util-linux/include/randutils.h

/*
 * SPDX-License-Identifier: BSD-3-Clause
 */
#ifndef UTIL_LINUX_RANDUTILS
#define UTIL_LINUX_RANDUTILS

#ifdef HAVE_SRANDOM
#define srand(x)	srandom(x)
#define rand()		random()
#endif

/* rand() based */
extern int rand_get_number(int low_n, int high_n);

/* /dev/urandom based with fallback to rand() */
extern int random_get_fd(void);
extern int ul_random_get_bytes(void *buf, size_t nbytes);
extern const char *random_tell_source(void);

#endif
include: add missing license lines The header files are usually based on code from lib/. This commit copies relevant license headers from lib/ to include/ to keep things consistent. The very generic things (e.g. MBR definitions) are always public domain. Fixes: https://github.com/util-linux/util-linux/issues/2010 Signed-off-by: Karel Zak <kzak@redhat.com> 2023-01-12 15:33:09 +01:00			`/*`
			`* SPDX-License-Identifier: BSD-3-Clause`
			`*/`
lib: random utilities Add a random number(s) generator specific file. The intial functions are based on what libuuid provide. I did some modifications like avoid WIN32 checks - this is util-LINUX. [kzak@redhat.com: - move jrand_seed to lib/randutils.c - use TLS for jrand_seed (like original code from libuuid) - use size_t for buffer sizes - add close() to random_get_bytes] Signed-off-by: Davidlohr Bueso <dave@gnu.org> Signed-off-by: Karel Zak <kzak@redhat.com> 2012-04-05 23:52:04 +02:00			`#ifndef UTIL_LINUX_RANDUTILS`
			`#define UTIL_LINUX_RANDUTILS`

			`#ifdef HAVE_SRANDOM`
			`#define srand(x) srandom(x)`
			`#define rand() random()`
			`#endif`

lib/randutils: add xsrand() and rand_get_number() Signed-off-by: Karel Zak <kzak@redhat.com> 2016-09-06 10:19:52 +02:00			`/* rand() based */`
			`extern int rand_get_number(int low_n, int high_n);`

			`/* /dev/urandom based with fallback to rand() */`
lib: random utilities Add a random number(s) generator specific file. The intial functions are based on what libuuid provide. I did some modifications like avoid WIN32 checks - this is util-LINUX. [kzak@redhat.com: - move jrand_seed to lib/randutils.c - use TLS for jrand_seed (like original code from libuuid) - use size_t for buffer sizes - add close() to random_get_bytes] Signed-off-by: Davidlohr Bueso <dave@gnu.org> Signed-off-by: Karel Zak <kzak@redhat.com> 2012-04-05 23:52:04 +02:00			`extern int random_get_fd(void);`
libuuid: check quality of random bytes If a libuuid application is unable to access /dev/random or /dev/urandom then uuid generation by uuid_generate falls back to uuid_generate_time. This could happen in chroot or container environments. The function ul_random_get_bytes from lib/randutils.c uses getrandom if it is available. This could either mean that the libuuid application skips good random bytes because the character special files do not exist or the application trusts in good random bytes just because these files are accessible but not necessarily usable, e.g. limit of open file descriptors reached, lack of data, kernel without getrandom, etc. This commit modifies ul_random_get_bytes to return an integer which indicates if random bytes are of good quality (0) or not (1). Callers can decide based on this information if they want to discard the random bytes. Only libuuid checks the return value. I decided to return 1 instead of -1 because -1 feels more like an error, but weak random bytes can be totally fine. Another issue is that getrandom sets errno to specific values only in case of an error, i.e. with return value -1. Set errno to 0 explicitly if getrandom succeeds so we do not enter the fallback routine for ENOSYS by mistake. I do not think that this is likely to happen, but it really depends on possible wrapper function supplied by a C library. Signed-off-by: Samanta Navarro <ferivoz@riseup.net> 2020-11-08 11:47:18 +00:00			`extern int ul_random_get_bytes(void *buf, size_t nbytes);`
mcookie: use lib/randutils The mcookie should reuse existing code, and there is definitely no need to prefer /dev/random for this utility. See reference for explanation about later statement. References: http://www.2uo.de/myths-about-urandom/ Signed-off-by: Sami Kerola <kerolasa@iki.fi> 2014-03-08 15:43:26 -06:00			`extern const char *random_tell_source(void);`
lib: random utilities Add a random number(s) generator specific file. The intial functions are based on what libuuid provide. I did some modifications like avoid WIN32 checks - this is util-LINUX. [kzak@redhat.com: - move jrand_seed to lib/randutils.c - use TLS for jrand_seed (like original code from libuuid) - use size_t for buffer sizes - add close() to random_get_bytes] Signed-off-by: Davidlohr Bueso <dave@gnu.org> Signed-off-by: Karel Zak <kzak@redhat.com> 2012-04-05 23:52:04 +02:00
			`#endif`