### Starting HrrRbSftp Server

Source: https://context7.com/hirura/hrr_rb_sftp/llms.txt

Initialize and start the HrrRbSftp server, providing it with a logger and standard input/output/error streams. The server handles SFTP protocol negotiation and packet framing automatically.

```ruby
server = HrrRbSftp::Server.new(logger: logger)
server.start($stdin, $stdout, $stderr)
```

--------------------------------

### Install hrr_rb_sftp Gem

Source: https://github.com/hirura/hrr_rb_sftp/blob/master/README.md

Add the gem to your application's Gemfile for installation via Bundler, or install it directly using the gem command.

```ruby
gem 'hrr_rb_sftp'
```

```bash
$ bundle install
```

```bash
$ gem install hrr_rb_sftp
```

--------------------------------

### Initialize HrrRbSftp Logging

Source: https://context7.com/hirura/hrr_rb_sftp/llms.txt

Demonstrates how to initialize the standard Logger and set its level for use with the HrrRbSftp::Loggable module. This setup is required for logging to function.

```ruby
require "logger"
require "hrr_rb_sftp"

logger = Logger.new($stdout)
logger.level = Logger::DEBUG


```

--------------------------------

### Start HrrRbSftp Server in Standalone Mode

Source: https://context7.com/hirura/hrr_rb_sftp/llms.txt

Starts the SFTP server request/response loop, processing requests from stdin and writing responses to stdout. This script is intended to be used as a standalone SFTP subsystem.

```ruby
#!/usr/bin/env ruby
# hrr_rb_sftp_server.rb — standalone executable used as an SFTP subsystem

require "logger"
require "hrr_rb_sftp"

logger = Logger.new("/var/log/hrr_rb_sftp.log")
logger.level = Logger::INFO

server = HrrRbSftp::Server.new(logger: logger)
# Blocks until the SSH client disconnects; raises on unrecoverable errors
server.start($stdin, $stdout, $stderr)
```

--------------------------------

### HrrRbSftp::Server#start

Source: https://context7.com/hirura/hrr_rb_sftp/llms.txt

Starts the SFTP server request/response loop. Negotiates the SFTP protocol version with the client, then continuously reads requests from `io_in`, processes them, and writes responses to `io_out`. Blocks until the client closes the connection.

```APIDOC
## HrrRbSftp::Server#start

### Description
Starts the SFTP server request/response loop. Negotiates the SFTP protocol version with the client, then continuously reads requests from `io_in`, processes them, and writes responses to `io_out`. Blocks until the client closes the connection. `io_err` is optional and used only for debug output.

### Usage
```ruby
#!/usr/bin/env ruby
# hrr_rb_sftp_server.rb — standalone executable used as an SFTP subsystem

require "logger"
require "hrr_rb_sftp"

logger = Logger.new("/var/log/hrr_rb_sftp.log")
logger.level = Logger::INFO

server = HrrRbSftp::Server.new(logger: logger)
# Blocks until the SSH client disconnects; raises on unrecoverable errors
server.start($stdin, $stdout, $stderr)
```
```

--------------------------------

### Standalone SFTP Server Script

Source: https://github.com/hirura/hrr_rb_sftp/blob/master/README.md

A minimal script to run the hrr_rb_sftp server, designed to be executed as a child process. It requires the 'hrr_rb_sftp' gem and starts the server using standard I/O streams.

```ruby
#!/usr/bin/env ruby

require "hrr_rb_sftp"

server = HrrRbSftp::Server.new(logger: nil)
server.start($stdin, $stdout, $stderr)

```

--------------------------------

### Get Supported SFTP Protocol Versions

Source: https://context7.com/hirura/hrr_rb_sftp/llms.txt

Use `HrrRbSftp::Protocol.versions` to retrieve a list of supported SFTP protocol version integers. The highest supported version is used as the local offer during the handshake.

```ruby
require "hrr_rb_sftp"

puts HrrRbSftp::Protocol.versions.inspect
# => [1, 2, 3]

puts HrrRbSftp::Protocol.versions.max
# => 3  (highest supported version, used as the local offer)
```

