Re: [PATCH 4/6] abbrev_sha1_in_line: don't leak memory
Jeff King <peff@peff.net> writes:
Show 15 quoted lines
> On Tue, Mar 29, 2016 at 09:30:38PM -0400, Eric Sunshine wrote:
>
>> The implementation of strbuf_list_free() is this:
>>
>> struct strbuf **s = sbs;
>> while (*s) {
>> strbuf_release(*s);
>> free(*s++);
>> }
>> free(sbs);
>>
>> which means that wt-status.c is leaking not only 'split', but also
>> each element of split[], right?
>
> Yeah, I didn't notice that, but I think you're right.Correct.
I suspect that we would be better off in the longer term if we made conscious effort to deprecate and eradicate the use of strbuf_split* API functions. They are easy to write crappy code with, inefficient, and error prone. You would rarely need to have N resulting pieces as strbufs to be easily manipulatable [*1*].
The function can be written by not using the "split and then rebuild" pattern, perhaps like so, and the result is even easier to read and understand, I would say. A sample rewrite is attached at the end.
[Footnote]
*1* I wouldn't be this harsh if the function were to fill an
array of pointers or offsets into the original string. wt-status.c | 43 +++++++++++++++++++------------------------
1 file changed, 19 insertions(+), 24 deletions(-)
Show changes to wt-status.c +19 −24
diff --git a/wt-status.c b/wt-status.c
index ef74864..4886c35 100644
--- a/wt-status.c
+++ b/wt-status.c
@@ -1037,35 +1037,30 @@ static int split_commit_in_progress(struct wt_status *s)
*/
static void abbrev_sha1_in_line(struct strbuf *line)
{
- struct strbuf **split;
- int i;
+ const char *cp, *ep, *abbrev;
+ unsigned char sha1[20];
- if (starts_with(line->buf, "exec ") ||
- starts_with(line->buf, "x "))
+ /* the oddball "exec" does not have 40-hex as the second token */
+ if (starts_with(line->buf, "exec ") || starts_with(line->buf, "x "))
return;
- split = strbuf_split_max(line, ' ', 3);
- if (split[0] && split[1]) {
- unsigned char sha1[20];
- const char *abbrev;
+ /* find the second token on the line */
+ cp = strchr(line->buf, ' ');
+ if (!cp)
+ return;
+ cp++;
+ ep = strchr(cp, ' ');
+ if (!ep)
+ return;
- /*
- * strbuf_split_max left a space. Trim it and re-add
- * it after abbreviation.
- */
- strbuf_trim(split[1]);
- if (!get_sha1(split[1]->buf, sha1)) {
- abbrev = find_unique_abbrev(sha1, DEFAULT_ABBREV);
- strbuf_reset(split[1]);
- strbuf_addf(split[1], "%s ", abbrev);
- strbuf_reset(line);
- for (i = 0; split[i]; i++)
- strbuf_addf(line, "%s", split[i]->buf);
- }
- }
- for (i = 0; split[i]; i++)
- strbuf_release(split[i]);
+ /* is it 40-hex? */
+ if (ep - cp != GIT_SHA1_HEXSZ || get_sha1_hex(cp, sha1))
+ return;
+ /* replace it with its abbreviation */
+ abbrev = find_unique_abbrev(sha1, DEFAULT_ABBREV);
+ strbuf_splice(line, cp - line->buf, GIT_SHA1_HEXSZ,
+ abbrev, strlen(abbrev));
}
static void read_rebase_todolist(const char *fname, struct string_list *lines)
Stefan Beller
