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[libc] implement sys/uio/writev (llvm#122233)
implement sys/uio/writev according to POSIX standard. This vectorized IO API is needed by many logging libraries to achieve atomic logging multiple strings.
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15 files changed

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‎libc/config/linux/aarch64/entrypoints.txt

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@@ -350,6 +350,9 @@ set(TARGET_LIBC_ENTRYPOINTS
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# wchar.h entrypoints
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libc.src.wchar.wctob
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# sys/uio.h entrypoints
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libc.src.sys.uio.writev
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)
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if(LLVM_LIBC_INCLUDE_SCUDO)

‎libc/config/linux/x86_64/entrypoints.txt

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# wchar.h entrypoints
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libc.src.wchar.wctob
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libc.src.wchar.btowc
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# sys/uio.h entrypoints
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libc.src.sys.uio.writev
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)
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if(LLVM_LIBC_INCLUDE_SCUDO)

‎libc/hdr/types/CMakeLists.txt

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@@ -333,3 +333,12 @@ add_proxy_header_library(
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FULL_BUILD_DEPENDS
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libc.include.llvm-libc-types.uid_t
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)
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add_proxy_header_library(
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struct_iovec
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HDRS
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struct_iovec.h
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FULL_BUILD_DEPENDS
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libc.include.llvm-libc-types.struct_iovec
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libc.include.sys_uio
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)

‎libc/hdr/types/struct_iovec.h

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//===-- Proxy for struct iovec -------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_LIBC_HDR_TYPES_STRUCT_IOVEC_H
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#define LLVM_LIBC_HDR_TYPES_STRUCT_IOVEC_H
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#ifdef LIBC_FULL_BUILD
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#include "include/llvm-libc-types/struct_iovec.h"
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#else
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#include <sys/uio.h>
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#endif // LIBC_FULL_BUILD
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#endif // LLVM_LIBC_HDR_TYPES_STRUCT_IOVEC_H

‎libc/include/CMakeLists.txt

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@@ -632,6 +632,16 @@ add_header_macro(
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.llvm-libc-types.struct_utsname
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)
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add_header_macro(
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sys_uio
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../libc/include/sys/uio.yaml
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sys/uio.h
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DEPENDS
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.llvm_libc_common_h
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.llvm-libc-types.struct_iovec
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.llvm-libc-types.ssize_t
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)
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add_header_macro(
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sys_wait
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../libc/include/sys/wait.yaml

‎libc/include/sys/uio.h.def

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//===-- POSIX header uio.h ------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_LIBC_SYS_UIO_H
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#define LLVM_LIBC_SYS_UIO_H
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#include "__llvm-libc-common.h"
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%%public_api()
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#endif // LLVM_LIBC_SYS_UIO_H

‎libc/include/sys/uio.yaml

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header: sys/uio.h
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header_template: uio.h.def
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macros: []
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types:
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- type_name: struct_iovec
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- type_name: ssize_t
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enums: []
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objects: []
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functions:
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- name: writev
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standards:
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- POSIX
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return_type: ssize_t
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arguments:
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- type: int
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- type: const struct iovec *
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- type: int

‎libc/src/sys/CMakeLists.txt

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@@ -11,3 +11,4 @@ add_subdirectory(statvfs)
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add_subdirectory(utsname)
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add_subdirectory(wait)
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add_subdirectory(prctl)
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add_subdirectory(uio)

‎libc/src/sys/uio/CMakeLists.txt

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if(EXISTS ${CMAKE_CURRENT_SOURCE_DIR}/${LIBC_TARGET_OS})
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add_subdirectory(${CMAKE_CURRENT_SOURCE_DIR}/${LIBC_TARGET_OS})
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endif()
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add_entrypoint_object(
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writev
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ALIAS
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DEPENDS
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.${LIBC_TARGET_OS}.writev
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)

‎libc/src/sys/uio/linux/CMakeLists.txt

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add_entrypoint_object(
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writev
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SRCS
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writev.cpp
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HDRS
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../writev.h
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DEPENDS
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libc.include.sys_syscall
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libc.src.__support.OSUtil.osutil
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libc.src.__support.common
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libc.src.errno.errno
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libc.hdr.types.ssize_t
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libc.hdr.types.struct_iovec
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)

‎libc/src/sys/uio/linux/writev.cpp

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//===-- Implementation file for writev ------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "src/sys/uio/writev.h"
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#include "src/__support/OSUtil/syscall.h"
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#include "src/__support/common.h"
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#include "src/errno/libc_errno.h"
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#include <sys/syscall.h>
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namespace LIBC_NAMESPACE_DECL {
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LLVM_LIBC_FUNCTION(ssize_t, writev, (int fd, const iovec *iov, int iovcnt)) {
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long ret = LIBC_NAMESPACE::syscall_impl<long>(SYS_writev, fd, iov, iovcnt);
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// On failure, return -1 and set errno.
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if (ret < 0) {
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libc_errno = static_cast<int>(-ret);
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return -1;
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}
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// On success, return number of bytes written.
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return static_cast<ssize_t>(ret);
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}
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} // namespace LIBC_NAMESPACE_DECL

‎libc/src/sys/uio/writev.h

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//===-- Implementation header for writev ----------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_LIBC_SRC_SYS_UIO_WRITEV_H
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#define LLVM_LIBC_SRC_SYS_UIO_WRITEV_H
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#include "hdr/types/ssize_t.h"
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#include "hdr/types/struct_iovec.h"
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#include "src/__support/macros/config.h"
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namespace LIBC_NAMESPACE_DECL {
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ssize_t writev(int fd, const iovec *iov, int iovcnt);
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} // namespace LIBC_NAMESPACE_DECL
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#endif // LLVM_LIBC_SRC_SYS_UIO_WRITEV_H

‎libc/test/src/sys/CMakeLists.txt

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add_subdirectory(prctl)
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add_subdirectory(auxv)
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add_subdirectory(epoll)
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add_subdirectory(uio)

‎libc/test/src/sys/uio/CMakeLists.txt

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add_custom_target(libc_sys_uio_unittests)
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add_libc_unittest(
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writev_test
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SUITE
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libc_sys_uio_unittests
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SRCS
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writev_test.cpp
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DEPENDS
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libc.src.errno.errno
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libc.src.__support.common
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libc.src.sys.uio.writev
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libc.src.unistd.close
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libc.src.fcntl.open
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libc.test.UnitTest.ErrnoSetterMatcher
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)

‎libc/test/src/sys/uio/writev_test.cpp

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//===-- Unittests for writev ----------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "src/fcntl/open.h"
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#include "src/sys/uio/writev.h"
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#include "src/unistd/close.h"
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#include "test/UnitTest/ErrnoSetterMatcher.h"
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#include "test/UnitTest/Test.h"
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using namespace LIBC_NAMESPACE::testing::ErrnoSetterMatcher;
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TEST(LlvmLibcSysUioWritevTest, SmokeTest) {
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int fd = LIBC_NAMESPACE::open("/dev/null", O_WRONLY);
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ASSERT_THAT(fd, returns(GT(0)).with_errno(EQ(0)));
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const char *data = "Hello, World!\n";
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struct iovec iov[2];
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iov[0].iov_base = const_cast<char *>(data);
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iov[0].iov_len = 7;
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iov[1].iov_base = const_cast<char *>(data + 7);
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iov[1].iov_len = 8;
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ASSERT_THAT(LIBC_NAMESPACE::writev(fd, iov, 2),
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returns(EQ(15)).with_errno(EQ(0)));
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ASSERT_THAT(LIBC_NAMESPACE::close(fd), Succeeds());
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}

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