Problem: filenames containing spaces (or other URL-unsafe characters)
caused curl to fail with "Unknown error" because the raw path was
concatenated directly into the FTP URL.
Solution: add `url_encode_path` to encode non-safe characters (excluding
`/`) before building the curl URL in `curl_ftp_url`.
Problem: FTP's RMD command fails with '550 Directory not empty'
if the directory has any contents. Unlike the S3 adapter which uses
`aws s3 rm --recursive`, FTP has no protocol-level recursive delete.
Solution: emit a Python rmtree helper inside the ftpcmd script that
walks the directory via MLSD, recursively deletes children (DELE for
files, rmtree for subdirs), then sends RMD on the now-empty directory.
Problem: `ftpcmd` wrapped every command in `ftp.voidcmd()`, which
expects a final 2xx response. `RNFR` returns 350 (intermediate),
so `voidcmd` raised an exception before `RNTO` was ever sent,
causing every rename to fail with '350 Ready for destination name'.
Solution: change `ftpcmd` to accept raw Python lines instead of FTP
command strings, then use `ftp.rename(src, dst)` for the rename case.
`ftplib.rename` handles the 350 intermediate response correctly
internally. All other callers now wrap their FTP commands in
`ftp.voidcmd()` explicitly.
Problem: `M.list` returned entries as `{0, name, type, meta}`.
`cache.store_entry` only assigns a fresh ID when `entry[FIELD_ID] == nil`;
passing 0 caused every entry to be stored as ID 0, all overwriting
each other. `get_entry_by_id(0)` then always returned the last-stored
entry, breaking navigation (always opened the same file), rename
(wrong entry matched), and create (wrong diff).
Solution: change the placeholder from 0 to nil, matching how
`cache.create_entry` itself builds entries.
Problem: DELE, RMD, MKD, and RNFR/RNTO were implemented using
curl --quote, which requires a subsequent LIST or STOR to trigger
the FTP connection. That data-channel operation hangs on slow or
busy servers, making every mutation appear stuck.
Solution: replace the curl --quote approach with a python3 ftplib
one-liner for all control-channel operations. ftplib executes DELE,
RMD, MKD, RNFR/RNTO, and SITE CHMOD without opening a data channel,
so they complete instantly. The curl wrapper is retained for LIST,
read_file, and write_file, which genuinely need a data channel.
Problem: canola has no way to browse or edit files on FTP servers,
despite the adapter system being designed for exactly this pattern.
curl speaks FTP natively, including FTPS (FTP over TLS), and requires
no new dependencies.
Solution: implement `lua/oil/adapters/ftp.lua` with `oil-ftp://` and
`oil-ftps://` schemes. Parses Unix and IIS LIST output, supports
`size`, `mtime`, and `permissions` columns, and implements the full
adapter API (list, read_file, write_file, render_action, perform_action).
Same-host renames use RNFR/RNTO; cross-host and local↔FTP copies use
curl download/upload through a tmpfile. Adds `extra_curl_args` config
option and documents the adapter in `doc/oil.txt`.
Based on: stevearc/oil.nvim#210
