summaryrefslogtreecommitdiffstats
path: root/xpcom/idl-parser/xpidl/rust.py
blob: 71ad5e98c8fa4f3f75450dea2bdf58f2b9a0cecb (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
# rust.py - Generate rust bindings from IDL.
#
# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, You can obtain one at http://mozilla.org/MPL/2.0/.

"""Print a runtime Rust bindings file for the IDL file specified"""

# --- Safety Hazards ---

# We currently don't generate some bindings for some IDL methods in rust code,
# due to there being ABI safety hazards if we were to do so. This is the
# documentation for the reasons why we don't generate certain types of bindings,
# so that we don't accidentally start generating them in the future.

# notxpcom methods and attributes return their results directly by value. The x86
# windows stdcall ABI returns aggregates by value differently for methods than
# functions, and rust only exposes the function ABI, so that's the one we're
# using. The correct ABI can be emulated for notxpcom methods returning aggregates
# by passing an &mut ReturnType parameter as the second parameter.  This strategy
# is used by the winapi-rs crate.
# https://github.com/retep998/winapi-rs/blob/7338a5216a6a7abeefcc6bb1bc34381c81d3e247/src/macros.rs#L220-L231
#
# Right now we can generate code for notxpcom methods and attributes, as we don't
# support passing aggregates by value over these APIs ever (the types which are
# allowed in xpidl.py shouldn't include any aggregates), so the code is
# correct. In the future if we want to start supporting returning aggregates by
# value, we will need to use a workaround such as the one used by winapi.rs.

# nostdcall methods on x86 windows will use the thiscall ABI, which is not
# stable in rust right now, so we cannot generate bindings to them.

# In general, passing C++ objects by value over the C ABI is not a good idea,
# and when possible we should avoid doing so. We don't generate bindings for
# these methods here currently.

import os.path
import re

from xpidl import xpidl


class AutoIndent(object):
    """A small autoindenting wrapper around a fd.
    Used to make the code output more readable."""

    def __init__(self, fd):
        self.fd = fd
        self.indent = 0

    def write(self, string):
        """A smart write function which automatically adjusts the
        indentation of each line as it is written by counting braces"""
        for s in string.split("\n"):
            s = s.strip()
            indent = self.indent
            if len(s) == 0:
                indent = 0
            elif s[0] == "}":
                indent -= 1

            self.fd.write("    " * indent + s + "\n")
            for c in s:
                if c == "(" or c == "{" or c == "[":
                    self.indent += 1
                elif c == ")" or c == "}" or c == "]":
                    self.indent -= 1


def rustSanitize(s):
    keywords = [
        "abstract",
        "alignof",
        "as",
        "become",
        "box",
        "break",
        "const",
        "continue",
        "crate",
        "do",
        "else",
        "enum",
        "extern",
        "false",
        "final",
        "fn",
        "for",
        "if",
        "impl",
        "in",
        "let",
        "loop",
        "macro",
        "match",
        "mod",
        "move",
        "mut",
        "offsetof",
        "override",
        "priv",
        "proc",
        "pub",
        "pure",
        "ref",
        "return",
        "Self",
        "self",
        "sizeof",
        "static",
        "struct",
        "super",
        "trait",
        "true",
        "type",
        "typeof",
        "unsafe",
        "unsized",
        "use",
        "virtual",
        "where",
        "while",
        "yield",
    ]
    if s in keywords:
        return s + "_"
    return s


# printdoccomments = False
printdoccomments = True

if printdoccomments:

    def printComments(fd, clist, indent):
        fd.write("%s%s" % (indent, doccomments(clist)))

    def doccomments(clist):
        if len(clist) == 0:
            return ""
        s = "/// ```text"
        for c in clist:
            for cc in c.splitlines():
                s += "\n/// " + cc
        s += "\n/// ```\n///\n"
        return s

else:

    def printComments(fd, clist, indent):
        pass

    def doccomments(clist):
        return ""


def firstCap(str):
    return str[0].upper() + str[1:]


