fix(storage): accept keys whose first segment starts with dots

[johnnyhuirilef]

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PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Other... Please describe:

What is the current behavior?

Issue Number: N/A

Hi! 👋 LocalDisk refuses a valid key when its first segment starts with two dots, like ..foo/a.

LocalDisk.inside() (lib/disks/local.disk.ts:361) checks !rel.startsWith('..') on the path of the key's parent directory, relative to the root. For ..foo/a the parent is ..foo, so the check reads it as a path above the root. put, copy and move throw StorageInvalidKeyError ("the key leads outside the disk's root through a link"). exists returns false. get and stat throw not found. delete does nothing. A prefix list returns no entries. InMemoryDisk accepts the same keys.

Repro: https://github.com/johnnyhuirilef/nestjs-repros/tree/main/storage-dotdot-prefixed-key

InMemoryDisk foo/a    put: ok   exists: true   get: hello   list: [foo/a]   delete: ok
InMemoryDisk ..foo/a  put: ok   exists: true   get: hello   list: [..foo/a]   delete: ok
InMemoryDisk ..a      put: ok   exists: true   get: hello   list: [..a]   delete: ok
LocalDisk    foo/a    put: ok   exists: true   get: hello   list: [foo/a]   delete: ok
LocalDisk    ..foo/a  put: StorageInvalidKeyError: Invalid storage key: the key leads outside the disk's root through a link   exists: false   get: StorageFileNotFoundError: No file at "..foo/a"   list: []   delete: ok
LocalDisk    ..a      put: ok   exists: true   get: hello   list: [..a]   delete: ok

LocalDisk root holds a "..foo" directory after the failed put of "..foo/a": true

RESULT: BUG: InMemoryDisk accepts "..foo/a" and LocalDisk refuses it

What is the new behavior?

• inside() treats a path as outside the root only when it is .. or starts with .. and a path separator.
• put, get, stat, exists, copy, move, delete and list work for keys like ..foo/a and ...dots/a, as they do on InMemoryDisk.
• Real escapes stay refused. A key with a .. segment is still invalid. A link that points outside the root, or at the parent of the root, still throws StorageInvalidKeyError. This holds for a link named ..escape too.

Does this PR introduce a breaking change?

• Yes
• No

No. The change only accepts keys that were valid but refused.

Other information

The shared contract suite in tests/disks.spec.ts now runs ..a, ..foo/a, ...dots/a and docs/..foo/a through put, get, exists, list, copy, move and delete on every disk. tests/local-disk.spec.ts checks that ..foo/a is stored inside the root and that a link named ..escape stays refused. It also checks a link to the parent of the root and a link to the internal directory.

The new ..foo/a cases fail on LocalDisk without the fix and pass with it.

If you prefer a different approach or smaller tests, I am happy to change it. 🙂