support slash-ended mkdir, such as "mkdir dir/".

[XinStellaris]

"mkdir dir/" will not work in littlefs, littlefs will return LFS_ERR_NOENT in such case. However, linux supports such commands. This patch adds support for such behavior.

Signed-off-by: 田昕 tianxin7@xiaomi.com

[XinStellaris]

Oh no, this patch causes other problems. If we input following commands:

1. echo 1 > testfile
2. echo 2 > testfile/
   the result is testfile has content of 2. However, step2 should fail because testfile/ is a dir.

I am confused now, how to support slash-ended mkdir command? Or, is this really necessary?
@geky

[geky]

Hi @XinStellaris sorry about the late response. Thanks for creating the PR, it would certainly be good to match Linux/POSIX here.

Hmm, this does look tricky to add. The simplest thing would be include a flag indicating that lfs_dir_find should ignore the trailing slash, this should only be set for lfs_mkdir. Sometimes special cases need to be special cases.

Then the test for the last name could be written:

const char *tail = name + strcspn(name, "/");
if (ignore_trailing_slashes) {
    tail += strspn(tail, "/");
}
// are we last name?
(*tail == '\0' ? id : NULL)

[geky]

I've gone ahead and reimplemented this in: #1046

The solution was a bit involved, I decided to solve the trailing slash issue in the calling functions by checking the modified path. It turns out after lfs_dir_find, since the modified path is no longer NULL-terminated (slash-terminated?), we can determine whether or not the path points to a directory or not based on what follows the last file name.

Let me know if you see any issues with #1046, and thanks for the original PR!