rand_util_posix.cc | Explore in Territory

// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "partition_alloc/partition_alloc_base/rand_util.h"

#include <fcntl.h>
#include <sys/syscall.h>
#include <unistd.h>

#include <cerrno>
#include <cstddef>
#include <cstdint>
#include <sstream>

#include "partition_alloc/build_config.h"
#include "partition_alloc/partition_alloc_base/check.h"
#include "partition_alloc/partition_alloc_base/compiler_specific.h"
#include "partition_alloc/partition_alloc_base/files/file_util.h"
#include "partition_alloc/partition_alloc_base/no_destructor.h"
#include "partition_alloc/partition_alloc_base/posix/eintr_wrapper.h"

#if PA_BUILDFLAG(IS_MAC)
// TODO(crbug.com/40641285): Waiting for this header to appear in the iOS SDK.
// (See below.)
#include <sys/random.h>
#endif

namespace {

#if PA_BUILDFLAG(IS_AIX)
// AIX has no 64-bit support for O_CLOEXEC.
static constexpr int kOpenFlags = O_RDONLY;
#else
static constexpr int kOpenFlags = …;
#endif

// On Android the 'open' function has two versions:
// int open(const char *pathname, int flags);
// int open(const char *pathname, int flags, mode_t mode);
//
// This doesn't play well with WrapEINTR template. This alias helps the compiler
// to make a decision.
int OpenFile(const char* pathname, int flags) { … }

// We keep the file descriptor for /dev/urandom around so we don't need to
// reopen it (which is expensive), and since we may not even be able to reopen
// it if we are later put in a sandbox. This class wraps the file descriptor so
// we can use a static-local variable to handle opening it on the first access.
class URandomFd { … };

int GetUrandomFD() { … }

}  // namespace

namespace partition_alloc::internal::base {

// NOTE: In an ideal future, all implementations of this function will just
// wrap BoringSSL's `RAND_bytes`. TODO(crbug.com/40641285): Figure out the
// build/test/performance issues with dcheng's CL
// (https://chromium-review.googlesource.com/c/chromium/src/+/1545096) and land
// it or some form of it.
void RandBytes(void* output, size_t output_length) { … }

}  // namespace partition_alloc::internal::base
chromium/base/allocator/partition_allocator/src/partition_alloc/partition_alloc_base/rand_util_posix.cc
