ioctl 手册页

ioctl() perform device-specific control functions	Function
	SYNOPSIS DESCRIPTION PARAMETERS RETURN VALUES CONFORMANCE MULTITHREAD SAFETY LEVEL PORTING ISSUES AVAILABILITY SEE ALSO

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#include

int ioctl(int fildes, int request, ...);

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The ioctl() function performs a variety of device-specific control functions on device special files. This function is supported for the following special file types:

• Sockets
• Console devices
• Communication port devices

Refer to the device-specific reference page listed in the section for specific information on the ioctl() requests supported for each device.

The following generic requests are supported as well:

FIOCLEX 

The call ioctl(fildes, FIOCLEX, NULL) is equivalent to:

fcntl(fildes, F_SETFD, FD_CLOEXEC)

FIONCLEX 

The call ioctl(fildes, FIONCLEX, NULL) is equivalent to:

fcntl(fildes, F_SETFD, 0)

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fildes 

Specifies an open file descriptor that refers to a device.

request 

Specifies the control function to be performed based upon the device being addressed.

... 

An optional third parameter (arg) for request-specific information. The data type depends upon the particular control request, but it is either an int or a pointer to a device-specific data structure.

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If successful, ioctl() returns a nonnegative integer value based on the device control function. On failure, it returns -1 and sets errno to one of the following values, or to another value described for the particular request.

EBADF 

The fildes parameter is not a valid open file descriptor.

EFAULT 

The request parameter requires a data transfer to or from a buffer that arg points to, but this pointer is invalid.

EINTR 

A signal interrupted the call.

EINVAL 

request or arg is not valid for this device.

EIO 

Some physical I/O error has occurred.

ENOTTY 

fildes is not associated with a device driver that accepts control functions.

ENXIO 

The request and arg parameters are valid for this device driver, but the service requested cannot be performed on this particular subdevice.

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UNIX 98, with exceptions.

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MT-Safe.

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ioctl() is inherently non-portable. the NuTCRACKER Platform supports only the documented ioctl() requests, only on the specified devices. Code that attempts to use any other requests, or on any other devices, must be revised.

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Functions:

Miscellaneous:

/dev/com, /dev/console,

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MKS Toolkit 9.1 Documentation Build 7.