[libc] Internal getrandom implementation

Implemented an internal getrandom to avoid calls to the public one in table.h

Author: Sriya Pratipati

libc/src/__support/HashTable/randomness.h

@@ -14,8 +14,8 @@
 #include "src/__support/macros/attributes.h"
 #include "src/__support/macros/config.h"
 #if defined(LIBC_HASHTABLE_USE_GETRANDOM)
+#include "src/__support/OSUtil/getrandom.h"
 #include "src/__support/libc_errno.h"
-#include "src/sys/random/getrandom.h"
 #endif
 
 namespace LIBC_NAMESPACE_DECL {
@@ -39,7 +39,7 @@ LIBC_INLINE uint64_t next_random_seed() {
     size_t count = sizeof(entropy);
     uint8_t *buffer = reinterpret_cast<uint8_t *>(entropy);
     while (count > 0) {
-      ssize_t len = getrandom(buffer, count, 0);
+      ssize_t len = internal::getrandom(buffer, count, 0);
       if (len == -1) {
         if (libc_errno == ENOSYS)
           break;

libc/src/__support/OSUtil/getrandom.h

@@ -0,0 +1,23 @@
+//===------------ Implementation of getrandom function ----------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC___SUPPORT_OSUTIL_GETRANDOM_H
+#define LLVM_LIBC_SRC___SUPPORT_OSUTIL_GETRANDOM_H
+
+#include "src/__support/macros/config.h"
+#include <sys/random.h>
+
+namespace LIBC_NAMESPACE_DECL {
+namespace internal {
+
+ssize_t getrandom(void *buf, size_t buflen, unsigned int flags);
+
+} // namespace internal
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC___SUPPORT_OSUTIL_GETRANDOM_H

libc/src/__support/OSUtil/linux/CMakeLists.txt

@@ -9,6 +9,7 @@ add_object_library(
   SRCS
     exit.cpp
     fcntl.cpp
+    getrandom.cpp
   HDRS
     io.h
     syscall.h

libc/src/__support/OSUtil/linux/getrandom.cpp

@@ -0,0 +1,30 @@
+//===------------ Linux implementation of getrandom -------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/__support/OSUtil/getrandom.h"
+#include "src/__support/OSUtil/linux/syscall.h" // syscall_impl
+#include "src/__support/common.h"
+#include "src/__support/libc_errno.h"
+#include "src/__support/macros/config.h"
+#include <sys/syscall.h> // For syscall numbers.
+
+namespace LIBC_NAMESPACE_DECL {
+namespace internal {
+
+ssize_t getrandom(void *buf, size_t buflen, unsigned int flags) {
+  ssize_t ret =
+      LIBC_NAMESPACE::syscall_impl<ssize_t>(SYS_getrandom, buf, buflen, flags);
+  if (ret < 0) {
+    libc_errno = static_cast<int>(-ret);
+    return -1;
+  }
+  return ret;
+}
+
+} // namespace internal
+} // namespace LIBC_NAMESPACE_DECL

libc/src/sys/random/linux/getrandom.cpp

@@ -10,6 +10,7 @@
 
 #include "src/__support/OSUtil/syscall.h" // For internal syscall function.
 #include "src/__support/common.h"
+#include "src/__support/OSUtil/getrandom.h"
 
 #include "src/__support/libc_errno.h"
 #include "src/__support/macros/config.h"
@@ -19,13 +20,7 @@ namespace LIBC_NAMESPACE_DECL {
 
 LLVM_LIBC_FUNCTION(ssize_t, getrandom,
                    (void *buf, size_t buflen, unsigned int flags)) {
-  ssize_t ret =
-      LIBC_NAMESPACE::syscall_impl<ssize_t>(SYS_getrandom, buf, buflen, flags);
-  if (ret < 0) {
-    libc_errno = static_cast<int>(-ret);
-    return -1;
-  }
-  return ret;
+  return internal::getrandom(buf, buflen, flags);
 }
 
 } // namespace LIBC_NAMESPACE_DECL