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Re: [PATCH v18 07/48] lockfile.c: make lock_file return a meaningful errno on failurei

From
Michael Haggerty <mhagger@alum.mit.edu>
Date
Jun 18, 2014, 20:36 UTC
Message-ID
<53A1F84F.2010308@alum.mit.edu>
In-Reply-To
<1403020442-31049-8-git-send-email-sahlberg@google.com>
On 06/17/2014 05:53 PM, Ronnie Sahlberg wrote:
Show 57 quoted lines
> Making errno when returning from lock_file() meaningful, which should
> fix
> 
>  * an existing almost-bug in lock_ref_sha1_basic where it assumes
>    errno==ENOENT is meaningful and could waste some work on retries
> 
>  * an existing bug in repack_without_refs where it prints
>    strerror(errno) and picks advice based on errno, despite errno
>    potentially being zero and potentially having been clobbered by
>    that point
> 
> Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
> ---
>  lockfile.c | 17 ++++++++++++-----
>  refs.c     |  1 +
>  refs.h     |  1 +
>  3 files changed, 14 insertions(+), 5 deletions(-)
> 
> diff --git a/lockfile.c b/lockfile.c
> index 464031b..a921d77 100644
> --- a/lockfile.c
> +++ b/lockfile.c
> @@ -121,7 +121,7 @@ static char *resolve_symlink(char *p, size_t s)
>  	return p;
>  }
>  
> -
> +/* Make sure errno contains a meaningful value on error */
>  static int lock_file(struct lock_file *lk, const char *path, int flags)
>  {
>  	/*
> @@ -130,8 +130,10 @@ static int lock_file(struct lock_file *lk, const char *path, int flags)
>  	 */
>  	static const size_t max_path_len = sizeof(lk->filename) - 5;
>  
> -	if (strlen(path) >= max_path_len)
> +	if (strlen(path) >= max_path_len) {
> +		errno = ENAMETOOLONG;
>  		return -1;
> +	}
>  	strcpy(lk->filename, path);
>  	if (!(flags & LOCK_NODEREF))
>  		resolve_symlink(lk->filename, max_path_len);
> @@ -148,9 +150,13 @@ static int lock_file(struct lock_file *lk, const char *path, int flags)
>  			lock_file_list = lk;
>  			lk->on_list = 1;
>  		}
> -		if (adjust_shared_perm(lk->filename))
> -			return error("cannot fix permission bits on %s",
> -				     lk->filename);
> +		if (adjust_shared_perm(lk->filename)) {
> +			int save_errno = errno;
> +			error("cannot fix permission bits on %s",
> +			      lk->filename);
> +			errno = save_errno;
> +			return -1;
> +		}

Wouldn't it make sense for error() to save and restore errno instead of scattering the save/restore code around everywhere? I saw the same type of code about three commits later, too.