--------------------------------

### Get SFTP Protocol Extension Pairs

Source: https://context7.com/hirura/hrr_rb_sftp/llms.txt

Use `HrrRbSftp::Protocol.extension_pairs` to get extension name/data pairs for a given protocol version. Only version 3 supports extensions; versions 1 and 2 return an empty array.

```ruby
require "hrr_rb_sftp"

puts HrrRbSftp::Protocol.extension_pairs(3).inspect
# => [
#      { :"extension-name" => "hardlink@openssh.com",      :"extension-data" => "1" },
#      { :"extension-name" => "fsync@openssh.com",         :"extension-data" => "1" },
#      { :"extension-name" => "posix-rename@openssh.com",  :"extension-data" => "1" },
#      { :"extension-name" => "lsetstat@openssh.com",      :"extension-data" => "1" },
#    ]

puts HrrRbSftp::Protocol.extension_pairs(1).inspect
# => []
```

--------------------------------

### Instantiate HrrRbSftp::Server with Logging

Source: https://context7.com/hirura/hrr_rb_sftp/llms.txt

Instantiates an SFTP server object with a logger. Pass nil for logger to disable logging.

```ruby
require "logger"
require "hrr_rb_sftp"

# With logging
logger = Logger.new($stdout)
logger.level = Logger::INFO
server = HrrRbSftp::Server.new(logger: logger)

# Without logging
server_no_log = HrrRbSftp::Server.new(logger: nil)
```

--------------------------------

### HrrRbSftp::Server.new

Source: https://context7.com/hirura/hrr_rb_sftp/llms.txt

Instantiates an SFTP server object. Accepts an optional Logger-compatible object; passing nil disables all logging. The server relies on external IO streams.

```APIDOC
## HrrRbSftp::Server.new

### Description
Instantiates an SFTP server object. Accepts an optional `Logger`-compatible object; passing `nil` disables all logging. The server does not bind to any port itself — it relies on an external SSH layer to provide `IO` streams.

### Usage
```ruby
require "logger"
require "hrr_rb_sftp"

# With logging
logger = Logger.new($stdout)
logger.level = Logger::INFO
server = HrrRbSftp::Server.new(logger: logger)

# Without logging
server_no_log = HrrRbSftp::Server.new(logger: nil)
```
```

--------------------------------

### Spawn SFTP Server as Child Process with hrr_rb_ssh

Source: https://github.com/hirura/hrr_rb_sftp/blob/master/README.md

Configure hrr_rb_ssh to spawn hrr_rb_sftp as a child process. This allows hrr_rb_sftp to run independently, communicating via standard input/output/error streams.

```ruby
subsys = HrrRbSsh::Connection::RequestHandler.new { |ctx|
  ctx.chain_proc {
    case ctx.subsystem_name
    when 'sftp'
      pid = spawn("/path/to/hrr_rb_sftp_server.rb", {in: ctx.io[0], out: ctx.io[1], err: ctx.io[2]})
      exitstatus = Process.waitpid(pid).to_i
    else
      # Do something for other subsystem, or just return exitstatus
      exitstatus = 0
    end
    exitstatus
  }
}

options['connection_channel_request_subsystem']  = subsys

```

--------------------------------

### Configure OpenSSH to Use HrrRbSftp

Source: https://context7.com/hirura/hrr_rb_sftp/llms.txt

This is a configuration snippet for OpenSSH's `sshd_config` file. It replaces the default `sftp-server` binary with `hrr_rb_sftp_server.rb`.

```bash
# /etc/ssh/sshd_config

```

--------------------------------

### Integrating with hrr_rb_ssh (in-process mode)

Source: https://context7.com/hirura/hrr_rb_sftp/llms.txt

Runs the SFTP server on the same Ruby process as the SSH server by hooking into `hrr_rb_ssh`'s subsystem request handler. The SFTP server receives `IO`s directly from the SSH channel context.

```APIDOC
## Integrating with `hrr_rb_ssh` — in-process mode

### Description
Runs the SFTP server on the same Ruby process as the SSH server by hooking into `hrr_rb_ssh`'s subsystem request handler. The SFTP server receives `IO`s directly from the SSH channel context.

### Usage
```ruby
require "socket"
require "logger"
require "hrr_rb_ssh"
require "hrr_rb_sftp"

