getentropy clarifications

getentropy clarifications

[Nikos Mavrogiannopoulos]

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Hi,
 The attached patches clarify some parts of the getentropy() functions.

regards,
Nikos

[-- Attachment #2: 0001-getentropy-corrected-the-header-it-is-defined-under.patch --]
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From be741e2dde51a060c4294780f5dad83e967955a2 Mon Sep 17 00:00:00 2001
From: Nikos Mavrogiannopoulos <nmav@redhat.com>
Date: Wed, 29 Mar 2017 14:43:14 +0200
Subject: [PATCH 1/2] getentropy: corrected the header it is defined under

Signed-off-by: Nikos Mavrogiannopoulos <nmav@redhat.com>
---
 man3/getentropy.3 | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/man3/getentropy.3 b/man3/getentropy.3
index 697f937..4cd4d61 100644
--- a/man3/getentropy.3
+++ b/man3/getentropy.3
@@ -26,7 +26,7 @@
 .SH NAME
 getentropy \- fill a buffer with random bytes
 .SH SYNOPSIS
-.B #include <sys/random.h>
+.B #include <unistd.h>
 .sp
 .BI "int getentropy(void *" buffer ", size_t " length );
 .SH DESCRIPTION
@@ -90,6 +90,10 @@ a cancellation point,
 .BR getentropy ()
 is not a cancellation point.
 
+In earlier versions of glibc this function was avaible under the
+.BR <sys/random.h>
+header.
+
 A call to
 .BR getentropy ()
 may block if the system has just booted and the kernel has
-- 
2.9.3


[-- Attachment #3: 0002-getentropy-clarify-returns.patch --]
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From 112c3653fd293453504bffff35b60785c9f82c40 Mon Sep 17 00:00:00 2001
From: Nikos Mavrogiannopoulos <nmav@redhat.com>
Date: Wed, 29 Mar 2017 14:44:21 +0200
Subject: [PATCH 2/2] getentropy: clarify "returns"

Signed-off-by: Nikos Mavrogiannopoulos <nmav@redhat.com>
---
 man3/getentropy.3 | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/man3/getentropy.3 b/man3/getentropy.3
index 4cd4d61..b341284 100644
--- a/man3/getentropy.3
+++ b/man3/getentropy.3
@@ -43,7 +43,7 @@ argument is 256.
 
 A successful call to
 .BR getentropy ()
-always returns the requested number of bytes of entropy.
+always returns zero and provides the requested number of bytes of entropy.
 .SH RETURN VALUE
 On success, this function returns zero,
 On error, \-1 is returned, and
-- 
2.9.3

Re: getentropy clarifications

[Florian Weimer]

* Nikos Mavrogiannopoulos:

> +In earlier versions of glibc this function was avaible under the
> +.BR <sys/random.h>
> +header.

It's still available in <sys/random.h>, and the declaration there can
still be useful if you want to compile without feature test macros.

In addition, I don't think there ever was a released glibc version
where getentropy was declared in <sys/random.h>, but not in <unistd.h>
(with the relevant feature test macros).
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Re: getentropy clarifications

[Michael Kerrisk (man-pages)]

On 03/29/2017 02:46 PM, Nikos Mavrogiannopoulos wrote:
> Hi,
>  The attached patches clarify some parts of the getentropy() functions.

Thanks, Nikos. Applied. I'll clarify things a little
in the light of Florian's comments.

Cheers,

Michael


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Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
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Re: getentropy clarifications

[Michael Kerrisk (man-pages)]

On 03/31/2017 01:31 PM, Florian Weimer wrote:
> * Nikos Mavrogiannopoulos:
> 
>> +In earlier versions of glibc this function was avaible under the
>> +.BR <sys/random.h>
>> +header.
> 
> It's still available in <sys/random.h>, and the declaration there can
> still be useful if you want to compile without feature test macros.
> 
> In addition, I don't think there ever was a released glibc version
> where getentropy was declared in <sys/random.h>, but not in <unistd.h>
> (with the relevant feature test macros).

Thanks, Florian. I tweaked the page to mention the FTM requirements
when using <unistd.h>, and modified the text in NOTES to read:

       getentropy() is also declared in <sys/random.h>.  (No feature test
       macro  need  be defined to obtain the declaration from that header
       file.)

Cheers,

Michael

-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
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