> [...]
Michael
-- 
Michael Haggerty
mhagger@alum.mit.edu
http://softwareswirl.blogspot.com/
Previous: Michael HaggertyNext: Ronnie Sahlberg
Message 10 of 61 in “Use ref transactions”
  1. 00/48 Use ref transactionsRonnie Sahlberg, Jun 17, 2014
  2. 01/48 refs.c: remove ref_transaction_rollbackRonnie Sahlberg, Jun 17, 2014
  3. 02/48 refs.c: ref_transaction_commit should not free the transactionRonnie Sahlberg, Jun 17, 2014
  4. 03/48 refs.c: constify the sha arguments for ref_transaction_create|delete|updateRonnie Sahlberg, Jun 17, 2014
  5. 04/48 refs.c: allow passing NULL to ref_transaction_freeRonnie Sahlberg, Jun 17, 2014
  6. 05/48 refs.c: add a strbuf argument to ref_transaction_commit for error loggingRonnie Sahlberg, Jun 17, 2014
  7. 06/48 lockfile.c: add a new public function unable_to_lock_messageRonnie Sahlberg, Jun 17, 2014
  8. 07/48 lockfile.c: make lock_file return a meaningful errno on failureiRonnie Sahlberg, Jun 17, 2014
  9. Michael HaggertyJun 18, 2014
  10. Michael HaggertyJun 18, 2014
  11. 08/48 refs.c: add an err argument to repack_without_refsRonnie Sahlberg, Jun 17, 2014
  12. 09/48 refs.c: make sure log_ref_setup returns a meaningful errnoRonnie Sahlberg, Jun 17, 2014
  13. 10/48 refs.c: verify_lock should set errno to something meaningfulRonnie Sahlberg, Jun 17, 2014
  14. Michael HaggertyJun 18, 2014
  15. Ronnie SahlbergJun 18, 2014
  16. 11/48 refs.c: make remove_empty_directories alwasy set errno to something saneRonnie Sahlberg, Jun 17, 2014
  17. Michael HaggertyJun 18, 2014
  18. Ronnie SahlbergJun 18, 2014
  19. 12/48 refs.c: commit_packed_refs to return a meaningful errno on failureRonnie Sahlberg, Jun 17, 2014
  20. 13/48 refs.c: make resolve_ref_unsafe set errno to something meaningful on errorRonnie Sahlberg, Jun 17, 2014
  21. 14/48 refs.c: log_ref_write should try to return meaningful errnoRonnie Sahlberg, Jun 17, 2014
  22. Michael HaggertyJun 18, 2014
  23. Ronnie SahlbergJun 18, 2014
  24. 15/48 refs.c: make ref_update_reject_duplicates take a strbuf argument for errorsRonnie Sahlberg, Jun 17, 2014
  25. 16/48 refs.c: add an err argument to delete_ref_looseRonnie Sahlberg, Jun 17, 2014
  26. Michael HaggertyJun 18, 2014
  27. Ronnie SahlbergJun 18, 2014
  28. Michael HaggertyJun 18, 2014
  29. Ronnie SahlbergJun 19, 2014
  30. 17/48 refs.c: make update_ref_write update a strbuf on failureRonnie Sahlberg, Jun 17, 2014
  31. 18/48 update-ref: use err argument to get error from ref_transaction_commitRonnie Sahlberg, Jun 17, 2014
  32. 19/48 refs.c: remove the onerr argument to ref_transaction_commitRonnie Sahlberg, Jun 17, 2014
  33. 20/48 refs.c: change ref_transaction_update() to do error checking and return statusRonnie Sahlberg, Jun 17, 2014
  34. 21/48 refs.c: change ref_transaction_create to do error checking and return statusRonnie Sahlberg, Jun 17, 2014
  35. 22/48 refs.c: update ref_transaction_delete to check for error and return statusRonnie Sahlberg, Jun 17, 2014
  36. 23/48 refs.c: make ref_transaction_begin take an err argumentRonnie Sahlberg, Jun 17, 2014
  37. 24/48 refs.c: add transaction.status and track OPEN/CLOSED/ERRORRonnie Sahlberg, Jun 17, 2014
  38. 25/48 tag.c: use ref transactions when doing updatesRonnie Sahlberg, Jun 17, 2014
  39. 26/48 replace.c: use the ref transaction functions for updatesRonnie Sahlberg, Jun 17, 2014
  40. 27/48 commit.c: use ref transactions for updatesRonnie Sahlberg, Jun 17, 2014
  41. 28/48 sequencer.c: use ref transactions for all ref updatesRonnie Sahlberg, Jun 17, 2014
  42. 29/48 fast-import.c: change update_branch to use ref transactionsRonnie Sahlberg, Jun 17, 2014
  43. 30/48 branch.c: use ref transaction for all ref updatesRonnie Sahlberg, Jun 17, 2014
  44. 31/48 refs.c: change update_ref to use a transactionRonnie Sahlberg, Jun 17, 2014
  45. 32/48 receive-pack.c: use a reference transaction for updating the refsRonnie Sahlberg, Jun 17, 2014
  46. 33/48 fast-import.c: use a ref transaction when dumping tagsRonnie Sahlberg, Jun 17, 2014
  47. 34/48 walker.c: use ref transaction for ref updatesRonnie Sahlberg, Jun 17, 2014
  48. 35/48 refs.c: make lock_ref_sha1 staticRonnie Sahlberg, Jun 17, 2014
  49. 36/48 refs.c: remove the update_ref_lock functionRonnie Sahlberg, Jun 17, 2014
  50. 37/48 refs.c: remove the update_ref_write functionRonnie Sahlberg, Jun 17, 2014
  51. 38/48 refs.c: remove lock_ref_sha1Ronnie Sahlberg, Jun 17, 2014
  52. 39/48 refs.c: make prune_ref use a transaction to delete the refRonnie Sahlberg, Jun 17, 2014
  53. 40/48 refs.c: make delete_ref use a transactionRonnie Sahlberg, Jun 17, 2014
  54. 41/48 refs.c: pass the ref log message to _create/delete/update instead of _commitRonnie Sahlberg, Jun 17, 2014
  55. 42/48 refs.c: pass NULL as *flags to read_ref_fullRonnie Sahlberg, Jun 17, 2014
  56. 43/48 refs.c: move the check for valid refname to lock_ref_sha1_basicRonnie Sahlberg, Jun 17, 2014
  57. 44/48 refs.c: call lock_ref_sha1_basic directly from commitRonnie Sahlberg, Jun 17, 2014
  58. 45/48 refs.c: pass a skip list to name_conflict_fnRonnie Sahlberg, Jun 17, 2014
  59. 46/48 refs.c: propagate any errno==ENOTDIR from _commit back to the callersRonnie Sahlberg, Jun 17, 2014
  60. 47/48 fetch.c: change s_update_ref to use a ref transactionRonnie Sahlberg, Jun 17, 2014
  61. 48/48 refs.c: make write_ref_sha1 staticRonnie Sahlberg, Jun 17, 2014

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