logger = Logger.new($stdout)
logger.level = Logger::INFO

# Accept any public-key authentication
auth_publickey = HrrRbSsh::Authentication::Authenticator.new { |ctx| true }

# Handle the "sftp" subsystem request in-process
conn_subsys = HrrRbSsh::Connection::RequestHandler.new { |ctx|
  ctx.chain_proc { |chain|
    case ctx.subsystem_name
    when "sftp"
      begin
        sftp_server = HrrRbSftp::Server.new(logger: logger)
        sftp_server.start(ctx.io[0], ctx.io[1], ctx.io[2])
        exitstatus = 0
      rescue => e
        logger.error { e.message }
        exitstatus = 1
      end
    else
      exitstatus = 1
    end
    exitstatus
  }
}

options = {}
options["authentication_publickey_authenticator"] = auth_publickey
options["connection_channel_request_subsystem"]   = conn_subsys

tcp = TCPServer.new(10022)
loop do
  Thread.new(tcp.accept) do |io|
    pid = fork do
      ssh_server = HrrRbSsh::Server.new(options, logger: logger)
      ssh_server.start(io)
    end
    io.close
    Process.waitpid2(pid)
  end
end
```
```

--------------------------------

### Integrate HrrRbSftp with hrr_rb_ssh (Spawned Child Process)

Source: https://context7.com/hirura/hrr_rb_sftp/llms.txt

Spawns `hrr_rb_sftp_server.rb` as a separate child process for each SFTP session. The child process's standard streams are connected to the SSH channel's IO objects.

```ruby
require "socket"
require "hrr_rb_ssh"

SFTP_SERVER_PATH = "/usr/local/bin/hrr_rb_sftp_server.rb"

conn_subsys = HrrRbSsh::Connection::RequestHandler.new { |ctx|
  ctx.chain_proc { |chain|
    case ctx.subsystem_name
    when "sftp"
      pid = spawn(SFTP_SERVER_PATH, in: ctx.io[0], out: ctx.io[1], err: ctx.io[2])
      exitstatus = Process.waitpid(pid).to_i
    else
      exitstatus = 1
    end
    exitstatus
  }
}

options = {}
options["authentication_publickey_authenticator"] = HrrRbSsh::Authentication::Authenticator.new { |ctx| true }
options["connection_channel_request_subsystem"]   = conn_subsys

tcp = TCPServer.new(10022)
loop do
  Thread.new(tcp.accept) do |io|
    pid = fork { HrrRbSsh::Server.new(options).start(io) }
    io.close
    Process.waitpid2(pid)
  end
end
```

--------------------------------

### Integrating with hrr_rb_ssh (spawned child process mode)

Source: https://context7.com/hirura/hrr_rb_sftp/llms.txt

Spawns `hrr_rb_sftp_server.rb` as a separate child process for each SFTP session. The child's `$stdin`/`$stdout`/`$stderr` are connected to the SSH channel's IO objects.

```APIDOC
## Integrating with `hrr_rb_ssh` — spawned child process mode

### Description
Spawns `hrr_rb_sftp_server.rb` as a separate child process for each SFTP session. The child's `$stdin`/`$stdout`/`$stderr` are connected to the SSH channel's IO objects.

### Usage
```ruby
require "socket"
require "hrr_rb_ssh"

SFTP_SERVER_PATH = "/usr/local/bin/hrr_rb_sftp_server.rb"

conn_subsys = HrrRbSsh::Connection::RequestHandler.new { |ctx|
  ctx.chain_proc { |chain|
    case ctx.subsystem_name
    when "sftp"
      pid = spawn(SFTP_SERVER_PATH, in: ctx.io[0], out: ctx.io[1], err: ctx.io[2])
      exitstatus = Process.waitpid(pid).to_i
    else
      exitstatus = 1
    end
    exitstatus
  }
}

options = {}
options["authentication_publickey_authenticator"] = HrrRbSsh::Authentication::Authenticator.new { |ctx| true }
options["connection_channel_request_subsystem"]   = conn_subsys

tcp = TCPServer.new(10022)
loop do
  Thread.new(tcp.accept) do |io|
    pid = fork { HrrRbSsh::Server.new(options).start(io) }
    io.close
    Process.waitpid2(pid)
  end
end
```
```

