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Re: [PATCH] Simplify handling of setup_git_directory_gently() failure cases.




Hi Erin,

On Thu, 13 Dec 2018, Erin Dahlgren wrote:

> setup_git_directory_gently() expects two types of failures to
> discover a git directory (e.g. .git/):
> 
>   - GIT_DIR_HIT_CEILING: could not find a git directory in any
> 	parent directories of the cwd.
>   - GIT_DIR_HIT_MOUNT_POINT: could not find a git directory in
> 	any parent directories up to the mount point of the cwd.
> 
> Both cases are handled in a similar way, but there are misleading
> and unimportant differences. In both cases, setup_git_directory_gently()
> should:
> 
>   - Die if we are not in a git repository. Otherwise:
>   - Set nongit_ok = 1, indicating that we are not in a git repository
> 	but this is ok.
>   - Call strbuf_release() on any non-static struct strbufs that we
> 	allocated.
> 
> Before this change are two misleading additional behaviors:
> 
>   - GIT_DIR_HIT_CEILING: setup_nongit() changes to the cwd for no
> 	apparent reason. We never had the chance to change directories
> 	up to this point so chdir(current cwd) is pointless.
>   - GIT_DIR_HIT_MOUNT_POINT: strbuf_release() frees the buffer
> 	of a static struct strbuf (cwd). This is unnecessary because the
> 	struct is static so its buffer is always reachable. This is also
> 	misleading because nowhere else in the function is this buffer
> 	released.
> 
> This change eliminates these two misleading additional behaviors and
> deletes setup_nogit() because the code is clearer without it. The
> result is that we can see clearly that GIT_DIR_HIT_CEILING and
> GIT_DIR_HIT_MOUNT_POINT lead to the same behavior (ignoring the
> different help messages).
> 
> Thanks-to: Johannes Schindelin <johannes.schindelin@xxxxxx>
> Signed-off-by: Erin Dahlgren <eedahlgren@xxxxxxxxx>

Thank you for working on this!

> ---
>  setup.c | 34 +++++++++++++---------------------
>  1 file changed, 13 insertions(+), 21 deletions(-)

Nice! It's always good to see a code reduction with such a cleanup.

Just one thing:

> diff --git a/setup.c b/setup.c
> index 1be5037..b441e39 100644
> --- a/setup.c
> +++ b/setup.c
> @@ -831,16 +831,6 @@ static const char *setup_bare_git_dir(struct strbuf *cwd, int offset,
>  	return NULL;
>  }
>  
> -static const char *setup_nongit(const char *cwd, int *nongit_ok)
> -{
> -	if (!nongit_ok)
> -		die(_("not a git repository (or any of the parent directories): %s"), DEFAULT_GIT_DIR_ENVIRONMENT);
> -	if (chdir(cwd))
> -		die_errno(_("cannot come back to cwd"));
> -	*nongit_ok = 1;
> -	return NULL;
> -}
> -
>  static dev_t get_device_or_die(const char *path, const char *prefix, int prefix_len)
>  {
>  	struct stat buf;
> @@ -1097,18 +1087,20 @@ const char *setup_git_directory_gently(int *nongit_ok)
>  		prefix = setup_bare_git_dir(&cwd, dir.len, &repo_fmt, nongit_ok);
>  		break;
>  	case GIT_DIR_HIT_CEILING:
> -		prefix = setup_nongit(cwd.buf, nongit_ok);
> -		break;
> +		if (!nongit_ok)
> +			die(_("not a git repository (or any of the parent directories): %s"),
> +					DEFAULT_GIT_DIR_ENVIRONMENT);
> +		*nongit_ok = 1;
> +		strbuf_release(&dir);
> +		return NULL;
>  	case GIT_DIR_HIT_MOUNT_POINT:
> -		if (nongit_ok) {
> -			*nongit_ok = 1;
> -			strbuf_release(&cwd);
> -			strbuf_release(&dir);
> -			return NULL;
> -		}
> -		die(_("not a git repository (or any parent up to mount point %s)\n"
> -		      "Stopping at filesystem boundary (GIT_DISCOVERY_ACROSS_FILESYSTEM not set)."),
> -		    dir.buf);
> +		if (!nongit_ok)
> +			die(_("not a git repository (or any parent up to mount point %s)\n"
> +						"Stopping at filesystem boundary (GIT_DISCOVERY_ACROSS_FILESYSTEM not set)."),
> +					dir.buf);

This indentation would probably be better aligned with the first
double-quote on the `die` line.

Otherwise: ACK!

Thank you,
Johannes

> +		*nongit_ok = 1;
> +		strbuf_release(&dir);
> +		return NULL;
>  	default:
>  		BUG("unhandled setup_git_directory_1() result");
>  	}
> -- 
> 2.7.4
> 
>