From 64da7b6c00400c0a5e5b02df98faec97c0954a3c Mon Sep 17 00:00:00 2001 From: Eric Blake Date: Fri, 16 Sep 2011 09:59:23 -0600 Subject: [PATCH] fdatasync: new module At least libvirt would like to use the lighter-weight fdatasync on platforms where it is supported, while still guaranteeing full sync (via the heavy-weight fsync fallback) on all platforms. I've got an open question to the Austin Group, since the POSIX 2008 wording is self-contradictory (unlike fsync, fdatasync requires EBADF on non-writable fds, but still mentions that read() errors must be propagated). I can see how fsync() would affect atime after read() while fdatasync() can skip that, explaining why fdatasync() might have the EBADF requirement, but on the other hand, that prevents an implementation (like ours) where fdatasync is a straight alias of fsync. At any rate, glibc allows fdatasync on read-only fds. * modules/fsync (Description): Document difference to fdatasync. * modules/fdatasync: New module. * m4/fdatasync.m4 (gl_FUNC_FDATASYNC): New file. * lib/fdatasync.c (fdatasync): Likewise. * m4/unistd_h.m4 (gl_UNISTD_H, gl_UNISTD_H_DEFAULTS): Set up defaults. * modules/unistd (Makefile.am): Set witnesses. * lib/unistd.in.h (fdatasync): Declare. * MODULES.html.sh: Document it. * doc/posix-functions/fdatasync.texi (fdatasync): Likewise. * modules/fdatasync-tests: New test. * tests/test-fdatasync.c: Likewise. Signed-off-by: Eric Blake --- ChangeLog | 16 ++++++++++ MODULES.html.sh | 1 + doc/posix-functions/fdatasync.texi | 8 ++--- lib/fdatasync.c | 25 +++++++++++++++ lib/unistd.in.h | 21 ++++++++++++- m4/fdatasync.m4 | 14 +++++++++ m4/unistd_h.m4 | 6 ++-- modules/fdatasync | 28 +++++++++++++++++ modules/fdatasync-tests | 13 ++++++++ modules/fsync | 2 +- modules/unistd | 2 ++ tests/test-fdatasync.c | 64 ++++++++++++++++++++++++++++++++++++++ 12 files changed, 192 insertions(+), 8 deletions(-) create mode 100644 lib/fdatasync.c create mode 100644 m4/fdatasync.m4 create mode 100644 modules/fdatasync create mode 100644 modules/fdatasync-tests create mode 100644 tests/test-fdatasync.c diff --git a/ChangeLog b/ChangeLog index e1f97a0c1..469037c77 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,5 +1,21 @@ 2011-09-16 Eric Blake + fdatasync: new module + * modules/fsync (Description): Document difference to fdatasync. + * modules/fdatasync: New module. + * m4/fdatasync.m4 (gl_FUNC_FDATASYNC): New file. + * lib/fdatasync.c (fdatasync): Likewise. + * m4/unistd_h.m4 (gl_UNISTD_H, gl_UNISTD_H_DEFAULTS): Set up + defaults. + * modules/unistd (Makefile.am): Set witnesses. + * lib/unistd.in.h (fdatasync): Declare. + * MODULES.html.sh: Document it. + * doc/posix-functions/fdatasync.texi (fdatasync): Likewise. + * modules/fdatasync-tests: New test. + * tests/test-fdatasync.c: Likewise. + +2011-09-16 Eric Blake + test-fsync: enhance tests * modules/fsync-tests (Depends-on): Add errno, for mingw. * tests/test-fsync.c (main): Enhance test. diff --git a/MODULES.html.sh b/MODULES.html.sh index 8785ff2ca..8273faa56 100755 --- a/MODULES.html.sh +++ b/MODULES.html.sh @@ -2356,6 +2356,7 @@ func_all_modules () func_module fclose func_module fcntl-h func_module fcntl + func_module fdatasync func_module flock func_module fopen func_module fprintf-posix diff --git a/doc/posix-functions/fdatasync.texi b/doc/posix-functions/fdatasync.texi index 88a497c33..8209ecdcf 100644 --- a/doc/posix-functions/fdatasync.texi +++ b/doc/posix-functions/fdatasync.texi @@ -4,15 +4,15 @@ POSIX specification:@* @url{http://www.opengroup.org/onlinepubs/9699919799/functions/fdatasync.html} -Gnulib module: --- +Gnulib module: fdatasync Portability problems fixed by Gnulib: @itemize +@item +This function is missing on some platforms: +MacOS X 10.5, FreeBSD 6.0, OpenBSD 3.8, Minix 3.1.8, IRIX 5.3, Solaris 2.4, mingw, MSVC 9, Interix 3.5, BeOS. @end itemize Portability problems not fixed by Gnulib: @itemize -@item -This function is missing on some platforms: -MacOS X 10.5, FreeBSD 6.0, OpenBSD 3.8, Minix 3.1.8, IRIX 5.3, Solaris 2.4, mingw, MSVC 9, Interix 3.5, BeOS. @end itemize diff --git a/lib/fdatasync.c b/lib/fdatasync.c new file mode 100644 index 000000000..54c10fd91 --- /dev/null +++ b/lib/fdatasync.c @@ -0,0 +1,25 @@ +/* Emulate fdatasync on platforms that lack it. + + Copyright (C) 2011 Free Software Foundation, Inc. + + This library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + This library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see . */ + +#include +#include + +int +fdatasync (int fd) +{ + return fsync (fd); +} diff --git a/lib/unistd.in.h b/lib/unistd.in.h index c1cfb5426..3ad166c67 100644 --- a/lib/unistd.in.h +++ b/lib/unistd.in.h @@ -484,10 +484,29 @@ _GL_WARN_ON_USE (fchownat, "fchownat is not portable - " #endif -#if @GNULIB_FSYNC@ +#if @GNULIB_FDATASYNC@ /* Synchronize changes to a file. Return 0 if successful, otherwise -1 and errno set. See POSIX:2001 specification + . */ +# if !@HAVE_FDATASYNC@ +_GL_FUNCDECL_SYS (fdatasync, int, (int fd)); +# endif +_GL_CXXALIAS_SYS (fdatasync, int, (int fd)); +_GL_CXXALIASWARN (fdatasync); +#elif defined GNULIB_POSIXCHECK +# undef fdatasync +# if HAVE_RAW_DECL_FDATASYNC +_GL_WARN_ON_USE (fdatasync, "fdatasync is unportable - " + "use gnulib module fdatasync for portability"); +# endif +#endif + + +#if @GNULIB_FSYNC@ +/* Synchronize changes, including metadata, to a file. + Return 0 if successful, otherwise -1 and errno set. + See POSIX:2001 specification . */ # if !