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getrandom.2: Clarify text with respect to GRND_NONBLOCK 

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
This commit is contained in:
Michael Kerrisk 2015-01-27 09:19:22 +01:00
parent 28ef3452e4
commit 973ff2fc67
1 changed files with 14 additions and 4 deletions
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18
man2/getrandom.2
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@ -66,6 +66,10 @@ argument.
If the
.IR /dev/urandom
pool has been initialized, reading from that pool never blocks.
If the pool has not yet been initialized, then the call blocks, unless
.B GRND_RANDOM
is specified in
.IR flags .
The
.I flags
@ -87,15 +91,17 @@ If the number of available bytes in
is less than requested in
.IR buflen ,
the call returns just the available random bytes.
If no random byte is available, the behavior depends on the
presence of
If no random bytes are available, the behavior depends on the presence of
.B GRND_NONBLOCK
in the
.I flags
argument.
.TP
.B GRND_NONBLOCK
By default, if there is no random byte available at all,
By default, if there are no random bytes available at all (when reading from
.IR /dev/random ),
or the entropy pool has not yet been initialized (when reading from
.IR /dev/urandom ),
.BR getrandom ()
blocks until data is available.
If the
@ -113,7 +119,11 @@ returns the number of bytes that were copied to the buffer
.IR buf .
This may be less than the number of bytes requested via
.I buflen
if insufficient entropy was present in the
if
.BR GRND_RANDOM
was specified in
.IR flags
and insufficient entropy was present in the
.IR /dev/random
pool, or if the system call was interrupted by a signal.
.PP