On Mon, Dec 19 2022, Lars Kellogg-Stedman wrote:
> When the -L argument to "git log" is passed the zero-width regular
> expression "$" (as in "-L :$:line-range.c"), this results in an
> infinite loop in find_funcname_matching_regexp().
>
> Modify find_funcname_matching_regexp to correctly match the entire line
> instead of the zero-width match at eol and update the loop condition to
> prevent an infinite loop in the event of other undiscovered corner cases.
>
> The primary change is that we pre-decrement the beginning-of-line marker
> ('bol') before comparing it to '\n'. In the case of '$', where we match the
> '\n' at the end of the line and start the loop with bol == eol, this
> ensures that bol will find the beginning of the line on which the match
> occurred.
>
> Originally reported in <https://stackoverflow.com/q/74690545/147356>.
>
> Signed-off-by: Lars Kellogg-Stedman <lars@xxxxxxxxxx>
> ---
> line-range.c | 7 ++++---
> t/t4211-line-log.sh | 22 ++++++++++++++++++++++
> 2 files changed, 26 insertions(+), 3 deletions(-)
>
> diff --git a/line-range.c b/line-range.c
> index 955a8a9535..47bf0d6f1a 100644
> --- a/line-range.c
> +++ b/line-range.c
> @@ -135,7 +135,7 @@ static const char *find_funcname_matching_regexp(xdemitconf_t *xecfg, const char
> {
> int reg_error;
> regmatch_t match[1];
> - while (1) {
> + while (*start) {
> const char *bol, *eol;
> reg_error = regexec(regexp, start, 1, match, 0);
> if (reg_error == REG_NOMATCH)
> @@ -148,8 +148,8 @@ static const char *find_funcname_matching_regexp(xdemitconf_t *xecfg, const char
> /* determine extent of line matched */
> bol = start+match[0].rm_so;
> eol = start+match[0].rm_eo;
> - while (bol > start && *bol != '\n')
> - bol--;
> + while (bol > start && *--bol != '\n')
> + ; /* nothing */
> if (*bol == '\n')
> bol++;
> while (*eol && *eol != '\n')
> @@ -161,6 +161,7 @@ static const char *find_funcname_matching_regexp(xdemitconf_t *xecfg, const char
> return bol;
> start = eol;
> }
> + return NULL;
> }
>
> static const char *parse_range_funcname(
> diff --git a/t/t4211-line-log.sh b/t/t4211-line-log.sh
> index ac9e4d0928..c6540e822f 100755
> --- a/t/t4211-line-log.sh
> +++ b/t/t4211-line-log.sh
> @@ -315,4 +315,26 @@ test_expect_success 'line-log with --before' '
> test_cmp expect actual
> '
>
> +test_expect_success 'setup tests for zero-width regular expressions' '
> + cat >expect <<-EOF
> + Modify func1() in file.c
> + Add func1() and func2() in file.c
> + EOF
> +'
> +
> +test_expect_success 'zero-width regex $ matches any function name' '
> + git log --format="%s" --no-patch "-L:$:file.c" >actual &&
> + test_cmp expect actual
> +'
> +
> +test_expect_success 'zero-width regex ^ matches any function name' '
> + git log --format="%s" --no-patch "-L:^:file.c" >actual &&
> + test_cmp expect actual
> +'
> +
> +test_expect_success 'zero-width regex .* matches any function name' '
> + git log --format="%s" --no-patch "-L:.*:file.c" >actual &&
> + test_cmp expect actual
> +'
> +
Untested, but as most of this is repeated & would fail if the "setup"
test is skipped, a one-off function would be better, e.g.:
test_zerowidth_regex () {
local rx="$1" &&
test_expect_success "zero-width regex '$rx' matches any function name" '
cat >expect <<-\EOF &&
Modify func1() in file.c
Add func1() and func2() in file.c
EOF
git log --format="%s" --no-patch -L:"$rx":file.c >actual &&
test_cmp expect actual
'
}
test_zerowidth_regex '$'
test_zerowidth_regex '^'
test_zerowidth_regex '.*'
The change of direction for the fix itself looks good to me (re my
earlier feedback on a previous round), i.e. that we should fix our own
code, not forbid '$' in regexes.
