123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141 |
- # fcntl-o.m4 serial 7
- dnl Copyright (C) 2006, 2009-2021 Free Software Foundation, Inc.
- dnl This file is free software
- 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.])
- ])
|