[libc] Internal getrandom implementation

[sribee8]

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

[llvmbot]

@llvm/pr-subscribers-libc

Author: None (sribee8)

Changes

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

---

Full diff: https://github.com/llvm/llvm-project/pull/144427.diff

5 Files Affected:

• (modified) libc/src/__support/HashTable/randomness.h (+2-2)
• (added) libc/src/__support/OSUtil/getrandom.h (+23)
• (modified) libc/src/__support/OSUtil/linux/CMakeLists.txt (+1)
• (added) libc/src/__support/OSUtil/linux/getrandom.cpp (+30)
• (modified) libc/src/sys/random/linux/getrandom.cpp (+2-7)

diff --git a/libc/src/__support/HashTable/randomness.h b/libc/src/__support/HashTable/randomness.h
index 6b58a4125f785..54fb9e51a5d67 100644
--- a/libc/src/__support/HashTable/randomness.h
+++ b/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;
diff --git a/libc/src/__support/OSUtil/getrandom.h b/libc/src/__support/OSUtil/getrandom.h
new file mode 100644
index 0000000000000..69468d7a5882c
--- /dev/null
+++ b/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
diff --git a/libc/src/__support/OSUtil/linux/CMakeLists.txt b/libc/src/__support/OSUtil/linux/CMakeLists.txt
index 4681d8c2bb73c..a725a7a6b318b 100644
--- a/libc/src/__support/OSUtil/linux/CMakeLists.txt
+++ b/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
diff --git a/libc/src/__support/OSUtil/linux/getrandom.cpp b/libc/src/__support/OSUtil/linux/getrandom.cpp
new file mode 100644
index 0000000000000..225c381e3540f
--- /dev/null
+++ b/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
diff --git a/libc/src/sys/random/linux/getrandom.cpp b/libc/src/sys/random/linux/getrandom.cpp
index 0b8471ed8b374..c58c4c1857037 100644
--- a/libc/src/sys/random/linux/getrandom.cpp
+++ b/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

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