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clarify the position argument for fs.read #14612

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clarify the position argument for fs.read #14612

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04d1ca0
clarify the position argument for fs.read
dcharbonnier Aug 3, 2017
ad9134f
fix typo
dcharbonnier Aug 3, 2017
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4 changes: 3 additions & 1 deletion doc/api/fs.md
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Expand Up @@ -1640,7 +1640,9 @@ Read data from the file specified by `fd`.
`length` is an integer specifying the number of bytes to read.

`position` is an integer specifying where to begin reading from in the file.
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@sam-github sam-github Aug 3, 2017

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I suggest "is an argument", its not always an integer, null is not an integer

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@dcharbonnier dcharbonnier Aug 4, 2017

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#14621

If `position` is `null`, data will be read from the current file position.
If `position` is `null`, data will be read from the current file position,
and the file position will be updated for subsequent read.
If `position` is an integer, the file position will remain unchanged.
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@sam-github sam-github Aug 3, 2017

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maybe it feels obvious, but for null you say where it reads from (current position) and what happens to current position (its updated). For the integer case this says file position is unchange, but it doesn't say where read is from, which is from the integer as a positive offset from beginning of file (-4 won't read from 4 bytes before end of file, for example).

also, the file position will be changed on Windows, though there is a UV PR to change windows to be like unix: libuv/libuv#1357, not sure if that has effected node yet, though.

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@cjihrig cjihrig Aug 4, 2017

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Looks like that PR landed in libuv 1.13.0, so it has at least made its way to Node.

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@dcharbonnier dcharbonnier Aug 4, 2017

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yeah and let's say what happen if you have a position that goes over the size of the file and specify that it's bytes, also say that the position in the end is the quantity that has been read + the previous position but let's wait that you do it on an other PR because this has noting to do with this one


The callback is given the three arguments, `(err, bytesRead, buffer)`.

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