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[libc] implement unistd/getentropy (#122692)

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Implement GNU extension getentropy. This function is used by many
programs to acquire entropy without handling the loop of getrandom.
This commit is contained in:
Schrodinger ZHU Yifan
2025-01-15 18:27:05 +08:00
committed by GitHub
parent 2a044f8a09
commit defd0d966d
16 changed files with 207 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

1
libc/config/linux/aarch64/entrypoints.txt
View File

@@ -322,6 +322,7 @@ set(TARGET_LIBC_ENTRYPOINTS
libc.src.unistd.fsync
libc.src.unistd.ftruncate
libc.src.unistd.getcwd
libc.src.unistd.getentropy
libc.src.unistd.geteuid
libc.src.unistd.getpid
libc.src.unistd.getppid

1
libc/config/linux/x86_64/entrypoints.txt
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@@ -321,6 +321,7 @@ set(TARGET_LIBC_ENTRYPOINTS
libc.src.unistd.fsync
libc.src.unistd.ftruncate
libc.src.unistd.getcwd
libc.src.unistd.getentropy
libc.src.unistd.geteuid
libc.src.unistd.getpid
libc.src.unistd.getppid

3
libc/config/windows/entrypoints.txt
View File

@@ -101,6 +101,9 @@ set(TARGET_LIBC_ENTRYPOINTS
# time.h entrypoints
libc.src.time.time
libc.src.time.clock_getres
# unistd.h entrypoints
libc.src.unistd.getentropy
)
set(TARGET_LIBM_ENTRYPOINTS

1
libc/config/windows/headers.txt
View File

@@ -6,4 +6,5 @@ set(TARGET_PUBLIC_HEADERS
libc.include.errno
libc.include.fenv
libc.include.math
libc.include.unistd
)

7
libc/include/sys/random.yaml
View File

@@ -15,3 +15,10 @@ functions:
- type: void *
- type: size_t
- type: unsigned int
- name: getentropy
standards:
- GNUExtensions
return_type: int
arguments:
- type: void *
- type: size_t

7
libc/include/unistd.yaml
View File

@@ -128,6 +128,13 @@ functions:
arguments:
- type: char *
- type: size_t
- name: getentropy
standards:
- GNUExtensions
return_type: int
arguments:
- type: void *
- type: size_t
- name: geteuid
standards:
- POSIX

2
libc/src/CMakeLists.txt
View File

@@ -15,6 +15,7 @@ add_subdirectory(string)
add_subdirectory(strings)
add_subdirectory(wchar)
add_subdirectory(time)
add_subdirectory(unistd)
if(${LIBC_TARGET_OS} STREQUAL "linux")
add_subdirectory(dirent)
@@ -23,7 +24,6 @@ if(${LIBC_TARGET_OS} STREQUAL "linux")
add_subdirectory(sched)
add_subdirectory(sys)
add_subdirectory(termios)
add_subdirectory(unistd)
endif()
if(NOT LLVM_LIBC_FULL_BUILD)

7
libc/src/unistd/CMakeLists.txt
View File

@@ -350,3 +350,10 @@ add_entrypoint_object(
DEPENDS
libc.src.__support.threads.identifier
)
add_entrypoint_object(
getentropy
ALIAS
DEPENDS
.${LIBC_TARGET_OS}.getentropy
)

19
libc/src/unistd/getentropy.h Normal file
View File

@@ -0,0 +1,19 @@
//===-- Implementation header for getentropy ------------------------------===//
//
// 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 "hdr/types/size_t.h"
#include "src/__support/common.h"
#ifndef LLVM_LIBC_SRC_UNISTD_GETENTROPY_H
#define LLVM_LIBC_SRC_UNISTD_GETENTROPY_H
namespace LIBC_NAMESPACE_DECL {
int getentropy(void *buffer, size_t length);
}
#endif // LLVM_LIBC_SRC_UNISTD_GETENTROPY_H

15
libc/src/unistd/linux/CMakeLists.txt
View File

@@ -570,3 +570,18 @@ add_entrypoint_object(
libc.src.__support.OSUtil.osutil
libc.src.errno.errno
)
add_entrypoint_object(
getentropy
SRCS
getentropy.cpp
HDRS
../getentropy.h
DEPENDS
libc.hdr.types.size_t
libc.hdr.types.ssize_t
libc.hdr.errno_macros
libc.include.sys_syscall
libc.src.__support.OSUtil.osutil
libc.src.errno.errno
)

