1 | //! The code in this module allows to call libxcb's C functions. |
2 | //! |
3 | //! At its heart, this module only contains an `extern "C"` block that defines the C functions so |
4 | //! that they can be called from Rust. |
5 | //! |
6 | //! However, this module also contains the implementation of the `dl-libxcb` features. When this |
7 | //! future is enabled, we do not link against libxcb, but instead use `libloading` to load |
8 | //! `libxcb.so` at runtime. Most of the code is actually responsible for this later feature. |
9 | |
10 | use super::{ |
11 | c_char, c_int, c_uint, c_void, iovec, xcb_connection_t, xcb_generic_error_t, |
12 | xcb_generic_event_t, xcb_protocol_request_t, xcb_setup_t, xcb_void_cookie_t, |
13 | }; |
14 | |
15 | #[cfg (feature = "dl-libxcb" )] |
16 | pub(crate) mod libxcb_library { |
17 | use super::LibxcbFuncs; |
18 | use crate::errors::LibxcbLoadError; |
19 | |
20 | pub(super) struct LibxcbLibrary { |
21 | // Needed to keep the library loaded |
22 | _library: libloading::Library, |
23 | pub(super) funcs: LibxcbFuncs, |
24 | } |
25 | |
26 | impl LibxcbLibrary { |
27 | /// # Safety |
28 | /// |
29 | /// The functions pointers in `funcs` do not have lifetime, |
30 | /// but they must not outlive the returned result. |
31 | #[cold ] |
32 | #[inline (never)] |
33 | unsafe fn load() -> Result<Self, LibxcbLoadError> { |
34 | // TODO: Names for non-unix platforms |
35 | #[cfg (not(unix))] |
36 | compile_error!("dl-libxcb feature is not supported on non-unix" ); |
37 | |
38 | #[cfg (all(unix, target_os = "linux" ))] |
39 | const LIB_NAME: &str = "libxcb.so.1" ; |
40 | |
41 | // libtool turns -version-info differently into SONAMES on NetBSD. |
42 | // Also, the library is apparently not in the default search path, hence use a full path. |
43 | #[cfg (all(unix, target_os = "netbsd" ))] |
44 | const LIB_NAME: &str = "/usr/X11R7/lib/libxcb.so.2" ; |
45 | |
46 | // If we do not know anything, just assume libxcb.so and hope for the best. |
47 | // This is actually the right thing to do on OpenBSD since the dynamic linker then does |
48 | // some magic to find the right SONAME. |
49 | #[cfg (all(unix, not(any(target_os = "linux" , target_os = "netbsd" ))))] |
50 | const LIB_NAME: &str = "libxcb.so" ; |
51 | |
52 | let library = libloading::Library::new(LIB_NAME) |
53 | .map_err(|e| LibxcbLoadError::OpenLibError(LIB_NAME.into(), e.to_string()))?; |
54 | let funcs = LibxcbFuncs::new(&library).map_err(|(symbol, e)| { |
55 | LibxcbLoadError::GetSymbolError(symbol.into(), e.to_string()) |
56 | })?; |
57 | Ok(Self { |
58 | _library: library, |
59 | funcs, |
60 | }) |
61 | } |
62 | } |
63 | |
64 | use once_cell::sync::Lazy; |
65 | |
66 | static LIBXCB_LIBRARY: Lazy<Result<LibxcbLibrary, LibxcbLoadError>> = |
67 | Lazy::new(|| unsafe { LibxcbLibrary::load() }); |
68 | |
69 | pub(super) fn get_libxcb() -> &'static LibxcbLibrary { |
70 | #[cold ] |
71 | #[inline (never)] |
72 | fn failed(e: &LibxcbLoadError) -> ! { |
73 | panic!("failed to load libxcb: {}" , e); |
74 | } |
75 | match *LIBXCB_LIBRARY { |
76 | Ok(ref library) => library, |
77 | Err(ref e) => failed(e), |
78 | } |
79 | } |
80 | |
81 | /// Tries to dynamically load libxcb, returning an error on failure. |
82 | /// |
83 | /// It is not required to call this function, as libxcb will be lazily loaded. |
84 | /// However, if a lazy load fails, a panic will be raised, missing the chance |
85 | /// to (nicely) handle the error. |
86 | /// |
87 | /// It is safe to call this function more than once from the same or different |
88 | /// threads. Only the first call will try to load libxcb, subsequent calls will |
