# [PATCH] We do not like "HEAD" as a new branch name 10 messages from 2005-12-15 to 2005-12-16. Participants: Johannes Schindelin, H. Peter Anvin, Alex Riesen, Junio C Hamano. Thread: https://gitlist.dev/t/2852 ## Johannes Schindelin, 2005-12-15 11:46 Subject: [PATCH] We do not like "HEAD" as a new branch name Message-ID: URL: https://gitlist.dev/e/Pine.LNX.4.63.0512151244230.22400%40wbgn013.biozentrum.uni-wuerzburg.de ``` This makes git-check-ref-format fail for "HEAD". Since the check is only executed when creating refs, the existing symbolic ref is safe. Signed-off-by: Johannes Schindelin --- This patch was triggered by Alex' mail. Even if it should be a rare case, it could catch some bad errors: Just try to run git checkout -b HEAD and imagine what a regular git user makes of the error message... refs.c | 5 +++++ t/t3300-funny-names.sh | 2 ++ 2 files changed, 7 insertions(+), 0 deletions(-) 04d60f0bf743f91d03e03acebf123db527cb7507 diff --git a/refs.c b/refs.c index bda45f7..293bfe7 100644 --- a/refs.c +++ b/refs.c @@ -332,6 +332,11 @@ int check_ref_format(const char *ref) if (ch == '.' || bad_ref_char(ch)) return -1; + /* do not allow "HEAD" as ref name */ + if (ch == 'H' && (!strcmp(cp, "EAD") || + !strncmp(cp, "EAD/", 4))) + return -1; + /* scan the rest of the path component */ while ((ch = *cp++) != 0) { if (bad_ref_char(ch)) diff --git a/t/t3300-funny-names.sh b/t/t3300-funny-names.sh index 897c378..8ebd896 100755 --- a/t/t3300-funny-names.sh +++ b/t/t3300-funny-names.sh @@ -139,4 +139,6 @@ test_expect_success 'git-apply non-git d git-apply --stat | sed -e "s/|.*//" -e "s/ *\$//" >current && diff -u expected current' +test_expect_failure 'HEAD is special' 'git checkout -b HEAD' + test_done -- 0.99.9.GIT ``` ## H. Peter Anvin, 2005-12-15 16:27 Subject: Re: [PATCH] We do not like "HEAD" as a new branch name Message-ID: <43A19962.2000202@zytor.com> URL: https://gitlist.dev/e/43A19962.2000202%40zytor.com In-Reply-To: ``` Johannes Schindelin wrote: > This makes git-check-ref-format fail for "HEAD". Since the check is only > executed when creating refs, the existing symbolic ref is safe. > diff --git a/refs.c b/refs.c > index bda45f7..293bfe7 100644 > --- a/refs.c > +++ b/refs.c > @@ -332,6 +332,11 @@ int check_ref_format(const char *ref) > if (ch == '.' || bad_ref_char(ch)) > return -1; > > + /* do not allow "HEAD" as ref name */ > + if (ch == 'H' && (!strcmp(cp, "EAD") || > + !strncmp(cp, "EAD/", 4))) > + return -1; > + > /* scan the rest of the path component */ > while ((ch = *cp++) != 0) { If you're have to open-code it, you might want to just do it all the way: if (ch == 'H' && cp[0] == 'E' && cp[1] == 'A' && cp[2] == 'D' && (cp[3] == '\0' || cp[3] == '/')) -hpa ``` ## Johannes Schindelin, 2005-12-15 16:40 Subject: Re: [PATCH] We do not like "HEAD" as a new branch name Message-ID: URL: https://gitlist.dev/e/Pine.LNX.4.63.0512151737240.3542%40wbgn013.biozentrum.uni-wuerzburg.de In-Reply-To: <43A19962.2000202@zytor.com> ``` Hi, On Thu, 15 Dec 2005, H. Peter Anvin wrote: > Johannes Schindelin wrote: > > This makes git-check-ref-format fail for "HEAD". Since the check is only > > executed when creating refs, the existing symbolic ref is safe. > > > diff --git a/refs.c b/refs.c > > index bda45f7..293bfe7 100644 > > --- a/refs.c > > +++ b/refs.c > > @@ -332,6 +332,11 @@ int check_ref_format(const char *ref) > > if (ch == '.' || bad_ref_char(ch)) > > return -1; > > + /* do not allow "HEAD" as ref name */ > > + if (ch == 'H' && (!strcmp(cp, "EAD") || > > + !strncmp(cp, "EAD/", 4))) > > + return -1; > > + > > /* scan the rest of the path component */ > > while ((ch = *cp++) != 0) { > > If you're have to open-code it, you might want to just do it all the way: > > if (ch == 'H' && cp[0] == 'E' && cp[1] == 'A' && cp[2] == 'D' && > (cp[3] == '\0' || cp[3] == '/')) ;-) I don't really care. I could have used !strcmp(cp - 1, "HEAD"), just as well... Ciao, Dscho ``` ## Alex Riesen, 2005-12-15 17:00 Subject: Re: [PATCH] We do not like "HEAD" as a new branch name Message-ID: <81b0412b0512150900j5b328e2fu72ffd8820e5140b7@mail.gmail.com> URL: https://gitlist.dev/e/81b0412b0512150900j5b328e2fu72ffd8820e5140b7%40mail.gmail.com In-Reply-To: ``` On 12/15/05, Johannes Schindelin wrote: > > > > If