{{ message }}
forked from python/cpython
-
Notifications
You must be signed in to change notification settings - Fork 0
Expand file tree
/
Copy pathemscripten_syscalls.c
More file actions
323 lines (300 loc) · 11.7 KB
/
Copy pathemscripten_syscalls.c
File metadata and controls
323 lines (300 loc) · 11.7 KB
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
#include "emscripten.h"
#include "stdio.h"
// All system calls: return nonnegative number on success, return -errno on
// failure. Negative results get stored back into errno here:
// https://github.com/emscripten-core/emscripten/blob/main/system/lib/libc/musl/src/internal/syscall_ret.c#L7
// If we're running in node, report the UID of the user in the native system as
// the UID of the user. Since the nodefs will report the uid correctly, if we
// don't make getuid report it correctly too we'll see some permission errors.
// Normally __syscall_getuid32 is a stub that always returns 0 but it is
// defined with weak linkage so we can override it.
EM_JS(int, __syscall_getuid32_js, (void), {
// If we're in node and we can, report the native uid
if (ENVIRONMENT_IS_NODE) {
return process.getuid();
}
// Fall back to the stub case of returning 0.
return 0;
})
int __syscall_getuid32(void) {
return __syscall_getuid32_js();
}
EM_JS(int, __syscall_umask_js, (int mask), {
// If we're in node and we can, call native process.umask()
if (ENVIRONMENT_IS_NODE) {
try {
return process.umask(mask);
} catch(e) {
// oops...
// NodeJS docs: "In Worker threads, process.umask(mask) will throw an exception."
// umask docs: "This system call always succeeds"
return 0;
}
}
// Fall back to the stub case of returning 0.
return 0;
})
int __syscall_umask(int mask) {
return __syscall_umask_js(mask);
}
#include <wasi/api.h>
#include <errno.h>
#include <fcntl.h>
// Variant of EM_JS that does C preprocessor substitution on the body
#define EM_JS_MACROS(ret, func_name, args, body...) \
EM_JS(ret, func_name, args, body)
EM_JS_MACROS(void, _emscripten_promising_main_js, (void), {
// Define FS.createAsyncInputDevice(), This is quite similar to
// FS.createDevice() defined here:
// https://github.com/emscripten-core/emscripten/blob/4.0.11/src/lib/libfs.js?plain=1#L1642
// but instead of returning one byte at a time, the input() function should
// return a Uint8Array. This makes the handler code simpler, the
// `createAsyncInputDevice` simpler, and everything faster.
FS.createAsyncInputDevice = function(parent, name, input) {
parent = typeof parent == 'string' ? parent : FS.getPath(parent);
var path = PATH.join2(parent, name);
var mode = FS_getMode(true, false);
FS.createDevice.major ||= 64;
var dev = FS.makedev(FS.createDevice.major++, 0);
async function getDataBuf() {
var buf;
try {
buf = await input();
} catch (e) {
throw new FS.ErrnoError(EIO);
}
if (!buf?.byteLength) {
throw new FS.ErrnoError(EAGAIN);
}
ops._dataBuf = buf;
}
var ops = {
_dataBuf: new Uint8Array(0),
open(stream) {
stream.seekable = false;
},
async readAsync(stream, buffer, offset, length, pos /* ignored */) {
buffer = buffer.subarray(offset, offset + length);
if (!ops._dataBuf.byteLength) {
await getDataBuf();
}
var toRead = Math.min(ops._dataBuf.byteLength, buffer.byteLength);
buffer.subarray(0, toRead).set(ops._dataBuf);
buffer = buffer.subarray(toRead);
ops._dataBuf = ops._dataBuf.subarray(toRead);
if (toRead) {
stream.node.atime = Date.now();
}
return toRead;
},
};
FS.registerDevice(dev, ops);
return FS.mkdev(path, mode, dev);
};
if (!WebAssembly.promising) {
// No stack switching support =(
return;
}
const origResolveGlobalSymbol = resolveGlobalSymbol;
if (ENVIRONMENT_IS_NODE && !Module.onExit) {
Module.onExit = (code) => process.exit(code);
}
// * wrap the main symbol with WebAssembly.promising,
// * call exit_with_live_runtime() to prevent emscripten from shutting down
// the runtime before the promise resolves,
// * call onExit / process.exit ourselves, since exit_with_live_runtime()
// prevented Emscripten from calling it normally.