# Attribute VTable Methods
def attributeNativeName(a, getter):
    binaryname = rustSanitize(a.binaryname if a.binaryname else firstCap(a.name))
    return "%s%s" % ("Get" if getter else "Set", binaryname)


def attributeReturnType(a, getter):
    if a.notxpcom:
        if getter:
            return a.realtype.rustType("in").strip()
        return "::libc::c_void"
    return "::nserror::nsresult"


def attributeParamName(a):
    return "a" + firstCap(a.name)


def attributeRawParamList(iface, a, getter):
    if getter and a.notxpcom:
        l = []
    else:
        l = [(attributeParamName(a), a.realtype.rustType("out" if getter else "in"))]
    if a.implicit_jscontext:
        raise xpidl.RustNoncompat("jscontext is unsupported")
    if a.nostdcall:
        raise xpidl.RustNoncompat("nostdcall is unsupported")
    return l


def attributeParamList(iface, a, getter):
    l = ["this: *const " + iface.name]
    l += ["%s: %s" % x for x in attributeRawParamList(iface, a, getter)]
    return ", ".join(l)


def attrAsVTableEntry(iface, m, getter):
    try:
        return 'pub %s: unsafe extern "system" fn (%s) -> %s' % (
            attributeNativeName(m, getter),
            attributeParamList(iface, m, getter),
            attributeReturnType(m, getter),
        )
    except xpidl.RustNoncompat as reason:
        return """\
/// Unable to generate binding because `%s`
pub %s: *const ::libc::c_void""" % (
            reason,
            attributeNativeName(m, getter),
        )


# Method VTable generation functions
def methodNativeName(m):
    binaryname = m.binaryname is not None and m.binaryname or firstCap(m.name)
    return rustSanitize(binaryname)


def methodReturnType(m):
    if m.notxpcom:
        return m.realtype.rustType("in").strip()
    return "::nserror::nsresult"


def methodRawParamList(iface, m):
    l = [(rustSanitize(p.name), p.rustType()) for p in m.params]

    if m.implicit_jscontext:
        raise xpidl.RustNoncompat("jscontext is unsupported")

    if m.optional_argc:
        raise xpidl.RustNoncompat("optional_argc is unsupported")

    if m.nostdcall:
        raise xpidl.RustNoncompat("nostdcall is unsupported")

    if not m.notxpcom and m.realtype.name != "void":
        l.append(("_retval", m.realtype.rustType("out")))

    return l


def methodParamList(iface, m):
    l = ["this: *const %s" % iface.name]
    l += ["%s: %s" % x for x in methodRawParamList(iface, m)]
    return ", ".join(l)


def methodAsVTableEntry(iface, m):
    try:
        return 'pub %s: unsafe extern "system" fn (%s) -> %s' % (
            methodNativeName(m),
            methodParamList(iface, m),
            methodReturnType(m),
        )
    except xpidl.RustNoncompat as reason:
        return """\
/// Unable to generate binding because `%s`
pub %s: *const ::libc::c_void""" % (
            reason,
            methodNativeName(m),
        )


method_impl_tmpl = """\
#[inline]
pub unsafe fn %(name)s(&self, %(params)s) -> %(ret_ty)s {
    ((*self.vtable).%(name)s)(self, %(args)s)
}
"""


def methodAsWrapper(iface, m):
    try:
        param_list = methodRawParamList(iface, m)
        params = ["%s: %s" % x for x in param_list]
        args = [x[0] for x in param_list]

        return method_impl_tmpl % {
            "name": methodNativeName(m),
            "params": ", ".join(params),
            "ret_ty": methodReturnType(m),
            "args": ", ".join(args),
        }
    except xpidl.RustNoncompat:
        # Dummy field for the doc comments to attach to.
        # Private so that it's not shown in rustdoc.
        return "const _%s: () = ();" % methodNativeName(m)


