Shell and exec integration

This guide explains the callback boundary for an application-defined interactive shell or one-shot command service. Use it when the product already has a command processor or needs a custom one.

SharkSSH does not require a command interpreter, process launcher, POSIX API, or particular terminal implementation. An application accepts or rejects SSH shell and exec requests through SharkSshServices and supplies the behavior appropriate for its product.

Service callbacks

The core first calls SharkSshServices.authorize for a shell or exec request. Only an approved request reaches shell or exec. The application then owns the service until the channel closes and receives its input, EOF, and output- resumption notifications through data, eof, and writable.

An implementation normally keeps one caller-owned state object per accepted channel. It must:

• retain incomplete command input within a documented bound;
• honor SSH channel-window backpressure when producing output;
• preserve pending output until writable resumes it;
• send an exit status and close in the correct order;
• release files, command state, and other resources on EOF, disconnect, or service close; and
• keep filesystem, authorization, scheduling, and platform behavior behind callbacks rather than assuming POSIX or a real-time operating system (RTOS) API.

Pseudo-terminal (PTY) requests arrive separately through pty. Applications that implement terminal editing should parse the SSH terminal-mode payload and honor at least the echo modes they advertise.

Use the provided implementation

The core can be integrated with a product-specific shell, or with the optional bounded SharkSshShell plugin. That implementation is allocation-free, supports interactive shell and single-command exec requests, includes bounded generic filesystem commands, and provides a fixed custom- command registry.

The plugin guide explains how to install and connect SharkSshShell.c, lists its commands and public APIs, and documents its read-only, authorization, audit, path, copy, and memory behavior.