Re: [PATCH 2/5] configure: search a sturdy POSIX shell to be used in the testsuite

[Eric Blake]

On 05/01/2012 10:04 AM, Stefano Lattarini wrote:
> * configure.ac: Add code (partially inspired to checks in gnulib's
> 'tests/init.sh') to search for a good-enough, not-buggy POSIX/XSI
> shell to be used in our testsuite.  Accordingly AC_SUBSTitute the
> variable 'AM_TEST_RUNNER_SHELL'.
> * NEWS: Update.
> 
> Signed-off-by: Stefano Lattarini <address@hidden>
> ---
>  NEWS         |   11 ++++
>  configure.ac |  190 
> ++++++++++++++++++++++++++++++++++++++++++++++++++++------
>  2 files changed, 184 insertions(+), 17 deletions(-)
> 

>  
> -# Shell used to run our test scripts.  The same as $SHELL/$CONFIG_SHELL
> -# for the moment.
> -AC_SUBST([AM_TEST_RUNNER_SHELL], [$SHELL])
> +dnl FIXME: could we extract this in a simpler way through autoconf
> +dnl FIXME: idioms or internals?
> +AC_DEFUN(
> +  [_AM_INIT_BOURNE_COMPATIBLE_VAR],
> +  [am_bourne_compatible="AS_ESCAPE(_m4_expand([AS_BOURNE_COMPATIBLE]))"])

As is, _m4_expand is already an autoconf internal.  Thankfully, since
you recently moved to requiring 2.65, it looks like this macro is safe
enough for you to use.

> +
> +dnl
> +dnl Arguments to this macro:
> +dnl
> +dnl   $1 - shell to test
> +dnl   $2 - description of the tested feature
> +dnl   $3 - shell code used to check the feature; to indicate success,
> +dnl        it can either exit with status 77, or have the last command
> +dnl        returning with exit status of zero
> +dnl   $4 - shell code to execute if the check on the shell is successful
> +dnl        (defaults to nothing)
> +dnl   $5 - shell code to execute if the check on the shell is not
> +dnl        successful (defaults to nothing)
> +dnl
> +AC_DEFUN([_AM_CHECK_SHELL_FEATURE],
> +  [AC_REQUIRE([_AM_INIT_BOURNE_COMPATIBLE_VAR])
> +  AC_MSG_CHECKING([whether $1 $2])
> +  if { $1 -c "$am_bourne_compatible
> +AS_ESCAPE([$3])
> +test \$? -eq 0 || exit 1
> +# Use 77 to indicate success (rather than 0), in case some shell
> +# acts like Solaris 10's /bin/sh, exiting successfully on some
> +# syntax errors.
> +exit 77" >&AS_MESSAGE_LOG_FD 2>&1; test $? -eq 77; }
> +  then
> +    AC_MSG_RESULT([yes])
> +    $4
> +  else
> +    AC_MSG_RESULT([no])
> +    $5
> +  fi])

Looks like as good a probe as we can do without something publicly
documented in autoconf for the same.


> +#
> +# Finally, we look for weird bugs and portability problems mentioned in
> +# the Autoconf manual, and reject shells that suffers from them. (TODO)

Any reason to leave the TODO comment here?

> +    _AM_CHECK_SHELL_FEATURE([$1],
> +      [supports address@hidden:@glob}],
> +      [v=a/b/c; test address@hidden:@*/} = b/c],
> +      [], [am_score=1; break])
> +
> +    _AM_CHECK_SHELL_FEATURE([$1],
> +      [supports address@hidden:@@%:@glob}],
> +      [v=a/b/c; test address@hidden:@@%:@*/} = c],
> +      [], [am_score=1; break])
> +
> +    _AM_CHECK_SHELL_FEATURE([$1],
> +      [supports \${var%glob}],
> +      [v=a.b.c; test ${v%.*} = a.b],
> +      [], [am_score=1; break])
> +
> +    _AM_CHECK_SHELL_FEATURE([$1],
> +      [supports \${var%%glob}],
> +      [v=a.b.c; test ${v%%.*} = a],
> +      [], [am_score=1; break])

Probably overkill to test all four; I don't know of any shell that
supports one of the XSI expansions, but not all four.


> +AC_CACHE_VAL(
> +  [ac_cv_AM_TEST_RUNNER_SHELL],
> +  [if test "$AM_TEST_RUNNER_SHELL"; then
> +    # Let the user override it.
> +    ac_cv_AM_TEST_RUNNER_SHELL=$AM_TEST_RUNNER_SHELL
> +  else
> +    ac_cv_AM_TEST_RUNNER_SHELL=no
> +    am_candidate_shells=${CONFIG_SHELL-}
> +    # For the benefit of Solaris.
> +    am_PATH=$PATH$PATH_SEPARATOR/usr/xpg4/bin$PATH_SEPARATOR/usr/xpg6/bin

This favors the user's PATH first, which seems reasonable (first
candidate on the user's path that does what we want).  But in the
fallback mode, wouldn't it be better to list xpg6 before xpg4, for the
additional fixes in xpg6?

Overall, looks reasonable for finding a decent shell.

-- 
Eric Blake   address@hidden    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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