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Re: [PATCH v20 43/48] refs.c: move the check for valid refname to lock_ref_sha1_basic

From
Ronnie Sahlberg <sahlberg@google.com>
Date
Jul 15, 2014, 16:40 UTC
Message-ID
<CAL=YDW=3aYhMNjCtT7BV=RDkRN2=Ac0uC_iEiQrO45i4C3zeDw@mail.gmail.com>
In-Reply-To
<53BC07FC.8080601@alum.mit.edu>
On Tue, Jul 8, 2014 at 8:02 AM, Michael Haggerty <mhagger@alum.mit.edu> wrote:
Show 35 quoted lines
> On 06/20/2014 04:43 PM, Ronnie Sahlberg wrote:
>> Move the check for check_refname_format from lock_any_ref_for_update
>> to lock_ref_sha1_basic. At some later stage we will get rid of
>> lock_any_ref_for_update completely.
>>
>> If lock_ref_sha1_basic fails the check_refname_format test, set errno to
>> EINVAL before returning NULL. This to guarantee that we will not return an
>> error without updating errno.
>>
>> This leaves lock_any_ref_for_updates as a no-op wrapper which could be removed.
>> But this wrapper is also called from an external caller and we will soon
>> make changes to the signature to lock_ref_sha1_basic that we do not want to
>> expose to that caller.
>>
>> This changes semantics for lock_ref_sha1_basic slightly. With this change
>> it is no longer possible to open a ref that has a badly name which breaks
>
> s/badly name/bad name,/
>
>> any codepaths that tries to open and repair badly named refs. The normal refs
>
> s/tries/try/
>
>> API should not allow neither creating nor accessing refs with invalid names.
>
> s/not allow neither/allow neither/
>
>> If we need such recovery code we could add it as an option to git fsck and have
>> git fsck be the only sanctioned way of bypassing the normal API and checks.
>
> I like the sentiment, but in the real world I'm not sure we can take
> such a step based only on good intentions.  Which callers would be
> affected?  Where is this "git fsck" code that would be needed to help
> people rescue their repos?
>

I think the repair things are already busted since a while, so I don't think this will make things worse, but I will change it to make it better than this patch and better than current master, please see below.

<current git>
$ cp .git/refs/heads/master .git/refs/heads/master.....@\*@\\.
$ git branch
   fatal: Reference has invalid format: 'refs/heads/master.....@*@\.'
$ git branch -D master.....@\*@\\.
  error: branch 'master.....@*@\.' not found.
git fsck does report that there is a problem with a broken ref
  fatal: Reference has invalid format: 'refs/heads/master.....@*@\.'
But I don't think there is any way to fix this other than manually
deleting the file from the command line.
(this is because we need to do a resolve_ref_unsafe which will not
work and if we can not do a resolve_ref_unsafe we can not delete the
ref,
 there is also the issue where we can not read the ref into ref-cache)
What I suggest doing here is to create a new patch towards the end of
the series that will :
* change the resolve_ref_unsafe(... , int reading, ...) argument to be
a bitmask of flags with
    #define RESOLVE_REF_READING 0x01  (== current flag)
    #define RESOLVE_REF_ALLOW_BAD_NAME 0x02  (== disable checking the
refname format during resolve)
* then provide the flag for RESOLVE_REF_ALLOW_BAD_NAME for the cases
where we try to resolve a ref in builtin/branch.c where we try to
delete a ref
* then also pass the same flag to lock_ref_sha1_basic when we are
deleting a ref from transaction_commit so we can disable the "check
refname" check there too.

I think that is all that is needed but I will see if there are additional changes needed once I implement it.

This will mean that the semantics will become :
* you can not create or access a branch with a bad name since both
resolving it and locking it will fail.
* but you can always delete a branch regardless of whether the name is
good or bad.
(this will also mean that you will be able to rename a bad branch name
to a new good name)
which I think would be pretty sane semantics.
I will implement these changes as a separate patch.
Comments?

