Files
2025-10-20 16:49:04 +02:00

207 lines
7.3 KiB
JavaScript

var S = require("./structs.js"),
_xok = require('xok');
// ponyfills for older node.js
exports.allocBuffer = Buffer.alloc || function (len, val) {
var b = Buffer(len);
if (arguments.length > 1) b.fill(val);
return b;
};
exports.bufferFrom = Buffer.from || function (arg0, arg1) {
return (arguments.length > 1) ? Buffer(arg0, arg1) : Buffer(arg0);
};
// flag for WORKAROUND: https://github.com/tessel/beta/issues/380
exports.workaroundTessel380 = !Buffer.from && function () {
var b = Buffer([0]),
s = b.slice(0);
return ((s[0] = 0xFF) !== b[0]);
}();
// WORKAROUND: https://github.com/tessel/beta/issues/433
var oldslice;
if (!Buffer.alloc && Buffer(5).slice(10).length < 0) oldslice = Buffer.prototype.slice, Buffer.prototype.slice = function (s, e) {
if (s > this.length) s = this.length;
// ~WORKAROUND: https://github.com/tessel/beta/issues/434
return (arguments.length > 1) ? oldslice.call(this, s, e) : oldslice.call(this, s);
}
exports.absoluteSteps = function (path) {
var steps = [];
path.split('/').forEach(function (str) {
// NOTE: these should actually be fine, just wasteful…
if (str === '..') steps.pop();
else if (str && str !== '.') steps.push(str);
});
return steps.map(exports.longname);
};
exports.absolutePath = function (path) {
return '/'+exports.absoluteSteps(path).join('/');
};
exports.parseFlags = function (flags) {
// read, write, append, create, truncate, exclusive
var info, _dir; // NOTE: there might be more clever ways to "parse", but…
if (flags[0] === '\\') {
// internal flag used internally to `fs.open` directories without `S.err.ISDIR()`
flags = flags.slice(1);
_dir = true;
}
switch (flags) {
case 'r': info = {read:true, write:false, create:false}; break;
case 'r+': info = {read:true, write:true, create:false}; break;
case 'rs': info = {read:true, write:false, create:false, sync:true}; break;
case 'rs+': info = {read:true, write:true, create:false, sync:true}; break;
case 'w': info = {read:false, write:true, create:true, truncate:true}; break;
case 'wx': info = {read:false, write:true, create:true, exclusive:true}; break;
case 'w+': info = {read:true, write:true, create:true, truncate:true}; break;
case 'wx+': info = {read:true, write:true, create:true, exclusive:true}; break;
case 'a': info = {read:false, write:true, create:true, append:true}; break;
case 'ax': info = {read:false, write:true, create:true, append:true, exclusive:true}; break;
case 'a+': info = {read:true, write:true, create:true, append:true}; break;
case 'ax+': info = {read:true, write:true, create:true, append:true, exclusive:true}; break;
default: throw Error("Unknown mode: "+flags); // TODO: throw as `S.err.INVAL`
}
if (info.sync) throw Error("Mode not implemented."); // TODO: what would this require of us?
if (_dir) info._openDir = true;
return info;
};
// TODO: these are great candidates for special test coverage!
var _snInvalid = /[^A-Z0-9$%'-_@~`!(){}^#&.]/g; // NOTE: '.' is not valid but we split it away
exports.shortname = function (name) {
var lossy = false;
// TODO: support preservation of case for otherwise non-lossy name!
name = name.toUpperCase().replace(/ /g, '').replace(/^\.+/, '');
name = name.replace(_snInvalid, function () {
lossy = true;
return '_';
});
var parts = name.split('.'),
basis3 = parts.pop(),
basis8 = parts.join('');
if (!parts.length) {
basis8 = basis3;
basis3 = ' ';
}
if (basis8.length > 8) {
basis8 = basis8.slice(0,8);
// NOTE: technically, spec's "lossy conversion" flag is NOT set by excess length.
