Rust Bindings for Hexchat Plugin API

1 files changed, 197 insertions, 0 deletions

diff --git a/src/lib.rs b/src/lib.rs
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+++ b/src/lib.rs
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+/*
+ * Hexchat Plugin API Bindings for Rust
+ * Copyright (C) 2018 Soni L.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+//! <!-- TODO (placeholder) -->
+
+#[doc(hidden)]
+pub extern crate libc;
+
+mod internals;
+
+use std::panic::catch_unwind;
+use std::thread;
+use std::ffi::{CString, CStr};
+use std::str::FromStr;
+
+const EMPTY_CSTRING_DATA: &[u8] = b"\0";
+
+/// A hexchat plugin
+pub trait Plugin {
+    fn init(&mut self, &mut PluginHandle) -> bool;
+}
+
+/// A handle for a hexchat plugin
+pub struct PluginHandle {
+    ph: *mut internals::Ph,
+    filename: Option<CString>,
+    registered: bool,
+    fakehandle: *const internals::PluginGuiHandle,
+}
+
+impl PluginHandle {
+    pub fn register(&mut self, name: &str, desc: &str, ver: &str) {
+        unsafe {
+            let ph = &mut *self.ph;
+            if let Some(hexchat_plugingui_add) = ph.hexchat_plugingui_add {
+                let filename = self.filename.take().expect("Attempt to re-register a plugin");
+                let name = CString::new(name).unwrap();
+                let desc = CString::new(desc).unwrap();
+                let ver = CString::new(ver).unwrap();
+                self.fakehandle = hexchat_plugingui_add(self.ph, filename.as_ptr(), name.as_ptr(), desc.as_ptr(), ver.as_ptr(), ::std::ptr::null_mut());
+            }
+            self.registered = true;
+        }
+    }
+}
+
+#[doc(hidden)]
+pub unsafe fn hexchat_plugin_init<T>(plugin_handle: *mut libc::c_void,
+                                     plugin_name: *mut *const libc::c_char,
+                                     plugin_desc: *mut *const libc::c_char,
+                                     plugin_version: *mut *const libc::c_char,
+                                     arg: *const libc::c_char) -> libc::c_int
+                                     where T: Plugin + Default {
+    if plugin_handle.is_null() {
+        // we can't really do anything here.
+        eprintln!("hexchat_plugin_init called with a null plugin_handle. This is an error!");
+        // TODO maybe call abort.
+        return 0;
+    }
+    let ph = &mut *(plugin_handle as *mut internals::Ph);
+    // clear the "userdata" field first thing - if the deinit function gets called (wrong hexchat
+    // version, other issues), we don't wanna try to drop the hexchat_dummy or hexchat_read_fd
+    // function as if it were a Box!
+    ph.userdata = ::std::ptr::null_mut();
+    // we set these to empty strings because rust strings aren't nul-terminated. which means we
+    // need to *allocate* nul-terminated strings for the real values, and hexchat has no way of
+    // freeing these.
+    // BUT before we set them, read the filename off plugin_name - we'll need it!
+    // (TODO figure out how to make this NOT break the plugins list)
+    let filename = CStr::from_ptr(*plugin_name).to_owned();
+    let empty_cstr = CStr::from_bytes_with_nul_unchecked(EMPTY_CSTRING_DATA).as_ptr();
+    *plugin_name = empty_cstr;
+    *plugin_desc = empty_cstr;
+    *plugin_version = empty_cstr;
+    // do some version checks for safety
+    if let Some(hexchat_get_info) = ph.hexchat_get_info {
+        let ver: *const libc::c_char = hexchat_get_info(ph, CStr::from_bytes_with_nul_unchecked(b"version\0").as_ptr());
+        let cstr = CStr::from_ptr(ver);
+        if let Ok(ver) = cstr.to_str() {
+            let mut iter = ver.split('.');
+            let a = iter.next().map(i32::from_str).and_then(Result::ok);
+            let b = iter.next().map(i32::from_str).and_then(Result::ok);
+            let c = iter.next().map(i32::from_str).and_then(Result::ok);
+            if !match a.unwrap_or(0) {
+                0 | 1 => false,
+                2 => match b.unwrap_or(0) {
+                    // range patterns are a bit broken
+                    0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 => false,
+                    9 => match c.unwrap_or(0) {
+                        0 | 1 | 2 | 3 | 4 | 5 => false,
+                        6 => 
+                            // min acceptable version = 2.9.6
+                            true,
+                        _ => true,
+                    },
+                    _ => true,
+                },
+                _ => true,
+            } {
+                // TODO print: "error loading plugin: hexchat too old"?
