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Make getentropy() faster

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Justine Tunney 2024-10-10 18:24:23 -07:00
parent 17a85e4790
commit 000d6dbb0f
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GPG key ID: BE714B4575D6E328
2 changed files with 19 additions and 19 deletions
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27
libc/stdio/getentropy.c
View file

@ -17,17 +17,16 @@
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/calls/blockcancel.internal.h"
#include "libc/calls/struct/sigset.internal.h"
#include "libc/calls/syscall_support-sysv.internal.h"
#include "libc/dce.h"
#include "libc/errno.h"
#include "libc/intrin/strace.h"
#include "libc/stdio/rand.h"
#include "libc/sysv/errfuns.h"
int sys_getentropy(void *, size_t) asm("sys_getrandom");
/**
* Returns random seeding bytes, the XNU/OpenBSD way.
* Returns random seeding bytes, the POSIX way.
*
* @return 0 on success, or -1 w/ errno
* @raise EFAULT if the `n` bytes at `p` aren't valid memory
@ -41,17 +40,23 @@ int getentropy(void *p, size_t n) {
} else if ((!p && n)) {
rc = efault();
} else if (IsXnu() || IsOpenbsd()) {
if (sys_getentropy(p, n))
notpossible;
rc = 0;
rc = sys_getentropy(p, n);
} else {
BLOCK_SIGNALS;
ssize_t got;
BLOCK_CANCELATION;
if (__getrandom(p, n, 0) != n)
notpossible;
ALLOW_CANCELATION;
ALLOW_SIGNALS;
rc = 0;
for (size_t i = 0; i < n; i += got) {
got = __getrandom(p + i, n - i, 0);
if (got == -1) {
if (errno == EAGAIN || errno == EINTR) {
got = 0;
} else {
rc = -1;
break;
}
}
}
ALLOW_CANCELATION;
}
STRACE("getentropy(%p, %'zu) → %'ld% m", p, n, rc);
return rc;

11
test/libc/stdio/getentropy_test.c
View file

@ -33,8 +33,6 @@
#include "libc/testlib/testlib.h"
#include "libc/thread/thread.h"
#ifndef __aarch64__
// TODO(jart): Make this test less resource intensive.
// TODO(jart): Why can EINTR happen on Windows?
atomic_int done;
atomic_int ready;
@ -51,11 +49,9 @@ void *TortureWorker(void *arg) {
ASSERT_SYS(0, 0, sigprocmask(SIG_SETMASK, &ss, 0));
ready = true;
while (!done) {
if (!IsWindows())
pthread_kill(parent, SIGUSR1);
pthread_kill(parent, SIGUSR1);
usleep(1);
if (!IsWindows())
pthread_kill(parent, SIGUSR2);
pthread_kill(parent, SIGUSR2);
usleep(1);
}
return 0;
@ -100,8 +96,7 @@ TEST(getentropy, test) {
}
done = true;
ASSERT_EQ(0, pthread_join(child, 0));
if (!IsWindows())
ASSERT_GT(gotsome, 0);
ASSERT_GT(gotsome, 0);
}
#endif /* __aarch64__ */