you're have to open-code it, you might want to just do it all the way: > > > I don't really care. I could have used !strcmp(cp - 1, "HEAD"), just as > well... > ...which would be more readable and greppable. ``` ## Junio C Hamano, 2005-12-15 19:34 Subject: Re: [PATCH] We do not like "HEAD" as a new branch name Message-ID: <7vacf2p320.fsf@assigned-by-dhcp.cox.net> URL: https://gitlist.dev/e/7vacf2p320.fsf%40assigned-by-dhcp.cox.net In-Reply-To: ``` Johannes Schindelin writes: > + /* do not allow "HEAD" as ref name */ > + if (ch == 'H' && (!strcmp(cp, "EAD") || > + !strncmp(cp, "EAD/", 4))) Why forbid HEAD in the middle, like "refs/heads/HEAD/frotz"? Confusion avoidance? We might want to forbid anything that matches /^.*_?HEAD$/ to catch ORIG_HEAD for example, though. ``` ## Johannes Schindelin, 2005-12-15 22:41 Subject: Re: [PATCH] We do not like "HEAD" as a new branch name Message-ID: URL: https://gitlist.dev/e/Pine.LNX.4.63.0512152339530.4962%40wbgn013.biozentrum.uni-wuerzburg.de In-Reply-To: <7vacf2p320.fsf@assigned-by-dhcp.cox.net> ``` Hi, On Thu, 15 Dec 2005, Junio C Hamano wrote: > Johannes Schindelin writes: > > > + /* do not allow "HEAD" as ref name */ > > + if (ch == 'H' && (!strcmp(cp, "EAD") || > > + !strncmp(cp, "EAD/", 4))) > > Why forbid HEAD in the middle, like "refs/heads/HEAD/frotz"? > Confusion avoidance? Exactly. > We might want to forbid anything that matches /^.*_?HEAD$/ to catch > ORIG_HEAD for example, though. Okay, I think this is what *I* would want to be illegal: HEAD, ORIG_HEAD, FETCH_HEAD MERGE_HEAD Others? Or should I really test for just *anything* ending in _HEAD besides HEAD itself? Ciao, Dscho ``` ## Junio C Hamano, 2005-12-15 23:38 Subject: Re: [PATCH] We do not like "HEAD" as a new branch name Message-ID: <7v4q5alyms.fsf@assigned-by-dhcp.cox.net> URL: https://gitlist.dev/e/7v4q5alyms.fsf%40assigned-by-dhcp.cox.net In-Reply-To: ``` Johannes Schindelin writes: > Okay, I think this is what *I* would want to be illegal: > > HEAD, > ORIG_HEAD, > FETCH_HEAD > MERGE_HEAD > > Others? Or should I really test for just *anything* ending in _HEAD > besides HEAD itself? Just to futureproof ourselves, how about this? /^(?:.*/)?(?:[A-Z0-9]+_)?HEAD$/ The last path component being "HEAD" or capital-or-digit followed by underscore followed by "HEAD". ``` ## Johannes Schindelin, 2005-12-16 01:40 Subject: Re: [PATCH] We do not like "HEAD" as a new branch name Message-ID: URL: https://gitlist.dev/e/Pine.LNX.4.63.0512160238300.6530%40wbgn013.biozentrum.uni-wuerzburg.de In-Reply-To: <7v4q5alyms.fsf@assigned-by-dhcp.cox.net> ``` Hi, On Thu, 15 Dec 2005, Junio C Hamano wrote: > Just to futureproof ourselves, how about this? > > /^(?:.*/)?(?:[A-Z0-9]+_)?HEAD$/ > > The last path component being "HEAD" or capital-or-digit > followed by underscore followed by "HEAD". Okay. Why not go the full nine yards, and not be difficult about it: diff --git a/refs.c b/refs.c --- a/refs.c +++ b/refs.c @@ -345,6 +345,11 @@ int check_ref_format(const char *ref) if (!ch) { if (level < 2) return -1; /* at least of form "heads/blah" */ + + /* do not allow ref name to end in "HEAD" */ + if (cp - ref > 4 && !strcmp(cp - 4, "HEAD")) + return -1; + return 0; } } Ciao, Dscho ``` ## Junio C Hamano, 2005-12-16 06:34 Subject: Re: [PATCH] We do not like "HEAD" as a new branch name Message-ID: <7v8xullfct.fsf@assigned-by-dhcp.cox.net> URL: https://gitlist.dev/e/7v8xullfct.fsf%40assigned-by-dhcp.cox.net In-Reply-To: ``` Johannes Schindelin writes: > Okay. Why not go the full nine yards, and not be difficult about it: That's fine. There is an off-by-one in your code, though. I've committed it with a tweak. ``` ## Johannes Schindelin, 2005-12-16 11:32 Subject: Re: [PATCH] We do not like "HEAD" as a new branch name Message-ID: URL: https://gitlist.dev/e/Pine.LNX.4.63.0512161231100.28757%40wbgn013.biozentrum.uni-wuerzburg.de In-Reply-To: <7v8xullfct.fsf@assigned-by-dhcp.cox.net> ``` Hi, On Thu, 15 Dec 2005, Junio C Hamano wrote: > Johannes Schindelin writes: > > > Okay. Why not go the full nine yards, and not be difficult about it: > > That's fine. There is an off-by-one in your code, though. > I've committed it with a tweak. Thanks. I did test it (quickly), and t3300 said it was fine. Strange. Ciao, Dscho ```