Inline __libc_arc4random_has_unlimited_entropy.
The name is misleading anyway.
Bug: http://b/67015565
Test: boots
Change-Id: Ic765e376d84e1ca474d3324eab32e14ea1ae9712
diff --git a/libc/bionic/bionic_arc4random.cpp b/libc/bionic/bionic_arc4random.cpp
index 391eb0c..fa2617f 100644
--- a/libc/bionic/bionic_arc4random.cpp
+++ b/libc/bionic/bionic_arc4random.cpp
@@ -28,8 +28,6 @@
#include "private/bionic_arc4random.h"
-#include <errno.h>
-#include <stdatomic.h>
#include <stdlib.h>
#include <string.h>
#include <sys/auxv.h>
@@ -39,15 +37,12 @@
#include "private/KernelArgumentBlock.h"
-bool __libc_arc4random_has_unlimited_entropy() {
- static bool have_urandom = access("/dev/urandom", R_OK) == 0;
- return have_urandom;
-}
-
void __libc_safe_arc4random_buf(void* buf, size_t n, KernelArgumentBlock& args) {
- // Only call arc4random_buf once we `have_urandom', since in getentropy_getrandom we may fallback
- // to use /dev/urandom, if the kernel entropy pool hasn't been initialized or not enough bytes
- if (__libc_arc4random_has_unlimited_entropy()) {
+ // Only call arc4random_buf once we have `/dev/urandom` because getentropy(3)
+ // will fall back to using `/dev/urandom` if getrandom(2) fails, and abort if
+ // if can't use `/dev/urandom`.
+ static bool have_urandom = access("/dev/urandom", R_OK) == 0;
+ if (have_urandom) {
arc4random_buf(buf, n);
return;
}
diff --git a/libc/private/bionic_arc4random.h b/libc/private/bionic_arc4random.h
index b51f818..0e9376e 100644
--- a/libc/private/bionic_arc4random.h
+++ b/libc/private/bionic_arc4random.h
@@ -33,18 +33,11 @@
#include "private/KernelArgumentBlock.h"
-/*
- * arc4random aborts if it's unable to fetch entropy, which is always the case
- * for init on devices without getrandom(2), since /dev/random hasn't been
- * created yet. Provide a wrapper function that falls back to AT_RANDOM if
- * we don't have getrandom and /dev/urandom is missing.
- */
+// arc4random(3) aborts if it's unable to fetch entropy, which is always
+// the case for init on devices. GCE kernels have a workaround to ensure
+// sufficient entropy during early boot, but no device kernels do. This
+// wrapper falls back to AT_RANDOM if the kernel doesn't have enough
+// entropy for getrandom(2) or /dev/urandom.
void __libc_safe_arc4random_buf(void* buf, size_t n, KernelArgumentBlock& args);
-/*
- * Return true if libc has an unlimited entropy source (something other than
- * AT_RANDOM), and arc4random* calls will always succeed.
- */
-bool __libc_arc4random_has_unlimited_entropy();
-
#endif