, 9 insertions, 0 deletions

diff --git a/NEWS b/NEWS
index b1ce067d27..5d253910b5 100644
--- a/NEWS
+++ b/NEWS
@@ -39,6 +39,15 @@ Major new features:
 * Building and running on GNU/Hurd systems now works without out-of-tree
   patches.
 
+* The renameat2 function has been added, a variant of the renameat function
+  which has a flags argument.  If the flags are zero, the renameat2 function
+  acts like renameat.  If the flag is not zero and there is no kernel
+  support for renameat2, the function will fail with an errno value of
+  EINVAL.  This is different from the existing gnulib function renameatu,
+  which performs a plain rename operation in case of a RENAME_NOREPLACE
+  flags and a non-existing destination (and therefore has a race condition
+  that can clobber the destination inadvertently).
+
 * IDN domain names in getaddrinfo and getnameinfo now use the system libidn2
   library if installed.  libidn2 version 2.0.5 or later is recommended.  If
   libidn2 is not available, internationalized domain names are not encoded