# name-ref on annotated-tags is null terminated, but lightweight tags arent 4 messages from 2020-06-05 to 2020-06-05. Participants: Max Resnick, Junio C Hamano. Thread: https://gitlist.dev/t/53618 ## Max Resnick, 2020-06-05 16:51 Subject: name-ref on annotated-tags is null terminated, but lightweight tags arent Message-ID: <20200605165109.jr6mjl6xz7upofdy@forgemax.local> URL: https://gitlist.dev/e/20200605165109.jr6mjl6xz7upofdy%40forgemax.local ``` Thank you for filling out a Git bug report! Please answer the following questions to help us understand your issue. What did you do before the bug happened? (Steps to reproduce your issue) I was using name-rev to resolve a commits tag name. Annotated tags seem to have a null termination and lightweight tags dont. ˋˋˋ /tmp ❯ git clone https://github.com/maxres-fr/null-termination-issue.git Cloning into 'null-termination-issue'... remote: Enumerating objects: 10, done. remote: Counting objects: 100% (10/10), done. remote: Compressing objects: 100% (4/4), done. remote: Total 10 (delta 0), reused 10 (delta 0), pack-reused 0 Unpacking objects: 100% (10/10), 757 bytes | 189.00 KiB/s, done. /tmp ❯ cd null-termination-issue /tmp/null-termination-issue on  master ❯ git pull --tags Already up to date. /tmp/null-termination-issue on  master ❯ git tag --list /tmp/null-termination-issue on  master ❯ git name-rev --tag --name-only 38bdebc9107cab4ab3718d0581632702e74d9209 annotated-tag^0 /tmp/null-termination-issue on  master ❯ git name-rev --tag --name-only a340894d3ee655ae6c336a85b42d2215d52609e3 lightweight-tag ˋˋˋ What did you expect to happen? (Expected behavior) `git name-rev --tag --name-only ANNOTATED-COMMIT-ID` to return the name without null termination What happened instead? (Actual behavior) `git name-rev --tag --name-only ANNOTATED-COMMIT-ID` returns the name but it's null terminated What's different between what you expected and what actually happened? a null control character exists. Anything else you want to add: I tried this with the following git versions: 2.11, 2.23, 2.26, 2.27. I've also been able to reproduce on MacOS. Please review the rest of the bug report below. You can delete any lines you don't wish to share. [System Info] git version: git version 2.27.0.rc0 cpu: x86_64 no commit associated with this build sizeof-long: 8 sizeof-size_t: 8 uname: Linux 5.6.0-1-amd64 #1 SMP Debian 5.6.7-1 (2020-04-29) x86_64 compiler info: gnuc: 9.3 libc info: glibc: 2.30 [Enabled Hooks] ``` ## Junio C Hamano, 2020-06-05 17:04 Subject: Re: name-ref on annotated-tags is null terminated, but lightweight tags arent Message-ID: URL: https://gitlist.dev/e/xmqqa71ho34p.fsf%40gitster.c.googlers.com In-Reply-To: <20200605165109.jr6mjl6xz7upofdy@forgemax.local> ``` Max Resnick writes: > What did you do before the bug happened? (Steps to reproduce your issue) > I was using name-rev to resolve a commits tag name. Annotated tags seem > to have a null termination and lightweight tags dont. > ❯ git name-rev --tag --name-only > 38bdebc9107cab4ab3718d0581632702e74d9209 > annotated-tag^0 > > /tmp/null-termination-issue on  master > ❯ git name-rev --tag --name-only > a340894d3ee655ae6c336a85b42d2215d52609e3 > lightweight-tag Presumably the long hexadecimal are supposed to be on the same line as the "name-rev" command itself? There is nothing broken in the above output. The anotated tag (annotated-tag in your example) is an object that merely points at another object (in which case, the object whose name is 38bdebc9, which I guess would be a commit) and it itself has an object name different from 38bdebc9. The suffix "^0" (which has nothing to do with null-termination) means "I do not mean the tag object itself, but the object that is pointed by it". On the other hand, your lightweight-tag is directly pointing at the object a340894d, so saying "lightweight-tag" is sufficient, as there is no extra layer of indirection (i.e. a tag object) involved. Hope it helps. ``` ## Max Resnick, 2020-06-05 17:16 Subject: Re: name-ref on annotated-tags is null terminated, but lightweight tags arent Message-ID: <20200605171607.rducvc4xretxacn5@forgemax.local> URL: https://gitlist.dev/e/20200605171607.rducvc4xretxacn5%40forgemax.local In-Reply-To: ``` Thanks Junio for the quick response. > Presumably the long hexadecimal are supposed to be on the same line > as the "name-rev" command itself? Yes, sorry I didn't see that the formatting was broken before I sent. > The suffix "^0" (which has nothing to do > with null-termination) means "I do not mean the tag object itself, > but the object that is pointed by it". Ok, thanks. I need to unpack that a bit more. I tried to dig around in the man to see if there was indication if that's what was expected but didn't find anything at less for name-rev. On 20/06/05 10:04AM, Junio C Hamano wrote: > Max Resnick writes: > > > What did you do before the bug happened? (Steps to reproduce your issue) > > I was using name-rev to resolve a commits tag name. Annotated tags seem > > to have a null termination and lightweight tags dont. > > > ❯ git name-rev --tag --name-only > > 38bdebc9107cab4ab3718d0581632702e74d9209 > > annotated-tag^0 > > > > /tmp/null-termination-issue on  master > > ❯ git name-rev --tag --name-only > > a340894d3ee655ae6c336a85b42d2215d52609e3 > > lightweight-tag > > Presumably the long hexadecimal are supposed to be on the same line > as the "name-rev" command itself? > > There is nothing broken in the above output. The anotated tag > (annotated-tag in your example) is an object that merely points at > another object (in which case, the object whose name is 38bdebc9, > which I guess would be a commit) and it itself has an object name > different from 38bdebc9. The suffix "^0" (which has nothing to do > with null-termination) means "I do not mean the tag object itself, > but the object that is pointed by it". > > On the other hand, your lightweight-tag is directly pointing at the > object a340894d, so saying "lightweight-tag" is sufficient, as there > is no extra layer of indirection (i.e. a tag object) involved. > > Hope it helps. ``` ## Junio C Hamano, 2020-06-05 17:59 Subject: Re: name-ref on annotated-tags is null terminated, but lightweight tags arent Message-ID: URL: https://gitlist.dev/e/xmqq3679o0lr.fsf%40gitster.c.googlers.com In-Reply-To: <20200605171607.rducvc4xretxacn5@forgemax.local> ``` Max Resnick writes: > Thanks Junio for the quick response. > >> Presumably the long hexadecimal are supposed to be on the same line >> as the "name-rev" command itself? > > Yes, sorry I didn't see that the formatting was broken before I sent. > >> The suffix "^0" (which has nothing to do >> with null-termination) means "I do not mean the tag object itself, >> but the object that is pointed by it". > > Ok, thanks. I need to unpack that a bit more. I tried to dig around in > the man to see if there was indication if that's what was expected but > didn't find anything at less for name-rev. "git help revisions" has this, which may help. ^[], e.g. HEAD^, v1.5.1^0 A suffix ^ to a revision parameter means the first parent of that commit object. ^ means the th parent (i.e. ^ is equivalent to ^1). As a special rule, ^0 means the commit itself and is used when is the object name of a tag object that refers to a commit object. The help text in "git help name-rev" only says "names suitable for human digestion", which may want to be clarified. Thanks. ```