@node renameat
@subsection @code{renameat}
@findex renameat

POSIX specification:@* @url{https://pubs.opengroup.org/onlinepubs/9799919799/functions/renameat.html}

Gnulib module: renameat
@mindex renameat

Portability problems fixed by Gnulib:
@itemize
@item
This function is missing on some platforms:
glibc 2.3.6, Mac OS X 10.5, FreeBSD 6.0, NetBSD 5.0, OpenBSD 3.8, Minix 3.1.8, AIX 5.1, HP-UX 11, Cygwin 1.5.x, mingw, MSVC 14.
But the replacement function is not safe to be used in libraries and is not
multithread-safe.
@item
This function is declared in @code{<unistd.h>}, not in @code{<stdio.h>},
on some platforms:
NetBSD 7.0, Solaris 11.4.
@item
This function is declared in @code{<sys/stat.h>}, not in @code{<stdio.h>},
on some platforms:
Android 4.3.
@item
This function does not reject trailing slashes on non-directories on
some platforms, as in @code{renameat(fd,"file",fd,"new/")}:
Solaris 11.4.
@item
This function ignores trailing slashes on symlinks on some platforms,
such that @code{renameat(fd,"link/",fd,"new")} corrupts @file{link}:
Solaris 9.
@item
@code{renameat (AT_FDCWD, "file", AT_FDCWD, "new/")} succeeds instead of
failing and setting @code{errno} to @code{ENOTDIR}, on some platforms:
@c https://sourceware.org/PR32570
GNU/Hurd with glibc 2.41.
@item
@code{renameat (ATFDCWD, "dir", AT_FDCWD, "new/")} fails with
@code{errno} set to @code{ENOENT}, on some platforms:
@c https://sourceware.org/PR33607
GNU/Hurd with glibc 2.42.
@item
@code{renameat (ATFDCWD, "dir/", AT_FDCWD, "new")} fails with
@code{errno} set to @code{ENOTDIR}, on some platforms:
@c https://sourceware.org/PR33608
GNU/Hurd with glibc 2.42.
@end itemize

Portability problems not fixed by Gnulib:
@itemize
@item
POSIX requires that @code{renameat(fd,"symlink-to-dir/",fd,"dir2")} rename
@file{dir} and leave @file{symlink-to-dir} dangling; likewise, it
requires that @code{renameat(fd,"dir",fd,"dangling/")} rename @file{dir} so
that @file{dangling} is no longer a dangling symlink.  This behavior
is counter-intuitive, so on some systems, @code{renameat} fails with
@code{ENOTDIR} if either argument is a symlink with a trailing slash:
glibc, OpenBSD, Cygwin 1.7.
@item
POSIX requires that @code{renameat} do nothing and return 0 if the
source and destination are hard links to the same file.  This behavior
is counterintuitive, and on some systems @code{renameat} is a no-op in
this way only if the source and destination identify the same
directory entry.  On these systems, for example, although renaming
@file{./f} to @file{f} is a no-op, renaming @file{f} to @file{g}
deletes @file{f} when @file{f} and @file{g} are hard links to the same
file:
NetBSD 7.0.
@item
After renaming a non-empty directory over an existing empty directory,
the old directory name is still visible through the @code{stat} function
for 30 seconds after the rename, on NFS file systems, on some platforms:
Linux 2.6.18.
@item
This function will not rename a source that is currently opened
by any process:
mingw, MSVC 14.
@end itemize
