gecko-dev/b2g/components/LogCapture.jsm

92 строки
2.4 KiB
JavaScript

/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
/* jshint moz: true */
/* global Uint8Array, Components, dump */
'use strict';
this.EXPORTED_SYMBOLS = ['LogCapture'];
/**
* readLogFile
* Read in /dev/log/{{log}} in nonblocking mode, which will return -1 if
* reading would block the thread.
*
* @param log {String} The log from which to read. Must be present in /dev/log
* @return {Uint8Array} Raw log data
*/
let readLogFile = function(logLocation) {
if (!this.ctypes) {
// load in everything on first use
Components.utils.import('resource://gre/modules/ctypes.jsm', this);
this.lib = this.ctypes.open(this.ctypes.libraryName('c'));
this.read = this.lib.declare('read',
this.ctypes.default_abi,
this.ctypes.int, // bytes read (out)
this.ctypes.int, // file descriptor (in)
this.ctypes.voidptr_t, // buffer to read into (in)
this.ctypes.size_t // size_t size of buffer (in)
);
this.open = this.lib.declare('open',
this.ctypes.default_abi,
this.ctypes.int, // file descriptor (returned)
this.ctypes.char.ptr, // path
this.ctypes.int // flags
);
this.close = this.lib.declare('close',
this.ctypes.default_abi,
this.ctypes.int, // error code (returned)
this.ctypes.int // file descriptor
);
}
const O_READONLY = 0;
const O_NONBLOCK = 1 << 11;
const BUF_SIZE = 2048;
let BufType = this.ctypes.ArrayType(this.ctypes.char);
let buf = new BufType(BUF_SIZE);
let logArray = [];
let logFd = this.open(logLocation, O_READONLY | O_NONBLOCK);
if (logFd === -1) {
return null;
}
let readStart = Date.now();
let readCount = 0;
while (true) {
let count = this.read(logFd, buf, BUF_SIZE);
readCount += 1;
if (count <= 0) {
// log has return due to being nonblocking or running out of things
break;
}
for(let i = 0; i < count; i++) {
logArray.push(buf[i]);
}
}
let logTypedArray = new Uint8Array(logArray);
this.close(logFd);
return logTypedArray;
};
let cleanup = function() {
this.lib.close();
this.read = this.open = this.close = null;
this.lib = null;
this.ctypes = null;
};
this.LogCapture = { readLogFile: readLogFile, cleanup: cleanup };