--------------------------------

### Integrate HrrRbSftp with hrr_rb_ssh (In-Process)

Source: https://context7.com/hirura/hrr_rb_sftp/llms.txt

Runs the SFTP server within the same Ruby process as the SSH server by hooking into hrr_rb_ssh's subsystem request handler. IO streams are provided directly from the SSH channel context.

```ruby
require "socket"
require "logger"
require "hrr_rb_ssh"
require "hrr_rb_sftp"

logger = Logger.new($stdout)
logger.level = Logger::INFO

# Accept any public-key authentication
auth_publickey = HrrRbSsh::Authentication::Authenticator.new { |ctx| true }

# Handle the "sftp" subsystem request in-process
conn_subsys = HrrRbSsh::Connection::RequestHandler.new { |ctx|
  ctx.chain_proc { |chain|
    case ctx.subsystem_name
    when "sftp"
      begin
        sftp_server = HrrRbSftp::Server.new(logger: logger)
        sftp_server.start(ctx.io[0], ctx.io[1], ctx.io[2])
        exitstatus = 0
      rescue => e
        logger.error { e.message }
        exitstatus = 1
      end
    else
      exitstatus = 1
    end
    exitstatus
  }
}

options = {}
options["authentication_publickey_authenticator"] = auth_publickey
options["connection_channel_request_subsystem"]   = conn_subsys

tcp = TCPServer.new(10022)
loop do
  Thread.new(tcp.accept) do |io|
    pid = fork do
      ssh_server = HrrRbSsh::Server.new(options, logger: logger)
      ssh_server.start(io)
    end
    io.close
    Process.waitpid2(pid)
  end
end
```

--------------------------------

### Configure OpenSSH to Use hrr_rb_sftp

Source: https://github.com/hirura/hrr_rb_sftp/blob/master/README.md

Replace the default OpenSSH SFTP server with hrr_rb_sftp by modifying the sshd_config file. Ensure to comment out the original line and add the path to your hrr_rb_sftp_server.rb script.

```bash
#Subsystem  sftp    /usr/lib/openssh/sftp-server    # Comment out the original line
Subsystem   sftp    /path/to/hrr_rb_sftp_server.rb

```

--------------------------------

### List SFTP Protocol Version 3 Extensions

Source: https://context7.com/hirura/hrr_rb_sftp/llms.txt

Retrieve a list of advertised extensions for SFTP protocol version 3. This is automatically handled during the SSH_FXP_VERSION handshake.

```ruby
# Version 3 is selected automatically when both sides support it.
# Advertised extensions are sent in the SSH_FXP_VERSION handshake response:

HrrRbSftp::Protocol.extension_pairs(3).map { |ep| ep[:"extension-name"] }
# => ["hardlink@openssh.com", "fsync@openssh.com",
#     "posix-rename@openssh.com", "lsetstat@openssh.com"]
```

--------------------------------

### Check SFTP Protocol Version Support

Source: https://context7.com/hirura/hrr_rb_sftp/llms.txt

Verify if SFTP protocol version 2 is supported by the library. This is a simple boolean check.

```ruby
HrrRbSftp::Protocol.versions.include?(2) # => true
```

--------------------------------

### Configure sshd to use HrrRbSftp Server

Source: https://context7.com/hirura/hrr_rb_sftp/llms.txt

Modify the sshd configuration file to use the HrrRbSftp server. Reload the sshd service after making changes. Test the connection using the sftp command.

```bash
# Comment out (or remove) the original line:
#Subsystem sftp /usr/lib/openssh/sftp-server

# Add the hrr_rb_sftp replacement:
Subsystem sftp /path/to/hrr_rb_sftp_server.rb
```

```ruby
# /path/to/hrr_rb_sftp_server.rb
#!/usr/bin/env ruby

require "hrr_rb_sftp"

server = HrrRbSftp::Server.new(logger: nil)
server.start($stdin, $stdout, $stderr)
```

```bash
# Reload sshd (systemd systems)
sudo systemctl reload sshd

# Test the connection
sftp -P 22 user@host
```

