On 9 December 2016 at 13:15, Karel Zak <kzak@xxxxxxxxxx> wrote:
Thank you Karel for good and easy to action review.
> On Sun, Dec 04, 2016 at 09:12:59AM +0000, Sami Kerola wrote:
>> +AC_CHECK_FUNCS([getrandom], [], [
>> + AS_IF([UL_CHECK_SYSCALL([getrandom])
>> + test "$ul_cv_syscall_getrandom" = SYS_getrandom],
>> + [AC_DEFINE([SYSTEM_GETRANDOM], [1],
>> + [Define if getrandom syscall is missing from libc])
>> + ])
>> +])
>
> I have doubts we need SYSTEM_GETRANDOM macro:
Removed, and getrandom() check added to long AC_CHECK_FUNCS list.
> Why not like in another utils (see sched utils for example):
>
> #ifndef HAVE_FALLOCATE
> # include <sys/syscall.h>
> #else
> # include <linux/random.h>
> #endif
>
> /* usable kernel-headers, but old glibc-headers */
> #if defined (__linux__) && !defined(SYS_getrandom) && defined(__NR_getrandom)
> # define SYS_getrandom __NR_getrandom
> #endif
>
> /* libc without function, but we have syscal */
> #if !defined(HAVE_GETRANDOM) && defined(SYS_getrandom)
> static int getrandom(void *buf, size_t buflen, unsigned int flags)
> {
> return (syscall(SYS_getrandom, buf, buflen, flags));
> }
> #define HAVE_GETRANDOM
> #endif
Done very similar way as above, with exception sys/syscall.h is
included only when __linux__ is defined. I am not entirely sure,
but osx compilation for example is less prone to break this way.
CC: Rudi
https://github.com/kerolasa/lelux-utiliteetit/blob/cc01c2dca4f62e36505570d5cb15f868aa44bf54/lib/randutils.c#L30
>> /*
>> * Generate a stream of random nbytes into buf.
>> * Use /dev/urandom if possible, and if not,
>> @@ -72,10 +87,19 @@ int random_get_fd(void)
>> */
>> void random_get_bytes(void *buf, size_t nbytes)
>> {
>> - size_t i, n = nbytes;
>> + size_t i;
>> + unsigned char *cp = (unsigned char *)buf;
>> +
>> +#if defined(SYSTEM_GETRANDOM) || defined(HAVE_GETRANDOM)
>
> #ifdef HAVE_GETRANDOM
>
>> const char *random_tell_source(void)
>> {
>> +#if defined(SYSTEM_GETRANDOM)
>> + return _("syscall(SYS_getrandom) function");
>> +#elif defined(HAVE_GETRANDOM)
>> + return _("libc getrandom() function");
>> +#else
>
> seems like overkill :-)
>
> #ifdef HAVE_GETRANDOM
> return _("getrandom function");
> #else
> ...
Unecessary fine grained detail from printiout is removed.
Updated changes are available in the git repository at:
git://github.com/kerolasa/lelux-utiliteetit.git getrandom
for you to fetch changes up to cc01c2dca4f62e36505570d5cb15f868aa44bf54:
lib/randutils: use getrandom(2) when it is available (2016-12-11
11:46:54 +0000)
--
Sami Kerola
http://www.iki.fi/kerolasa/
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