+                return 0;
+            }
+        } else {
+            return 0;
+        }
+    }
+    let r: thread::Result<Option<Box<_>>> = catch_unwind(|| {
+        let mut plug = T::default();
+        let mut pluginhandle = PluginHandle {
+            ph: plugin_handle as *mut _,
+            registered: false,
+            filename: Some(filename),
+            fakehandle: ::std::ptr::null(),
+        };
+        if plug.init(&mut pluginhandle) {
+            if pluginhandle.registered {
+                Some(Box::new((plug, pluginhandle.fakehandle)))
+            } else {
+                // TODO log: forgot to call register
+                None
+            }
+        } else {
+            None
+        }
+    });
+    if r.is_ok() {
+        if let Ok(Some(plug)) = r {
+            ph.userdata = Box::into_raw(plug) as *mut libc::c_void;
+            1
+        } else {
+            0
+        }
+    } else {
+        // TODO try to log panic?
+        0
+    }
+}
+
+#[doc(hidden)]
+pub unsafe fn hexchat_plugin_deinit<T>(plugin_handle: *mut libc::c_void) where T: Plugin {
+    // plugin_handle should never be null, but just in case...
+    if !plugin_handle.is_null() {
+        let ph = &mut *(plugin_handle as *mut internals::Ph);
+        if !ph.userdata.is_null() {
+            // 
+            let userdata = ph.userdata;
+            ph.userdata = ::std::ptr::null_mut();
+            // we use an explicit drop (instead of an implicit one) so this is less confusing/weird
+            // to read.
+            catch_unwind(|| {
+                let ph = &mut *(plugin_handle as *mut internals::Ph);
+                let (plug, fakehandle) = *Box::from_raw(userdata as *mut (T, *const internals::PluginGuiHandle));
+                if let Some(hexchat_plugingui_remove) = ph.hexchat_plugingui_remove {
+                    hexchat_plugingui_remove(ph, fakehandle);
+                }
+                ::std::mem::drop(plug); // suppress compiler warnings
+            }).ok();
+        }
+    } else {
+        eprintln!("hexchat_plugin_deinit called with a null plugin_handle. This is an error!");
+    }
+}
+
+/// Exports a hexchat plugin.
+#[macro_export]
+macro_rules! hexchat_plugin {
+    ($t:ty) => {
+        #[no_mangle]
+        pub unsafe extern "C" fn hexchat_plugin_init(plugin_handle: *mut $crate::libc::c_void,
+                                              plugin_name: *mut *const $crate::libc::c_char,
+                                              plugin_desc: *mut *const $crate::libc::c_char,
+                                              plugin_version: *mut *const $crate::libc::c_char,
+                                              arg: *const $crate::libc::c_char) -> $crate::libc::c_int {
+            $crate::hexchat_plugin_init::<$t>(plugin_handle, plugin_name, plugin_desc, plugin_version, arg)
+        }
+        #[no_mangle]
+        pub unsafe extern "C" fn hexchat_plugin_deinit(plugin_handle: *mut $crate::libc::c_void) {
+            $crate::hexchat_plugin_deinit::<$t>(plugin_handle);
+        }
+        // unlike what the documentation states, there's no need to define hexchat_plugin_get_info.
+        // so we don't. it'd be impossible to make it work well with rust anyway.
+    };
+}