chroot function availability disqualifiers

15 years ago by Justin Martin — view source — reply

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Hello everyone,

As a bit of proactive documentation, I'm trying to determine exactly
what the disqualifying conditions are for chroot's availability in PHP.

So far as I can tell, from ext/standard/dir.c, chroot is only compiled
in #if defined(HAVE_CHROOT) && !defined(ZTS) && ENABLE_CHROOT_FUNC

HAVE_CHROOT seems to always be set to 1 by php_config.h, so far as I can
tell. ZTS, as I understand it, indicates whether PHP is being compiled
threadsafe, and ENABLE_CHROOT_FUNC seems to be related to the
deprecated(?) --enable-chroot-func switch.

Could someone with a better understanding of the compile process
illuminate me as to all of the reasons why chroot might not be available?

Thanks,
Justin Martin, a.k.a. FrozenFire

15 years ago by johannes@schlueters.de — view source — reply

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Hi,

So far as I can tell, from ext/standard/dir.c, chroot is only compiled
in #if defined(HAVE_CHROOT) && !defined(ZTS) && ENABLE_CHROOT_FUNC

The relevant checks are in ext/standard/config.m4:

    if test "$PHP_SAPI" = "cgi" || test "$PHP_SAPI" = "cli" || test "$PHP_SAPI" = "embed"; then
      AC_DEFINE(ENABLE_CHROOT_FUNC, 1, [Whether to enable chroot() function])
    fi

and configure.in:

    AC_CHECK_FUNCS(
    ...
    chroot \
    ...
    )

The first test checks the sapi as we don't want to allow chroot() from
withina server module, like chroot()ing an apache child etc.

The later check sets HAVE_CHROOT if it can be found on the host OS. I
assume any used "Unix" system has chroot() in it's libc library.

johannes