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added workflow and API description
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Falk Werner
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README.md
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README.md
@ -5,6 +5,263 @@ fuse-wsfs combines libwebsockets and libfuse. It allows ot attach a remote files
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**Status**: Proof of concept
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**Status**: Proof of concept
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***Latest Build on travis***: [https://travis-ci.com/falk-werner/fuse-wsfs](https://travis-ci.com/falk-werner/fuse-wsfs)
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***Latest Build on travis***: [https://travis-ci.com/falk-werner/fuse-wsfs](https://travis-ci.com/falk-werner/fuse-wsfs)
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# Workflow an API
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+---------------------+ +-------------+ +------+
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| Filesystem Provider | | wsfs daemon | | user |
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| (e.g. Webbrowser) | | | | |
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+----------+----------+ +------+------+ +---+--+
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| +-+-+ |
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| | +--+ |
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| | | | fuse_mount |
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| | +<-+ |
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| | +--+ |
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| | | | start ws |
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| | +<-+ |
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| +-+-+ |
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+-+-+ connect +-+-+ |
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| |--------------->| | |
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+-+-+ +-+-+ |
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| +-+-+ ls +-+-+
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+-+-+ readdir | |<------------+ |
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| |<---------------+ | | |
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| | | | | |
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| | readdir_resp | | | |
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| +--------------->| | [., ..] | |
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+-+-+ | +------------>| |
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| +-+-+ +-+-+
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With fuse-wsfs it is possible to implement remote filesystems based on websockets.
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A reference implementation of such a daemon is provided within the examples. The picture above describes the workflow:
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- The websocket filesystem daemon (*wsfs daemon*) mounts a filesystem on startup.
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It starts the websocket server and waits for incoming connections.
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- A remote filesystem provider connects to wsfs daemon via websocket protocol.
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The example includes such a provider implemented in HTML and JavaScript.
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- Whenever the user makes filesystem requests, such as *ls*, the request is redirected via wsfs daemon to the connected filesystem provider
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Currently all requests are initiated by wsfs daemon and responded by filesystem provider. This may change in future, e.g. when authentication is supported.
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## Requests, responses and notifications
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There are three types of messages, used for communication between wsfs daemon and filesystem provider. All message types are encoded in [JSON](https://www.json.org/) and strongly inspired by [JSON-RPC](https://www.jsonrpc.org/).
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### Request
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A request is used by a sender to invoke a method on the receiver. The sender awaits a response from the receiver. Since requests and responses can be sendet or answered in any order, an id is provided in each request to identify it.
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{
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"method": <method_name>,
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"params": <params>,
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"id" : <id>
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}
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| Item | Data type | Description |
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| ----------- |:---------:| --------------------------------- |
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| method_name | string | name of the method to invoke |
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| params | array | method specific parameters |
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| id | integer | id, which is repeated in response |
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### Response
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A response is used to answer a prior request. There are two kinds of responses:
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#### Successful Results
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{
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"result": <result>,
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"id": <id>
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}
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| Item | Data type | Description |
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| ----------- |:---------:| ----------------------- |
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| result | any | request specific result |
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| id | integer | id, same as request |
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#### Error notifications
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{
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"error": {
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"code": <code>
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},
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"id": <id>
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}
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| Item | Data type | Description |
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| ----------- |:---------:| ------------------- |
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| code | integer | error code |
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| id | integer | id, same as request |
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#### Error codes
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| Symbolic name | Code | Description |
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| ------------------ | ---------:| ---------------------- |
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| GOOD | 0 | no error |
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| BAD | 1 | generic error |
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| BAD_NOTIMPLEMENTED | 2 | method not implemented |
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| BAD_TIMEOUT | 3 | timeout occured |
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| BAD_BUSY | 4 | resource busy |
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| BAD_FORMAT | 5 | invalid formt |
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| BAD_NOENTRY | 101 | invalid entry |
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| BAD_NOACCESS | 102 | access not allowed |
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### Notification
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Notfications are used to inform a receiver about something. Unlike requests, notifications are not answered. Therefore, an id is not supplied.
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{
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"method": <method_name>,
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"params": <params>
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}
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| Item | Data type | Description |
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| ----------- |:---------:| --------------------------------- |
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| method_name | string | name of the method to invoke |
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| params | array | method specific parameters |
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## Requests
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### lookup
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Retrieve information about a filesystem entry by name.
