gh-93475: Expose FICLONE and FICLONERANGE constants in fcntl (#93478)

Doc/library/fcntl.rst

@@ -50,6 +50,12 @@ descriptor.
    constants, which allow to duplicate a file descriptor, the latter setting
    ``FD_CLOEXEC`` flag in addition.
 
+.. versionchanged:: 3.12
+   On Linux >= 4.5, the :mod:`fcntl` module exposes the ``FICLONE`` and
+   ``FICLONERANGE`` constants, which allow to share some data of one file with
+   another file by reflinking on some filesystems (e.g., btrfs, OCFS2, and
+   XFS). This behavior is commonly referred to as "copy-on-write".
+
 The module defines the following functions:
 
 

Misc/NEWS.d/next/Library/2022-06-04-00-11-54.gh-issue-93475.vffFw1.rst

@@ -0,0 +1,2 @@
+Expose ``FICLONE`` and ``FICLONERANGE`` constants in :mod:`fcntl`. Patch by
+Illia Volochii.

Modules/fcntlmodule.c

@@ -8,6 +8,9 @@
 #ifdef HAVE_SYS_FILE_H
 #include <sys/file.h>
 #endif
+#ifdef HAVE_LINUX_FS_H
+#include <linux/fs.h>
+#endif
 
 #include <sys/ioctl.h>
 #include <fcntl.h>
@@ -572,6 +575,12 @@ all_ins(PyObject* m)
 #ifdef F_GETPIPE_SZ
     if (PyModule_AddIntMacro(m, F_GETPIPE_SZ)) return -1;
 #endif
+#ifdef FICLONE
+    if (PyModule_AddIntMacro(m, FICLONE)) return -1;
+#endif
+#ifdef FICLONERANGE
+    if (PyModule_AddIntMacro(m, FICLONERANGE)) return -1;
+#endif
 
 /* OS X specifics */
 #ifdef F_FULLFSYNC

configure.ac

@@ -2504,7 +2504,8 @@ AC_DEFINE(STDC_HEADERS, 1, [Define to 1 if you have the ANSI C header files.])
 # checks for header files
 AC_CHECK_HEADERS([ \
   alloca.h asm/types.h bluetooth.h conio.h crypt.h direct.h dlfcn.h endian.h errno.h fcntl.h grp.h \
-  ieeefp.h io.h langinfo.h libintl.h libutil.h linux/auxvec.h sys/auxv.h linux/memfd.h linux/random.h linux/soundcard.h \
+  ieeefp.h io.h langinfo.h libintl.h libutil.h linux/auxvec.h sys/auxv.h linux/fs.h linux/memfd.h \
+  linux/random.h linux/soundcard.h \
   linux/tipc.h linux/wait.h netinet/in.h netpacket/packet.h poll.h process.h pthread.h pty.h \
   sched.h setjmp.h shadow.h signal.h spawn.h stropts.h sys/audioio.h sys/bsdtty.h sys/devpoll.h \
   sys/endian.h sys/epoll.h sys/event.h sys/eventfd.h sys/file.h sys/ioctl.h sys/kern_control.h \

pyconfig.h.in

@@ -685,6 +685,9 @@
 /* Define if compiling using Linux 4.1 or later. */
 #undef HAVE_LINUX_CAN_RAW_JOIN_FILTERS
 
+/* Define to 1 if you have the <linux/fs.h> header file. */
+#undef HAVE_LINUX_FS_H
+
 /* Define to 1 if you have the <linux/memfd.h> header file. */
 #undef HAVE_LINUX_MEMFD_H