DragonFly On-Line Manual Pages

ERRNO(9)              DragonFly Kernel Developer's Manual             ERRNO(9)

NAME
     errno -- kernel internal error numbers

SYNOPSIS
     #include <sys/errno.h>

DESCRIPTION
     This section provides an overview of the error numbers used internally by
     the kernel and indicate neither success nor failure.  These error numbers
     are not returned to userland code.

DIAGNOSTICS
     Kernel functions that indicate success or failure by means of either 0 or
     an errno(2) value sometimes have a need to indicate that ``special''
     handling is required at an upper layer or, in the case of ioctl(2)
     processing, that ``nothing was wrong but the request was not handled''.
     To handle these cases, some negative errno(2) values are defined which
     are handled by the kernel before returning a different errno(2) value to
     userland or simply zero.

     The following is a list of the defined names and their meanings as given
     in <errno.h>.

     -1 ERESTART Restart syscall.  The system call should be restarted.  This
             typically means that the machine dependent system call trap code
             will reposition the process's instruction pointer or program
             counter to re-execute the current system call with no other work
             required.

     -2 EJUSTRETURN Do not modify regs, just return.  No more work is required
             and the function should just return.

     -3 ENOIOCTL Ioctl not handled by this layer.  The ioctl(2) was not
             handled and should be passed through to another layer.

     -4 EMOUNTEXIT Mountpoint released via vfs_start().  Specific to mfs(8).

SEE ALSO
     errno(2), ioctl(9)

HISTORY
     An errno manual page appeared in Version 6 AT&T UNIX.  This errno manual
     page appeared in NetBSD 3.0.

DragonFly 5.3                    May 16, 2018                    DragonFly 5.3