From: Junio C Hamano <gitster@pobox.com>
To: "Johannes Schindelin via GitGitGadget" <gitgitgadget@gmail.com>
Cc: git@vger.kernel.org, Denton Liu <liu.denton@gmail.com>,
Johannes Schindelin <johannes.schindelin@gmx.de>
Subject: Re: [PATCH v2 02/13] msvc: avoid using minus operator on unsigned types
Date: Fri, 04 Oct 2019 07:44:03 +0900 [thread overview]
Message-ID: <xmqqy2y1a1qk.fsf@gitster-ct.c.googlers.com> (raw)
In-Reply-To: <8800320590e4d7218a80f80abca23a7f44b8747d.1569837329.git.gitgitgadget@gmail.com> (Johannes Schindelin via GitGitGadget's message of "Mon, 30 Sep 2019 02:55:31 -0700 (PDT)")
"Johannes Schindelin via GitGitGadget" <gitgitgadget@gmail.com>
writes:
> While at it, we take care of reporting overflows (which are unlikely,
> but hey, defensive programming is good!).
>
> We _also_ take pains of casting the unsigned value to signed: otherwise,
> the signed operand (i.e. the `-1`) would be cast to unsigned before
> doing the arithmetic.
These three look good and too similar to each other, which makes me
wonder if we want to allow them simply write
return insert_pos_as_negative_offset(nr);
with something like
static int insert_pos_as_negative_offset(uintmax_t nr)
{
if (INT_MAX < nr)
die("overflow: -1 - %"PRIuMAX, nr);
return -1 - (int)nr;
}
to avoid repetition.
> Helped-by: Denton Liu <liu.denton@gmail.com>
> Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
> ---
> read-cache.c | 9 ++++++---
> sha1-lookup.c | 12 +++++++++---
> 2 files changed, 15 insertions(+), 6 deletions(-)
>
> diff --git a/read-cache.c b/read-cache.c
> index c701f7f8b8..97745c2a31 100644
> --- a/read-cache.c
> +++ b/read-cache.c
> @@ -1275,8 +1275,11 @@ static int add_index_entry_with_check(struct index_state *istate, struct cache_e
> * we can avoid searching for it.
> */
> if (istate->cache_nr > 0 &&
> - strcmp(ce->name, istate->cache[istate->cache_nr - 1]->name) > 0)
> - pos = -istate->cache_nr - 1;
> + strcmp(ce->name, istate->cache[istate->cache_nr - 1]->name) > 0) {
> + if (istate->cache_nr > INT_MAX)
> + die("overflow: -1 - %u", istate->cache_nr);
> + pos = -1 - (int)istate->cache_nr;
> + }
> else
> pos = index_name_stage_pos(istate, ce->name, ce_namelen(ce), ce_stage(ce));
>
> @@ -1894,7 +1897,7 @@ static size_t estimate_cache_size(size_t ondisk_size, unsigned int entries)
> /*
> * Account for potential alignment differences.
> */
> - per_entry += align_padding_size(sizeof(struct cache_entry), -sizeof(struct ondisk_cache_entry));
> + per_entry += align_padding_size(per_entry, 0);
> return ondisk_size + entries * per_entry;
> }
>
> diff --git a/sha1-lookup.c b/sha1-lookup.c
> index 796ab68da8..bb786b5420 100644
> --- a/sha1-lookup.c
> +++ b/sha1-lookup.c
> @@ -69,8 +69,12 @@ int sha1_pos(const unsigned char *sha1, void *table, size_t nr,
> miv = take2(sha1 + ofs);
> if (miv < lov)
> return -1;
> - if (hiv < miv)
> - return -1 - nr;
> + if (hiv < miv) {
> + if (nr > INT_MAX)
> + die("overflow: -1 - %"PRIuMAX,
> + (uintmax_t)nr);
> + return -1 - (int)nr;
> + }
> if (lov != hiv) {
> /*
> * At this point miv could be equal
> @@ -97,7 +101,9 @@ int sha1_pos(const unsigned char *sha1, void *table, size_t nr,
> lo = mi + 1;
> mi = lo + (hi - lo) / 2;
> } while (lo < hi);
> - return -lo-1;
> + if (nr > INT_MAX)
> + die("overflow: -1 - %"PRIuMAX, (uintmax_t)lo);
