Re: [PATCH 2/3] range-diff: handle commit ranges other than A..B
- From
Junio C Hamano <gitster@pobox.com>
- Date
- Jan 21, 2021, 23:42 UTC
- Message-ID
- <xmqq1redc0x9.fsf@gitster.c.googlers.com>
- In-Reply-To
- <88c15617b4ba8ae3211b1a01861eb4165f3eda38.1611267638.git.gitgitgadget@gmail.com>
"Johannes Schindelin via GitGitGadget" <gitgitgadget@gmail.com> writes:
Show 33 quoted lines
> From: Johannes Schindelin <johannes.schindelin@gmx.de>
>
> In the `SPECIFYING RANGES` section of gitrevisions[7], two ways are
> described to specify commit ranges that `range-diff` does not yet
> accept: "<commit>^!" and "<commit>^-<n>".
>
> Let's accept them.
>
> Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
> ---
> builtin/range-diff.c | 21 ++++++++++++++++++++-
> t/t3206-range-diff.sh | 8 ++++++++
> 2 files changed, 28 insertions(+), 1 deletion(-)
>
> diff --git a/builtin/range-diff.c b/builtin/range-diff.c
> index 551d3e689cb..6097635c432 100644
> --- a/builtin/range-diff.c
> +++ b/builtin/range-diff.c
> @@ -13,7 +13,26 @@ NULL
>
> static int is_range(const char *range)
> {
> - return !!strstr(range, "..");
> + size_t i;
> + char c;
> +
> + if (strstr(range, ".."))
> + return 1;
> +
> + i = strlen(range);
> + c = i ? range[--i] : 0;
> + if (c == '!')
> + i--; /* might be ...^! or ...^@ */I am confused. If it ends with '!', I do not see how it can end with "^@".
If the input were "!", i gets strlen("!") which is 1, c gets '!' while predecrementing i down to 0, and we notice c is '!' and decrement i again to make it (size_t)(-1) which is a fairly large number.
Then we skip all the else/if cascade, ensure that i is positive, and happily access range[i], which likely is way out of bounds (but it probably is almost one turn around the earth out of bounds, it may access just a single byte before the array).
Am I reading the code right?
IOW, "git range-diff \! A..B" would do something strange, I would guess.
Show 32 quoted lines
> + else if (isdigit(c)) {
> + /* handle ...^-<n> */
> + while (i > 2 && isdigit(range[--i]))
> + ; /* keep trimming trailing digits */
> + if (i < 2 || range[i--] != '-')
> + return 0;
> + } else
> + return 0;
> +
> + return i > 0 && range[i] == '^';
> }
>
> int cmd_range_diff(int argc, const char **argv, const char *prefix)
> diff --git a/t/t3206-range-diff.sh b/t/t3206-range-diff.sh
> index 6eb344be031..e217cecac9e 100755
> --- a/t/t3206-range-diff.sh
> +++ b/t/t3206-range-diff.sh
> @@ -150,6 +150,14 @@ test_expect_success 'simple A B C (unmodified)' '
> test_cmp expect actual
> '
>
> +test_expect_success 'A^! and A^-<n> (unmodified)' '
> + git range-diff --no-color topic^! unmodified^-1 >actual &&
> + cat >expect <<-EOF &&
> + 1: $(test_oid t4) = 1: $(test_oid u4) s/12/B/
> + EOF
> + test_cmp expect actual
> +'
> +
> test_expect_success 'trivial reordering' '
> git range-diff --no-color master topic reordered >actual &&
> cat >expect <<-EOF &&