Xamarin Android share PDF. Permission denied for the attachment [duplicate] - xamarin

Question

My app creates mails with attachments, and uses an intent with Intent.ACTION_SEND to launch a mail app.
It works with all the mail apps I tested with, except for the new Gmail 5.0 (it works with Gmail 4.9), where the mail opens without attachment, showing the error: "Permission denied for the attachment".
There are no useful messages from Gmail on logcat. I only tested Gmail 5.0 on Android KitKat, but on multiple devices.
I create the file for the attachment like this:
String fileName = "file-name_something_like_this";
FileOutputStream output = context.openFileOutput(
fileName, Context.MODE_WORLD_READABLE);
// Write data to output...
output.close();
File fileToSend = new File(context.getFilesDir(), fileName);
I'm aware of the security concerns with MODE_WORLD_READABLE.
I send the intent like this:
public static void compose(
Context context,
String address,
String subject,
String body,
File attachment) {
Intent emailIntent = new Intent(Intent.ACTION_SEND);
emailIntent.setType("message/rfc822");
emailIntent.putExtra(
Intent.EXTRA_EMAIL, new String[] { address });
emailIntent.putExtra(Intent.EXTRA_SUBJECT, subject);
emailIntent.putExtra(Intent.EXTRA_TEXT, body);
emailIntent.putExtra(
Intent.EXTRA_STREAM,
Uri.fromFile(attachment));
Intent chooser = Intent.createChooser(
emailIntent,
context.getString(R.string.send_mail_chooser));
context.startActivity(chooser);
}
Is there anything I do wrong when creating the file or sending the intent? Is there a better way to start a mail app with attachment? Alternatively - has someone encountered this problem and found a workaround for it?
Thanks!

Answer 1

I was able to pass a screenshot .jpeg file from my app to GMail 5.0 through an Intent. The key was in this answer.
Everything I have from #natasky 's code is nearly identical but instead, I have the file's directory as
context.getExternalCacheDir();
Which "represents the external storage directory where you should save cache files" (documentation)

Answer 2

GMail 5.0 added some security checks to attachments it receives from an Intent. These are unrelated to unix permissions, so the fact that the file is readable doesn't matter.
When the attachment Uri is a file://, it'll only accept files from external storage, the private directory of gmail itself, or world-readable files from the private data directory of the calling app.
The problem with this security check is that it relies on gmail being able to find the caller app, which is only reliable when the caller has asked for result. In your code above, you do not ask for result and therefore gmail does not know who the caller is, and rejects your file.
Since it worked for you in 4.9 but not in 5.0, you know it's not a unix permission problem, so the reason must be the new checks.
TL;DR answer:
replace startActivity with startActivityForResult.
Or better yet, use a content provider.

Answer 3

Use getExternalCacheDir() with File.createTempFile.
Use the following to create a temporary file in the external cache directory:
File tempFile = File.createTempFile("fileName", ".txt", context.getExternalCacheDir());
Then copy your original file's content to tempFile,
FileWriter fw = new FileWriter(tempFile);
FileReader fr = new FileReader(Data.ERR_BAK_FILE);
int c = fr.read();
while (c != -1) {
fw.write(c);
c = fr.read();
}
fr.close();
fw.flush();
fw.close();
now put your file to intent,
emailIntent.putExtra(Intent.EXTRA_STREAM, Uri.fromFile(tempFile));

Answer 4

You should implement a FileProvider, which can create Uris for your app's internal files. Other apps are granted permission to read these Uris. Then, simply instead of calling Uri.fromFile(attachment), you instantiate your FileProvider and use:
fileProvider.getUriForFile(attachment);

Answer 5

Google have an answer for that issue:
Store the data in your own ContentProvider, making sure that other apps have the correct permission to access your provider. The preferred mechanism for providing access is to use per-URI permissions which are temporary and only grant access to the receiving application. An easy way to create a ContentProvider like this is to use the FileProvider helper class.
Use the system MediaStore. The MediaStore is primarily aimed at video, audio and image MIME types, however beginning with Android 3.0 (API level 11) it can also store non-media types (see MediaStore.Files for more info). Files can be inserted into the MediaStore using scanFile() after which a content:// style Uri suitable for sharing is passed to the provided onScanCompleted() callback. Note that once added to the system MediaStore the content is accessible to any app on the device.
Also you can try set permissions for your file:
emailIntent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
And finally you can copy/store your files in external storage - permissions not needed there.

Answer 6

I tested it and I found out that it was definitely private storage access problem.
When you attach some file to Gmail (over 5.0) do not use the file from private storage such as /data/data/package/. Try to use /storage/sdcard.
You can successfully attach your file.

Answer 7

Not sure why GMail 5.0 doesn't like certain file paths (which I've confirmed it does have read access to), but an apparently better solution is to implement your own ContentProvider class to serve the file. It's actually somewhat simple, and I found a decent example here: http://stephendnicholas.com/archives/974
Be sure to add the tag to your app manifest, and include a "android:grantUriPermissions="true"" within that. You'll also want to implement getType() and return the appropriate MIME type for the file URI, otherwise some apps wont work with this... There's an example of that in the comment section on the link.

Answer 8

I was having this problem and finally found an easy way to send email with attachment. Here is the code
public void SendEmail(){
try {
//saving image
String randomNameOfPic = Calendar.DAY_OF_YEAR+DateFormat.getTimeInstance().toString();
File file = new File(ActivityRecharge.this.getCacheDir(), "slip"+ randomNameOfPic+ ".jpg");
FileOutputStream fOut = new FileOutputStream(file);
myPic.compress(Bitmap.CompressFormat.JPEG, 100, fOut);
fOut.flush();
fOut.close();
file.setReadable(true, false);
//sending email
Intent intent = new Intent(Intent.ACTION_SEND);
intent.setType("text/plain");
intent.putExtra(Intent.EXTRA_EMAIL, new String[]{"zohabali5#gmail.com"});
intent.putExtra(Intent.EXTRA_SUBJECT, "Recharge Account");
intent.putExtra(Intent.EXTRA_TEXT, "body text");
//Uri uri = Uri.parse("file://" + fileAbsolutePath);
intent.putExtra(Intent.EXTRA_STREAM, Uri.fromFile(file));
intent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
startActivityForResult(Intent.createChooser(intent, "Send email..."),12);
}catch (Exception e){
Toast.makeText(ActivityRecharge.this,"Unable to open Email intent",Toast.LENGTH_LONG).show();
}
}
In this code "myPic" is bitmap which was returned by camera intent

Answer 9

Step 1: Add authority in your attached URI
Uri uri = FileProvider.getUriForFile(context, ""com.yourpackage", file);
Same as your manifest file provide name
android:authorities="com.yourpackage"
Step 2`; Add flag for allow to read
myIntent.setFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);