@HAVE_FSYNC@ _GL_FUNCDECL_SYS (fsync, int, (int fd)); diff --git a/m4/fdatasync.m4 b/m4/fdatasync.m4 new file mode 100644 index 000000000..8eceeb547 --- /dev/null +++ b/m4/fdatasync.m4 @@ -0,0 +1,14 @@ +# fdatasync.m4 serial 1 +dnl Copyright (C) 2008-2011 Free Software Foundation, Inc. +dnl This file is free software; the Free Software Foundation +dnl gives unlimited permission to copy and/or distribute it, +dnl with or without modifications, as long as this notice is preserved. + +AC_DEFUN([gl_FUNC_FDATASYNC], +[ + AC_REQUIRE([gl_UNISTD_H_DEFAULTS]) + AC_CHECK_FUNCS_ONCE([fdatasync]) + if test $ac_cv_func_fdatasync = no; then + HAVE_FDATASYNC=0 + fi +]) diff --git a/m4/unistd_h.m4 b/m4/unistd_h.m4 index 33897ae92..29f3947b5 100644 --- a/m4/unistd_h.m4 +++ b/m4/unistd_h.m4 @@ -1,4 +1,4 @@ -# unistd_h.m4 serial 58 +# unistd_h.m4 serial 59 dnl Copyright (C) 2006-2011 Free Software Foundation, Inc. dnl This file is free software; the Free Software Foundation dnl gives unlimited permission to copy and/or distribute it, @@ -40,7 +40,7 @@ AC_DEFUN([gl_UNISTD_H], # endif #endif ]], [chown dup2 dup3 environ euidaccess faccessat fchdir fchownat - fsync ftruncate getcwd getdomainname getdtablesize getgroups + fdatasync fsync ftruncate getcwd getdomainname getdtablesize getgroups gethostname getlogin getlogin_r getpagesize getusershell setusershell endusershell group_member lchown link linkat lseek pipe pipe2 pread pwrite readlink readlinkat rmdir sleep symlink symlinkat ttyname_r unlink unlinkat @@ -67,6 +67,7 @@ AC_DEFUN([gl_UNISTD_H_DEFAULTS], GNULIB_FACCESSAT=0; AC_SUBST([GNULIB_FACCESSAT]) GNULIB_FCHDIR=0; AC_SUBST([GNULIB_FCHDIR]) GNULIB_FCHOWNAT=0; AC_SUBST([GNULIB_FCHOWNAT]) + GNULIB_FDATASYNC=0; AC_SUBST([GNULIB_FDATASYNC]) GNULIB_FSYNC=0; AC_SUBST([GNULIB_FSYNC]) GNULIB_FTRUNCATE=0; AC_SUBST([GNULIB_FTRUNCATE]) GNULIB_GETCWD=0; AC_SUBST([GNULIB_GETCWD]) @@ -110,6 +111,7 @@ AC_DEFUN([gl_UNISTD_H_DEFAULTS], HAVE_FACCESSAT=1; AC_SUBST([HAVE_FACCESSAT]) HAVE_FCHDIR=1; AC_SUBST([HAVE_FCHDIR]) HAVE_FCHOWNAT=1; AC_SUBST([HAVE_FCHOWNAT]) + HAVE_FDATASYNC=1; AC_SUBST([HAVE_FDATASYNC]) HAVE_FSYNC=1; AC_SUBST([HAVE_FSYNC]) HAVE_FTRUNCATE=1; AC_SUBST([HAVE_FTRUNCATE]) HAVE_GETDTABLESIZE=1; AC_SUBST([HAVE_GETDTABLESIZE]) diff --git a/modules/fdatasync b/modules/fdatasync new file mode 100644 index 000000000..7b78a800b --- /dev/null +++ b/modules/fdatasync @@ -0,0 +1,28 @@ +Description: +fdatasync(2) function: synchronize writes to a file. + +Files: +lib/fdatasync.c +m4/fdatasync.m4 + +Depends-on: +fsync +unistd + +configure.ac: +gl_FUNC_FDATASYNC +if test $HAVE_FDATASYNC = 0; then + AC_LIBOBJ([fdatasync]) +fi +gl_UNISTD_MODULE_INDICATOR([fdatasync]) + +Makefile.am: + +Include: + + +License: +LGPLv2+ + +Maintainer: +Eric Blake diff --git a/modules/fdatasync-tests b/modules/fdatasync-tests new file mode 100644 index 000000000..9afd058de --- /dev/null +++ b/modules/fdatasync-tests @@ -0,0 +1,13 @@ +Files: +tests/test-fdatasync.c +tests/signature.h +tests/macros.h + +Depends-on: +errno + +configure.ac: + +Makefile.am: +TESTS += test-fdatasync +check_PROGRAMS += test-fdatasync diff --git a/modules/fsync b/modules/fsync index 0092226ca..0f5b3fc79 100644 --- a/modules/fsync +++ b/modules/fsync @@ -1,5 +1,5 @@ Description: -fsync(2) function: synchronize writes to a file. +fsync(2) function: synchronize writes, including metadata, to a file. Files: lib/fsync.c diff --git a/modules/unistd b/modules/unistd index d6642a7f0..f843a2ff3 100644 --- a/modules/unistd +++ b/modules/unistd @@ -39,6 +39,7 @@ unistd.h: unistd.in.h $(top_builddir)/config.status $(CXXDEFS_H) $(ARG_NONNULL_H -e 's/@''GNULIB_FACCESSAT''@/$(GNULIB_FACCESSAT)/g' \ -e 's/@''GNULIB_FCHDIR''@/$(GNULIB_FCHDIR)/g' \ -e 's/@''GNULIB_FCHOWNAT''@/$(GNULIB_FCHOWNAT)/g' \ + -e 's/@''GNULIB_FDATASYNC''@/$(GNULIB_FDATASYNC)/g' \ -e 's/@''GNULIB_FSYNC''@/$(GNULIB_FSYNC)/g' \ -e 's/@''GNULIB_FTRUNCATE''@/$(GNULIB_FTRUNCATE)/g' \ -e 's/@''GNULIB_GETCWD''@/$(GNULIB_GETCWD)/g' \ @@ -82,6 +83,7 @@ unistd.h: unistd.in.h $(top_builddir)/config.status $(CXXDEFS_H) $(ARG_NONNULL_H -e 's|@''HAVE_FACCESSAT''@|$(HAVE_FACCESSAT)|g' \ -e 's|@''HAVE_FCHDIR''@|$(HAVE_FCHDIR)|g' \ -e 's|@''HAVE_FCHOWNAT''@|$(HAVE_FCHOWNAT)|g' \ + -e 's|@''HAVE_FDATASYNC''@|$(HAVE_FDATASYNC)|g' \ -e 's|@''HAVE_FSYNC''@|$(HAVE_FSYNC)|g' \ -e 's|@''HAVE_FTRUNCATE''@|$(HAVE_FTRUNCATE)|g' \ -e 's|@''HAVE_GETDTABLESIZE''@|$(HAVE_GETDTABLESIZE)|g' \ diff --git a/tests/test-fdatasync.c b/tests/test-fdatasync.c new file mode 100644 index 000000000..d23e6db38 --- /dev/null +++ b/tests/test-fdatasync.c @@ -0,0 +1,64 @@ +/* Test of fdatasync() function. + Copyright (C) 2008-2011 Free Software Foundation, Inc. + + This program is free software: you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 3 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see . */ + +#include + +#include + +#include "signature.h" +SIGNATURE_CHECK (fdatasync, int, (int)); + +#include +#include + +#include "macros.h" + +int +main (void) +{ + int fd; + const char *file = "test-fdatasync.txt"; + + if (fdatasync (STDOUT_FILENO) != 0) + { + ASSERT (errno == EINVAL /* POSIX */ + || errno == ENOTSUP /* seen on MacOS X 10.5 */ + || errno == EBADF /* seen on AIX 7.1 */ + ); + } + errno = 0; + ASSERT (fdatasync (-1) == -1); + ASSERT (errno == EBADF); + fd = open (file, O_WRONLY|O_CREAT|O_TRUNC, 0644); + ASSERT (0 <= fd); + ASSERT (write (fd, "hello", 5) == 5); + ASSERT (fdatasync (fd) == 0); + ASSERT (close (fd) == 0); +#if 0 + /* POSIX is self-contradictory on whether fdatasync must fail on + read-only file descriptors. Glibc allows it, as does our + implementation if fsync allows it. */ + fd = open (file, O_RDONLY); + ASSERT (0 <= fd); + errno = 0; + ASSERT (fdatasync (fd) == -1); + ASSERT (errno == EBADF); + ASSERT (close (fd) == 0); +#endif + ASSERT (unlink (file) == 0); + + return 0; +} -- 2.11.0