# readlink.m4 serial 12

dnl Copyright (C) 2003, 2007, 2009-2017 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.

AC_DEFUN([gl_FUNC_READLINK],

[

  AC_REQUIRE([gl_UNISTD_H_DEFAULTS])

  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles

  AC_CHECK_FUNCS_ONCE([readlink])

  if test $ac_cv_func_readlink = no; then

    HAVE_READLINK=0

  else

    AC_CACHE_CHECK([whether readlink signature is correct],

      [gl_cv_decl_readlink_works],

      [AC_COMPILE_IFELSE(

         [AC_LANG_PROGRAM(

           [[#include <unistd.h>

      /* Cause compilation failure if original declaration has wrong type.  */

      ssize_t readlink (const char *, char *, size_t);]])],

         [gl_cv_decl_readlink_works=yes], [gl_cv_decl_readlink_works=no])])

    dnl Solaris 9 ignores trailing slash.

    dnl FreeBSD 7.2 dereferences only one level of links with trailing slash.

    AC_CACHE_CHECK([whether readlink handles trailing slash correctly],

      [gl_cv_func_readlink_works],

      [# We have readlink, so assume ln -s works.

       ln -s conftest.no-such conftest.link

       ln -s conftest.link conftest.lnk2

       AC_RUN_IFELSE(

         [AC_LANG_PROGRAM(

           [[#include <unistd.h>

]], [[char buf[20];

      return readlink ("conftest.lnk2/", buf, sizeof buf) != -1;]])],

         [gl_cv_func_readlink_works=yes], [gl_cv_func_readlink_works=no],

         [case "$host_os" in

                    # Guess yes on glibc systems.

            *-gnu*) gl_cv_func_readlink_works="guessing yes" ;;

                    # If we don't know, assume the worst.

            *)      gl_cv_func_readlink_works="guessing no" ;;

          esac

         ])

      rm -f conftest.link conftest.lnk2])

    case "$gl_cv_func_readlink_works" in

      *yes)

        if test "$gl_cv_decl_readlink_works" != yes; then

          REPLACE_READLINK=1

        fi

        ;;

      *)

        AC_DEFINE([READLINK_TRAILING_SLASH_BUG], [1], [Define to 1 if readlink

          fails to recognize a trailing slash.])

        REPLACE_READLINK=1

        ;;

    esac

  fi

])

# Like gl_FUNC_READLINK, except prepare for separate compilation

# (no REPLACE_READLINK, no AC_LIBOBJ).

AC_DEFUN([gl_FUNC_READLINK_SEPARATE],

[

  AC_CHECK_FUNCS_ONCE([readlink])

  gl_PREREQ_READLINK

])

# Prerequisites of lib/readlink.c.

AC_DEFUN([gl_PREREQ_READLINK],

[

  :

])