infallible_impl_tmpl = """\
#[inline]
pub unsafe fn %(name)s(&self) -> %(realtype)s {
    let mut result = <%(realtype)s as ::std::default::Default>::default();
    let _rv = ((*self.vtable).%(name)s)(self, &mut result);
    debug_assert!(_rv.succeeded());
    result
}
"""


def attrAsWrapper(iface, m, getter):
    try:
        if m.implicit_jscontext:
            raise xpidl.RustNoncompat("jscontext is unsupported")

        if m.nostdcall:
            raise xpidl.RustNoncompat("nostdcall is unsupported")

        name = attributeParamName(m)

        if getter and m.infallible and m.realtype.kind == "builtin":
            # NOTE: We don't support non-builtin infallible getters in Rust code.
            return infallible_impl_tmpl % {
                "name": attributeNativeName(m, getter),
                "realtype": m.realtype.rustType("in"),
            }

        param_list = attributeRawParamList(iface, m, getter)
        params = ["%s: %s" % x for x in param_list]
        return method_impl_tmpl % {
            "name": attributeNativeName(m, getter),
            "params": ", ".join(params),
            "ret_ty": attributeReturnType(m, getter),
            "args": "" if getter and m.notxpcom else name,
        }

    except xpidl.RustNoncompat:
        # Dummy field for the doc comments to attach to.
        # Private so that it's not shown in rustdoc.
        return "const _%s: () = ();" % attributeNativeName(m, getter)


header = """\
//
// DO NOT EDIT.  THIS FILE IS GENERATED FROM $SRCDIR/%(relpath)s
//

"""


def idl_basename(f):
    """returns the base name of a file with the last extension stripped"""
    return os.path.splitext(os.path.basename(f))[0]


def print_rust_bindings(idl, fd, relpath):
    fd = AutoIndent(fd)

    fd.write(header % {"relpath": relpath})

    # All of the idl files will be included into the same rust module, as we
    # can't do forward declarations. Because of this, we want to ignore all
    # import statements

    for p in idl.productions:
        if p.kind == "include" or p.kind == "cdata" or p.kind == "forward":
            continue

        if p.kind == "interface":
            write_interface(p, fd)
            continue

        if p.kind == "typedef":
            try:
                if printdoccomments:
                    fd.write(
                        "/// `typedef %s %s;`\n///\n"
                        % (p.realtype.nativeType("in"), p.name)
                    )
                    fd.write(doccomments(p.doccomments))
                fd.write("pub type %s = %s;\n\n" % (p.name, p.realtype.rustType("in")))
            except xpidl.RustNoncompat as reason:
                fd.write(
                    "/* unable to generate %s typedef because `%s` */\n\n"
                    % (p.name, reason)
                )


base_vtable_tmpl = """
/// We need to include the members from the base interface's vtable at the start
/// of the VTable definition.
pub __base: %sVTable,

"""


vtable_tmpl = """\
// This struct represents the interface's VTable. A pointer to a statically
// allocated version of this struct is at the beginning of every %(name)s
// object. It contains one pointer field for each method in the interface. In
// the case where we can't generate a binding for a method, we include a void
// pointer.
#[doc(hidden)]
#[repr(C)]
pub struct %(name)sVTable {%(base)s%(entries)s}

"""


# NOTE: This template is not generated for nsISupports, as it has no base interfaces.
deref_tmpl = """\
// Every interface struct type implements `Deref` to its base interface. This
// causes methods on the base interfaces to be directly avaliable on the
// object. For example, you can call `.AddRef` or `.QueryInterface` directly
// on any interface which inherits from `nsISupports`.
impl ::std::ops::Deref for %(name)s {
    type Target = %(base)s;
    #[inline]
    fn deref(&self) -> &%(base)s {
        unsafe {
            ::std::mem::transmute(self)
        }
    }
}

// Ensure we can use .coerce() to cast to our base types as well. Any type which
// our base interface can coerce from should be coercable from us as well.
impl<T: %(base)sCoerce> %(name)sCoerce for T {
    #[inline]
    fn coerce_from(v: &%(name)s) -> &Self {
        T::coerce_from(v)
    }
}
"""


struct_tmpl = """\
// The actual type definition for the interface. This struct has methods
// declared on it which will call through its vtable. You never want to pass
// this type around by value, always pass it behind a reference.