89 | /// always return the same result. |
90 | pub fn load_libxcb() -> Result<(), LibxcbLoadError> { |
91 | match Lazy::force(&LIBXCB_LIBRARY) { |
92 | Ok(_) => Ok(()), |
93 | Err(e) => Err(e.clone()), |
94 | } |
95 | } |
96 | } |
97 | |
98 | macro_rules! make_ffi_fn_defs { |
99 | { |
100 | $( |
101 | $(#[$fn_attr:meta])* |
102 | fn $fn_name:ident($($fn_arg_name:ident: $fn_arg_type:ty),*) $(-> $fn_ret_ty:ty)?; |
103 | )* |
104 | } => { |
105 | #[cfg(not(feature = "dl-libxcb" ))] |
106 | #[link(name = "xcb" )] |
107 | extern "C" { |
108 | $( |
109 | $(#[$fn_attr])* |
110 | pub(crate) fn $fn_name($($fn_arg_name: $fn_arg_type),*) $(-> $fn_ret_ty)?; |
111 | )* |
112 | } |
113 | |
114 | #[cfg(feature = "dl-libxcb" )] |
115 | struct LibxcbFuncs { |
116 | $( |
117 | $(#[$fn_attr])* |
118 | $fn_name: unsafe extern "C" fn($($fn_arg_name: $fn_arg_type),*) $(-> $fn_ret_ty)?, |
119 | )* |
120 | } |
121 | |
122 | #[cfg(feature = "dl-libxcb" )] |
123 | impl LibxcbFuncs { |
124 | unsafe fn new(library: &libloading::Library) -> Result<Self, (&'static [u8], libloading::Error)> { |
125 | Ok(Self { |
126 | $($fn_name: { |
127 | let symbol_name = concat!(stringify!($fn_name), " \0" ).as_bytes(); |
128 | *library.get(symbol_name).map_err(|e| (stringify!($fn_name).as_bytes(), e))? |
129 | },)* |
130 | }) |
131 | } |
132 | } |
133 | |
134 | $( |
135 | #[cfg(feature = "dl-libxcb" )] |
136 | $(#[$fn_attr])* |
137 | pub(crate) unsafe fn $fn_name($($fn_arg_name: $fn_arg_type),*) $(-> $fn_ret_ty)? { |
138 | (libxcb_library::get_libxcb().funcs.$fn_name)($($fn_arg_name),*) |
139 | } |
140 | )* |
141 | }; |
142 | } |
143 | |
144 | make_ffi_fn_defs! { |
145 | // From xcb.h |
146 | fn xcb_flush(c: *mut xcb_connection_t) -> c_int; |
147 | fn xcb_get_maximum_request_length(c: *mut xcb_connection_t) -> u32; |
148 | fn xcb_prefetch_maximum_request_length(c: *mut xcb_connection_t); |
149 | fn xcb_wait_for_event(c: *mut xcb_connection_t) -> *mut xcb_generic_event_t; |
150 | fn xcb_poll_for_event(c: *mut xcb_connection_t) -> *mut xcb_generic_event_t; |
151 | fn xcb_request_check( |
152 | c: *mut xcb_connection_t, |
153 | void_cookie: xcb_void_cookie_t |
154 | ) -> *mut xcb_generic_error_t; |
155 | fn xcb_discard_reply64(c: *mut xcb_connection_t, sequence: u64); |
156 | fn xcb_get_setup(c: *mut xcb_connection_t) -> *const xcb_setup_t; |
157 | #[cfg (unix)] |
158 | fn xcb_get_file_descriptor(c: *mut xcb_connection_t) -> c_int; |
159 | fn xcb_connection_has_error(c: *mut xcb_connection_t) -> c_int; |
160 | fn xcb_disconnect(c: *mut xcb_connection_t); |
161 | fn xcb_connect( |
162 | displayname: *const c_char, |
163 | screenp: *mut c_int |
164 | ) -> *mut xcb_connection_t; |
165 | fn xcb_generate_id(c: *mut xcb_connection_t) -> u32; |
166 | |
167 | // From xcbext.h |
168 | fn xcb_send_request64( |
169 | c: *mut xcb_connection_t, |
170 | flags: c_int, |
171 | vector: *mut iovec, |
172 | request: *const xcb_protocol_request_t |
173 | ) -> u64; |
174 | #[cfg (unix)] |
175 | fn xcb_send_request_with_fds64( |
176 | c: *mut xcb_connection_t, |
177 | flags: c_int, |
178 | vector: *mut iovec, |
179 | request: *const xcb_protocol_request_t, |
180 | num_fds: c_uint, |
181 | fds: *mut c_int |
182 | ) -> u64; |
183 | fn xcb_wait_for_reply64( |
184 | c: *mut xcb_connection_t, |
185 | request: u64, |
186 | e: *mut *mut xcb_generic_error_t |
187 | ) -> *mut c_void; |
188 | fn xcb_poll_for_reply64( |
189 | c: *mut xcb_connection_t, |
190 | request: u64, |
191 | reply: *mut *mut c_void, |
192 | error: *mut *mut xcb_generic_error_t |
193 | ) -> c_int; |
194 | } |
195 | |