--------------------------------

### Run SFTP Server in Same Process with hrr_rb_ssh

Source: https://github.com/hirura/hrr_rb_sftp/blob/master/README.md

Integrate hrr_rb_sftp as an SFTP subsystem handler within the same process as hrr_rb_ssh. This approach uses hrr_rb_ssh's request handler mechanism.

```ruby
subsys = HrrRbSsh::Connection::RequestHandler.new { |ctx|
  ctx.chain_proc {
    case ctx.subsystem_name
    when 'sftp'
      begin
        sftp_server = HrrRbSftp::Server.new(logger: nil)
        sftp_server.start(ctx.io[0], ctx.io[1], ctx.io[2])
        exitstatus = 0
      rescue
        exitstatus = 1
      end
    else
      # Do something for other subsystem, or just return exitstatus
      exitstatus = 0
    end
    exitstatus
  }
}

options['connection_channel_request_subsystem']  = subsys

```

--------------------------------

### SSH_FXP_SYMLINK Argument Order

Source: https://github.com/hirura/hrr_rb_sftp/blob/master/README.md

Note on the argument order for SSH_FXP_SYMLINK requests. This library follows the convention used by OpenSSH's sftp-server, where linkpath and targetpath are provided in a specific order.

```plaintext
uint32          id
string          targetpath
string          linkpath

```

--------------------------------

### SFTP Extension: fsync@openssh.com

Source: https://context7.com/hirura/hrr_rb_sftp/llms.txt

Constants and server-side behavior for the 'fsync@openssh.com' extension, used to flush kernel buffers to disk for an open file handle. Available only in protocol version 3.

```ruby
HrrRbSftp::Protocol::Version3::Extensions::FsyncAtOpensshCom::EXTENSION_NAME # => "fsync@openssh.com"
HrrRbSftp::Protocol::Version3::Extensions::FsyncAtOpensshCom::EXTENSION_DATA # => "1"

# Server-side behaviour:
#   file = handles[request[:handle]]
#   file.fsync
#
# Possible SSH_FXP_STATUS response codes:
#   SSH_FX_OK      — fsync completed
#   SSH_FX_FAILURE — handle not found in the open-handles map
```

--------------------------------

### HrrRbSftp::Protocol.extension_pairs

Source: https://context7.com/hirura/hrr_rb_sftp/llms.txt

Fetches the list of extension name/data pairs advertised for a specific protocol version. Only version 3 supports extensions; versions 1 and 2 return an empty array.

```APIDOC
## HrrRbSftp::Protocol.extension_pairs

Returns the list of extension name/data pairs advertised for a given protocol version. Only version 3 carries extensions; versions 1 and 2 return an empty array.

```ruby
require "hrr_rb_sftp"

puts HrrRbSftp::Protocol.extension_pairs(3).inspect
# => [
#      { :"extension-name" => "hardlink@openssh.com",      :"extension-data" => "1" },
#      { :"extension-name" => "fsync@openssh.com",         :"extension-data" => "1" },
#      { :"extension-name" => "posix-rename@openssh.com",  :"extension-data" => "1" },
#      { :"extension-name" => "lsetstat@openssh.com",      :"extension-data" => "1" },
#    ]

puts HrrRbSftp::Protocol.extension_pairs(1).inspect
# => []
```
```

--------------------------------

### SFTP Extension: posix-rename@openssh.com

Source: https://context7.com/hirura/hrr_rb_sftp/llms.txt

Constants and server-side behavior for the 'posix-rename@openssh.com' extension, which performs an atomic POSIX rename operation, replacing the destination if it exists. Available only in protocol version 3.

```ruby
HrrRbSftp::Protocol::Version3::Extensions::PosixRenameAtOpensshCom::EXTENSION_NAME # => "posix-rename@openssh.com"
HrrRbSftp::Protocol::Version3::Extensions::PosixRenameAtOpensshCom::EXTENSION_DATA # => "1"

# Server-side behaviour:
#   File.rename(request[:oldpath], request[:newpath])
#
# Possible SSH_FXP_STATUS response codes:
#   SSH_FX_OK               — rename succeeded
#   SSH_FX_NO_SUCH_FILE     — oldpath does not exist
#   SSH_FX_PERMISSION_DENIED — insufficient permissions
```

