commit e48ff95649f55732b22b8d9b616718f5fb006821
author Alexander Markov <alexmarkov@google.com> Thu Oct 02 07:37:07 2025 -0700
committer Commit Queue <dart-scoped@luci-project-accounts.iam.gserviceaccount.com> Thu Oct 02 07:37:07 2025 -0700
tree 66973c7102733c1bdbbcc191a5bae199d9d93bd7
parent 80087cbbb0a9b72872e8c524ac392aa69e5c4917

Revert "[standalone] Use fewer syscalls to get entropy on Linux and Mac."

This reverts commit ea162825d3f0a366cb885e16fe5623051200deef.

Revert "[standalone] Fix Linux Crypto::GetRandomBytes on MSAN."

This reverts commit c3e5b7c268cbda93e6a171cb5217a7dbd49176c6.

Reason for revert: build failures on "Mac mac_ios_engine" Flutter bot:
```
../../../flutter/third_party/dart/runtime/bin/crypto_macos.cc:10:10: fatal error: 'sys/random.h' file not found
   10 | #include <sys/random.h>
      |          ^~~~~~~~~~~~~~
1 error generated.
```

https://ci.chromium.org/ui/p/flutter/builders/try/Mac%20mac_ios_engine/50544/overview

TEST=ci

Change-Id: Ib0656cbf1268fc48f42097b09ca60c5bf2c1e2bd
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/452843
Reviewed-by: Slava Egorov <vegorov@google.com>
Commit-Queue: Alexander Markov <alexmarkov@google.com>

runtime/bin/crypto_linux.cc

diff --git a/runtime/bin/crypto_linux.cc b/runtime/bin/crypto_linux.cc
index 16a0c86..cda1684 100644
--- a/runtime/bin/crypto_linux.cc
+++ b/runtime/bin/crypto_linux.cc
@@ -5,19 +5,17 @@
 #include "platform/globals.h"
 #if defined(DART_HOST_OS_LINUX) || defined(DART_HOST_OS_ANDROID)
 
-#include <errno.h>
-#include <fcntl.h>
-#include <sys/syscall.h>
+#include <errno.h>  // NOLINT
+#include <fcntl.h>  // NOLINT
 
 #include "bin/crypto.h"
 #include "bin/fdutils.h"
-#include "platform/memory_sanitizer.h"
 #include "platform/signal_blocker.h"
 
 namespace dart {
 namespace bin {
 
-static bool GetRandomFromDev(intptr_t count, uint8_t* buffer) {
+bool Crypto::GetRandomBytes(intptr_t count, uint8_t* buffer) {
   ThreadSignalBlocker signal_blocker(SIGPROF);
   intptr_t fd = TEMP_FAILURE_RETRY_NO_SIGNAL_BLOCKER(
       open("/dev/urandom", O_RDONLY | O_CLOEXEC));
@@ -40,28 +38,6 @@
   return true;
 }
 
-bool Crypto::GetRandomBytes(intptr_t count, uint8_t* buffer) {
-  intptr_t bytes_read = 0;
-  do {
-    ssize_t res;
-    do {
-      res = syscall(__NR_getrandom, buffer + bytes_read, count - bytes_read,
-                    /*flags=*/0);
-    } while (res == -1 && errno == EINTR);
-    if (res == -1) {
-      if (errno == ENOSYS) {
-        return GetRandomFromDev(count, buffer);
-      }
-      return false;
-    }
-    bytes_read += res;
-  } while (bytes_read < count);
-  // Not using the libc wrapper `getrandom`, which MSAN is missing an
-  // interceptor for anyway.
-  MSAN_UNPOISON(buffer, count);
-  return true;
-}
-
 }  // namespace bin
 }  // namespace dart
 

runtime/bin/crypto_macos.cc

diff --git a/runtime/bin/crypto_macos.cc b/runtime/bin/crypto_macos.cc
index c63f03a..24dfe9b 100644
--- a/runtime/bin/crypto_macos.cc
+++ b/runtime/bin/crypto_macos.cc
@@ -5,9 +5,8 @@
 #include "platform/globals.h"
 #if defined(DART_HOST_OS_MACOS)
 
-#include <errno.h>
-#include <fcntl.h>
-#include <sys/random.h>
+#include <errno.h>  // NOLINT
+#include <fcntl.h>  // NOLINT
 
 #include "bin/crypto.h"
 #include "bin/fdutils.h"
@@ -17,18 +16,23 @@
 namespace bin {
 
 bool Crypto::GetRandomBytes(intptr_t count, uint8_t* buffer) {
+  intptr_t fd = TEMP_FAILURE_RETRY(open("/dev/urandom", O_RDONLY | O_CLOEXEC));
+  if (fd < 0) {
+    return false;
+  }
   intptr_t bytes_read = 0;
   do {
-    intptr_t chunk_size = count - bytes_read;
-    if (chunk_size > 256) {
-      chunk_size = 256;
-    }
-    int res = getentropy(buffer + bytes_read, chunk_size);
+    int res =
+        TEMP_FAILURE_RETRY(read(fd, buffer + bytes_read, count - bytes_read));
     if (res < 0) {
+      int err = errno;
+      close(fd);
+      errno = err;
       return false;
     }
-    bytes_read += chunk_size;
+    bytes_read += res;
   } while (bytes_read < count);
+  close(fd);
   return true;
 }