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wsfs daemon: {"method": "lookup", "params": [<parent>, <name>], "id": <id>}
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fs provider: {"result": {
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"inode": <inode>,
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"mode" : <mode>,
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"type" : <type>,
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"size" : <size>,
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"atime": <atime>,
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"mtime": <mtime>,
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"ctime": <ctime>
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}, "id": <id>}
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| Item | Data type | Description |
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| ----------- | --------------- | ------------------------------------------- |
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| parent | integer | inode of parent directory (1 = root) |
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| name | string | name of the filesystem object to look up |
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| inode | integer | inode of the filesystem object |
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| mode | integer | unix file mode |
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| type | "file" or "dir" | type of filesystem object |
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| size | integer | required for files; file size in bytes |
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| atime | integer | optional; unix time of last access |
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| mtime | integer | optional; unix time of last modification |
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| ctime | intefer | optional; unix time of last metadata change |
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### getattr
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Get file attributes.
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wsfs daemon: {"method": "getattr", "params": [<inode>], "id": <id>}
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fs provider: {"result": {
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"mode" : <mode>,
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"type" : <type>,
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"size" : <size>,
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"atime": <atime>,
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"mtime": <mtime>,
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"ctime": <ctime>
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}, "id": <id>}
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| Item | Data type | Description |
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| ----------- | --------------- | ------------------------------------------- |
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| inode | integer | inode of the filesystem object |
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| mode | integer | unix file mode |
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| type | "file" or "dir" | type of filesystem object |
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| size | integer | required for files; file size in bytes |
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| atime | integer | optional; unix time of last access |
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| mtime | integer | optional; unix time of last modification |
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| ctime | intefer | optional; unix time of last metadata change |
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### readdir
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Read directory contents.
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Result is an array of name-inode pairs for each entry. The generic entries
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"." and ".." should also be provided.
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wsfs daemon: {"method": "readdir", "params": [<dir_inode>], "id": <id>}
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fs provider: {"result": [
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{"name": <name>, "inode": <inode>},
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...
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], "id": <id>}
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| Item | Data type | Description |
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| ----------- | --------------- | ------------------------------ |
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| dir_inode | integer | inode of the directory to read |
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| name | integer | name of the entry |
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| inode | integer | inode of the entry |
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### open
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Open a file.
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wsfs daemon: {"method": "readdir", "params": [<inode>, <flags>], "id": <id>}
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fs provider: {"result": {"handle": <handle>}, "id": <id>}
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| Item | Data type | Description |
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| ----------- | ----------| ----------------------------- |
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| inode | integer | inode of the file |
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| flags | integer | access mode flags (see below) |
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| handle | integer | handle of the file |
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#### Flags
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| Symbolic name | Code | Description |
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| --------------| ---------:| --------------------------- |
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| O_ACCMODE | 0x003 | access mode mask |
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| O_RDONLY | 0x000 | open for reading only |
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| O_WRONLY | 0x001 | open for writing only |
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| O_RDWR | 0x002 | open for reading an writing |
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| O_CREAT | 0x040 | create (a new) file |
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| O_EXCL | 0x080 | open file exclusivly |
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| O_TRUNK | 0x200 | open file to trunkate |
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| O_APPEND | 0x400 | open file to append |
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### close
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Informs filesystem provider, that a file is closed.
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Since `close` is a notification, it cannot fail.
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wsfs daemon: {"method": "close", "params": [<inode>, <handle>, <flags>], "id": <id>}
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| Item | Data type | Description |
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| ----------- | ----------| ---------------------------- |
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| inode | integer | inode of the file |
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| handle | integer | handle of the file |
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| flags | integer | access mode flags (see open) |
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### read
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Read from an open file.
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wsfs daemon: {"method": "close", "params": [<inode>, <handle>, <offset>, <length>], "id": <id>}
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fs provider: {"result": {
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"data": <data>,
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"format": <format>,
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"count": <count>
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}, "id": <id>}
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| Item | Data type | Description |
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| ----------- | ----------| ----------------------------- |
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| inode | integer | inode of the file |
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| handle | integer | handle of the file |
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| offset | integer | Offet to start read operation |
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| length | integer | Max. number of bytes to read |
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| data | integer | handle of the file |
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| format | string | Encoding of data (see below) |
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| count | integer | Actual number of bytes read |
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#### Format
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| Format | Description |
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| ---------- | ----------------------------------------------- |
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| "identiy" | Use data as is; note that json is UTF-8 encoded |
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# Build and run
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# Build and run
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To install dependencies, see below.
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To install dependencies, see below.
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