> + return -1 - (int)lo;
> }
>
> int bsearch_hash(const unsigned char *sha1, const uint32_t *fanout_nbo,
next prev parent reply other threads:[~2019-10-03 22:44 UTC|newest]
Thread overview: 72+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-26 8:30 [PATCH 00/13] ci: include a Visual Studio build & test in our Azure Pipeline Johannes Schindelin via GitGitGadget
2019-09-26 8:30 ` [PATCH 01/13] push: do not pretend to return `int` from `die_push_simple()` Johannes Schindelin via GitGitGadget
2019-09-26 8:30 ` [PATCH 02/13] msvc: avoid using minus operator on unsigned types Johannes Schindelin via GitGitGadget
2019-09-26 17:20 ` Denton Liu
2019-09-26 21:01 ` Johannes Schindelin
2019-09-26 23:57 ` Denton Liu
2019-09-30 9:50 ` Johannes Schindelin
2019-09-26 8:30 ` [PATCH 03/13] winansi: use FLEX_ARRAY to avoid compiler warning Johannes Schindelin via GitGitGadget
2019-09-26 8:30 ` [PATCH 04/13] compat/win32/path-utils.h: add #include guards Johannes Schindelin via GitGitGadget
2019-09-26 8:30 ` [PATCH 05/13] msvc: ignore some libraries when linking Johannes Schindelin via GitGitGadget
2019-09-26 8:30 ` [PATCH 06/13] msvc: handle DEVELOPER=1 Johannes Schindelin via GitGitGadget
2019-09-26 8:30 ` [PATCH 07/13] msvc: work around a bug in GetEnvironmentVariable() Johannes Schindelin via GitGitGadget
2019-09-26 8:30 ` [PATCH 08/13] vcxproj: only copy `git-remote-http.exe` once it was built Johannes Schindelin via GitGitGadget
2019-09-26 8:30 ` [PATCH 09/13] vcxproj: include more generated files Johannes Schindelin via GitGitGadget
2019-09-26 8:30 ` [PATCH 10/13] test-tool run-command: learn to run (parts of) the testsuite Johannes Schindelin via GitGitGadget
2019-09-26 8:30 ` [PATCH 11/13] tests: let --immediate and --write-junit-xml play well together Johannes Schindelin via GitGitGadget
2019-09-28 22:22 ` Junio C Hamano
2019-09-30 9:52 ` Johannes Schindelin
2019-09-26 8:30 ` [PATCH 12/13] ci: really use shallow clones on Azure Pipelines Johannes Schindelin via GitGitGadget
2019-09-26 8:30 ` [PATCH 13/13] ci: also build and test with MS Visual Studio " Johannes Schindelin via GitGitGadget
2019-09-30 9:55 ` [PATCH v2 00/13] ci: include a Visual Studio build & test in our Azure Pipeline Johannes Schindelin via GitGitGadget
2019-09-30 9:55 ` [PATCH v2 01/13] push: do not pretend to return `int` from `die_push_simple()` Johannes Schindelin via GitGitGadget
2019-10-03 22:37 ` Junio C Hamano
2019-10-04 9:36 ` Johannes Schindelin
2019-09-30 9:55 ` [PATCH v2 02/13] msvc: avoid using minus operator on unsigned types Johannes Schindelin via GitGitGadget
2019-10-03 22:44 ` Junio C Hamano [this message]
2019-10-04 9:55 ` Johannes Schindelin
2019-10-04 17:09 ` Johannes Sixt
2019-10-04 21:24 ` Johannes Schindelin
2019-10-06 0:02 ` Junio C Hamano
2019-10-06 10:53 ` Johannes Sixt
2019-10-08 12:04 ` Johannes Schindelin
2019-10-08 21:13 ` Johannes Sixt
2019-09-30 9:55 ` [PATCH v2 03/13] winansi: use FLEX_ARRAY to avoid compiler warning Johannes Schindelin via GitGitGadget
2019-09-30 9:55 ` [PATCH v2 04/13] compat/win32/path-utils.h: add #include guards Johannes Schindelin via GitGitGadget
2019-09-30 9:55 ` [PATCH v2 05/13] msvc: ignore some libraries when linking Johannes Schindelin via GitGitGadget
