Re: [PATCH] Fix GDBHISTSIZE test failure on i686

[Patrick Palka <patrick at parcs dot ath dot cx>]

On Tue, Jun 23, 2015 at 10:30 AM, Patrick Palka <patrick@parcs.ath.cx> wrote:
> The test
>
>   test_histsize_history_setting "99999999999999999999999999999999999" "unlimited"
>
> was failing on i686 because the condition in init_history() for
> determining whether to map a large GDBHISTSIZE value to infinity was
>
>   long var = strtol (tmpenv);
>   if (var > INT_MAX)
>     history_size = unlimited;
>
> but this condition is never true on i686 because INT_MAX == LONG_MAX.
> So in order to properly map large out-of-range values of GDBHISTSIZE to
> infinity on targets where LONG_MAX > INT_MAX as well as on i686, we have
> to instead change the above condition to
>
>   if (var > INT_MAX
>       || (var == INT_MAX && errno == ERANGE))
>     history_size = unlimited;
>
> [ I did not test this patch on i686 because I don't have access to
>   such a machine.  But the patch seems straightforward enough... ]
>
> gdb/ChangeLog:
>
>         * top.c (init_history): Look at the errno set by strtol to
>         properly map large GDBHISTSIZE values to infinity.
> ---
>  gdb/top.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/gdb/top.c b/gdb/top.c
> index 5114c2e..afb14be 100644
> --- a/gdb/top.c
> +++ b/gdb/top.c
> @@ -1734,10 +1734,12 @@ init_history (void)
>    if (tmpenv)
>      {
>        long var;
> +      int saved_errno;
>        char *endptr;
>
>        tmpenv = skip_spaces (tmpenv);
>        var = strtol (tmpenv, &endptr, 10);
> +      saved_errno = errno;

errno should be set to 0 before the call to strtol.

>        endptr = skip_spaces (endptr);
>
>        /* If GDBHISTSIZE is non-numeric then ignore it.  If GDBHISTSIZE is the
> @@ -1749,7 +1751,12 @@ init_history (void)
>         ;
>        else if (*tmpenv == '\0'
>                || var < 0
> -              || var > INT_MAX)
> +              || var > INT_MAX
> +              /* On targets where INT_MAX == LONG_MAX, we have to look at
> +                 the errno set by strtol to distinguish between a value that
> +                 is exactly INT_MAX and an overflowing value that was clamped
> +                 to INT_MAX.  */
> +              || (var == INT_MAX && saved_errno == ERANGE))
>         history_size_setshow_var = -1;
>        else
>         history_size_setshow_var = var;
> --
> 2.4.4.410.g43ed522.dirty
>