51
libc/src/unistd/linux/getentropy.cpp Normal file
View File

@@ -0,0 +1,51 @@
//===-- Linux implementation of getentropy --------------------------------===//
//
// 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/unistd/getentropy.h"
#include "hdr/errno_macros.h"
#include "src/__support/OSUtil/syscall.h"
#include "src/__support/common.h"
#include "src/errno/libc_errno.h"
#include <sys/syscall.h> // For syscall numbers.
namespace LIBC_NAMESPACE_DECL {
LLVM_LIBC_FUNCTION(int, getentropy, (void *buffer, size_t length)) {
// check the length limit
if (length > 256) {
libc_errno = EIO;
return -1;
}
char *cursor = static_cast<char *>(buffer);
while (length != 0) {
// 0 flag means urandom and blocking, which meets the assumption of
// getentropy
auto ret = syscall_impl<long>(SYS_getrandom, cursor, length, 0);
// on success, advance the buffer pointer
if (ret >= 0) {
length -= static_cast<size_t>(ret);
cursor += ret;
continue;
}
auto error = -static_cast<int>(ret);
// on EINTR, try again
if (error == EINTR)
continue;
// on ENOSYS, forward errno and exit;
// otherwise, set EIO and exit
libc_errno = (error == ENOSYS) ? ENOSYS : EIO;
return -1;
}
return 0;
}
} // namespace LIBC_NAMESPACE_DECL

11
libc/src/unistd/windows/CMakeLists.txt Normal file
View File

@@ -0,0 +1,11 @@
add_entrypoint_object(
getentropy
SRCS
getentropy.cpp
HDRS
../getentropy.h
DEPENDS
libc.hdr.types.size_t
libc.hdr.errno_macros
libc.src.errno.errno
)

42
libc/src/unistd/windows/getentropy.cpp Normal file
View File

@@ -0,0 +1,42 @@
//===-- Windows implementation of getentropy ------------------------------===//
//
// 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/unistd/getentropy.h"
#include "hdr/errno_macros.h"
#include "src/__support/common.h"
#include "src/errno/libc_errno.h"
#define WIN32_LEAN_AND_MEAN
#include <Windows.h>
#include <bcrypt.h>
#include <ntstatus.h>
#pragma comment(lib, "bcrypt.lib")
namespace LIBC_NAMESPACE_DECL {
LLVM_LIBC_FUNCTION(int, getentropy, (void *buffer, size_t length)) {
__try {
// check the length limit
if (length > 256)
__leave;
NTSTATUS result = ::BCryptGenRandom(nullptr, static_cast<PUCHAR>(buffer),
static_cast<ULONG>(length),
BCRYPT_USE_SYSTEM_PREFERRED_RNG);
if (result == STATUS_SUCCESS)
return 0;
} __except (EXCEPTION_EXECUTE_HANDLER) {
// no need to handle exceptions specially
}
libc_errno = EIO;
return -1;
}
} // namespace LIBC_NAMESPACE_DECL

2
libc/test/src/CMakeLists.txt
View File

@@ -61,6 +61,7 @@ add_subdirectory(string)
add_subdirectory(strings)
add_subdirectory(wchar)
add_subdirectory(time)
add_subdirectory(unistd)
# Depends on utilities in stdlib
add_subdirectory(inttypes)
@@ -70,7 +71,6 @@ if(${LIBC_TARGET_OS} STREQUAL "linux")
add_subdirectory(sched)
add_subdirectory(sys)
add_subdirectory(termios)
add_subdirectory(unistd)
endif()
if(NOT LLVM_LIBC_FULL_BUILD)

12
libc/test/src/unistd/CMakeLists.txt
View File

@@ -488,6 +488,18 @@ add_libc_test(
libc.src.stdio.fflush
)
add_libc_test(
getentropy_test
SUITE
libc_unistd_unittests
SRCS
getentropy_test.cpp
DEPENDS
libc.src.unistd.getentropy
libc.src.errno.errno
libc.test.UnitTest.ErrnoSetterMatcher
)
if(LLVM_LIBC_FULL_BUILD)
add_libc_test(
_exit_test

28
libc/test/src/unistd/getentropy_test.cpp Normal file
View File

@@ -0,0 +1,28 @@
//===-- Unittests for getentropy ------------------------------------------===//
//
// 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 "hdr/errno_macros.h"
#include "src/unistd/getentropy.h"
#include "test/UnitTest/ErrnoSetterMatcher.h"
#include "test/UnitTest/Test.h"
using namespace LIBC_NAMESPACE::testing::ErrnoSetterMatcher;
TEST(LlvmLibcUnistdGetEntropyTest, LengthTooLong) {
char buf[1024];
ASSERT_THAT(LIBC_NAMESPACE::getentropy(buf, 257), Fails(EIO));
}
TEST(LlvmLibcUnistdGetEntropyTest, SmokeTest) {
char buf[256];
ASSERT_THAT(LIBC_NAMESPACE::getentropy(buf, 256), Succeeds());
}
TEST(LlvmLibcUnistdGetEntropyTest, OtherError) {
ASSERT_THAT(LIBC_NAMESPACE::getentropy(nullptr, 1), Fails(EIO));
}