Re: [PATCH v2 13/17] remove_dir_recurse(): handle disappearing files and directories

[Junio C Hamano <gitster@pobox.com>]

Michael Haggerty <mhagger@alum.mit.edu> writes:

> If a file or directory that we are trying to remove disappears (e.g.,
> because another process has pruned it), do not consider it an error.
>
> Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
> ---
>  dir.c | 22 ++++++++++++++++------
>  1 file changed, 16 insertions(+), 6 deletions(-)
>
> diff --git a/dir.c b/dir.c
> index 11e1520..716b613 100644
> --- a/dir.c
> +++ b/dir.c
> @@ -1476,7 +1476,9 @@ static int remove_dir_recurse(struct strbuf *path, int flag, int *kept_up)
>  	flag &= ~REMOVE_DIR_KEEP_TOPLEVEL;
>  	dir = opendir(path->buf);
>  	if (!dir) {
> -		if (errno == EACCES && !keep_toplevel)
> +		if (errno == ENOENT)
> +			return keep_toplevel ? -1 : 0;

If we were told that "foo/bar must go, but do not bother removing
foo/", is it an error if foo itself did not exist?  I think this
step does not change the behaviour from the original (we used to say
"oh, we were told to keep_toplevel, and the top-level cannot be read
for whatever reason, so it is an error"), but because this series is
giving us a finer grained error diagnosis, we may want to think
about it further, perhaps as a follow-up.

I also wonder why the keep-toplevel logic is in this "recurse" part
of the callchain. If everything in "foo/bar/" can be removed but
"foo/bar/" is unreadable, it is OK, when opendir("foo/bar") failed
with EACCESS, to attempt to rmdir("foo/bar") whether we were told
not to attempt removing "foo/", no?

> +		else if (errno == EACCES && !keep_toplevel)

That is, I am wondering why this part just checks !keep_toplevel,
not

	(!keep_toplevel || has_dir_separator(path->buf))

or something.

>  			/*
>  			 * An empty dir could be removable even if it
>  			 * is unreadable:
> @@ -1496,13 +1498,21 @@ static int remove_dir_recurse(struct strbuf *path, int flag, int *kept_up)
>  
>  		strbuf_setlen(path, len);
>  		strbuf_addstr(path, e->d_name);
> -		if (lstat(path->buf, &st))
> -			; /* fall thru */
> -		else if (S_ISDIR(st.st_mode)) {
> +		if (lstat(path->buf, &st)) {
> +			if (errno == ENOENT)
> +				/*
> +				 * file disappeared, which is what we
> +				 * wanted anyway
> +				 */
> +				continue;
> +			/* fall thru */
> +		} else if (S_ISDIR(st.st_mode)) {
>  			if (!remove_dir_recurse(path, flag, &kept_down))
>  				continue; /* happy */
> -		} else if (!only_empty && !unlink(path->buf))
> +		} else if (!only_empty &&
> +			   (!unlink(path->buf) || errno == ENOENT)) {
>  			continue; /* happy, too */
> +		}
>  
>  		/* path too long, stat fails, or non-directory still exists */
>  		ret = -1;
> @@ -1512,7 +1522,7 @@ static int remove_dir_recurse(struct strbuf *path, int flag, int *kept_up)
>  
>  	strbuf_setlen(path, original_len);
>  	if (!ret && !keep_toplevel && !kept_down)
> -		ret = rmdir(path->buf);
> +		ret = (!rmdir(path->buf) || errno == ENOENT) ? 0 : -1;
>  	else if (kept_up)
>  		/*
>  		 * report the uplevel that it is not an error that we