Is Ioctl Blocking Call?

Is ioctl thread safe?

ioctl() is not one of them, so it IS thread-safe.

However, ioctl() is a cancellation point, so the thread can be terminated once it reaches ioctl()..

What is ioctl in Linux kernel?

ioctl() is the most common way for applications to interface with device drivers. It is flexible and easily extended by adding new commands and can be passed through character devices, block devices as well as sockets and other special file descriptors.

How do you pronounce ioctl?

Like the Linux ioctl. Pronounced “i-oct-el”.

Where is ioctl defined?

Macros and defines used in specifying an ioctl() request are located in the file

What is Dev Net Tun?

1. Description TUN/TAP provides packet reception and transmission for user space programs. … If you want to create persistent devices and give ownership of them to unprivileged users, then you need the /dev/net/tun device to be usable by those users.

What is an ioctl call?

In computing, ioctl (an abbreviation of input/output control) is a system call for device-specific input/output operations and other operations which cannot be expressed by regular system calls.

What does ioctl return?

On success, 0 is returned. An ioctl() may use the return value as an output parameter and return a non-negative value on success. On error, -1 is returned and the global variable errno is set appropriately.

Why ioctl is used in Linux?

The ioctl function is useful for implementing a device driver to set the configuration on the device. e.g. a printer that has configuration options to check and set the font family, font size etc. ioctl could be used to get the current font as well as set the font to a new one.

What is ioctl error?

The explain_ioctl function is used to obtain an explanation of an error returned by the ioctl(2) system call. The least the message will contain is the value of strerror(errno), but usually it will do much better, and indicate the underlying cause in more detail.

What does Sysctl stand for?

sysctl is a software utility of some Unix-like operating systems that reads and modifies the attributes of the system kernel such as its version number, maximum limits, and security settings.