问题
I have built a Firefox extension using the Addon SDK that opens up a new tab with a HTML page from the extensions directory and attaches a content script to it:
function openHtmlLoadFormTab(htmlFileName, jsWorkerFileName) {
tabs.open({
url: data.url(htmlFileName),
onReady: function(tab) {
var tabWorker = tab.attach({
contentScriptFile: [ data.url(jsJquery), data.url(jsWorkerFileName) ]
});
}
});
}
I have an <input type="file"> in the HTML file and some code that handles the "submit" event in the JS file (these files are given by htmlFileName and jsWorkerFileName respectively)
Because of security reasons, I cannot access the full file path in JS with document.getElementById('uploadid').value. I only get the file's name.
However, since this is a Firefox extension, I'm wondering if there is anyway to override this restriction?
I have been looking into netscape.security.PrivilegeManager.enablePrivilege("UniversalFileRead") and mozFullPath but I haven't been able to get it to work. I believe it's deprecated anyway?
The other solution is to build an XUL-based UI and prompt for the file there somehow, but I would like to know for sure if there is anyway to get this to work in HTML.
First edit with small example code
I built a small sample extension to illustrate how I'm doing things.
lib/main.js
var self = require('self');
var tabs = require('tabs');
var data = self.data;
var jsLoadForm = "load-form.js", htmlLoadForm = "load-form.html";
var jsJquery = 'jquery-1.8.0.min.js';
exports.onUnload = function(reason) {};
exports.main = function(options, callbacks) {
// TODO: remove this debugging line
openHtmlLoadFormTab(htmlLoadForm, jsLoadForm);
};
function openHtmlLoadFormTab(htmlFileName, jsWorkerFileName) {
tabs.open({
url: data.url(htmlFileName),
onReady: function(tab) {
var tabWorker = tab.attach({
contentScriptFile: [ data.url(jsJquery), data.url(jsWorkerFileName) ]
});
}
});
}
data/load-form.html
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<title>Form</title>
<script lang="text/javascript">
function fileChanged(e) {
// this is just the file name
alert("html js: files[0].name: " + e.files[0].name);
// mozFullPath is indeed empty, NOT undefined
alert("html js: files[0].mozFullPath: " + e.files[0].mozFullPath);
}
</script>
</head>
<body>
<form name="my-form" id="my-form" action="">
<div>
<label for="uploadid1" id="uploadlabel1">File (JS in HTML):</label>
<input type="file" name="uploadid1" id="uploadid1" onchange="fileChanged(this)"/>
</div>
<div>
<label for="uploadid2" id="uploadlabel2">File (JS in content script): </label>
<input type="file" name="uploadid2" id="uploadid2" onchange="fileChangedInContentScript(this)"/>
</div>
<div>
<label for="uploadid3" id="uploadlabel3">File (JS using jQuery in content script):</label>
<input type="file" name="uploadid3" id="uploadid3" />
</div>
</form>
</body>
</html>
data/load-form.js
$(document).ready(function() {
$("#uploadid3").change(function(e) {
// in jquery, e.files is null
if(e.files != null)
console.log("jquery: e.files is defined");
else
console.log("jquery: e.files is null");
// this works, prints the file name though
console.log("$('#uploadid3').val(): " + $("#uploadid3").val());
// this is undefined
console.log("$('#uploadid3').mozFullPath: " + $("#uploadid3").mozFullPath);
});
});
// this handler never gets called
function fileChangedInContentScript(e) {
alert("js content script: filechanged in content script called");
}
As you can see in main.js, I used jquery-1.8.0.min.js, downloaded from the jQuery website.
Note: I also tried these without jQuery included as a content script when I opened the tab in main.js, but no luck.
The conclusion is that mozFullPath is indeed empty when I access it from JS embedded in the HTML page and I cannot find a way to access mozFullPath from jQuery, nor can I find a way to add a onchange handler in load-form.html that's defined in load-form.js
Second edit with onchange handler in the load-form.js content-script
I added the following code to load-form.js to catch the onchange event. I also removed the jQuery content script from main.js
document.addEventListener("DOMContentLoaded", function() {
try {
document.getElementById("uploadid2").addEventListener('change', function(e) {
console.log("addeventlistener worked!");
console.log("e: " + e);
console.log("e.target: " + e.target);
console.log("e.target.files: " + e.target.files);
console.log("e.target.files[0].name: " + e.target.files[0].name);
console.log("e.target.files[0].mozFullPath: " + e.target.files[0].mozFullPath);
});
console.log('added event listener')
} catch(e) {
console.log('adding event listener failed: ' + e);
}
}, false);
This still outputs an empty string for mozFullPath:
info: added event listener
info: addeventlistener worked!
info: e: [object Event]
info: e.target: [object HTMLInputElement]
info: e.target.files: [object FileList]
info: e.target.files[0].name: test.sh
info: e.target.files[0].mozFullPath:
Is there anyway to acquire the needed permissions? How can I get my hands on that full path? I need the full path so I can pass it to an application the extension launches. (There are workaround solutions where I can do without the full path, but they decrease the quality of the extension)
回答1:
fileInput.value property is meant to be accessible to web pages so it will only give you the file name, not the full path - web pages have no reason to know the full path on your machine. However, as a privileged extension you should be able to access the File.mozFullPath property. In this particular case you would do it like this:
var files = document.getElementById('uploadid').files;
if (files.length > 0)
{
// Assuming that only one file can be selected
// we care only about the first entry
console.log(files[0].mozFullPath);
}
The big question of course is whether your code is allowed to access File.mozFullPath. I suspect that a content script in the Add-on SDK won't have the necessary privileges. The main extension code will have the privileges but getting to the input field from there is hard...
来源：https://stackoverflow.com/questions/12145622/firefox-extensions-and-full-file-paths-from-html-form