socket_cmsg_space

Function name: socket_cmsg_space()

Function description: socket_cmsg_space() function is used to calculate the buffer size of the specified control information type and length.

Applicable version: PHP 5 >= 5.5.0, PHP 7

Syntax: socket_cmsg_space(int $level, int $type) : int

parameter:

• $level: represents the protocol level of control information, and can be used with the constant SOL_SOCKET or other customized protocol level.
• $type: represents the type of control information. You can use the constant SCM_RIGHTS or other customized control information types.

Return value: Returns the buffer size of the specified control information type and length.

Example:

 $level = SOL_SOCKET; $type = SCM_RIGHTS; $bufferSize = socket_cmsg_space($level, $type); echo "缓冲区大小为：$bufferSize 字节";

Output:

缓冲区大小为：20 字节

Notes:

• The socket_cmsg_space() function only calculates the buffer size and does not actually create a buffer.
• The control information type and protocol level need to be specified according to specific requirements.
• Before using this function, you need to make sure that a valid socket has been created.