--------------------------------

### SFTP Extension: lsetstat@openssh.com

Source: https://context7.com/hirura/hrr_rb_sftp/llms.txt

Constants and server-side behavior for the 'lsetstat@openssh.com' extension, used to set attributes on a symbolic link itself without following it. Available only in protocol version 3.

```ruby
HrrRbSftp::Protocol::Version3::Extensions::LsetstatAtOpensshCom::EXTENSION_NAME # => "lsetstat@openssh.com"
HrrRbSftp::Protocol::Version3::Extensions::LsetstatAtOpensshCom::EXTENSION_DATA # => "1"

# Server-side behaviour depending on attrs fields present:
#   File.lutime(attrs[:atime], attrs[:mtime], path)  — set timestamps (requires Ruby >= 2.x lutime support)
#   File.lchown(attrs[:uid],   attrs[:gid],   path)  — set ownership
#   File.lchmod(attrs[:permissions],          path)  — set permissions
#
# Possible SSH_FXP_STATUS response codes:
#   SSH_FX_OK               — all requested attrs applied
#   SSH_FX_BAD_MESSAGE      — :size attribute provided (not supported by lsetstat)
#   SSH_FX_FAILURE          — File.lutime not supported by this Ruby build
#   SSH_FX_NO_SUCH_FILE     — path does not exist
#   SSH_FX_PERMISSION_DENIED — insufficient permissions
```

--------------------------------

### HrrRbSftp::Protocol.versions

Source: https://context7.com/hirura/hrr_rb_sftp/llms.txt

Retrieves the list of SFTP protocol version integers supported by the library. This is used during the handshake to determine the highest common version.

```APIDOC
## HrrRbSftp::Protocol.versions

Returns the list of SFTP protocol version integers that the library supports. During the handshake, the server selects `min(remote_version, local_version)`.

```ruby
require "hrr_rb_sftp"

puts HrrRbSftp::Protocol.versions.inspect
# => [1, 2, 3]

puts HrrRbSftp::Protocol.versions.max
# => 3  (highest supported version, used as the local offer)
```
```

--------------------------------

### SFTP Protocol Version 1 — Core Packet Types

Source: https://context7.com/hirura/hrr_rb_sftp/llms.txt

Details the core packet types for SFTP Protocol Version 1, including their TYPE constants and purposes. These packets form the foundation for all subsequent versions.

```APIDOC
## SFTP Protocol Version 1 — Core Packet Types

Version 1 implements the foundational SFTP packet set. All subsequent versions inherit and extend this set. The packets and their TYPE constants are:

| Packet | TYPE | Direction | Purpose |
|---|---|---|---|
| `SSH_FXP_OPEN` | 3 | request | Open or create a file |
| `SSH_FXP_CLOSE` | 4 | request | Close a file or directory handle |
| `SSH_FXP_READ` | 5 | request | Read bytes from an open file |
| `SSH_FXP_WRITE` | 6 | request | Write bytes to an open file |
| `SSH_FXP_LSTAT` | 7 | request | Stat a path without following symlinks |
| `SSH_FXP_FSTAT` | 8 | request | Stat an open handle |
| `SSH_FXP_SETSTAT` | 9 | request | Set attributes on a path |
| `SSH_FXP_FSETSTAT` | 10 | request | Set attributes on an open handle |
| `SSH_FXP_OPENDIR` | 11 | request | Open a directory |
| `SSH_FXP_READDIR` | 12 | request | Read directory entries |
| `SSH_FXP_REMOVE` | 13 | request | Remove a file |
| `SSH_FXP_MKDIR` | 14 | request | Create a directory |
| `SSH_FXP_RMDIR` | 15 | request | Remove a directory |
| `SSH_FXP_REALPATH` | 16 | request | Canonicalize a path |
| `SSH_FXP_STAT` | 17 | request | Stat a path following symlinks |
| `SSH_FXP_STATUS` | 101 | response | Operation status |
| `SSH_FXP_HANDLE` | 102 | response | File/directory handle |
| `SSH_FXP_DATA` | 103 | response | File data |
| `SSH_FXP_NAME` | 104 | response | File name list |
| `SSH_FXP_ATTRS` | 105 | response | File attributes |

