On Fri, Feb 29, 2008 at 05:41:53PM -0800, Junio C Hamano wrote:
> The function returned NULL when no object that matches the name
> was found, but that made the callers more complicated, as nobody
> used that NULL return as an indication that no object with such
> a name exists. They (at least the careful ones) instead took
> the full 40-hexdigit and used in such a case, and the careless
> ones segfaulted.
>
> With this "git rev-parse --short 5555555555555555555555555555555555555555"
> would stop segfaulting.
I have been meaning to clean up and submit a similar patch from the
1.5.4 freeze period. However, your patch will always print the
40-hexdigit version, which looks quite ugly in status output. Instead,
we can do much better by finding the longest subsequence we _do_ know
about, and adding one digit to it.
So you get:
# this is the current master, abbreviated
$ git rev-parse --short 97b97c58e609a1cd23b3c2514f41cdb0405870ee
97b97c5
# this is an object we don't have, but similar to that
$ git rev-parse --short 97b97c58e609a1cd23b3c2514f41cdb0405870ff
97b97c58e609a1cd23b3c2514f41cdb0405870f
# and less similar means we can abbreviate more
$ git rev-parse --short 97b97c58e609a1cd23b3c2514fffffffffffffff
97b97c58e609a1cd23b3c2514ff
Implementation is below:
> --- a/sha1_name.c
> +++ b/sha1_name.c
> @@ -202,16 +202,14 @@ const char *find_unique_abbrev(const unsigned char *sha1, int len)
> while (len < 40) {
> unsigned char sha1_ret[20];
> status = get_short_sha1(hex, len, sha1_ret, 1);
> - if (!status ||
> - (is_null && status != SHORT_NAME_AMBIGUOUS)) {
> + if ((!is_null && !status) ||
> + (is_null && status == SHORT_NAME_NOT_FOUND)) {
> hex[len] = 0;
> return hex;
> }
> - if (status != SHORT_NAME_AMBIGUOUS)
> - return NULL;
> len++;
> }
> - return NULL;
> + return hex;
> }
All we have to do is treat the "missing" case like we treat "is_null"
(and in fact, is_null is just a specialized case of something we don't
have). So replace this hunk with:
diff --git a/sha1_name.c b/sha1_name.c
index 05c2e7a..9c71d1b 100644
--- a/sha1_name.c
+++ b/sha1_name.c
@@ -192,18 +192,18 @@ static int get_short_sha1(const char *name, int len, unsigned char *sha1,
const char *find_unique_abbrev(const unsigned char *sha1, int len)
{
- int status, is_null;
+ int status, missing;
static char hex[41];
- is_null = is_null_sha1(sha1);
+ missing = !has_sha1_file(sha1);
memcpy(hex, sha1_to_hex(sha1), 40);
if (len == 40 || !len)
return hex;
while (len < 40) {
unsigned char sha1_ret[20];
status = get_short_sha1(hex, len, sha1_ret, 1);
- if ((!is_null && !status) ||
- (is_null && status == SHORT_NAME_NOT_FOUND)) {
+ if ((!missing && !status) ||
+ (missing && status == SHORT_NAME_NOT_FOUND)) {
hex[len] = 0;
return hex;
}
-Peff
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