Eric Sunshine <sunshine@xxxxxxxxxxxxxx> writes:
> If you trace through it, you will see the flaw.
> Here is what the code is actually doing (pseudo-code):
>
> if $SHELL supports functions
> # Yay!
> else
> case $CONFIG_SHELL in
> '')
> CONFIG_SHELL=try_to_find_suitable_shell()
> if CONFIG_SHELL is set
At this point, CONFIG_SHELL must support functions, right?
> exec $CONFIG_SHELL $this_script
> endif
> ;;
> *)
> echo "Failed to find suitable shell" <<-- WRONG!
> ;;
> esac
> endif
>
> Assuming the $SHELL test fails, the first time through CONFIG_SHELL is not
> set, so it tries to find a suitable shell. If it finds one, then it exports
> CONFIG_SHELL re-invokes the script. Now, the second time through,
> CONFIG_SHELL is set, so it falls down to the '*' case
I don't see how. The 2nd time through, $CONFIG_SHELL must support
functions so the code must execute the "Yay!" comment only.
Unless CONFIG_SHELL differs from SHELL the 2nd time through, i.e.
they identify different shells the 2nd time through? Then that would
explain your problem; but in that case it seems to me that we might
have more serious problems since SHELL is incorrect, and we should fix
SHELL somehow.
(There is another problem here: the current code is testing SHELL
rather than CONFIG_SHELL. It is appropriate to test SHELL since that
(presumably) is the shell that is running this script. But if SHELL
and CONFIG_SHELL differ, the code won't be testing CONFIG_SHELL, even
though perhaps it should be (if only to warn the user that the
CONFIG_SHELL setting may have problems). But this is a different
matter than the one you're trying to to address.)
> One way to correct the logic is as follows:
>
> case $CONFIG_SHELL in
> CONFIG_SHELL=try_to_find_suitable_shell()
> ....
This doesn't sound right either, because if CONFIG_SHELL is unset and
SHELL is suitable, the code should use SHELL rather than trying to
find one of our own. (That is what the code does now.)
> >>> option 1 <<<
>
> --- lib/m4sugar/m4sh.m4 Tue Jan 6 18:39:20 2004
> +++ lib/m4sugar/m4sh.m4-fix Tue Jan 6 18:37:32 2004
> @@ -264,9 +264,11 @@
> exec "$CONFIG_SHELL" "$as_myself" ${1+"$[@]"}
> ]);;
> esac
> - done]);;
> - *)
> + done])
> + # If we got this far, we failed to find a function-supporting shell.
> $1;;
> + *)
> + ;;
> esac
> ])
This won't print a diagnostic in the case where SHELL doesn't support
shell functions and CONFIG_SHELL is set. The code should print a
diagnostic in that case, since the rest of the script will be executed
with SHELL and it may not work because of the lack of support for
shell functions.
Option 2 has the same problem.
