[libc] Add implementation of POSIX "uname" function.

libc/config/linux/aarch64/entrypoints.txt

set(TARGET_LIBC_ENTRYPOINTS
 
     # sys/stat.h entrypoints
     libc.src.sys.stat.chmod
     libc.src.sys.stat.fchmod
     libc.src.sys.stat.fchmodat
     libc.src.sys.stat.mkdir
     libc.src.sys.stat.mkdirat
 
+    # sys/utsname.h entrypoints
+    libc.src.sys.utsname.uname
+
     # unistd.h entrypoints
     libc.src.unistd.access
     libc.src.unistd.chdir
     libc.src.unistd.close
     libc.src.unistd.dup
     libc.src.unistd.dup2
     libc.src.unistd.dup3
     libc.src.unistd.fchdir

libc/config/linux/api.td

 
 def SysStatAPI : PublicAPI<"sys/stat.h"> {
   let Types = ["mode_t"];
 }
 
 def SysSendfileAPI : PublicAPI<"sys/sendfile.h"> {
   let Types = ["off_t", "size_t", "ssize_t"];
 }
+
+def SysUtsNameAPI : PublicAPI<"sys/utsname.h"> {
+  let Types = ["struct utsname"];
+}

libc/config/linux/x86_64/entrypoints.txt

set(TARGET_LIBC_ENTRYPOINTS
 
     # sys/stat.h entrypoints
     libc.src.sys.stat.chmod
     libc.src.sys.stat.fchmod
     libc.src.sys.stat.fchmodat
     libc.src.sys.stat.mkdir
     libc.src.sys.stat.mkdirat
 
+    # sys/utsname.h entrypoints
+    libc.src.sys.utsname.uname
+
     # unistd.h entrypoints
     libc.src.unistd.access
     libc.src.unistd.chdir
     libc.src.unistd.close
     libc.src.unistd.dup
     libc.src.unistd.dup2
     libc.src.unistd.dup3
     libc.src.unistd.fchdir

libc/include/CMakeLists.txt

add_gen_header(
   DEF_FILE sys/syscall.h.def
   GEN_HDR sys/syscall.h
   PARAMS
     syscall_numbers=../config/${LIBC_TARGET_OS}/syscall_numbers.h.inc
   DATA_FILES
     ../config/${LIBC_TARGET_OS}/syscall_numbers.h.inc
 )
 
+add_gen_header(
+  sys_utsname
+  DEF_FILE sys/utsname.h.def
+  GEN_HDR sys/utsname.h
+  DEPENDS
+    .llvm_libc_common_h
+    .llvm-libc-types.struct_utsname
+)
+
 if(NOT LLVM_LIBC_FULL_BUILD)
   # We don't install headers in non-fullbuild mode.
   return()
 endif()
 
 function(get_all_install_header_targets out_var)
   set(all_deps ${ARGN})
   foreach(target IN LISTS ARGN)

libc/include/llvm-libc-types/CMakeLists.txt

 add_header(pthread_key_t HDR pthread_key_t.h)
 add_header(pthread_mutex_t HDR pthread_mutex_t.h DEPENDS .__futex_word .__mutex_type)
 add_header(pthread_t HDR pthread_t.h DEPENDS .__thread_type)
 add_header(pthread_mutexattr_t HDR pthread_mutexattr_t.h)
 add_header(ssize_t HDR ssize_t.h)
 add_header(struct_dirent HDR struct_dirent.h DEPENDS .ino_t .off_t)
 add_header(struct_sigaction HDR struct_sigaction.h)
 add_header(struct_tm HDR struct_tm.h)
+add_header(struct_utsname HDR struct_utsname.h)
 add_header(thrd_start_t HDR thrd_start_t.h)
 add_header(thrd_t HDR thrd_t.h DEPENDS .__thread_type)
 add_header(time_t HDR time_t.h)
 add_header(tss_t HDR tss_t.h)
 add_header(tss_dtor_t HDR tss_dtor_t.h)
 add_header(__atexithandler_t HDR __atexithandler_t.h)

libc/include/llvm-libc-types/struct_utsname.h

+//===-- Definition of struct utsname --------------------------------------===//
+//
+// 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_TYPES_STRUCT_UTSNAME_H__
+#define __LLVM_LIBC_TYPES_STRUCT_UTSNAME_H__
+
+#ifdef __unix__
+#define __UTS_NAME_LENGTH 65
+#else
+// Arbitray default. Should be specialized for each platform.
+#define __UTS_NAME_LENGTH 1024
+#endif
+
+struct utsname {
+  char sysname[__UTS_NAME_LENGTH];
+  char nodename[__UTS_NAME_LENGTH];
+  char release[__UTS_NAME_LENGTH];
+  char version[__UTS_NAME_LENGTH];
+  char machine[__UTS_NAME_LENGTH];
+#ifdef __unix__
+  char domainname[__UTS_NAME_LENGTH];
+#endif
+};
+
+#undef __UTS_NAME_LENGTH
+
+#endif // __LLVM_LIBC_TYPES_STRUCT_UTSNAME_H__