```ruby
# Open flags used in SSH_FXP_OPEN pflags field (version 1+)
HrrRbSftp::Protocol::Version1::Packets::SSH_FXP_OPEN::SSH_FXF_READ   # => 0x00000001
HrrRbSftp::Protocol::Version1::Packets::SSH_FXP_OPEN::SSH_FXF_WRITE  # => 0x00000002
HrrRbSftp::Protocol::Version1::Packets::SSH_FXP_OPEN::SSH_FXF_APPEND # => 0x00000004
HrrRbSftp::Protocol::Version1::Packets::SSH_FXP_OPEN::SSH_FXF_CREAT  # => 0x00000008
HrrRbSftp::Protocol::Version1::Packets::SSH_FXP_OPEN::SSH_FXF_TRUNC  # => 0x00000010
HrrRbSftp::Protocol::Version1::Packets::SSH_FXP_OPEN::SSH_FXF_EXCL   # => 0x00000020

# SSH_FXP_STATUS response codes (version 1+)
HrrRbSftp::Protocol::Version1::Packets::SSH_FXP_STATUS::SSH_FX_OK                # => 0
HrrRbSftp::Protocol::Version1::Packets::SSH_FXP_STATUS::SSH_FX_EOF               # => 1
HrrRbSftp::Protocol::Version1::Packets::SSH_FXP_STATUS::SSH_FX_NO_SUCH_FILE      # => 2
HrrRbSftp::Protocol::Version1::Packets::SSH_FXP_STATUS::SSH_FX_PERMISSION_DENIED # => 3
HrrRbSftp::Protocol::Version1::Packets::SSH_FXP_STATUS::SSH_FX_FAILURE           # => 4
HrrRbSftp::Protocol::Version1::Packets::SSH_FXP_STATUS::SSH_FX_BAD_MESSAGE       # => 5
HrrRbSftp::Protocol::Version1::Packets::SSH_FXP_STATUS::SSH_FX_NO_CONNECTION     # => 6
HrrRbSftp::Protocol::Version1::Packets::SSH_FXP_STATUS::SSH_FX_CONNECTION_LOST   # => 7
HrrRbSftp::Protocol::Version1::Packets::SSH_FXP_STATUS::SSH_FX_OP_UNSUPPORTED    # => 8
```
```

--------------------------------

### SFTP Extension: hardlink@openssh.com

Source: https://context7.com/hirura/hrr_rb_sftp/llms.txt

Constants and server-side behavior for the 'hardlink@openssh.com' extension, used to create hard links on the server. Available only in protocol version 3.

```ruby
# Extension constants
HrrRbSftp::Protocol::Version3::Extensions::HardlinkAtOpensshCom::EXTENSION_NAME # => "hardlink@openssh.com"
HrrRbSftp::Protocol::Version3::Extensions::HardlinkAtOpensshCom::EXTENSION_DATA # => "1"

# Server-side behaviour (internally executed when the extension request arrives):
#   File.link(request[:oldpath], request[:newpath])
#
# Possible SSH_FXP_STATUS response codes:
#   SSH_FX_OK               — link created successfully
#   SSH_FX_NO_SUCH_FILE     — oldpath does not exist (Errno::ENOENT)
#   SSH_FX_PERMISSION_DENIED — insufficient permissions (Errno::EACCES)
#   SSH_FX_FAILURE          — link already exists (Errno::EEXIST)
```

--------------------------------

### SFTP Protocol Version 2 — SSH_FXP_RENAME

Source: https://context7.com/hirura/hrr_rb_sftp/llms.txt

Introduces the `SSH_FXP_RENAME` packet (TYPE 18) for version 2, allowing clients to rename files and directories. This version is automatically negotiated if supported by both client and server.

```APIDOC
## SFTP Protocol Version 2 — `SSH_FXP_RENAME`

Version 2 adds the `SSH_FXP_RENAME` packet (TYPE 18), enabling clients to rename files and directories. All version 1 packets are also available.