#[repr(C)]
pub struct %(name)s {
    vtable: &'static %(name)sVTable,

    /// This field is a phantomdata to ensure that the VTable type and any
    /// struct containing it is not safe to send across threads by default, as
    /// XPCOM is generally not threadsafe.
    ///
    /// If this type is marked as [rust_sync], there will be explicit `Send` and
    /// `Sync` implementations on this type, which will override the inherited
    /// negative impls from `Rc`.
    __nosync: ::std::marker::PhantomData<::std::rc::Rc<u8>>,

    // Make the rust compiler aware that there might be interior mutability
    // in what actually implements the interface. This works around UB
    // introduced by https://github.com/llvm/llvm-project/commit/01859da84bad95fd51d6a03b08b60c660e642a4f
    // that a rust lint would make blatantly obvious, but doesn't exist.
    // (See https://github.com/rust-lang/rust/issues/111229).
    // This prevents optimizations, but those optimizations weren't available
    // before rustc switched to LLVM 16, and they now cause problems because
    // of the UB.
    // Until there's a lint available to find all our UB, it's simpler to
    // avoid the UB in the first place, at the cost of preventing optimizations
    // in places that don't cause UB. But again, those optimizations weren't
    // available before.
    __maybe_interior_mutability: ::std::cell::UnsafeCell<[u8; 0]>,
}

// Implementing XpCom for an interface exposes its IID, which allows for easy
// use of the `.query_interface<T>` helper method. This also defines that
// method for %(name)s.
unsafe impl XpCom for %(name)s {
    const IID: nsIID = nsID(0x%(m0)s, 0x%(m1)s, 0x%(m2)s,
                            [%(m3joined)s]);
}

// We need to implement the RefCounted trait so we can be used with `RefPtr`.
// This trait teaches `RefPtr` how to manage our memory.
unsafe impl RefCounted for %(name)s {
    #[inline]
    unsafe fn addref(&self) {
        self.AddRef();
    }
    #[inline]
    unsafe fn release(&self) {
        self.Release();
    }
}

// This trait is implemented on all types which can be coerced to from %(name)s.
// It is used in the implementation of `fn coerce<T>`. We hide it from the
// documentation, because it clutters it up a lot.
#[doc(hidden)]
pub trait %(name)sCoerce {
    /// Cheaply cast a value of this type from a `%(name)s`.
    fn coerce_from(v: &%(name)s) -> &Self;
}

// The trivial implementation: We can obviously coerce ourselves to ourselves.
impl %(name)sCoerce for %(name)s {
    #[inline]
    fn coerce_from(v: &%(name)s) -> &Self {
        v
    }
}

impl %(name)s {
    /// Cast this `%(name)s` to one of its base interfaces.
    #[inline]
    pub fn coerce<T: %(name)sCoerce>(&self) -> &T {
        T::coerce_from(self)
    }
}
"""


sendsync_tmpl = """\
// This interface is marked as [rust_sync], meaning it is safe to be transferred
// and used from multiple threads silmultaneously.  These override the default
// from the __nosync marker type allowng the type to be sent between threads.
unsafe impl Send for %(name)s {}
unsafe impl Sync for %(name)s {}
"""


wrapper_tmpl = """\
// The implementations of the function wrappers which are exposed to rust code.
// Call these methods rather than manually calling through the VTable struct.
impl %(name)s {
%(consts)s
%(methods)s
}

