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module: validate that strip-types does not insert any code #54141

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module: validate that strip-types does not insert any code #54141

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346469c
module: set swc transform mode explicitly to 'strip-only'
ChALkeR Jul 31, 2024
ae27328
module: validate that strip-types does not insert any code
ChALkeR Jul 31, 2024
1e8101d
Update lib/internal/modules/helpers.js
ChALkeR Jul 31, 2024
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51 changes: 50 additions & 1 deletion lib/internal/modules/helpers.js
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Original file line number Diff line number Diff line change
Expand Up @@ -24,6 +24,7 @@ const internalFS = require('internal/fs/utils');
const path = require('path');
const { pathToFileURL, fileURLToPath } = require('internal/url');
const assert = require('internal/assert');
const { Buffer: { from: BufferFrom } } = require('buffer');

const { getOptionValue } = require('internal/options');
const { setOwnProperty } = require('internal/util');
Expand Down Expand Up @@ -307,10 +308,58 @@ function lazyLoadTSParser() {
return parseTS;
}

function doesTSStripTypesResultMatchSource(code, source) {
const sourceBuf = BufferFrom(source);
const codeBuf = BufferFrom(code);
if (sourceBuf.length !== codeBuf.length) { return false; }
Comment on lines +312 to +314
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@aduh95 aduh95 Jul 31, 2024 •
edited
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btw, have you considered doing a comparison of the JS strings? It seems to me it would be much simpler (and maybe more performant) than comparing buffers, especially given the parameters are already strings. wdyt?

for (let i = 0; i < source.length; i++) {
  const char = StringPrototypeCodePointAt(code, i);
  if (char !== 0x3b && char !== 0x20 && char !== StringPrototypeCodePointAt(source, i)) {
     return false;
  }
}
return true;

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@aduh95 will recheck!

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I didn't use that because the original impl which this rechecks is byte-level based
But it can be done, yes

and maybe more performant

perf results are inconclusive on this even after initial optimization of this for fast paths -- this is faster for multi-byte but slower for regular ascii sources

will try another version shortly

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@ChALkeR ChALkeR Jul 31, 2024 •
edited
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For context, the code I used was:

  function doesTSStripTypesResultMatchSource2(code, source) {
    if (code.length !== source.length) { return false; }
    for (let i = 0; i < code.length; i++) {
      const a = code.codePointAt(i)
      if (a === source.codePointAt(i)) continue
      if (a !== 0x20 && a !== 0x3b && a !== 0xa0 && a !== 0x2002 && a !== 0xfeff) return false
    }
    return true
  }
  1. The set of chars is different
  2. This also misses a check for now that 0xfeff can come only after a space

I think we can land Buffer-based impl and optimize it later if needed (hopefully not)

for (let i = 0; i < codeBuf.length; i++) {
// Should match either the source buffer or spaces (sometimes multi-byte) or semicolon
const val = codeBuf[i];
if (val === sourceBuf[i]) {
// Source match
continue;
}
// https://github.com/nodejs/amaro/blob/e533394f576f946add41dd8816816435e8100c3b/deps/swc/crates/swc_fast_ts_strip/src/lib.rs#L400-L414
if (val === 0x3b) {
// Semicolon 3b
continue;
}
// https://github.com/nodejs/amaro/blob/e533394f576f946add41dd8816816435e8100c3b/deps/swc/crates/swc_fast_ts_strip/src/lib.rs#L200-L226
if (val === 0x20) {
// Space 20
continue;
}
if (val === 0xc2) {
// No-Break Space 00A0
if (i + 1 >= codeBuf.length) { return false; }
if (codeBuf[++i] !== 0xa0) { return false; }
continue;
}
if (val === 0xe2) {
// En Space 2002
if (i + 2 >= codeBuf.length) { return false; }
if (codeBuf[++i] !== 0x80) { return false; }
if (codeBuf[++i] !== 0x82) { return false; }
continue;
}
if (val === 0xef) {
// ZWNBSP FEFF
if (i < 1 || codeBuf[i - 1] !== 0x20) { return false; } // Only can get insterted after a space
if (i + 2 >= codeBuf.length) { return false; }
if (codeBuf[++i] !== 0xbb) { return false; }
if (codeBuf[++i] !== 0xbf) { return false; }
continue;
}
return false;
}
return true;
}

function tsParse(source) {
if (!source || typeof source !== 'string') { return; }
const transformSync = lazyLoadTSParser();
const { code } = transformSync(source);
const { code } = transformSync(source, { __proto__: null, mode: 'strip-only' });
assert(doesTSStripTypesResultMatchSource(code, source), 'Unexpected strip-types result');
return code;
}

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