Re: [PATCH] entry.c: use dir-iterator to avoid explicit dir traversal
- From
Matheus Tavares Bernardino <matheus.bernardino@usp.br>
- Date
- Dec 9, 2019, 17:41 UTC
- Message-ID
- <CAHd-oW4MzH9Wrb2zNPF0JBN8+FRB4NtDX0166Qt2Kbqs0mDgcw@mail.gmail.com>
- In-Reply-To
- <20191208180439.19018-1-otalpster@gmail.com>
On Sun, Dec 8, 2019 at 3:06 PM <otalpster@gmail.com> wrote:
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> > From: Plato <otalpster@gmail.com> > > Replace usage of opendir/readdir/closedir API to traverse directories > recursively, at remove_subtree() function, by the dir-iterator API. This > simplifies the code and avoids recursive calls to remove_subtree(). > > Signed-off-by: Plato <otalpster@gmail.com> > --- > Hello, > > This is my first patch.
Hello Plato, and welcome! Thanks for working on this.
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> I hope I cc'd the correct people and didn't mess up.
>
> The changes pass the test suite t/ and Travis CI.
> Please point out any mistakes.
>
> Thanks for your time! :)
>
> entry.c | 32 +++++++++++++++-----------------
> 1 file changed, 15 insertions(+), 17 deletions(-)
>
> diff --git a/entry.c b/entry.c
> index 53380bb614..e7f4881d3b 100644
> --- a/entry.c
> +++ b/entry.c
> @@ -2,6 +2,8 @@
> #include "blob.h"
> #include "object-store.h"
> #include "dir.h"
> +#include "iterator.h"
> +#include "dir-iterator.h"
> #include "streaming.h"
> #include "submodule.h"
> #include "progress.h"
> @@ -50,29 +52,25 @@ static void create_directories(const char *path, int path_len,
>
> static void remove_subtree(struct strbuf *path)
> {
> - DIR *dir = opendir(path->buf);
> - struct dirent *de;
> - int origlen = path->len;
> + int ok;
> + unsigned int flags = DIR_ITERATOR_PEDANTIC;
> + struct dir_iterator *iter = dir_iterator_begin(path->buf, flags);
>
> - if (!dir)
> + if (!iter)
> die_errno("cannot opendir '%s'", path->buf);Nitpick: since dir_iterator_begin() might fail for reasons other than an opendir() error, I think the error message here could be more generic. Maybe "failed to start iterator over %s"?
Show 6 quoted lines
> - while ((de = readdir(dir)) != NULL) {
> - struct stat st;
>
> - if (is_dot_or_dotdot(de->d_name))
> + while ((ok = dir_iterator_advance(iter)) == ITER_OK) {
> + if (is_dot_or_dotdot(iter->path.buf))This check is already done by dir-iterator internally, so you may remove it here.
Show 12 quoted lines
> 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))
> - die_errno("cannot unlink '%s'", path->buf);
> - strbuf_setlen(path, origlen);
> + if (unlink(iter->path.buf)) {unlink()-ing a directory in Linux will return a EISDIR error. So I think you still need to use S_ISDIR() to check if iter->path.buf is a directory and call rmdir(), in this case.
However, note that the dir-iterator API gives entries in pre-order. I.e. a directory appears before its subentries. In the use case of remove_subtree(), though, we need to traverse in post-order, since we have to remove the subentries before removing the directory where they reside. My suggestion is that you add a preliminary patch, implementing a new DIR_ITERATOR_POST_ORDER flag to dir-iterator.h, and then use it in this patch.
You may also want to check this[1] series, which worked towards the same goal of converting remove_subtree(). It ended up not getting merged, back them, but some of the patches were re-used in this[2] series which got merged. I think you could also re-use some of the code from [1] that implements the post-order traversing and a test[3] for remove_subtree().
Thanks, Matheus
[1]: https://public-inbox.org/git/1493226219-33423-1-git-send-email-bnmvco@gmail.com/ [2]: https://public-inbox.org/git/cover.1562801254.git.matheus.bernardino@usp.br/ [3]: https://public-inbox.org/git/1493226219-33423-3-git-send-email-bnmvco@gmail.com/