kc3-lang/gnulib/m4/fcntl-o.m4

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• Hash : 32a72f45
  Author :
  Date : 2023-01-01T01:14:21
  

  maint: run 'make update-copyright'
  

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• m4/fcntl-o.m4

• # fcntl-o.m4 serial 7
  dnl Copyright (C) 2006, 2009-2023 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.])
  ])
  

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