fs: make sure to write entire buffer

[atlowChemi]

fs.write(v) is not guaranteed to write everything in a single
call. Make sure we don't assume so.

Refs: #42434 (comment)

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/53460/

[atlowChemi]

benchmark output:

 confidence improvement accuracy (*) (**) (***) fs/write-stream-throughput.js size=1024 encodingType='asc' dur=5 -0.97 % ±2.40% ±3.19% ±4.15% fs/write-stream-throughput.js size=1024 encodingType='buf' dur=5 0.81 % ±1.53% ±2.03% ±2.65% fs/write-stream-throughput.js size=1024 encodingType='utf' dur=5 1.61 % ±1.75% ±2.33% ±3.06% fs/write-stream-throughput.js size=1048576 encodingType='asc' dur=5 0.09 % ±2.32% ±3.09% ±4.02% fs/write-stream-throughput.js size=1048576 encodingType='buf' dur=5 -0.38 % ±0.60% ±0.80% ±1.03% fs/write-stream-throughput.js size=1048576 encodingType='utf' dur=5 -0.38 % ±1.50% ±1.99% ±2.60% fs/write-stream-throughput.js size=2 encodingType='asc' dur=5 -0.31 % ±2.03% ±2.71% ±3.53% fs/write-stream-throughput.js size=2 encodingType='buf' dur=5 -0.53 % ±1.74% ±2.32% ±3.02% fs/write-stream-throughput.js size=2 encodingType='utf' dur=5 -0.13 % ±2.22% ±2.96% ±3.85% fs/write-stream-throughput.js size=65535 encodingType='asc' dur=5 ** -1.64 % ±1.05% ±1.40% ±1.85% fs/write-stream-throughput.js size=65535 encodingType='buf' dur=5 0.09 % ±1.02% ±1.37% ±1.80% fs/write-stream-throughput.js size=65535 encodingType='utf' dur=5 0.06 % ±1.18% ±1.57% ±2.04% Be aware that when doing many comparisons the risk of a false-positive result increases. In this case, there are 142 comparisons, you can thus expect the following amount of false-positive results: 7.10 false positives, when considering a 5% risk acceptance (*, **, ***), 1.42 false positives, when considering a 1% risk acceptance (**, ***), 0.14 false positives, when considering a 0.1% risk acceptance (***) 

[ronag]

Existing tests pass and it's quite tricky make tests for this. You probably need to pass a custom "fs" implementation into the stream which will return EAGAIN.

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/53493/

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/53497/

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/53504/

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/53505/

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/53521/

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/53530/

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/53534/

[atlowChemi]

Landed in feb5b0f