[PATCH 1/2] sha1_name.c: signal if @{-N} was a true branch nameor a detached head
- From
Junio C Hamano <gitster@pobox.com>
- Date
- May 8, 2013, 21:12 UTC
- Message-ID
- <7vk3n9dvlu.fsf@alter.siamese.dyndns.org>
The original API read "checkout: moving from (.*) to ..." from the reflog of the HEAD, and returned the substring between "from" and "to", but there was no way, if the substring was a 40-hex string, to tell if we were on a detached HEAD at that commit object, or on a branch whose name happened to be the 40-hex string.
At this point, we cannot afford to change the format recorded in the reflog, so introduce a heuristics to see if the 40-hex matches the object name of the commit we are switching out of. This will unfortunately mishandle this case:
HEX=$(git rev-parse master) git checkout -b $HEX master git checkout master
where we were indeed on a non-detached $HEX branch (i.e. HEAD was pointing at refs/heads/$HEX, not storing $HEX), of course, but otherwise should be fairly reliable.
Signed-off-by: Junio C Hamano <gitster@pobox.com> ---
* This is a preparatory step for the beginning of a much larger
series. Peff is Cc'ed because one of the most tricky issue
involves what d46a8301930a (fix parsing of @{-1}@{u} combination,
2010-01-28) did.sha1_name.c | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-)
diff --git a/sha1_name.c b/sha1_name.c index 3820f28..1473bb6 100644 --- a/sha1_name.c +++ b/sha1_name.c @@ -862,6 +862,7 @@ static int get_sha1_oneline(const char *prefix, unsigned char *sha1, struct grab_nth_branch_switch_cbdata { int remaining; struct strbuf buf; + int detached; }; static int grab_nth_branch_switch(unsigned char *osha1, unsigned char *nsha1, @@ -880,9 +881,14 @@ static int grab_nth_branch_switch(unsigned char *osha1, unsigned char *nsha1, if (!match || !target) return 0; if (--(cb->remaining) == 0) { + unsigned char sha1[20]; + len = target - match; strbuf_reset(&cb->buf); strbuf_add(&cb->buf, match, len); + cb->detached = (len == 40 && + !get_sha1_hex(match, sha1) && + !hashcmp(osha1, sha1)); return 1; /* we are done */ } return 0; @@ -891,8 +897,12 @@ static int grab_nth_branch_switch(unsigned char *osha1, unsigned char *nsha1, /* * Parse @{-N} syntax, return the number of characters parsed * if successful; otherwise signal an error with negative value. + * The string in buf.buf is either a branch name (needs to be + * prefixed with "refs/heads/" if the caller wants to make it + * a fully spelled refname) or 40-hex object name of the detached + * HEAD, and *detached is set to true for the latter. */ -static int interpret_nth_prior_checkout(const char *name, struct strbuf *buf) +static int interpret_nth_prior_checkout(const char *name, struct strbuf *buf, int *detached) { long nth; int retval; @@ -917,6 +927,8 @@ static int interpret_nth_prior_checkout(const char *name, struct strbuf *buf) if (0 < for_each_reflog_ent_reverse("HEAD", grab_nth_branch_switch, &cb)) { strbuf_reset(buf); strbuf_add(buf, cb.buf.buf, cb.buf.len); + if (detached) + *detached = cb.detached; retval = brace - name + 1; } @@ -992,7 +1004,7 @@ int interpret_branch_name(const char *name, struct strbuf *buf) char *cp; struct branch *upstream; int namelen = strlen(name); - int len = interpret_nth_prior_checkout(name, buf); + int len = interpret_nth_prior_checkout(name, buf, NULL); int tmp_len; if (!len)
-- 1.8.3-rc1-182-gc61d106