src,lib: support path in v8.writeHeapSnapshot output

[juanarbol]

---

I'm a bit rusty with my C++. Any feedback will be more than valuable.

[codecov]

Codecov Report

❌ Patch coverage is 78.94737% with 8 lines in your changes missing coverage. Please review.
✅ Project coverage is 88.52%. Comparing base (a65421a) to head (d93774c).
⚠️ Report is 30 commits behind head on main.

Files with missing lines	Patch %	Lines
src/heap_utils.cc	72.41%	3 Missing and 5 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #58959      +/-   ##
==========================================
- Coverage   88.54%   88.52%   -0.02%     
==========================================
  Files         703      703              
  Lines      208545   208608      +63     
  Branches    40216    40233      +17     
==========================================
+ Hits       184652   184674      +22     
- Misses      15905    15952      +47     
+ Partials     7988     7982       -6     

Files with missing lines	Coverage Δ
lib/v8.js	99.04% <100.00%> (+0.01%)	⬆️
src/node_internals.h	83.01% <ø> (ø)
src/heap_utils.cc	79.22% <72.41%> (-0.92%)	⬇️

... and 43 files with indirect coverage changes

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[jasnell]

The BufferValue uses need to be cleaned up

[juanarbol]

@addaleax @jasnell @Renegade334 PTAL :-)

[jasnell]

Unfortunately this is going to be a problem because it assumes the final_filename is utf8 encoded. Consider the following case:

const path = Buffer.from([0xe6]);  // latin 1 character
fs.mkdirSync(path);
const res = v8.writeHeapSnapshot(undefined, { path });
fs.readfileSync(res);  // fails! path doesn't exist

The reason fs.readfileSync would fail here is because the returned res will have interpreted the 0xe6 character incorrectly and will have replaced it with the unicode replacement char. The snapshot will have been written to disk correctly, but the returned path is wrong.

This likely needs to return the resulting path as a Buffer if the path was given as a Buffer and allow the API to accept an encoding option that optionally decodes the result as a string. But, that gets a bit awkward.

[juanarbol]

I love how picky this is, aaah, let me put the encoding option to make this a bit more consistent and leave utf8 as default encoding.

Nice catch, thanks! Anything else missing?

[jasnell]

Nothing that sticks out, but I should have time to take another pass through by end of day monday

[juanarbol]

Hey James, I know its been a while; I've been quite busy lately, but now I have some bandwidth...

James, your snippet won't work.

node:fs:1326
  const result = binding.mkdir(
                         ^

Error: EILSEQ: illegal byte sequence, mkdir '�'
    at Object.mkdirSync (node:fs:1326:26)
    at Object.<anonymous> (/private/tmp/case.js:5:4)
    at Module._compile (node:internal/modules/cjs/loader:1759:14)
    at Object..js (node:internal/modules/cjs/loader:1890:10)
    at Module.load (node:internal/modules/cjs/loader:1480:32)
    at Module._load (node:internal/modules/cjs/loader:1299:12)
    at TracingChannel.traceSync (node:diagnostics_channel:328:14)
    at wrapModuleLoad (node:internal/modules/cjs/loader:245:24)
    at Module.executeUserEntryPoint [as runMain] (node:internal/modules/run_main:154:5)
    at node:internal/main/run_main_module:33:47 {
  errno: -92,
  code: 'EILSEQ',
  syscall: 'mkdir',
  path: '�'
}

I'm not able to create a latin1 folder in Node.js. I get the encoding requirements and stuff... but your snippet per se is not valid. What would you like me to do in this case? What should I consider adding in the test case?

[juanarbol]

I'm gonna use StringBytes::Encode but I would like to get my question answered before doing something

[juanarbol]

Hey James, I know its been a while; I've been quite busy lately, but now I have some bandwidth...

James, your snippet won't work.

node:fs:1326
  const result = binding.mkdir(
                         ^

Error: EILSEQ: illegal byte sequence, mkdir '�'
    at Object.mkdirSync (node:fs:1326:26)
    at Object.<anonymous> (/private/tmp/case.js:5:4)
    at Module._compile (node:internal/modules/cjs/loader:1759:14)
    at Object..js (node:internal/modules/cjs/loader:1890:10)
    at Module.load (node:internal/modules/cjs/loader:1480:32)
    at Module._load (node:internal/modules/cjs/loader:1299:12)
    at TracingChannel.traceSync (node:diagnostics_channel:328:14)
    at wrapModuleLoad (node:internal/modules/cjs/loader:245:24)
    at Module.executeUserEntryPoint [as runMain] (node:internal/modules/run_main:154:5)
    at node:internal/main/run_main_module:33:47 {
  errno: -92,
  code: 'EILSEQ',
  syscall: 'mkdir',
  path: '�'
}

I'm not able to create a latin1 folder in Node.js. I get the encoding requirements and stuff... but your snippet per se is not valid. What would you like me to do in this case? What should I consider adding in the test case?

[juanarbol]

@jasnell PTAL

[juanarbol]

Fixing linter and CI, sorry.