Skip to content
Closed
Show file tree
Hide file tree
Changes from 1 commit
Commits
File filter

Filter by extension

Filter by extension

Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
10 changes: 4 additions & 6 deletions line-log.c
Original file line number Diff line number Diff line change
Expand Up @@ -897,13 +897,13 @@ static void print_line(const char *prefix, char first,
fputs("\\ No newline at end of file\n", file);
Copy link

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

On the Git mailing list, Patrick Steinhardt wrote (reply to this):

On Thu, Oct 03, 2024 at 11:58:42AM +0000, Derrick Stolee via GitGitGadget wrote:
> From: Derrick Stolee <[email protected]>
> 
> The output_prefix() method in line-log.c may call a function pointer via
> the diff_options struct. This function pointer returns a strbuf struct
> and then its buffer is passed back. However, that implies that the
> consumer is responsible to free the string. This is especially true
> because the default behavior is to duplicate the empty string.
> 
> The existing functions used in the output_prefix pointer include:
> 
>  1. idiff_prefix_cb() in diff-lib.c. This returns the data pointer, so
>     the value exists across multiple calls.
> 
>  2. diff_output_prefix_callback() in graph.c. This uses a static strbuf
>     struct, so it reuses buffers across calls. These should not be
>     freed.
> 
>  3. output_prefix_cb() in range-diff.c. This is similar to the
>     diff-lib.c case.
> 
> In each case, we should not be freeing this buffer. We can convert the
> output_prefix() function to return a const char pointer and stop freeing
> the result.
> 
> This choice is essentially the opposite of what was done in 394affd46d
> (line-log: always allocate the output prefix, 2024-06-07).
> 
> This was discovered via 'valgrind' while investigating a public report
> of a bug in 'git log --graph -L' [1].
> 
> [1] https://github.com/git-for-windows/git/issues/5185
> 
> This issue would have been caught by the new test, when Git is compiled
> with ASan to catch these double frees.

Thanks a bunch for fixing this! The change looks good to me.

Patrick

}

static char *output_prefix(struct diff_options *opt)
static const char *output_prefix(struct diff_options *opt)
{
if (opt->output_prefix) {
struct strbuf *sb = opt->output_prefix(opt, opt->output_prefix_data);
return sb->buf;
} else {
return xstrdup("");
return "";
}
}

Expand All @@ -916,7 +916,7 @@ static void dump_diff_hacky_one(struct rev_info *rev, struct line_log_data *rang
struct diff_ranges *diff = &range->diff;

struct diff_options *opt = &rev->diffopt;
char *prefix = output_prefix(opt);
const char *prefix = output_prefix(opt);
const char *c_reset = diff_get_color(opt->use_color, DIFF_RESET);
const char *c_frag = diff_get_color(opt->use_color, DIFF_FRAGINFO);
const char *c_meta = diff_get_color(opt->use_color, DIFF_METAINFO);
Expand Down Expand Up @@ -1003,7 +1003,6 @@ static void dump_diff_hacky_one(struct rev_info *rev, struct line_log_data *rang
out:
free(p_ends);
free(t_ends);
free(prefix);
}

/*
Expand All @@ -1012,10 +1011,9 @@ static void dump_diff_hacky_one(struct rev_info *rev, struct line_log_data *rang
*/
static void dump_diff_hacky(struct rev_info *rev, struct line_log_data *range)
{
char *prefix = output_prefix(&rev->diffopt);
const char *prefix = output_prefix(&rev->diffopt);

fprintf(rev->diffopt.file, "%s\n", prefix);
free(prefix);

while (range) {
dump_diff_hacky_one(rev, range);
Expand Down
28 changes: 28 additions & 0 deletions t/t4211-line-log.sh
Original file line number Diff line number Diff line change
Expand Up @@ -337,4 +337,32 @@ test_expect_success 'zero-width regex .* matches any function name' '
test_cmp expect actual
'

test_expect_success 'show line-log with graph' '
qz_to_tab_space >expect <<-EOF &&
* $head_oid Modify func2() in file.c
|Z
| diff --git a/file.c b/file.c
| --- a/file.c
| +++ b/file.c
| @@ -6,4 +6,4 @@
| int func2()
| {
| - return F2;
| + return F2 + 2;
| }
* $root_oid Add func1() and func2() in file.c
ZZ
diff --git a/file.c b/file.c
--- /dev/null
+++ b/file.c
@@ -0,0 +6,4 @@
+int func2()
+{
+ return F2;
+}
EOF
git log --graph --oneline -L:func2:file.c >actual &&
test_cmp expect actual
'

test_done