45 lines
913 B
JavaScript
45 lines
913 B
JavaScript
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const { FIRST_DESCRIPTOR } = require('./constants');
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const openFiles = {};
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/**
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* Start at FIRST_DESCRIPTOR and go until we find
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* an empty file descriptor, then return it.
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*/
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const getEmptyDescriptor = () => {
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let fd = FIRST_DESCRIPTOR;
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while(getOpenFileDescription(fd)) {
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fd++;
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}
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return fd;
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};
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/**
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* Look up the open file description object for a given
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* file descriptor.
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*/
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const getOpenFileDescription = ofd => openFiles[ofd];
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/**
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* Allocate a new file descriptor for the given
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* open file description.
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*/
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const allocDescriptor = openFileDescription => {
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const ofd = getEmptyDescriptor();
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openFiles[ofd] = openFileDescription;
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return ofd;
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};
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/**
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* Release the given existing file descriptor created
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* with allocDescriptor().
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*/
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const releaseDescriptor = ofd => delete openFiles[ofd];
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module.exports = {
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allocDescriptor,
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releaseDescriptor,
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getOpenFileDescription
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};
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