mbox
Version:
Evented wrapper for mboxrd files
293 lines (201 loc) • 9.07 kB
JavaScript
/*
node-mbox library
Copyright (C) 2011 Ditesh Shashikant Gathani <ditesh@gathani.org>
Permission is hereby granted, free of charge, to any person obtaining a copy of
this software and associated documentation files (the "Software"), to deal in
the Software without restriction, including without limitation the rights to
use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
of the Software, and to permit persons to whom the Software is furnished to do
so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
*/
var fs = require("fs");
var util = require("util");
var events = require("events");
var unixlib = require("unixlib");
this.mbox = function(fd, options) {
if (options === undefined) options = {};
// Private members follow
var self = this;
options.init = false;
options.bufsize = (options.bufsize === undefined) ? 4096: options.bufsize; // Read/write buffer size
options.tmppath = (options.tmppath === undefined) ? "/tmp": options.tmppath; // Temp buffer size
var debug = options.debug || false;
// This structure is the original data structure
var omessages = {
size: 0,
count: 0,
sizes: [],
deleted: [],
offsets: [],
};
// This structure can be manipulated (thru message deletion)
var messages = {
size: 0,
count: 0,
sizes: [],
deleted: [],
offsets: [],
};
// Priviledged methods follow
this.count = function() {
return messages.count;
};
this.get = function(msgnumber) {
var self = this;
if (options.init === false) {
self.emit("error", "Specified mboxrd has not been fully parsed yet or there was an error parsing it (trap 'init' event for more details)");
return false;
}
if (msgnumber > omessages.count || messages.deleted[msgnumber] !== undefined) {
self.emit("get", false, msgnumber);
return false;
} else {
var buffer = new Buffer(messages.sizes[msgnumber]);
fs.read(fd, buffer, 0, messages.sizes[msgnumber], messages.offsets[msgnumber], function(err, bytesRead, buffer) {
self.emit("get", true, msgnumber, buffer.toString());
});
}
};
this.reset = function() {
var self = this;
if (options.init === false) {
self.emit("error", "Specified mboxrd has not been fully parsed yet or there was an error parsing it (trap 'init' event for more details)");
return false;
}
messages = omessages;
self.emit("reset", true);
};
this.delete = function(msgnumber) {
var self = this;
if (options.init === false) {
self.emit("error", "Specified mboxrd has not been fully parsed yet or there was an error parsing it (trap 'init' event for more details)");
return false;
}
if (msgnumber > omessages.count || messages.deleted[msgnumber] !== undefined) {
self.emit("delete", false, msgnumber);
return false;
}
var messagesize = messages.sizes[msgnumber]
delete messages.offsets[msgnumber];
delete messages.sizes[msgnumber];
messages.count -= 1;
messages.size -= messagesize;
// We take advantage of implicity JS hashing to avoid O(n) lookups
messages.deleted[msgnumber] = 1;
self.emit("delete", true, msgnumber);
};
// Note that this closes fd
this.write = function(filename) {
unixlib.mkstemp(options.tmppath + "/mboxXXXXXX", function(err, tmpfd, tmpfilename) {
syncToTmp(tmpfd, 1, function() {
fs.close(fd, function() { // This should automagically release any locks
fs.close(tmpfd, function() {
fs.rename(tmpfilename, filename, function() {
self.emit("write", true);
});
});
});
});
});
}; // Don't you love the chain of closing function calls? :)
// Private methods follow
// Write modifications to temp file
function syncToTmp(tmpfd, msgnumber, cb) {
// Pass the last msg
if (msgnumber > messages.offsets.length) cb();
// Skip deleted messages
else if (messages.offsets[msgnumber] === undefined) syncToTmp(tmpfd, msgnumber + 1, cb);
else {
var buffer = new Buffer(omessages.sizes[msgnumber]);
fs.read(fd, buffer, 0, omessages.sizes[msgnumber], messages.offsets[msgnumber], function(err, bytesRead, buffer) {
fs.write(tmpfd, buffer, 0, bytesRead, null, function(err, written, buffer) {
syncToTmp(tmpfd, msgnumber + 1, cb);
});
});
}
}
function read(position, previousbuf, cb) {
var i = 0;
var minlen = 0;
var msgsize = 0;
var buffer = new Buffer(options.bufsize);
fs.read(fd, buffer, 0, options.bufsize, position, function(err, bytesRead, buffer) {
var previousbuflen = 0;
if (err) cb(err);
else {
// This combines previous buffer with the newly read buffer
if (previousbuf !== null) {
if (position > 0) previousbuflen = previousbuf.length;
var newbuffer = new Buffer(previousbuf.length + buffer.length)
// Fast memcpy()'s for the win
previousbuf.copy(newbuffer);
buffer.copy(newbuffer, previousbuf.length);
buffer = newbuffer;
previousbuf = null;
delete newbuffer;
}
i = 0;
minlen = (bytesRead === buffer.length) ? buffer.length : bytesRead;
while (i < minlen) {
// Match for newline (\n), ASCII code 10
if (buffer[i] === 10) {
// We're at the end of the buffer
if (i === buffer.length-1) break;
// \nFrom may be split between the buffers
else if (i+5 > buffer.length-1) {
previousbuf = new Buffer(buffer.length-i-1);
buffer.copy(previousbuf, 0, i+1);
break;
// \nFrom is within buffer
} else if (buffer.slice(i+1, i+6).toString() === "From ") {
messages.offsets.push(position + (i+1)-previousbuflen);
}
}
i++;
}
// There is more to read!
if (bytesRead === options.bufsize) read(position + options.bufsize + 1, previousbuf, cb);
else {
i = 0;
while (i < messages.offsets.length - 1) {
msgsize = messages.offsets[i+1] - messages.offsets[i];
messages.size += msgsize;
messages.sizes.push(msgsize);
i++;
}
if (messages.offsets.length > 0) {
msgsize = position + bytesRead - messages.offsets[i];
messages.sizes.push(msgsize);
messages.size += msgsize;
messages.count = messages.offsets.length;
}
// Make a copy
// JS seriously needs a good, fast and built-in object clone() method
omessages.size = messages.size;
omessages.count = messages.count;
for (var i in messages.sizes) omessages.sizes.push(messages.sizes[i]);
for (var i in messages.offsets) omessages.offsets.push(messages.offsets[i]);
cb(null);
}
}
});
}
// Constructor code follows
read(-1, new Buffer("\n"), function(err) {
if (err) self.emit("init", false, err);
else {
options.init = true;
self.emit("init", true);
};
});
};
util.inherits(this.mbox, events.EventEmitter);