2019-09-30 9:55 ` [PATCH v2 06/13] msvc: handle DEVELOPER=1 Johannes Schindelin via GitGitGadget
2019-09-30 9:55 ` [PATCH v2 07/13] msvc: work around a bug in GetEnvironmentVariable() Johannes Schindelin via GitGitGadget
2019-09-30 9:55 ` [PATCH v2 09/13] vcxproj: include more generated files Johannes Schindelin via GitGitGadget
2019-09-30 9:55 ` [PATCH v2 08/13] vcxproj: only copy `git-remote-http.exe` once it was built Johannes Schindelin via GitGitGadget
2019-09-30 9:55 ` [PATCH v2 10/13] test-tool run-command: learn to run (parts of) the testsuite Johannes Schindelin via GitGitGadget
2019-09-30 9:55 ` [PATCH v2 11/13] tests: let --immediate and --write-junit-xml play well together Johannes Schindelin via GitGitGadget
2019-09-30 9:55 ` [PATCH v2 13/13] ci: also build and test with MS Visual Studio on Azure Pipelines Johannes Schindelin via GitGitGadget
2019-09-30 9:55 ` [PATCH v2 12/13] ci: really use shallow clones " Johannes Schindelin via GitGitGadget
2019-10-04 15:09 ` [PATCH v3 00/13] ci: include a Visual Studio build & test in our Azure Pipeline Johannes Schindelin via GitGitGadget
2019-10-04 15:09 ` [PATCH v3 01/13] push: do not pretend to return `int` from `die_push_simple()` Johannes Schindelin via GitGitGadget
2019-10-04 15:09 ` [PATCH v3 02/13] msvc: avoid using minus operator on unsigned types Johannes Schindelin via GitGitGadget
2019-10-04 15:09 ` [PATCH v3 03/13] winansi: use FLEX_ARRAY to avoid compiler warning Johannes Schindelin via GitGitGadget
2019-10-07 19:16 ` Alban Gruin
2019-10-04 15:09 ` [PATCH v3 04/13] compat/win32/path-utils.h: add #include guards Johannes Schindelin via GitGitGadget
2019-10-04 15:09 ` [PATCH v3 05/13] msvc: ignore some libraries when linking Johannes Schindelin via GitGitGadget
2019-10-04 15:09 ` [PATCH v3 07/13] msvc: work around a bug in GetEnvironmentVariable() Johannes Schindelin via GitGitGadget
2019-10-04 15:09 ` [PATCH v3 06/13] msvc: handle DEVELOPER=1 Johannes Schindelin via GitGitGadget
2019-10-04 15:09 ` [PATCH v3 08/13] vcxproj: only copy `git-remote-http.exe` once it was built Johannes Schindelin via GitGitGadget
2019-10-04 15:09 ` [PATCH v3 09/13] vcxproj: include more generated files Johannes Schindelin via GitGitGadget
2019-10-04 15:09 ` [PATCH v3 10/13] test-tool run-command: learn to run (parts of) the testsuite Johannes Schindelin via GitGitGadget
2019-10-04 15:09 ` [PATCH v3 11/13] tests: let --immediate and --write-junit-xml play well together Johannes Schindelin via GitGitGadget
2019-10-04 15:09 ` [PATCH v3 12/13] ci: really use shallow clones on Azure Pipelines Johannes Schindelin via GitGitGadget
2019-10-04 15:09 ` [PATCH v3 13/13] ci: also build and test with MS Visual Studio " Johannes Schindelin via GitGitGadget
2019-10-06 0:19 ` [PATCH v3 00/13] ci: include a Visual Studio build & test in our Azure Pipeline Junio C Hamano
2019-10-06 10:45 ` Johannes Schindelin
2019-10-06 20:38 ` Johannes Schindelin
2019-10-07 1:14 ` Junio C Hamano
2019-10-07 21:51 ` Johannes Schindelin
2019-10-08 2:19 ` Junio C Hamano
2019-10-08 12:46 ` Johannes Schindelin
2019-10-09 13:57 ` Philip Oakley
2019-10-10 9:03 ` Johannes Schindelin
2019-10-10 10:12 ` Philip Oakley
2019-10-07 0:59 ` Junio C Hamano
2019-10-07 16:08 ` Thomas Gummerer
2019-10-11 22:06 ` Johannes Schindelin
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