code.delx.au - gnu-emacs/blob - m4/readlinkat.m4

   1 # serial 5
   2 # See if we need to provide readlinkat replacement.
   3
   4 dnl Copyright (C) 2009-2016 Free Software Foundation, Inc.
   5 dnl This file is free software; the Free Software Foundation
   6 dnl gives unlimited permission to copy and/or distribute it,
   7 dnl with or without modifications, as long as this notice is preserved.
   8
   9 # Written by Eric Blake.
  10
  11 AC_DEFUN([gl_FUNC_READLINKAT],
  12 [
  13   AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
  14   AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
  15   AC_CHECK_FUNCS_ONCE([readlinkat])
  16   AC_REQUIRE([gl_FUNC_READLINK])
  17   if test $ac_cv_func_readlinkat = no; then
  18     HAVE_READLINKAT=0
  19   else
  20     AC_CACHE_CHECK([whether readlinkat signature is correct],
  21       [gl_cv_decl_readlinkat_works],
  22       [AC_COMPILE_IFELSE(
  23          [AC_LANG_PROGRAM(
  24            [[#include <unistd.h>
  25              /* Check whether original declaration has correct type.  */
  26              ssize_t readlinkat (int, char const *, char *, size_t);]])],
  27          [gl_cv_decl_readlinkat_works=yes],
  28          [gl_cv_decl_readlinkat_works=no])])
  29     # Assume readinkat has the same trailing slash bug as readlink,
  30     # as is the case on Mac Os X 10.10
  31     case "$gl_cv_func_readlink_works" in
  32       *yes)
  33         if test "$gl_cv_decl_readlinkat_works" != yes; then
  34           REPLACE_READLINKAT=1
  35         fi
  36         ;;
  37       *)
  38         REPLACE_READLINKAT=1
  39         ;;
  40     esac
  41   fi
  42 ])