| # fcntl-o.m4 serial 7 |
| dnl Copyright (C) 2006, 2009-2021 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. |
| |
| dnl Written by Paul Eggert. |
| |
| AC_PREREQ([2.60]) |
| |
| # Test whether the flags O_NOATIME and O_NOFOLLOW actually work. |
| # Define HAVE_WORKING_O_NOATIME to 1 if O_NOATIME works, or to 0 otherwise. |
| # Define HAVE_WORKING_O_NOFOLLOW to 1 if O_NOFOLLOW works, or to 0 otherwise. |
| AC_DEFUN([gl_FCNTL_O_FLAGS], |
| [ |
| dnl Persuade glibc <fcntl.h> to define O_NOATIME and O_NOFOLLOW. |
| AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS]) |
| |
| AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles |
| AC_CHECK_HEADERS_ONCE([unistd.h]) |
| AC_CHECK_FUNCS_ONCE([symlink]) |
| AC_CACHE_CHECK([for working fcntl.h], [gl_cv_header_working_fcntl_h], |
| [AC_RUN_IFELSE( |
| [AC_LANG_PROGRAM( |
| [[#include <sys/types.h> |
| #include <sys/stat.h> |
| #if HAVE_UNISTD_H |
| # include <unistd.h> |
| #else /* on Windows with MSVC */ |
| # include <io.h> |
| # include <stdlib.h> |
| # defined sleep(n) _sleep ((n) * 1000) |
| #endif |
| #include <fcntl.h> |
| ]GL_MDA_DEFINES[ |
| #ifndef O_NOATIME |
| #define O_NOATIME 0 |
| #endif |
| #ifndef O_NOFOLLOW |
| #define O_NOFOLLOW 0 |
| #endif |
| static int const constants[] = |
| { |
| O_CREAT, O_EXCL, O_NOCTTY, O_TRUNC, O_APPEND, |
| O_NONBLOCK, O_SYNC, O_ACCMODE, O_RDONLY, O_RDWR, O_WRONLY |
| }; |
| ]], |
| [[ |
| int result = !constants; |
| #if HAVE_SYMLINK |
| { |
| static char const sym[] = "conftest.sym"; |
| if (symlink ("/dev/null", sym) != 0) |
| result |= 2; |
| else |
| { |
| int fd = open (sym, O_WRONLY | O_NOFOLLOW | O_CREAT, 0); |
| if (fd >= 0) |
| { |
| close (fd); |
| result |= 4; |
| } |
| } |
| if (unlink (sym) != 0 || symlink (".", sym) != 0) |
| result |= 2; |
| else |
| { |
| int fd = open (sym, O_RDONLY | O_NOFOLLOW); |
| if (fd >= 0) |
| { |
| close (fd); |
| result |= 4; |
| } |
| } |
| unlink (sym); |
| } |
| #endif |
| { |
| static char const file[] = "confdefs.h"; |
| int fd = open (file, O_RDONLY | O_NOATIME); |
| if (fd < 0) |
| result |= 8; |
| else |
| { |
| struct stat st0; |
| if (fstat (fd, &st0) != 0) |
| result |= 16; |
| else |
| { |
| char c; |
| sleep (1); |
| if (read (fd, &c, 1) != 1) |
| result |= 24; |
| else |
| { |
| if (close (fd) != 0) |
| result |= 32; |
| else |
| { |
| struct stat st1; |
| if (stat (file, &st1) != 0) |
| result |= 40; |
| else |
| if (st0.st_atime != st1.st_atime) |
| result |= 64; |
| } |
| } |
| } |
| } |
| } |
| return result;]])], |
| [gl_cv_header_working_fcntl_h=yes], |
| [case $? in #( |
| 4) gl_cv_header_working_fcntl_h='no (bad O_NOFOLLOW)';; #( |
| 64) gl_cv_header_working_fcntl_h='no (bad O_NOATIME)';; #( |
| 68) gl_cv_header_working_fcntl_h='no (bad O_NOATIME, O_NOFOLLOW)';; #( |
| *) gl_cv_header_working_fcntl_h='no';; |
| esac], |
| [case "$host_os" in |
| # Guess 'no' on native Windows. |
| mingw*) gl_cv_header_working_fcntl_h='no' ;; |
| *) gl_cv_header_working_fcntl_h=cross-compiling ;; |
| esac |
| ]) |
| ]) |
| |
| case $gl_cv_header_working_fcntl_h in #( |
| *O_NOATIME* | no | cross-compiling) ac_val=0;; #( |
| *) ac_val=1;; |
| esac |
| AC_DEFINE_UNQUOTED([HAVE_WORKING_O_NOATIME], [$ac_val], |
| [Define to 1 if O_NOATIME works.]) |
| |
| case $gl_cv_header_working_fcntl_h in #( |
| *O_NOFOLLOW* | no | cross-compiling) ac_val=0;; #( |
| *) ac_val=1;; |
| esac |
| AC_DEFINE_UNQUOTED([HAVE_WORKING_O_NOFOLLOW], [$ac_val], |
| [Define to 1 if O_NOFOLLOW works.]) |
| ]) |