Differential D5162 Diff 13432 head/lib/libc/sys/lseek.2

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head/lib/libc/sys/lseek.2

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	.Dv SEEK_HOLE .			.Dv SEEK_HOLE .
	File systems are allowed to expose ranges of zeros with			File systems are allowed to expose ranges of zeros with
	.Dv SEEK_HOLE ,			.Dv SEEK_HOLE ,
	but not required to.			but not required to.
	Applications can use			Applications can use
	.Dv SEEK_HOLE			.Dv SEEK_HOLE
	to optimise their behavior for ranges of zeros, but must not depend on it to			to optimise their behavior for ranges of zeros, but must not depend on it to
	find all such ranges in a file.			find all such ranges in a file.
				Each file is presented as having a zero-size virtual hole at the very
				end of the file.
	The existence of a hole at the end of every data region allows for easy			The existence of a hole at the end of every data region allows for easy
	programming and implies that a virtual hole exists at the end of the file.			programming and also provides compatibility to the original imlementation
				in Solaris.
				It also causes the current file size (i.e. end-of-file offset) to be returned
				to indicate that there are no more holes past the supplied
				.Fa offset .
	Applications should use			Applications should use
	.Fn fpathconf _PC_MIN_HOLE_SIZE			.Fn fpathconf _PC_MIN_HOLE_SIZE
	or			or
	.Fn pathconf _PC_MIN_HOLE_SIZE			.Fn pathconf _PC_MIN_HOLE_SIZE
	to determine if a file system supports			to determine if a file system supports
	.Dv SEEK_HOLE .			.Dv SEEK_HOLE .
	See			See
	.Xr pathconf 2 .			.Xr pathconf 2 .
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	argument			argument
	is not a proper value			is not a proper value
	or the resulting file offset would			or the resulting file offset would
	be negative for a non-character special file.			be negative for a non-character special file.
	.It Bq Er ENXIO			.It Bq Er ENXIO
	For			For
	.Dv SEEK_DATA ,			.Dv SEEK_DATA ,
	there are no more data regions past the supplied offset.			there are no more data regions past the supplied offset.
	For			Due to existence of the hole at the end of the file, for
	.Dv SEEK_HOLE ,			.Dv SEEK_HOLE
	there are no more holes past the supplied offset.			this error is only returned when the
				.Fa offset
				already points to the end-of-file position.
	.It Bq Er EOVERFLOW			.It Bq Er EOVERFLOW
	The resulting file offset would be a value which cannot be represented			The resulting file offset would be a value which cannot be represented
	correctly in an object of type			correctly in an object of type
	.Fa off_t .			.Fa off_t .
	.It Bq Er ESPIPE			.It Bq Er ESPIPE
	The			The
	.Fa fildes			.Fa fildes
	argument			argument
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