mirror of
https://github.com/urbit/shrub.git
synced 2024-11-24 13:06:09 +03:00
63 lines
1.5 KiB
C
63 lines
1.5 KiB
C
// Use `getentropy` from unistd.h //////////////////////////////////////////////
|
|
|
|
#if defined(ENT_GETENTROPY_UNISTD)
|
|
#include <stddef.h>
|
|
#include <unistd.h>
|
|
int ent_getentropy(void* buf, size_t len) {
|
|
return getentropy(buf, len);
|
|
}
|
|
|
|
|
|
// Use `getentropy` from sys/random.h //////////////////////////////////////////
|
|
|
|
#elif defined(ENT_GETENTROPY_SYSRANDOM)
|
|
#include <stddef.h>
|
|
#include <sys/random.h>
|
|
int ent_getentropy(void* buf, size_t len) {
|
|
return getentropy(buf, len);
|
|
}
|
|
|
|
|
|
// Use the `getrandom` syscall /////////////////////////////////////////////////
|
|
|
|
#elif defined(ENT_GETRANDOM_SYSCALL)
|
|
#include <stddef.h>
|
|
#include <errno.h>
|
|
#define _GNU_SOURCE
|
|
#include <unistd.h>
|
|
#include <sys/syscall.h>
|
|
|
|
#define ENTFAIL { errno=EIO; return -1; }
|
|
|
|
int ent_getentropy(void* buf, size_t len) {
|
|
if (len > 256) ENTFAIL
|
|
int r = syscall(SYS_getrandom, buf, len, 0);
|
|
if (r < 0) return r;
|
|
if (r != len) ENTFAIL
|
|
return 0;
|
|
}
|
|
|
|
|
|
// Use `/dev/urandom` //////////////////////////////////////////////////////////
|
|
|
|
#elif defined(ENT_DEV_URANDOM)
|
|
#include <stddef.h>
|
|
#include <errno.h>
|
|
#include <stdio.h>
|
|
|
|
#define ENTFAIL { errno=EIO; return -1; }
|
|
|
|
int ent_getentropy(void* buf, size_t len) {
|
|
if (len > 256) ENTFAIL;
|
|
FILE *f = fopen("/dev/urandom", "re");
|
|
if (!f) return -1;
|
|
int r = fread(buf, 1, len, f);
|
|
(void) fclose(f);
|
|
if (r != len) ENTFAIL
|
|
return 0;
|
|
}
|
|
|
|
#else
|
|
#error "One of these must be set: ENT_DEV_URANDOM, ENT_GETENTROPY_UNISTD, ENT_GETENTROPY_SYSRANDOM, ENT_GETRANDOM_SYSCALL"
|
|
#endif
|