Re: [PATCH v3] MSVC: fix t0040-parse-options crash
- From
Junio C Hamano <gitster@pobox.com>
- Date
- Mar 30, 2014, 02:01 UTC
- Message-ID
- <7vtxago359.fsf@alter.siamese.dyndns.org>
- In-Reply-To
- <1396123762-28673-1-git-send-email-marat@slonopotamus.org>
Marat Radchenko <marat@slonopotamus.org> writes:
Show 12 quoted lines
> On 64-bit MSVC, pointers are 64 bit but `long` is only 32. > Thus, casting string to `unsigned long`, which is redundand on other > platforms, throws away important bits and when later cast to `intptr_t` > results in corrupt pointer. > > This patch fixes test-parse-options by replacing harming cast with > correct one. > > Signed-off-by: Marat Radchenko <marat@slonopotamus.org> > --- > > Aargh! Didn't notice that V2 introduced compilation warning. Take three.
I am glad that I asked you to clarify, as I totally forgot that there are L32P64 boxes.
I love it every time to see an attempt to describe why the solution works clearly results in a better patch. It is not about writing verbose log message; it is about thinking things through and clearly cut to the core of the issue. Moving the string literal to a separate variable to be used in the constructor in v1 was totally a red-herring. Your updated log message makes it crystal clear that using the correct typecast, not "unsigned long" but "intptr_t", is the core of the solution.
As OPT_SET_PTR() is about setting the pointer value to intptr_t defval, a follow-up patch on top of this fix (see attached) may not be a bad thing to have, but that patch alone will not fix this issue without dropping the unneeded and unwanted cast to unsigned long.
Thanks.
Show 16 quoted lines
> test-parse-options.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/test-parse-options.c b/test-parse-options.c
> index 434e8b8..6f6c656 100644
> --- a/test-parse-options.c
> +++ b/test-parse-options.c
> @@ -60,7 +60,7 @@ int main(int argc, char **argv)
> OPT_STRING('o', NULL, &string, "str", "get another string"),
> OPT_NOOP_NOARG(0, "obsolete"),
> OPT_SET_PTR(0, "default-string", &string,
> - "set string to default", (unsigned long)"default"),
> + "set string to default", (intptr_t)"default"),
> OPT_STRING_LIST(0, "list", &list, "str", "add str to list"),
> OPT_GROUP("Magic arguments"),
> OPT_ARGUMENT("quux", "means --quux"),parse-options.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/parse-options.h b/parse-options.h index d670cb9..7a24d2e 100644 --- a/parse-options.h +++ b/parse-options.h @@ -129,7 +129,7 @@ struct option { #define OPT_HIDDEN_BOOL(s, l, v, h) { OPTION_SET_INT, (s), (l), (v), NULL, \ (h), PARSE_OPT_NOARG | PARSE_OPT_HIDDEN, NULL, 1} #define OPT_SET_PTR(s, l, v, h, p) { OPTION_SET_PTR, (s), (l), (v), NULL, \ - (h), PARSE_OPT_NOARG, NULL, (p) } + (h), PARSE_OPT_NOARG, NULL, (intptr_t)(p) } #define OPT_CMDMODE(s, l, v, h, i) { OPTION_CMDMODE, (s), (l), (v), NULL, \ (h), PARSE_OPT_NOARG|PARSE_OPT_NONEG, NULL, (i) } #define OPT_INTEGER(s, l, v, h) { OPTION_INTEGER, (s), (l), (v), N_("n"), (h) }