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libiconv 1.16

    1: # fcntl-o.m4 serial 6
    2: dnl Copyright (C) 2006, 2009-2019 Free Software Foundation, Inc.
    3: dnl This file is free software; the Free Software Foundation
    4: dnl gives unlimited permission to copy and/or distribute it,
    5: dnl with or without modifications, as long as this notice is preserved.
    6: 
    7: dnl Written by Paul Eggert.
    8: 
    9: AC_PREREQ([2.60])
   10: 
   11: # Test whether the flags O_NOATIME and O_NOFOLLOW actually work.
   12: # Define HAVE_WORKING_O_NOATIME to 1 if O_NOATIME works, or to 0 otherwise.
   13: # Define HAVE_WORKING_O_NOFOLLOW to 1 if O_NOFOLLOW works, or to 0 otherwise.
   14: AC_DEFUN([gl_FCNTL_O_FLAGS],
   15: [
   16:   dnl Persuade glibc <fcntl.h> to define O_NOATIME and O_NOFOLLOW.
   17:   AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
   18: 
   19:   AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
   20:   AC_CHECK_HEADERS_ONCE([unistd.h])
   21:   AC_CHECK_FUNCS_ONCE([symlink])
   22:   AC_CACHE_CHECK([for working fcntl.h], [gl_cv_header_working_fcntl_h],
   23:     [AC_RUN_IFELSE(
   24:        [AC_LANG_PROGRAM(
   25:           [[#include <sys/types.h>
   26:            #include <sys/stat.h>
   27:            #if HAVE_UNISTD_H
   28:            # include <unistd.h>
   29:            #else /* on Windows with MSVC */
   30:            # include <io.h>
   31:            # include <stdlib.h>
   32:            # defined sleep(n) _sleep ((n) * 1000)
   33:            #endif
   34:            #include <fcntl.h>
   35:            #ifndef O_NOATIME
   36:             #define O_NOATIME 0
   37:            #endif
   38:            #ifndef O_NOFOLLOW
   39:             #define O_NOFOLLOW 0
   40:            #endif
   41:            static int const constants[] =
   42:             {
   43:               O_CREAT, O_EXCL, O_NOCTTY, O_TRUNC, O_APPEND,
   44:               O_NONBLOCK, O_SYNC, O_ACCMODE, O_RDONLY, O_RDWR, O_WRONLY
   45:             };
   46:           ]],
   47:           [[
   48:             int result = !constants;
   49:             #if HAVE_SYMLINK
   50:             {
   51:               static char const sym[] = "conftest.sym";
   52:               if (symlink ("/dev/null", sym) != 0)
   53:                 result |= 2;
   54:               else
   55:                 {
   56:                   int fd = open (sym, O_WRONLY | O_NOFOLLOW | O_CREAT, 0);
   57:                   if (fd >= 0)
   58:                     {
   59:                       close (fd);
   60:                       result |= 4;
   61:                     }
   62:                 }
   63:               if (unlink (sym) != 0 || symlink (".", sym) != 0)
   64:                 result |= 2;
   65:               else
   66:                 {
   67:                   int fd = open (sym, O_RDONLY | O_NOFOLLOW);
   68:                   if (fd >= 0)
   69:                     {
   70:                       close (fd);
   71:                       result |= 4;
   72:                     }
   73:                 }
   74:               unlink (sym);
   75:             }
   76:             #endif
   77:             {
   78:               static char const file[] = "confdefs.h";
   79:               int fd = open (file, O_RDONLY | O_NOATIME);
   80:               if (fd < 0)
   81:                 result |= 8;
   82:               else
   83:                 {
   84:                   struct stat st0;
   85:                   if (fstat (fd, &st0) != 0)
   86:                     result |= 16;
   87:                   else
   88:                     {
   89:                       char c;
   90:                       sleep (1);
   91:                       if (read (fd, &c, 1) != 1)
   92:                         result |= 24;
   93:                       else
   94:                         {
   95:                           if (close (fd) != 0)
   96:                             result |= 32;
   97:                           else
   98:                             {
   99:                               struct stat st1;
  100:                               if (stat (file, &st1) != 0)
  101:                                 result |= 40;
  102:                               else
  103:                                 if (st0.st_atime != st1.st_atime)
  104:                                   result |= 64;
  105:                             }
  106:                         }
  107:                     }
  108:                 }
  109:             }
  110:             return result;]])],
  111:        [gl_cv_header_working_fcntl_h=yes],
  112:        [case $? in #(
  113:         4) gl_cv_header_working_fcntl_h='no (bad O_NOFOLLOW)';; #(
  114:         64) gl_cv_header_working_fcntl_h='no (bad O_NOATIME)';; #(
  115:         68) gl_cv_header_working_fcntl_h='no (bad O_NOATIME, O_NOFOLLOW)';; #(
  116:          *) gl_cv_header_working_fcntl_h='no';;
  117:         esac],
  118:        [case "$host_os" in
  119:                   # Guess 'no' on native Windows.
  120:           mingw*) gl_cv_header_working_fcntl_h='no' ;;
  121:           *)      gl_cv_header_working_fcntl_h=cross-compiling ;;
  122:         esac
  123:        ])
  124:     ])
  125: 
  126:   case $gl_cv_header_working_fcntl_h in #(
  127:   *O_NOATIME* | no | cross-compiling) ac_val=0;; #(
  128:   *) ac_val=1;;
  129:   esac
  130:   AC_DEFINE_UNQUOTED([HAVE_WORKING_O_NOATIME], [$ac_val],
  131:     [Define to 1 if O_NOATIME works.])
  132: 
  133:   case $gl_cv_header_working_fcntl_h in #(
  134:   *O_NOFOLLOW* | no | cross-compiling) ac_val=0;; #(
  135:   *) ac_val=1;;
  136:   esac
  137:   AC_DEFINE_UNQUOTED([HAVE_WORKING_O_NOFOLLOW], [$ac_val],
  138:     [Define to 1 if O_NOFOLLOW works.])
  139: ])