Re: [PATCH v4 3/5] remove_subtree(): reimplement using iterators

[Michael Haggerty <mhagger@alum.mit.edu>]

On 03/29/2017 02:32 AM, Daniel Ferreira wrote:
> Use dir_iterator to traverse through remove_subtree()'s directory tree,
> avoiding the need for recursive calls to readdir(). Simplify
> remove_subtree()'s code.
> 
> A conversion similar in purpose was previously done at 46d092a
> ("for_each_reflog(): reimplement using iterators", 2016-05-21).
> 
> Signed-off-by: Daniel Ferreira <bnmvco@gmail.com>
> ---
>  entry.c | 31 ++++++++++---------------------
>  1 file changed, 10 insertions(+), 21 deletions(-)
> 
> diff --git a/entry.c b/entry.c
> index c6eea24..bbebd16 100644
> --- a/entry.c
> +++ b/entry.c
> @@ -2,6 +2,8 @@
>  #include "blob.h"
>  #include "dir.h"
>  #include "streaming.h"
> +#include "iterator.h"
> +#include "dir-iterator.h"
> 
>  static void create_directories(const char *path, int path_len,
>  			       const struct checkout *state)
> @@ -46,29 +48,16 @@ static void create_directories(const char *path, int path_len,
> 
>  static void remove_subtree(struct strbuf *path)

The reason that this function took a `strbuf` as argument was that it
used to modify the strbuf while it was working. Now that `dir_iterator`
does all of that work, you could simplify it to take a `const char *`
argument, and change the caller to pass `path.buf`.

>  {
> -	DIR *dir = opendir(path->buf);
> -	struct dirent *de;
> -	int origlen = path->len;
> -
> -	if (!dir)
> -		die_errno("cannot opendir '%s'", path->buf);
> -	while ((de = readdir(dir)) != NULL) {
> -		struct stat st;
> -
> -		if (is_dot_or_dotdot(de->d_name))
> -			continue;
> -
> -		strbuf_addch(path, '/');
> -		strbuf_addstr(path, de->d_name);
> -		if (lstat(path->buf, &st))
> -			die_errno("cannot lstat '%s'", path->buf);
> -		if (S_ISDIR(st.st_mode))
> -			remove_subtree(path);
> -		else if (unlink(path->buf))
> +	struct dir_iterator *diter = dir_iterator_begin(path->buf, DIR_ITERATOR_DEPTH_FIRST);
> +
> +	while (dir_iterator_advance(diter) == ITER_OK) {
> +		if (S_ISDIR(diter->st.st_mode)) {
> +			if (rmdir(diter->path.buf))
> +				die_errno("cannot rmdir '%s'", path->buf);
> +		} else if (unlink(diter->path.buf))
>  			die_errno("cannot unlink '%s'", path->buf);

The two `die_errno()` calls must be changed to use `diter->path.buf`
rather than `path->buf`.

> -		strbuf_setlen(path, origlen);
>  	}
> -	closedir(dir);
> +
>  	if (rmdir(path->buf))
>  		die_errno("cannot rmdir '%s'", path->buf);
>  }

Michael