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getrandom.2, random.7: wfix 

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
This commit is contained in:
Michael Kerrisk 2016-11-11 22:36:09 +01:00
parent 379df7a0ec
commit dce6b79650
2 changed files with 22 additions and 22 deletions
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34
man2/getrandom.2
View File

@ -46,7 +46,7 @@ By default,
.BR getrandom () .BR getrandom ()
draws entropy from the draws entropy from the
.I urandom .I urandom
pool (i.e., the same source as the source (i.e., the same source as the
.IR /dev/urandom .IR /dev/urandom
device). device).
This behavior can be changed via the This behavior can be changed via the
@ -55,7 +55,7 @@ argument.
If the If the
.I urandom .I urandom
pool has been initialized, source has been initialized,
reads of up to 256 bytes will always return as many bytes as reads of up to 256 bytes will always return as many bytes as
requested and will not be interrupted by signals. requested and will not be interrupted by signals.
No such guarantees apply for larger buffer sizes. No such guarantees apply for larger buffer sizes.
@ -65,7 +65,7 @@ it may return a partially filled buffer, or fail with the error
If the If the
.I urandom .I urandom
pool has not yet been initialized, then source has not yet been initialized, then
.BR getrandom () .BR getrandom ()
will block, unless will block, unless
.B GRND_NONBLOCK .B GRND_NONBLOCK
@ -80,20 +80,20 @@ ORed together:
.B GRND_RANDOM .B GRND_RANDOM
If this bit is set, then random bytes are drawn from the If this bit is set, then random bytes are drawn from the
.I random .I random
pool source
(i.e., the same source as the (i.e., the same source as the
.IR /dev/random .IR /dev/random
device) device)
instead of the instead of the
.I urandom .I urandom
pool. source.
The The
.I random .I random
pool is limited based on the entropy that can be obtained from environmental source is limited based on the entropy that can be obtained from environmental
noise. noise.
If the number of available bytes in the If the number of available bytes in the
.I random .I random
pool is less than requested in source is less than requested in
.IR buflen , .IR buflen ,
the call returns just the available random bytes. the call returns just the available random bytes.
If no random bytes are available, the behavior depends on the presence of If no random bytes are available, the behavior depends on the presence of
@ -105,12 +105,12 @@ argument.
.B GRND_NONBLOCK .B GRND_NONBLOCK
By default, when reading from the By default, when reading from the
.IR random .IR random
pool, source,
.BR getrandom () .BR getrandom ()
blocks if no random bytes are available, blocks if no random bytes are available,
and when reading from the and when reading from the
.IR urandom .IR urandom
pool, it blocks if the entropy pool has not yet been initialized. source, it blocks if the entropy pool has not yet been initialized.
If the If the
.B GRND_NONBLOCK .B GRND_NONBLOCK
flag is set, then flag is set, then
@ -132,7 +132,7 @@ was specified in
.IR flags .IR flags
and insufficient entropy was present in the and insufficient entropy was present in the
.IR random .IR random
pool or the system call was interrupted by a signal. source or the system call was interrupted by a signal.
.PP .PP
On error, \-1 is returned, and On error, \-1 is returned, and
.I errno .I errno
@ -196,7 +196,7 @@ As of Linux 3.19 the following limits apply:
.IP * 3 .IP * 3
When reading from the When reading from the
.IR urandom .IR urandom
pool, a maximum of 33554431 bytes is returned by a single call to source, a maximum of 33554431 bytes is returned by a single call to
.BR getrandom () .BR getrandom ()
on systems where on systems where
.I int .I int
@ -204,11 +204,11 @@ has a size of 32 bits.
.IP * .IP *
When reading from the When reading from the
.IR random .IR random
pool, a maximum of 512 bytes is returned. source, a maximum of 512 bytes is returned.
.SS Interruption by a signal handler .SS Interruption by a signal handler
When reading from the When reading from the
.I urandom .I urandom
pool source
.RB ( GRND_RANDOM .RB ( GRND_RANDOM
is not set), is not set),
.BR getrandom () .BR getrandom ()
@ -223,7 +223,7 @@ from kernel memory to
.IR buf . .IR buf .
When reading from the When reading from the
.I random .I random
pool source
.RB ( GRND_RANDOM .RB ( GRND_RANDOM
is set), is set),
.BR getrandom () .BR getrandom ()
@ -236,7 +236,7 @@ The behavior when a call to
.BR getrandom () .BR getrandom ()
that is blocked while reading from the that is blocked while reading from the
.I urandom .I urandom
pool is interrupted by a signal handler source is interrupted by a signal handler
depends on the initialization state of the entropy buffer depends on the initialization state of the entropy buffer
and on the request size, and on the request size,
.IR buflen . .IR buflen .
@ -259,7 +259,7 @@ Instead, it will return all of the bytes that have been requested.
When reading from the When reading from the
.IR random .IR random
pool, blocking requests of any size can be interrupted by a signal handler source, blocking requests of any size can be interrupted by a signal handler
(the call fails with the error (the call fails with the error
.BR EINTR ). .BR EINTR ).
@ -267,7 +267,7 @@ Using
.BR getrandom () .BR getrandom ()
to read small buffers (<=\ 256 bytes) from the to read small buffers (<=\ 256 bytes) from the
.I urandom .I urandom
pool is the preferred mode of usage. source is the preferred mode of usage.
The special treatment of small values of The special treatment of small values of
.I buflen .I buflen

10
man7/random.7
View File

@ -47,17 +47,17 @@ This system call provides access either to the same source as
.I /dev/urandom .I /dev/urandom
(called the (called the
.I urandom .I urandom
pool in this page) source in this page)
or to the same source as or to the same source as
.I /dev/random .I /dev/random
(called the (called the
.I random .I random
pool in this page). source in this page).
The default is the The default is the
.I urandom .I urandom
pool; the source; the
.I random .I random
pool is selected by specifying the source is selected by specifying the
.BR GRND_RANDOM .BR GRND_RANDOM
flag to the system call. flag to the system call.
.\" .\"
@ -85,7 +85,7 @@ flag or the
device. device.
The cryptographic algorithms used for the The cryptographic algorithms used for the
.IR urandom .IR urandom
pool are quite conservative, and so should be sufficient for all purposes. source are quite conservative, and so should be sufficient for all purposes.
The disadvantage of The disadvantage of
.B GRND_RANDOM .B GRND_RANDOM