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134 lines
4.6 KiB
134 lines
4.6 KiB
# fcntl-o.m4 serial 4 |
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dnl Copyright (C) 2006, 2009-2017 Free Software Foundation, Inc. |
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dnl This file is free software; the Free Software Foundation |
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dnl gives unlimited permission to copy and/or distribute it, |
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dnl with or without modifications, as long as this notice is preserved. |
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|
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dnl Written by Paul Eggert. |
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# Test whether the flags O_NOATIME and O_NOFOLLOW actually work. |
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# Define HAVE_WORKING_O_NOATIME to 1 if O_NOATIME works, or to 0 otherwise. |
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# Define HAVE_WORKING_O_NOFOLLOW to 1 if O_NOFOLLOW works, or to 0 otherwise. |
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AC_DEFUN([gl_FCNTL_O_FLAGS], |
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[ |
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dnl Persuade glibc <fcntl.h> to define O_NOATIME and O_NOFOLLOW. |
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dnl AC_USE_SYSTEM_EXTENSIONS was introduced in autoconf 2.60 and obsoletes |
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dnl AC_GNU_SOURCE. |
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m4_ifdef([AC_USE_SYSTEM_EXTENSIONS], |
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[AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])], |
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[AC_REQUIRE([AC_GNU_SOURCE])]) |
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AC_CHECK_HEADERS_ONCE([unistd.h]) |
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AC_CHECK_FUNCS_ONCE([symlink]) |
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AC_CACHE_CHECK([for working fcntl.h], [gl_cv_header_working_fcntl_h], |
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[AC_RUN_IFELSE( |
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[AC_LANG_PROGRAM( |
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[[#include <sys/types.h> |
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#include <sys/stat.h> |
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#if HAVE_UNISTD_H |
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# include <unistd.h> |
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#else /* on Windows with MSVC */ |
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# include <io.h> |
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# include <stdlib.h> |
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# defined sleep(n) _sleep ((n) * 1000) |
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#endif |
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#include <fcntl.h> |
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#ifndef O_NOATIME |
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#define O_NOATIME 0 |
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#endif |
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#ifndef O_NOFOLLOW |
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#define O_NOFOLLOW 0 |
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#endif |
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static int const constants[] = |
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{ |
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O_CREAT, O_EXCL, O_NOCTTY, O_TRUNC, O_APPEND, |
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O_NONBLOCK, O_SYNC, O_ACCMODE, O_RDONLY, O_RDWR, O_WRONLY |
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}; |
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]], |
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[[ |
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int result = !constants; |
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#if HAVE_SYMLINK |
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{ |
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static char const sym[] = "conftest.sym"; |
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if (symlink ("/dev/null", sym) != 0) |
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result |= 2; |
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else |
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{ |
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int fd = open (sym, O_WRONLY | O_NOFOLLOW | O_CREAT, 0); |
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if (fd >= 0) |
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{ |
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close (fd); |
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result |= 4; |
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} |
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} |
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if (unlink (sym) != 0 || symlink (".", sym) != 0) |
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result |= 2; |
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else |
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{ |
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int fd = open (sym, O_RDONLY | O_NOFOLLOW); |
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if (fd >= 0) |
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{ |
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close (fd); |
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result |= 4; |
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} |
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} |
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unlink (sym); |
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} |
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#endif |
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{ |
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static char const file[] = "confdefs.h"; |
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int fd = open (file, O_RDONLY | O_NOATIME); |
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if (fd < 0) |
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result |= 8; |
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else |
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{ |
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struct stat st0; |
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if (fstat (fd, &st0) != 0) |
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result |= 16; |
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else |
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{ |
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char c; |
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sleep (1); |
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if (read (fd, &c, 1) != 1) |
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result |= 24; |
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else |
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{ |
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if (close (fd) != 0) |
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result |= 32; |
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else |
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{ |
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struct stat st1; |
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if (stat (file, &st1) != 0) |
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result |= 40; |
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else |
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if (st0.st_atime != st1.st_atime) |
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result |= 64; |
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} |
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} |
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} |
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} |
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} |
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return result;]])], |
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[gl_cv_header_working_fcntl_h=yes], |
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[case $? in #( |
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4) gl_cv_header_working_fcntl_h='no (bad O_NOFOLLOW)';; #( |
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64) gl_cv_header_working_fcntl_h='no (bad O_NOATIME)';; #( |
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68) gl_cv_header_working_fcntl_h='no (bad O_NOATIME, O_NOFOLLOW)';; #( |
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*) gl_cv_header_working_fcntl_h='no';; |
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esac], |
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[gl_cv_header_working_fcntl_h=cross-compiling])]) |
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case $gl_cv_header_working_fcntl_h in #( |
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*O_NOATIME* | no | cross-compiling) ac_val=0;; #( |
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*) ac_val=1;; |
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esac |
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AC_DEFINE_UNQUOTED([HAVE_WORKING_O_NOATIME], [$ac_val], |
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[Define to 1 if O_NOATIME works.]) |
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case $gl_cv_header_working_fcntl_h in #( |
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*O_NOFOLLOW* | no | cross-compiling) ac_val=0;; #( |
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*) ac_val=1;; |
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esac |
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AC_DEFINE_UNQUOTED([HAVE_WORKING_O_NOFOLLOW], [$ac_val], |
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[Define to 1 if O_NOFOLLOW works.]) |
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])
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