# serial 30

# Determine whether we need the chown wrapper.

dnl Copyright (C) 1997-2001, 2003-2005, 2007, 2009-2018 Free Software

dnl 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.

# chown should accept arguments of -1 for uid and gid, and it should

# dereference symlinks.  If it doesn't, arrange to use the replacement

# function.

# From Jim Meyering.

# This is taken from the following Autoconf patch:

# https://git.savannah.gnu.org/gitweb/?p=autoconf.git;a=commitdiff;h=7fbb553727ed7e0e689a17594b58559ecf3ea6e9

AC_DEFUN([AC_FUNC_CHOWN],

[

  AC_REQUIRE([AC_TYPE_UID_T])dnl

  AC_REQUIRE([AC_CANONICAL_HOST])dnl for cross-compiles

  AC_CHECK_HEADERS([unistd.h])

  AC_CACHE_CHECK([for working chown],

    [ac_cv_func_chown_works],

    [AC_RUN_IFELSE(

       [AC_LANG_PROGRAM(

          [AC_INCLUDES_DEFAULT

           [#include <fcntl.h>

          ]],

          [[

            char *f = "conftest.chown";

            struct stat before, after;

            if (creat (f, 0600) < 0)

              return 1;

            if (stat (f, &before) < 0)

              return 1;

            if (chown (f, (uid_t) -1, (gid_t) -1) == -1)

              return 1;

            if (stat (f, &after) < 0)

              return 1;

            return ! (before.st_uid == after.st_uid && before.st_gid == after.st_gid);

          ]])

       ],

       [ac_cv_func_chown_works=yes],

       [ac_cv_func_chown_works=no],

       [case "$host_os" in # ((

                           # Guess yes on Linux systems.

          linux-* | linux) ac_cv_func_chown_works="guessing yes" ;;

                           # Guess yes on glibc systems.

          *-gnu* | gnu*)   ac_cv_func_chown_works="guessing yes" ;;

                           # Guess no on native Windows.

          mingw*)          ac_cv_func_chown_works="guessing no" ;;

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

          *)               ac_cv_func_chown_works="guessing no" ;;

        esac

       ])

     rm -f conftest.chown

    ])

  case "$ac_cv_func_chown_works" in

    *yes)

      AC_DEFINE([HAVE_CHOWN], [1],

        [Define to 1 if your system has a working `chown' function.])

      ;;

  esac

])# AC_FUNC_CHOWN

AC_DEFUN_ONCE([gl_FUNC_CHOWN],

[

  AC_REQUIRE([gl_UNISTD_H_DEFAULTS])

  AC_REQUIRE([AC_TYPE_UID_T])

  AC_REQUIRE([AC_FUNC_CHOWN])

  AC_REQUIRE([gl_FUNC_CHOWN_FOLLOWS_SYMLINK])

  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles

  AC_CHECK_FUNCS_ONCE([chown fchown])

  dnl mingw lacks chown altogether.

  if test $ac_cv_func_chown = no; then

    HAVE_CHOWN=0

  else

    dnl Some old systems treated chown like lchown.

    if test $gl_cv_func_chown_follows_symlink = no; then

      REPLACE_CHOWN=1

    fi

    dnl Some old systems tried to use uid/gid -1 literally.

    case "$ac_cv_func_chown_works" in

      *no)

        AC_DEFINE([CHOWN_FAILS_TO_HONOR_ID_OF_NEGATIVE_ONE], [1],

          [Define if chown is not POSIX compliant regarding IDs of -1.])

        REPLACE_CHOWN=1

        ;;

    esac

    dnl Solaris 9 ignores trailing slash.

    dnl FreeBSD 7.2 mishandles trailing slash on symlinks.

    dnl Likewise for AIX 7.1.

    AC_CACHE_CHECK([whether chown honors trailing slash],

      [gl_cv_func_chown_slash_works],

      [touch conftest.file && rm -f conftest.link

       AC_RUN_IFELSE([AC_LANG_PROGRAM([[

#include <unistd.h>

#include <stdlib.h>

#include <errno.h>

]], [[    if (symlink ("conftest.file", "conftest.link")) return 1;

          if (chown ("conftest.link/", getuid (), getgid ()) == 0) return 2;

        ]])],

        [gl_cv_func_chown_slash_works=yes],

        [gl_cv_func_chown_slash_works=no],

        [case "$host_os" in

                   # Guess yes on glibc systems.

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

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

           *)      gl_cv_func_chown_slash_works="guessing no" ;;

         esac

        ])

      rm -f conftest.link conftest.file])

    case "$gl_cv_func_chown_slash_works" in

      *yes) ;;

      *)

        AC_DEFINE([CHOWN_TRAILING_SLASH_BUG], [1],

          [Define to 1 if chown mishandles trailing slash.])

        REPLACE_CHOWN=1

        ;;

    esac

    dnl OpenBSD fails to update ctime if ownership does not change.

    AC_CACHE_CHECK([whether chown always updates ctime],

      [gl_cv_func_chown_ctime_works],

      [AC_RUN_IFELSE([AC_LANG_PROGRAM([[

#include <unistd.h>

#include <stdlib.h>

#include <errno.h>

#include <fcntl.h>

#include <sys/stat.h>

]], [[    struct stat st1, st2;

          if (close (creat ("conftest.file", 0600))) return 1;

          if (stat ("conftest.file", &st1)) return 2;

          sleep (1);

          if (chown ("conftest.file", st1.st_uid, st1.st_gid)) return 3;

          if (stat ("conftest.file", &st2)) return 4;

          if (st2.st_ctime <= st1.st_ctime) return 5;

        ]])],

        [gl_cv_func_chown_ctime_works=yes],

        [gl_cv_func_chown_ctime_works=no],

        [case "$host_os" in

                   # Guess yes on glibc systems.

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

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

           *)      gl_cv_func_chown_ctime_works="guessing no" ;;

         esac

        ])

      rm -f conftest.file])

    case "$gl_cv_func_chown_ctime_works" in

      *yes) ;;

      *)

        AC_DEFINE([CHOWN_CHANGE_TIME_BUG], [1], [Define to 1 if chown fails

          to change ctime when at least one argument was not -1.])

        REPLACE_CHOWN=1

        ;;

    esac

  fi

])

# Determine whether chown follows symlinks (it should).

AC_DEFUN_ONCE([gl_FUNC_CHOWN_FOLLOWS_SYMLINK],

[

  AC_CACHE_CHECK(

    [whether chown dereferences symlinks],

    [gl_cv_func_chown_follows_symlink],

    [

      AC_RUN_IFELSE([AC_LANG_SOURCE([[

#include <unistd.h>

#include <stdlib.h>

#include <errno.h>

        int

        main ()

        {

          int result = 0;

          char const *dangling_symlink = "conftest.dangle";

          unlink (dangling_symlink);

          if (symlink ("conftest.no-such", dangling_symlink))

            abort ();

          /* Exit successfully on a conforming system,

             i.e., where chown must fail with ENOENT.  */

          if (chown (dangling_symlink, getuid (), getgid ()) == 0)

            result |= 1;

          if (errno != ENOENT)

            result |= 2;

          return result;

        }

        ]])],

        [gl_cv_func_chown_follows_symlink=yes],

        [gl_cv_func_chown_follows_symlink=no],

        [gl_cv_func_chown_follows_symlink=yes]

      )

    ]

  )

  if test $gl_cv_func_chown_follows_symlink = no; then

    AC_DEFINE([CHOWN_MODIFIES_SYMLINK], [1],

      [Define if chown modifies symlinks.])

  fi

])