src/etc/wasm32-shim.js

   1 // Copyright 2017 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 // This is a small "shim" program which is used when wasm32 unit tests are run
  12 // in this repository. This program is intended to be run in node.js and will
  13 // load a wasm module into memory, instantiate it with a set of imports, and
  14 // then run it.
  15 //
  16 // There's a bunch of helper functions defined here in `imports.env`, but note
  17 // that most of them aren't actually needed to execute most programs. Many of
  18 // these are just intended for completeness or debugging. Hopefully over time
  19 // nothing here is needed for completeness.
  20
  21 const fs = require('fs');
  22 const process = require('process');
  23 const buffer = fs.readFileSync(process.argv[2]);
  24
  25 Error.stackTraceLimit = 20;
  26
  27 let m = new WebAssembly.Module(buffer);
  28
  29 let memory = null;
  30
  31 function viewstruct(data, fields) {
  32   return new Uint32Array(memory.buffer).subarray(data/4, data/4 + fields);
  33 }
  34
  35 function copystr(a, b) {
  36   let view = new Uint8Array(memory.buffer).subarray(a, a + b);
  37   return String.fromCharCode.apply(null, view);
  38 }
  39
  40 function syscall_write([fd, ptr, len]) {
  41   let s = copystr(ptr, len);
  42   switch (fd) {
  43     case 1: process.stdout.write(s); break;
  44     case 2: process.stderr.write(s); break;
  45   }
  46 }
  47
  48 function syscall_exit([code]) {
  49   process.exit(code);
  50 }
  51
  52 function syscall_args(params) {
  53   let [ptr, len] = params;
  54
  55   // Calculate total required buffer size
  56   let totalLen = -1;
  57   for (let i = 2; i < process.argv.length; ++i) {
  58     totalLen += Buffer.byteLength(process.argv[i]) + 1;
  59   }
  60   if (totalLen < 0) { totalLen = 0; }
  61   params[2] = totalLen;
  62
  63   // If buffer is large enough, copy data
  64   if (len >= totalLen) {
  65     let view = new Uint8Array(memory.buffer);
  66     for (let i = 2; i < process.argv.length; ++i) {
  67       let value = process.argv[i];
  68       Buffer.from(value).copy(view, ptr);
  69       ptr += Buffer.byteLength(process.argv[i]) + 1;
  70     }
  71   }
  72 }
  73
  74 function syscall_getenv(params) {
  75   let [keyPtr, keyLen, valuePtr, valueLen] = params;
  76
  77   let key = copystr(keyPtr, keyLen);
  78   let value = process.env[key];
  79
  80   if (value == null) {
  81     params[4] = 0xFFFFFFFF;
  82   } else {
  83     let view = new Uint8Array(memory.buffer);
  84     let totalLen = Buffer.byteLength(value);
  85     params[4] = totalLen;
  86     if (valueLen >= totalLen) {
  87       Buffer.from(value).copy(view, valuePtr);
  88     }
  89   }
  90 }
  91
  92 function syscall_time(params) {
  93   let t = Date.now();
  94   let secs = Math.floor(t / 1000);
  95   let millis = t % 1000;
  96   params[1] = Math.floor(secs / 0x100000000);
  97   params[2] = secs % 0x100000000;
  98   params[3] = Math.floor(millis * 1000000);
  99 }
 100
 101 let imports = {};
 102 imports.env = {
 103   // These are generated by LLVM itself for various intrinsic calls. Hopefully
 104   // one day this is not necessary and something will automatically do this.
 105   fmod: function(x, y) { return x % y; },
 106   exp2: function(x) { return Math.pow(2, x); },
 107   exp2f: function(x) { return Math.pow(2, x); },
 108   ldexp: function(x, y) { return x * Math.pow(2, y); },
 109   ldexpf: function(x, y) { return x * Math.pow(2, y); },
 110   sin: Math.sin,
 111   sinf: Math.sin,
 112   cos: Math.cos,
 113   cosf: Math.cos,
 114   log: Math.log,
 115   log2: Math.log2,
 116   log10: Math.log10,
 117   log10f: Math.log10,
 118
 119   rust_wasm_syscall: function(index, data) {
 120     switch (index) {
 121       case 1: syscall_write(viewstruct(data, 3)); return true;
 122       case 2: syscall_exit(viewstruct(data, 1)); return true;
 123       case 3: syscall_args(viewstruct(data, 3)); return true;
 124       case 4: syscall_getenv(viewstruct(data, 5)); return true;
 125       case 6: syscall_time(viewstruct(data, 4)); return true;
 126       default:
 127         console.log("Unsupported syscall: " + index);
 128         return false;
 129     }
 130   }
 131 };
 132
 133 let instance = new WebAssembly.Instance(m, imports);
 134 memory = instance.exports.memory;
 135 try {
 136   instance.exports.main();
 137 } catch (e) {
 138   console.error(e);
 139   process.exit(101);
 140 }