regards ronnie sahlberg

Show 52 quoted lines
> I can also imagine that we will tighten up the check_refname_format
> checks in the future; for example, I think it would be a good idea to
> prohibit reference names that start with '-' because it is almost
> impossible to work with them (their names look like command-line
> options).  If we ever make a change like that, we will need some amount
> of tolerance in git versions around the transition.
>
> So...I like the idea of enforcing refname checks at the lowest level
> possible, but I think that the change you propose is too abrupt.  I
> think it needs either more careful analysis showing that it won't hurt
> anybody, or some kind of tooling or non-strict mode that people can use
> to fix their repositories.
>
> Michael
>
>> Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
>> ---
>>  refs.c | 7 +++++--
>>  1 file changed, 5 insertions(+), 2 deletions(-)
>>
>> diff --git a/refs.c b/refs.c
>> index 389a55f..bccf8c3 100644
>> --- a/refs.c
>> +++ b/refs.c
>> @@ -2088,6 +2088,11 @@ static struct ref_lock *lock_ref_sha1_basic(const char *refname,
>>       int missing = 0;
>>       int attempts_remaining = 3;
>>
>> +     if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) {
>> +             errno = EINVAL;
>> +             return NULL;
>> +     }
>> +
>>       lock = xcalloc(1, sizeof(struct ref_lock));
>>       lock->lock_fd = -1;
>>
>> @@ -2179,8 +2184,6 @@ struct ref_lock *lock_any_ref_for_update(const char *refname,
>>                                        const unsigned char *old_sha1,
>>                                        int flags, int *type_p)
>>  {
>> -     if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL))
>> -             return NULL;
>>       return lock_ref_sha1_basic(refname, old_sha1, flags, type_p);
>>  }
>>
>>
>
>
> --
> Michael Haggerty
> mhagger@alum.mit.edu
>
Previous: Michael HaggertyNext: Jonathan Nieder
Message 71 of 99 in “Use ref transactions”
  1. 00/48 Use ref transactionsRonnie Sahlberg, Jun 20, 2014
  2. 01/48 refs.c: remove ref_transaction_rollbackRonnie Sahlberg, Jun 20, 2014
  3. 02/48 refs.c: ref_transaction_commit should not free the transactionRonnie Sahlberg, Jun 20, 2014
  4. 03/48 refs.c: constify the sha arguments for ref_transaction_create|delete|updateRonnie Sahlberg, Jun 20, 2014
  5. 04/48 refs.c: allow passing NULL to ref_transaction_freeRonnie Sahlberg, Jun 20, 2014
  6. 05/48 refs.c: add a strbuf argument to ref_transaction_commit for error loggingRonnie Sahlberg, Jun 20, 2014
  7. 06/48 lockfile.c: add a new public function unable_to_lock_messageRonnie Sahlberg, Jun 20, 2014
  8. 07/48 lockfile.c: make lock_file return a meaningful errno on failureiRonnie Sahlberg, Jun 20, 2014
  9. Michael HaggertyJul 8, 2014
  10. 08/48 refs.c: add an err argument to repack_without_refsRonnie Sahlberg, Jun 20, 2014
  11. 09/48 refs.c: make sure log_ref_setup returns a meaningful errnoRonnie Sahlberg, Jun 20, 2014
  12. 10/48 refs.c: verify_lock should set errno to something meaningfulRonnie Sahlberg, Jun 20, 2014
  13. 11/48 refs.c: make remove_empty_directories always set errno to something saneRonnie Sahlberg, Jun 20, 2014
  14. 12/48 refs.c: commit_packed_refs to return a meaningful errno on failureRonnie Sahlberg, Jun 20, 2014
  15. 13/48 refs.c: make resolve_ref_unsafe set errno to something meaningful on errorRonnie Sahlberg, Jun 20, 2014
  16. Karsten BleesJun 26, 2014
  17. 14/48 refs.c: log_ref_write should try to return meaningful errnoRonnie Sahlberg, Jun 20, 2014
  18. 15/48 refs.c: make ref_update_reject_duplicates take a strbuf argument for errorsRonnie Sahlberg, Jun 20, 2014
  19. 16/48 refs.c: make update_ref_write update a strbuf on failureRonnie Sahlberg, Jun 20, 2014
  20. 17/48 update-ref: use err argument to get error from ref_transaction_commitRonnie Sahlberg, Jun 20, 2014
  21. 18/48 refs.c: remove the onerr argument to ref_transaction_commitRonnie Sahlberg, Jun 20, 2014
  22. 19/48 refs.c: change ref_transaction_update() to do error checking and return statusRonnie Sahlberg, Jun 20, 2014
  23. 20/48 refs.c: change ref_transaction_create to do error checking and return statusRonnie Sahlberg, Jun 20, 2014
  24. Michael HaggertyJul 8, 2014
