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kandi X-RAY | pyblog Summary
kandi X-RAY | pyblog Summary
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Top functions reviewed by kandi - BETA
- Initialize the UI elements .
- Creates a new UndoManager .
- Shows the preview panel .
- Creates a new textarea state .
- Hash for HTML tags
- creates and returns the Swagger row of the button
- Formats text anchor attributes
- Process an individual list of items
- Replace list lists with lists .
- Merge an HTML string
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Community Discussions
Trending Discussions on pyblog
QUESTION
I want to use Mach Exception Ports to handle exceptions for all tasks (processes) running on macOS. My understanding is that host_set_exception_ports
is to be used in this case. However, host_set_exception_ports
returns KERN_NO_ACCESS
(error code 8) even when I execute my program with sudo
. My experimental code works to handle exceptions for a single task using task_set_exception_ports
.
I already had a look at the Mach kernel code of host_set_exception_ports
. There is a single line of code where KERN_NO_ACCESS
is returned from the function. I have a bit of a hard time to understand what's going on there. It seems the kernel code checks the exception mask I pass to host_set_exception_ports
. I tested with different exception masks but I always get the same negative result.
My questions: Does this mean there is a general restriction to use host_set_exception_ports
in a user-space application? If not, how would I set the host exception ports to receive system-wide exceptions in my application?
The following program is a minimal example to show the behavior and does not have much use otherwise. Use gcc example.c
to compile the program and sudo ./a.out
to execute it.
ANSWER
Answered 2019-May-01 at 07:46Digging through the source, host_set_exception_ports
is calling mac_task_check_set_host_exception_ports
, as you've noted.
Drilling down on that, you can find that mac_task_check_set_host_exception_ports
is retrieving credentials based on the task, then invoking MAC_CHECK(proc_check_set_host_exception_port, cred, exception)
.
That's a macro defined in security/mac_internals.h
. See the xnu code here. Reading, this walks the policy module list checking whether the policy modules will allow or deny the request.
Based on the code, all policy modules must agree and not post an error. So it looks like you need to have the right privileges. There is some documentation from the GNU Mach project that indicates rights to send to the privileged host port are granted to the first task, and can only be passed on from there. See GNU Mach definition of host_ports, etc.
Piecing that together, not only can you not make the change as a user proc, you will need to specially inherit the privileges through a chain from boot time.
QUESTION
I was trying to deep dive into how the UITableView
works internally. I've already read multiple posts regarding that like,
https://www.mikeash.com/pyblog/friday-qa-2013-02-22-lets-build-uitableview.html
I want to know if there is any way we can look into the content of the reusable pool, i.e. how many and what all UITableViewCell
types are available inside it at a moment.
I already know that we'll have the cells
as per the screen size and the cell
height. But I'm trying to figure out what happens if the tableView
accepts different types of cells
at different indexPaths
.
ANSWER
Answered 2019-Aug-13 at 16:31Well, you can dig down into the objects in debug...
I set a breakpoint in didSelectRowAt
and looked into the Variables View pane:
I had one row (index path [0,3]
that used TestCellB
and 90 rows that used TestCell
, and the table was scrolled to row 21 (so row [0,3]
was well off-screen.
As you can see, there is an internal Dictionary
named _reusableTableCells
which, in my example, currently contains 1 TestCellB
and 2 TestCell
s.
EDIT
I just gave this a try - might give you some additional info:
QUESTION
I want fully understand what going inside weak and unowned referance in Swift. For this i read MikeAsh and got some questions.
What already known:
- when there is no weak (and, i suppose, unowned) object reference, the strong reference counter is stored directly in the memory area of the object
- when a weak link appears, the second word in the object memory is reused to reference the side table
- side table has link to the object
- weak link refers to this side table
And what i want to clearify:
- What else side table store inside except link to the object and number of strong reference?
- Is unowned reference link to the side table too? If not and unowned link refers to the object memory what about performance between weak and unowned ?
ANSWER
Answered 2019-Jul-29 at 19:54Okay, i found out.
- Unowned link points to the object as well as strong.
- Unowned link faster than weak.
- Side table stores strong RC, weak RC, unowned RC, link to the object and some flags
QUESTION
I'm setting up a simple WKNavigationDelegate
in my dynamic framework to get WKWebView
's default user agent string:
ANSWER
Answered 2018-Aug-12 at 17:01+load
is rife with danger and fragility. I have had to track down many a fun bug due to +load
surprises over the decades. In general, it should be avoided. And when used, it should touch a minimal amount of the rest of the system specifically because you'll be changing the order within which things are initialized at runtime.
I would recommend that you have some kind of initialization hook in your framework that your framework's clients are expected to call in the app, typically during the app delegate's didFinishLaunching:....
method.
You can put in assert()s
along other code paths that can warn or raise if the framework was not properly initialized.
QUESTION
I'm trying to understand why the where clause of a generic method is ignored
I've made a simple use case in Swift 3 (you can copy the code in a playground if you wanna fiddle with it):
...ANSWER
Answered 2017-Jan-13 at 10:34The type of the method to be called is selected during compile time. What does the compiler know about your types?
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