"""

vtable_entry_tmpl = """\
/* %(idl)s */
%(entry)s,
"""


const_wrapper_tmpl = """\
%(docs)s
pub const %(name)s: %(type)s = %(val)s;
"""


method_wrapper_tmpl = """\
%(docs)s
/// `%(idl)s`
%(wrapper)s
"""


uuid_decoder = re.compile(
    r"""(?P<m0>[a-f0-9]{8})-
                              (?P<m1>[a-f0-9]{4})-
                              (?P<m2>[a-f0-9]{4})-
                              (?P<m3>[a-f0-9]{4})-
                              (?P<m4>[a-f0-9]{12})$""",
    re.X,
)


def write_interface(iface, fd):
    if iface.namemap is None:
        raise Exception("Interface was not resolved.")

    assert iface.base or (iface.name == "nsISupports")

    # Extract the UUID's information so that it can be written into the struct definition
    names = uuid_decoder.match(iface.attributes.uuid).groupdict()
    m3str = names["m3"] + names["m4"]
    names["m3joined"] = ", ".join(["0x%s" % m3str[i : i + 2] for i in range(0, 16, 2)])
    names["name"] = iface.name

    if printdoccomments:
        if iface.base is not None:
            fd.write("/// `interface %s : %s`\n///\n" % (iface.name, iface.base))
        else:
            fd.write("/// `interface %s`\n///\n" % iface.name)
    printComments(fd, iface.doccomments, "")
    fd.write(struct_tmpl % names)

    if iface.attributes.rust_sync:
        fd.write(sendsync_tmpl % {"name": iface.name})

    if iface.base is not None:
        fd.write(
            deref_tmpl
            % {
                "name": iface.name,
                "base": iface.base,
            }
        )

    entries = []
    for member in iface.members:
        if type(member) == xpidl.Attribute:
            entries.append(
                vtable_entry_tmpl
                % {
                    "idl": member.toIDL(),
                    "entry": attrAsVTableEntry(iface, member, True),
                }
            )
            if not member.readonly:
                entries.append(
                    vtable_entry_tmpl
                    % {
                        "idl": member.toIDL(),
                        "entry": attrAsVTableEntry(iface, member, False),
                    }
                )

        elif type(member) == xpidl.Method:
            entries.append(
                vtable_entry_tmpl
                % {
                    "idl": member.toIDL(),
                    "entry": methodAsVTableEntry(iface, member),
                }
            )

    fd.write(
        vtable_tmpl
        % {
            "name": iface.name,
            "base": base_vtable_tmpl % iface.base if iface.base is not None else "",
            "entries": "\n".join(entries),
        }
    )

    # Get all of the constants
    consts = []
    for member in iface.members:
        if type(member) == xpidl.ConstMember:
            consts.append(
                const_wrapper_tmpl
                % {
                    "docs": doccomments(member.doccomments),
                    "type": member.realtype.rustType("in"),
                    "name": member.name,
                    "val": member.getValue(),
                }
            )
        if type(member) == xpidl.CEnum:
            for var in member.variants:
                consts.append(
                    const_wrapper_tmpl
                    % {
                        "docs": "",
                        "type": member.rustType("in"),
                        "name": var.name,
                        "val": var.getValue(),
                    }
                )

    methods = []
    for member in iface.members:
        if type(member) == xpidl.Attribute:
            methods.append(
                method_wrapper_tmpl
                % {
                    "docs": doccomments(member.doccomments),
                    "idl": member.toIDL(),
                    "wrapper": attrAsWrapper(iface, member, True),
                }
            )
            if not member.readonly:
                methods.append(
                    method_wrapper_tmpl
                    % {
                        "docs": doccomments(member.doccomments),
                        "idl": member.toIDL(),
                        "wrapper": attrAsWrapper(iface, member, False),
                    }
                )

        elif type(member) == xpidl.Method:
            methods.append(
                method_wrapper_tmpl
                % {
                    "docs": doccomments(member.doccomments),
                    "idl": member.toIDL(),
                    "wrapper": methodAsWrapper(iface, member),
                }
            )

    fd.write(
        wrapper_tmpl
        % {
            "name": iface.name,
            "consts": "\n".join(consts),
            "methods": "\n".join(methods),
        }
    )