resolveGlobalSymbol = function (name, direct = false) {
const orig = origResolveGlobalSymbol(name, direct);
if (name === "main") {
const main = WebAssembly.promising(orig.sym);
orig.sym = (...args) => {
(async () => {
const ret = await main(...args);
Module.onExit?.(ret);
})();
_emscripten_exit_with_live_runtime();
};
}
return orig;
};
})
__attribute__((constructor)) void _emscripten_promising_main(void) {
_emscripten_promising_main_js();
}
#define IOVEC_T_BUF_OFFSET 0
#define IOVEC_T_BUF_LEN_OFFSET 4
#define IOVEC_T_SIZE 8
_Static_assert(offsetof(__wasi_iovec_t, buf) == IOVEC_T_BUF_OFFSET,
"Unexpected __wasi_iovec_t layout");
_Static_assert(offsetof(__wasi_iovec_t, buf_len) == IOVEC_T_BUF_LEN_OFFSET,
"Unexpected __wasi_iovec_t layout");
_Static_assert(sizeof(__wasi_iovec_t) == IOVEC_T_SIZE,
"Unexpected __wasi_iovec_t layout");
// If the stream has a readAsync handler, read to buffer defined in iovs, write
// number of bytes read to *nread, and return a promise that resolves to the
// errno. Otherwise, return null.
EM_JS_MACROS(__externref_t, __maybe_fd_read_async, (
__wasi_fd_t fd,
const __wasi_iovec_t *iovs,
size_t iovcnt,
__wasi_size_t *nread
), {
if (!WebAssembly.promising) {
return null;
}
var stream;
try {
stream = SYSCALLS.getStreamFromFD(fd);
} catch (e) {
// If the fd was already closed or never existed, getStreamFromFD()
// raises. We'll let fd_read_orig() handle setting errno.
return null;
}
if (!stream.stream_ops.readAsync) {
// Not an async device. Fall back to __wasi_fd_read_orig().
return null;
}
return (async () => {
// This is the same as libwasi.js fd_read() and doReadv() except we use
// readAsync and we await it.
// https://github.com/emscripten-core/emscripten/blob/4.0.11/src/lib/libwasi.js?plain=1#L331
// https://github.com/emscripten-core/emscripten/blob/4.0.11/src/lib/libwasi.js?plain=1#L197
try {
var ret = 0;
for (var i = 0; i < iovcnt; i++) {
var ptr = HEAP32[(iovs + IOVEC_T_BUF_OFFSET)/4];
var len = HEAP32[(iovs + IOVEC_T_BUF_LEN_OFFSET)/4];
iovs += IOVEC_T_SIZE;
var curr = await stream.stream_ops.readAsync(stream, HEAP8, ptr, len);
if (curr < 0) return -1;
ret += curr;
if (curr < len) break; // nothing more to read
}
HEAP32[nread/4] = ret;
return 0;
} catch (e) {
if (e.name !== 'ErrnoError') {
throw e;
}
return e["errno"];
}
})();
};
);
// Bind original fd_read syscall to __wasi_fd_read_orig().
__wasi_errno_t __wasi_fd_read_orig(__wasi_fd_t fd, const __wasi_iovec_t *iovs,
size_t iovs_len, __wasi_size_t *nread)
__attribute__((__import_module__("wasi_snapshot_preview1"),
__import_name__("fd_read"), __warn_unused_result__));
// Take a promise that resolves to __wasi_errno_t and suspend until it resolves,
// get the output.
EM_JS(int, __block_for_int, (__externref_t p), {
return p;
}
if (WebAssembly.Suspending) {
__block_for_int = new WebAssembly.Suspending(__block_for_int);
}
)
// Replacement for fd_read syscall. Call __maybe_fd_read_async. If it returned
// null, delegate back to __wasi_fd_read_orig. Otherwise, use __block_for_int
// to get the result.