```ruby
# Version 2 is selected automatically when both client and server support it.
# No application-level code is needed — the server negotiates the version
# in the SSH_FXP_INIT / SSH_FXP_VERSION handshake and routes packets accordingly.
```
```

--------------------------------

### Custom Logger Formatter for HrrRbSftp

Source: https://context7.com/hirura/hrr_rb_sftp/llms.txt

Define a custom logger formatter to control the output format of log messages. This is useful for integrating with existing logging systems or for custom log analysis.

```ruby
class MyLoggerFormatter < Logger::Formatter
  def call(severity, time, progname, msg)
    "%s, [%s#%d.%x] %5s -- %s: %s\n" % [
      severity[0],
      format_datetime(time),
      Process.pid,
      Thread.current.object_id,
      severity,
      progname,
      msg2str(msg)
    ]
  end
end
logger.formatter = MyLoggerFormatter.new
```

--------------------------------

### SFTP Version 1 Core Packet Type Constants

Source: https://context7.com/hirura/hrr_rb_sftp/llms.txt

Access constants for SFTP protocol version 1 packet types, including open flags and status codes. These constants are used for defining and interpreting SFTP packets.

```ruby
# Open flags used in SSH_FXP_OPEN pflags field (version 1+)
HrrRbSftp::Protocol::Version1::Packets::SSH_FXP_OPEN::SSH_FXF_READ   # => 0x00000001
HrrRbSftp::Protocol::Version1::Packets::SSH_FXP_OPEN::SSH_FXF_WRITE  # => 0x00000002
HrrRbSftp::Protocol::Version1::Packets::SSH_FXP_OPEN::SSH_FXF_APPEND # => 0x00000004
HrrRbSftp::Protocol::Version1::Packets::SSH_FXP_OPEN::SSH_FXF_CREAT  # => 0x00000008
HrrRbSftp::Protocol::Version1::Packets::SSH_FXP_OPEN::SSH_FXF_TRUNC  # => 0x00000010
HrrRbSftp::Protocol::Version1::Packets::SSH_FXP_OPEN::SSH_FXF_EXCL   # => 0x00000020

# SSH_FXP_STATUS response codes (version 1+)
HrrRbSftp::Protocol::Version1::Packets::SSH_FXP_STATUS::SSH_FX_OK                # => 0
HrrRbSftp::Protocol::Version1::Packets::SSH_FXP_STATUS::SSH_FX_EOF               # => 1
HrrRbSftp::Protocol::Version1::Packets::SSH_FXP_STATUS::SSH_FX_NO_SUCH_FILE      # => 2
HrrRbSftp::Protocol::Version1::Packets::SSH_FXP_STATUS::SSH_FX_PERMISSION_DENIED # => 3
HrrRbSftp::Protocol::Version1::Packets::SSH_FXP_STATUS::SSH_FX_FAILURE           # => 4
HrrRbSftp::Protocol::Version1::Packets::SSH_FXP_STATUS::SSH_FX_BAD_MESSAGE       # => 5
HrrRbSftp::Protocol::Version1::Packets::SSH_FXP_STATUS::SSH_FX_NO_CONNECTION     # => 6
HrrRbSftp::Protocol::Version1::Packets::SSH_FXP_STATUS::SSH_FX_CONNECTION_LOST   # => 7
HrrRbSftp::Protocol::Version1::Packets::SSH_FXP_STATUS::SSH_FX_OP_UNSUPPORTED    # => 8
```

--------------------------------

### SFTP Protocol Version 2 - SSH_FXP_RENAME Packet

Source: https://context7.com/hirura/hrr_rb_sftp/llms.txt

Version 2 of the SFTP protocol introduces the `SSH_FXP_RENAME` packet (TYPE 18) for renaming files and directories. This functionality is automatically negotiated during the SSH handshake.

```ruby
# Version 2 is selected automatically when both client and server support it.
# No application-level code is needed — the server negotiates the version
# in the SSH_FXP_INIT / SSH_FXP_VERSION handshake and routes packets accordingly.
```

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