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Programming Leftovers

Submitted by Roy Schestowitz on Wednesday 19th of January 2022 06:46:49 AM Filed under

Development

C: sigprocmask Function Usage

You may have heard about socket programming in C. One of the socket functions is the “sigprocmask” function. This function has been usually utilized in the code to inspect or alter the signal mask of the calling function. The signal mask is a term used for a group of signals that are presently blocked and cannot be conveyed for the calling function. Such kind of signal is known as “Blocked Signals.” You can say that a process can still receive the blocked signals, but it will not be used until they are unblocked and released, i.e., raised. Until then, it will be pending. Therefore, within today’s guide, we will be discussing the use of the sigprocmask function in C programming. Let’s have a start.

After the Ubuntu 20.04 successful login, you need to launch the shell of the Ubuntu 20.04 system first after the login. So, try out the “Ctrl+Alt+T” shortcut simply on the desktop screen. It will launch the terminal shell for you in some seconds. Make sure to update your system using the apt package of your system. After that, you have to execute the “touch” instruction along with the file name you want to generate, i.e., to create the C file via the shell. This newly created file can be found in the “home” folder of your system’s file explorer. You can try opening it with the “text” editor to create code in it. Another way to open it in the shell is using the “GNU Nano” editor using the “nano” keyword with a file name as demonstrated beneath.
C: sigaction function usage

A sigaction() is a function that allows to call/observe or examine a specific action associated with a particular signal. It is thought to consider a signal and sigaction function on the same page. But in reality, it has not occurred. The signal() function does not block other signals when the current handler’s execution is under process. At the same time, the sigaction function can block other signals until the current handler has returned.
delegation of authority from the systems programming perspective – Ariadne's Space

As I have been griping on Twitter lately, about how I dislike the design of modern UNIX operating systems, an interesting conversation about object capabilities came up with the author of musl-libc. This conversation caused me to realize that systems programmers don’t really have a understanding of object capabilities, and how they can be used to achieve environments that are aligned with the principle of least authority.

In general, I think this is largely because we’ve failed to effectively disseminate the research output in this area to the software engineering community at large — for various reasons, people complete their distributed systems degrees and go to work in decentralized finance, as unfortunately, Coinbase pays better. An unfortunate reality is that the security properties guaranteed by Web3 platforms are built around object capabilities, by necessity – the output of a transaction, which then gets consumed for another transaction, is a form of object capability. And while Web3 is largely a planet-incinerating Ponzi scheme run by grifters, object capabilities are a useful concept for building practical security into real-world systems.

Most literature on this topic try to describe these concepts in the framing of, say, driving a car: by default, nobody has permission to drive a given car, so it is compliant with the principle of least authority, meanwhile the car’s key can interface with the ignition, and allow the car to be driven. In this example, the car’s key is an object capability: it is an opaque object, that can be used to acquire the right to drive the car. Afterwards, they usually go on to describe the various aspects of their system without actually discussing why anybody would want this.
Pip Install: Install and Remove Python Packages
A dog-cat-horse-turtle problem

Sometimes the text-processing problems posted on Stack Exchange have so many solutions, it's hard to decide which is best.

A problem like that was posted in the "Unix & Linux" section in December 2021...

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