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FETCH(9)	       FreeBSD Kernel Developer's Manual	      FETCH(9)

NAME
     fetch, fubyte, fuword, fuword16, fuword32,	fuword64, fueword, fueword32,
     fueword64 -- fetch	data from user-space

SYNOPSIS
     #include <sys/types.h>
     #include <sys/systm.h>

     int
     fubyte(volatile const void	*base);

     long
     fuword(volatile const void	*base);

     int
     fuword16(volatile const void *base);

     int32_t
     fuword32(volatile const void *base);

     int64_t
     fuword64(volatile const void *base);

     long
     fueword(volatile const void *base,	long *val);

     int32_t
     fueword32(volatile	const void *base, int32_t *val);

     int64_t
     fueword64(volatile	const void *base, int64_t *val);

     #include <sys/resourcevar.h>

DESCRIPTION
     The fetch functions are designed to copy small amounts of data from user-
     space of the current process.  If read is successful, it is performed
     atomically.  The data read	must be	naturally aligned.

     The fetch routines	provide	the following functionality:

     fubyte()	  Fetches a byte of data from the user-space address base.
		  The byte read	is zero-extended into the results variable.

     fuword()	  Fetches a word of data (long)	from the user-space address
		  base.

     fuword16()	  Fetches 16 bits of data from the user-space address base.
		  The half-word	read is	zero-extended into the results vari-
		  able.

     fuword32()	  Fetches 32 bits of data from the user-space address base.

     fuword64()	  Fetches 64 bits of data from the user-space address base.

     fueword()	  Fetches a word of data (long)	from the user-space address
		  base and stores the result in	the variable pointed by	val.

     fueword32()  Fetches 32 bits of data from the user-space address base and
		  stores the result in the variable pointed by val.

     fueword64()  Fetches 64 bits of data from the user-space address base and
		  stores the result in the variable pointed by val.

     The callers of fuword(), fuword32() and fuword64()	functions cannot dis-
     tinguish between -1 read from userspace and function failure.

RETURN VALUES
     The fubyte(), fuword(), fuword16(), fuword32(), and fuword64() functions
     return the	data fetched or	-1 on failure.	The fueword(), fueword32() and
     fueword64() functions return 0 on success and -1 on failure.

SEE ALSO
     copy(9), store(9)

FreeBSD	13.0			April 17, 2018			  FreeBSD 13.0
NAME | SYNOPSIS | DESCRIPTION | RETURN VALUES | SEE ALSO

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