// But since lossy conversion and truncated names both need a numeric tail…
lossy = true;
} else while (basis8.length < 8) basis8 += ' ';
if (basis3.length > 3) {
basis3 = basis3.slice(0,3);
lossy = true;
} else while (basis3.length < 3) basis3 += ' ';
return {filename:basis8, extension:basis3, _lossy:lossy};
return {basis:[basis8,basis3], lossy:lossy};
};
//shortname("autoexec.bat") => {basis:['AUTOEXEC','BAT'],lossy:false}
//shortname("autoexecutable.batch") => {basis:['AUTOEXEC','BAT'],lossy:true}
// TODO: OS X stores `shortname("._.Trashes")` as ['~1', 'TRA'] — should we?
var _lnInvalid = /[^a-zA-Z0-9$%'-_@~`!(){}^#&.+,;=[\] ]/g;
exports.longname = function (name) {
name = name.trim().replace(/\.+$/, '').replace(_lnInvalid, function (c) {
if (c.length > 1) throw Error("Internal problem: unexpected match length!");
if (c.charCodeAt(0) > 127) return c;
else throw Error("Invalid character "+JSON.stringify(c)+" in name.");
lossy = true;
return '_';
});
if (name.length > 255) throw Error("Name is too long.");
return name;
};
function nameChkSum(sum, c) {
return ((sum & 1) ? 0x80 : 0) + (sum >>> 1) + c & 0xFF;
}
// WORKAROUND: https://github.com/tessel/beta/issues/335
function reduceBuffer(buf, start, end, fn, res) {
// NOTE: does not handle missing `res` like Array.prototype.reduce would
for (var i = start; i < end; ++i) {
res = fn(res, buf[i]);
}
return res;
}
exports.checksumName = function (buf,off) {
off || (off = 0);
var len = S.dirEntry.fields['Name'].size;
return reduceBuffer(buf, off, off+len, nameChkSum, 0);
};
/* comparing C rounding trick from FAT spec with Math.ceil
function tryBoth(d) {
var a = ((D.RootEntCnt * 32) + (D.BytsPerSec - 1)) / D.BytsPerSec >>> 0,
b = Math.ceil((D.RootEntCnt * 32) / D.BytsPerSec);
if (b !== a) console.log("try", b, a, (b === a) ? '' : '*');
return (b === a);
}
// BytsPerSec — "may take on only the following values: 512, 1024, 2048 or 4096"
[512, 1024, 2048, 4096].forEach(function (bps) {
// RootEntCnt — "a count that when multiplied by 32 results in an even multiple of BPB_BytsPerSec"
for (var evenMultiplier = 0; evenMultiplier < 1024*1024*16; evenMultiplier += 2) {
var rec = (bps * evenMultiplier) / 32;
tryBoth({RootEntCnt:rec, BytsPerSec:bps});
}
});
*/
exports.fmtHex = function (n, ff) {
return (1+ff+n).toString(16).slice(1);
};
exports.delayedCall = function (fn) {
if (!fn) throw Error("No function provided!"); // debug aid
var ctx = this,
args = Array.prototype.slice.call(arguments, 1);
setImmediate(function () {
fn.apply(ctx, args);
});
};
exports.adjustedPos = function (vol, pos, bytes) {
var _pos = {
chain: pos.chain,
sector: pos.sector,
offset: pos.offset + bytes
}, secSize = vol._sectorSize;
while (_pos.offset >= secSize) {
_pos.sector += 1;
_pos.offset -= secSize;
}
return _pos;
};
exports.extend = _xok;
var _prevDbg = Date.now(),
_thresh = 50;
function log(level) {
if (level < log.level) return;
var now = Date.now(),
diff = now - _prevDbg;
arguments[0] = ((diff < _thresh) ? " " : '') + diff.toFixed(0) + "ms";
console.log.apply(console, arguments);
_prevDbg = now;
}
log.DBG = -4;
log.INFO = -3;
log.WARN = -2;
log.ERR = -1;
log.level = log.WARN;
exports.log = log;