__wasi_errno_t __wasi_fd_read(__wasi_fd_t fd, const __wasi_iovec_t *iovs,
size_t iovs_len, __wasi_size_t *nread) {
__externref_t p = __maybe_fd_read_async(fd, iovs, iovs_len, nread);
if (__builtin_wasm_ref_is_null_extern(p)) {
return __wasi_fd_read_orig(fd, iovs, iovs_len, nread);
}
return __block_for_int(p);
}
#include <poll.h>
#define POLLFD_FD 0
#define POLLFD_EVENTS 4
#define POLLFD_REVENTS 6
#define POLLFD_SIZE 8
_Static_assert(offsetof(struct pollfd, fd) == 0, "Unepxected pollfd struct layout");
_Static_assert(offsetof(struct pollfd, events) == 4, "Unepxected pollfd struct layout");
_Static_assert(offsetof(struct pollfd, revents) == 6, "Unepxected pollfd struct layout");
_Static_assert(sizeof(struct pollfd) == 8, "Unepxected pollfd struct layout");
EM_JS_MACROS(__externref_t, __maybe_poll_async, (intptr_t fds, int nfds, int timeout), {
if (!WebAssembly.promising) {
return null;
}
return (async function() {
try {
var nonzero = 0;
var promises = [];
for (var i = 0; i < nfds; i++) {
var pollfd = fds + POLLFD_SIZE * i;
var fd = HEAP32[(pollfd + POLLFD_FD)/4];
var events = HEAP16[(pollfd + POLLFD_EVENTS)/2];
var mask = POLLNVAL;
var stream = FS.getStream(fd);
if (stream) {
mask = POLLIN | POLLOUT;
if (stream.stream_ops.pollAsync) {
promises.push(stream.stream_ops.pollAsync(stream, timeout).then((mask) => {
mask &= events | POLLERR | POLLHUP;
HEAP16[(pollfd + POLLFD_REVENTS)/2] = mask;
if (mask) {
nonzero ++;
}
}));
} else if (stream.stream_ops.poll) {
var mask = stream.stream_ops.poll(stream, timeout);
mask &= events | POLLERR | POLLHUP;
HEAP16[(pollfd + POLLFD_REVENTS)/2] = mask;
if (mask) {
nonzero ++;
}
}
}
}
await Promise.all(promises);
return nonzero;
} catch(e) {
if (e?.name !== "ErrnoError") throw e;
return -e["errno"];
}
})();
});
// Bind original poll syscall to syscall_poll_orig().
int syscall_poll_orig(intptr_t fds, int nfds, int timeout)
__attribute__((__import_module__("env"),
__import_name__("__syscall_poll"), __warn_unused_result__));
int __syscall_poll(intptr_t fds, int nfds, int timeout) {
__externref_t p = __maybe_poll_async(fds, nfds, timeout);
if (__builtin_wasm_ref_is_null_extern(p)) {
return syscall_poll_orig(fds, nfds, timeout);
}
return __block_for_int(p);
}
#include <sys/ioctl.h>
int syscall_ioctl_orig(int fd, int request, void* varargs)
__attribute__((__import_module__("env"),
__import_name__("__syscall_ioctl"), __warn_unused_result__));
int __syscall_ioctl(int fd, int request, void* varargs) {
if (request == FIOCLEX || request == FIONCLEX) {
return 0;
}
if (request == FIONBIO) {
// Implement FIONBIO via fcntl.
// TODO: Upstream this.
int flags = fcntl(fd, F_GETFL, 0);
int nonblock = **((int**)varargs);
if (flags < 0) {
return -errno;
}
if (nonblock) {
flags |= O_NONBLOCK;
} else {
flags &= (~O_NONBLOCK);
}
int res = fcntl(fd, F_SETFL, flags);
if (res < 0) {
return -errno;
}
return res;
}
return syscall_ioctl_orig(fd, request, varargs);
}
You can’t perform that action at this time.