# ptsname.m4 serial 9
dnl Copyright (C) 2010-2023 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.

AC_DEFUN([gl_FUNC_PTSNAME],
[
  AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles

  dnl Persuade glibc <stdlib.h> to declare ptsname().
  AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])

  AC_CHECK_FUNCS([ptsname])
  if test $ac_cv_func_ptsname = no; then
    HAVE_PTSNAME=0
  else
    AC_CACHE_CHECK([whether ptsname sets errno on failure],
      [gl_cv_func_ptsname_sets_errno],
      [AC_RUN_IFELSE(
         [AC_LANG_PROGRAM([[
              #include <stdlib.h>
              #include <errno.h>
            ]], [[
              return ptsname (-1) || !errno;
            ]])],
         [gl_cv_func_ptsname_sets_errno=yes],
         [gl_cv_func_ptsname_sets_errno=no],
         [case "$host_os" in
                           # Guess yes on glibc systems.
            *-gnu* | gnu*) gl_cv_func_ptsname_sets_errno="guessing yes" ;;
                           # Guess yes on musl systems.
            *-musl*)       gl_cv_func_ptsname_sets_errno="guessing yes" ;;
                           # Guess yes on systems that emulate the Linux system calls.
            midipix*)      gl_cv_func_ptsname_sets_errno="guessing yes" ;;
                           # If we don't know, obey --enable-cross-guesses.
            *)             gl_cv_func_ptsname_sets_errno="$gl_cross_guess_normal" ;;
          esac
         ])])
    case $gl_cv_func_ptsname_sets_errno in
      *no) REPLACE_PTSNAME=1 ;;
    esac
  fi
])

# Prerequisites of lib/ptsname.c.
AC_DEFUN([gl_PREREQ_PTSNAME], [
  :
])