# perror.m4 serial 6

dnl Copyright (C) 2008-2017 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_PERROR],

[

  AC_REQUIRE([gl_STDIO_H_DEFAULTS])

  AC_REQUIRE([gl_HEADER_ERRNO_H])

  AC_REQUIRE([gl_FUNC_STRERROR_R])

  AC_REQUIRE([gl_FUNC_STRERROR_0])

  dnl We intentionally do not check for the broader REPLACE_STRERROR_R,

  dnl since on glibc systems, strerror_r is replaced only for signature

  dnl issues, and perror is just fine.  Rather, we only want to

  dnl replace perror if strerror_r was replaced for a content fix.

  if test "$ERRNO_H:$REPLACE_STRERROR_0" != :0; then

    dnl The system's perror() cannot know about the new errno values we add

    dnl to <errno.h>, or any fix for strerror(0). Replace it.

    REPLACE_PERROR=1

  fi

  case ${gl_cv_func_strerror_r_works-unset} in

    unset|*yes)

      AC_CACHE_CHECK([whether perror matches strerror],

        [gl_cv_func_perror_works],

        [AC_RUN_IFELSE(

           [AC_LANG_PROGRAM(

              [[#include <errno.h>

                #include <stdio.h>

                #include <stdlib.h>

                #include <string.h>

              ]],

              [[char *str = strerror (-1);

                if (!getenv("CONFTEST_OUTPUT")) return 0;

                if (!str) str = "";

                puts (str);

                errno = -1;

                perror ("");

                return 0;

              ]])],

           [if CONFTEST_OUTPUT=1 ./conftest$EXEEXT >conftest.txt1 2>conftest.txt2 \

               && cmp conftest.txt1 conftest.txt2 >/dev/null; then

              gl_cv_func_perror_works=yes

            else

              gl_cv_func_perror_works=no

            fi

            rm -rf conftest.txt1 conftest.txt2],

           [gl_cv_func_perror_works=no],

           [dnl Guess no when cross-compiling.

            gl_cv_func_perror_works="guessing no"

           ])

        ])

      if test "$gl_cv_func_perror_works" != yes; then

        REPLACE_PERROR=1

      fi

      ;;

    *)

      dnl The system's perror() probably inherits the bugs in the

      dnl system's strerror_r(). Replace it.

      REPLACE_PERROR=1

      ;;

  esac

])