  25. Ronnie SahlbergJul 14, 2014
  26. 21/48 refs.c: update ref_transaction_delete to check for error and return statusRonnie Sahlberg, Jun 20, 2014
  27. 22/48 refs.c: make ref_transaction_begin take an err argumentRonnie Sahlberg, Jun 20, 2014
  28. Michael HaggertyJul 8, 2014
  29. Ronnie SahlbergJul 14, 2014
  30. 23/48 refs.c: add transaction.status and track OPEN/CLOSED/ERRORRonnie Sahlberg, Jun 20, 2014
  31. Michael HaggertyJul 8, 2014
  32. Ronnie SahlbergJul 14, 2014
  33. 24/48 tag.c: use ref transactions when doing updatesRonnie Sahlberg, Jun 20, 2014
  34. Michael HaggertyJul 8, 2014
  35. 25/48 replace.c: use the ref transaction functions for updatesRonnie Sahlberg, Jun 20, 2014
  36. Michael HaggertyJul 8, 2014
  37. Ronnie SahlbergJul 14, 2014
  38. 26/48 commit.c: use ref transactions for updatesRonnie Sahlberg, Jun 20, 2014
  39. 27/48 sequencer.c: use ref transactions for all ref updatesRonnie Sahlberg, Jun 20, 2014
  40. Michael HaggertyJul 8, 2014
  41. Ronnie SahlbergJul 14, 2014
  42. 28/48 fast-import.c: change update_branch to use ref transactionsRonnie Sahlberg, Jun 20, 2014
  43. 29/48 branch.c: use ref transaction for all ref updatesRonnie Sahlberg, Jun 20, 2014
  44. 30/48 refs.c: change update_ref to use a transactionRonnie Sahlberg, Jun 20, 2014
  45. Michael HaggertyJul 8, 2014
  46. Ronnie SahlbergJul 14, 2014
  47. 31/48 receive-pack.c: use a reference transaction for updating the refsRonnie Sahlberg, Jun 20, 2014
  48. Michael HaggertyJul 8, 2014
  49. Ronnie SahlbergJul 14, 2014
  50. 32/48 fast-import.c: use a ref transaction when dumping tagsRonnie Sahlberg, Jun 20, 2014
  51. 33/48 walker.c: use ref transaction for ref updatesRonnie Sahlberg, Jun 20, 2014
  52. Michael HaggertyJul 8, 2014
  53. Ronnie SahlbergJul 14, 2014
  54. 34/48 refs.c: make lock_ref_sha1 staticRonnie Sahlberg, Jun 20, 2014
  55. 35/48 refs.c: remove the update_ref_lock functionRonnie Sahlberg, Jun 20, 2014
  56. 36/48 refs.c: remove the update_ref_write functionRonnie Sahlberg, Jun 20, 2014
  57. 37/48 refs.c: remove lock_ref_sha1Ronnie Sahlberg, Jun 20, 2014
  58. Michael HaggertyJul 8, 2014
  59. 38/48 refs.c: make prune_ref use a transaction to delete the refRonnie Sahlberg, Jun 20, 2014
  60. 39/48 refs.c: make delete_ref use a transactionRonnie Sahlberg, Jun 20, 2014
  61. Michael HaggertyJul 8, 2014
  62. Ronnie SahlbergJul 14, 2014
  63. 40/48 refs.c: add an err argument to delete_ref_looseRonnie Sahlberg, Jun 20, 2014
  64. Michael HaggertyJul 8, 2014
  65. Ronnie SahlbergJul 16, 2014
  66. 41/48 refs.c: pass the ref log message to _create/delete/update instead of _commitRonnie Sahlberg, Jun 20, 2014
  67. Michael HaggertyJul 8, 2014
  68. 42/48 refs.c: pass NULL as *flags to read_ref_fullRonnie Sahlberg, Jun 20, 2014
  69. 43/48 refs.c: move the check for valid refname to lock_ref_sha1_basicRonnie Sahlberg, Jun 20, 2014
  70. Michael HaggertyJul 8, 2014
  71. Ronnie SahlbergJul 15, 2014
  72. Jonathan NiederJul 15, 2014
  73. Jonathan NiederJul 15, 2014
  74. Junio C HamanoJul 15, 2014
  75. Ronnie SahlbergJul 15, 2014
  76. Ronnie SahlbergJul 15, 2014
  77. Ronnie SahlbergJul 15, 2014
  78. Michael HaggertyAug 20, 2014
  79. Ronnie SahlbergAug 20, 2014
  80. Jonathan NiederAug 20, 2014
  81. Ronnie SahlbergAug 20, 2014
  82. Michael HaggertyAug 20, 2014
  83. Ronnie SahlbergAug 21, 2014
  84. Junio C HamanoAug 20, 2014
  85. Michael HaggertyAug 20, 2014
  86. Junio C HamanoAug 20, 2014
  87. Ronnie SahlbergAug 20, 2014
  88. Michael HaggertyAug 22, 2014
  89. 44/48 refs.c: call lock_ref_sha1_basic directly from commitRonnie Sahlberg, Jun 20, 2014
  90. Michael HaggertyJul 8, 2014
  91. 45/48 refs.c: pass a skip list to name_conflict_fnRonnie Sahlberg, Jun 20, 2014
  92. 46/48 refs.c: propagate any errno==ENOTDIR from _commit back to the callersRonnie Sahlberg, Jun 20, 2014
  93. 47/48 fetch.c: change s_update_ref to use a ref transactionRonnie Sahlberg, Jun 20, 2014
  94. 48/48 refs.c: make write_ref_sha1 staticRonnie Sahlberg, Jun 20, 2014
  95. Michael HaggertyJul 8, 2014
  96. Junio C HamanoJul 8, 2014
  97. Jeff KingJul 9, 2014
  98. Ronnie SahlbergJul 14, 2014
  99. Ronnie SahlbergJul 14, 2014

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