~mcf/plan9front

2c776d9da513930030f8691af5bc483e1643cd75 — 5 months ago 0bb7920
memory(2): mention tsmemcmp (thanks kemal)
1 files changed, 22 insertions(+), 1 deletions(-)

M sys/man/2/memory
M sys/man/2/memory => sys/man/2/memory +22 -1
@@ 1,6 1,6 @@
.TH MEMORY 2
.SH NAME
memccpy, memchr, memcmp, memcpy, memmove, memset \- memory operations
memccpy, memchr, memcmp, memcpy, memmove, memset, tsmemcmp \- memory operations
.SH SYNOPSIS
.B #include <u.h>
.br


@@ 24,6 24,11 @@ void*	memmove(void *s1, void *s2, ulong n)
.PP
.B
void*	memset(void *s, int c, ulong n)
.PP
.B #include <libsec.h>
.PP
.B
int	tsmemcmp(void *s1, void *s2, ulong n)
.SH DESCRIPTION
These functions operate efficiently on memory areas
(arrays of bytes bounded by a count, not terminated by a zero byte).


@@ 103,11 108,22 @@ to the value of byte
.IR c .
It returns
.IR s .
.PP
.I Tsmemcmp
is a variant of
.I memcmp
that is safe against timing attacks.
It does not stop when it sees a difference, this way it's runtime is function of
.I n
and not something that can lead clues to attackers.
.SH SOURCE
All these routines have portable C implementations in
.BR /sys/src/libc/port .
Most also have machine-dependent assembly language implementations in
.BR /sys/src/libc/$objtype .
.I Tsmemcmp
is found on
.BR /sys/src/libsec/port/tsmemcmp.c .
.SH SEE ALSO
.IR strcat (2)
.SH BUGS


@@ 124,3 140,8 @@ If
and
.I memmove
are handed a negative count, they abort.
.PP
.I Memcmp
should not be used to compare sensitive data as it's vulnerable to timing attacks. Instead, 
.I tsmemcmp
should be used.