libc/include/sys/utsname.h.def

+//===-- Linux sys/utsname.h -----------------------------------------------===//
+//
+// 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_SYS_UTSNAME_H
+#define LLVM_LIBC_SYS_UTSNAME_H
+
+#include <__llvm-libc-common.h>
+
+%%public_api()
+
+#endif // LLVM_LIBC_SYS_UTSNAME_H

libc/spec/posix.td

[
         FunctionSpec<
             "mkdirat",
             RetValSpec<IntType>,
             [ArgSpec<IntType>, ArgSpec<ConstCharPtr>, ArgSpec<ModeTType>]
         >,
     ]
   >;
 
+  NamedType StructUtsName = NamedType<"struct utsname">;
+  PtrType StructUtsNamePtr = PtrType<StructUtsName>;
+  HeaderSpec SysUtsName = HeaderSpec<
+    "sys/utsname.h",
+    [], // Macros
+    [StructUtsName], // Types
+    [], // Enumerations
+    [
+        FunctionSpec<
+            "uname",
+            RetValSpec<IntType>,
+            [ArgSpec<StructUtsNamePtr>]
+        >,
+    ]
+  >;
+
   HeaderSpec PThread = HeaderSpec<
     "pthread.h",
     [], // Macros
     [
         PThreadAttrTType,
         PThreadKeyT,
         PThreadMutexAttrTType,
         PThreadMutexTType,
let Headers = [
     Errno,
     FCntl,
     PThread,
     Signal,
     StdIO,
     StdLib,
     SysMMan,
     SysStat,
+    SysUtsName,
     UniStd,
     String
   ];
 }

libc/src/sys/CMakeLists.txt

 add_subdirectory(mman)
 add_subdirectory(sendfile)
 add_subdirectory(stat)
+add_subdirectory(utsname)

libc/src/sys/utsname/CMakeLists.txt

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

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

+add_entrypoint_object(
+  uname
+  SRCS
+    uname.cpp
+  HDRS
+    ../uname.h
+  DEPENDS
+    libc.include.sys_utsname
+    libc.include.sys_syscall
+    libc.src.__support.OSUtil.osutil
+    libc.src.errno.errno
+)
+

libc/src/sys/utsname/linux/uname.cpp

+//===-- Linux implementation of uname -------------------------------------===//
+//
+// 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/sys/utsname/uname.h"
+
+#include "src/__support/OSUtil/syscall.h" // For internal syscall function.
+#include "src/__support/common.h"
+
+#include <errno.h>
+#include <sys/syscall.h> // For syscall numbers.
+#include <sys/utsname.h>
+
+namespace __llvm_libc {
+
+LLVM_LIBC_FUNCTION(int, uname, (struct utsname * name)) {
+  long ret = __llvm_libc::syscall(SYS_uname, name);
+
+  if (ret >= 0)
+    return 1;
+  errno = -ret;
+  return -1;
+}
+
+} // namespace __llvm_libc

libc/src/sys/utsname/uname.h

+//===-- Implementation header for uname -------------------------*- 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_SYS_UTSNAME_UNAME_H
+#define LLVM_LIBC_SRC_SYS_UTSNAME_UNAME_H
+
+#include <sys/utsname.h>
+
+namespace __llvm_libc {
+
+int uname(struct utsname *name);
+
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_SRC_SYS_UTSNAME_UNAME_H

libc/test/src/sys/CMakeLists.txt

 add_subdirectory(mman)
 add_subdirectory(sendfile)
 add_subdirectory(stat)
+add_subdirectory(utsname)

libc/test/src/sys/utsname/CMakeLists.txt

+add_libc_testsuite(libc_sys_utsname_unittests)
+
+add_libc_unittest(
+  uname_test
+  SUITE
+    libc_sys_utsname_unittests
+  SRCS
+    uname_test.cpp
+  DEPENDS
+    libc.include.errno
+    libc.include.sys_utsname
+    libc.src.__support.common
+    libc.src.sys.utsname.uname
+    libc.test.errno_setter_matcher
+)

libc/test/src/sys/utsname/uname_test.cpp

+//===-- Unittests for uname -----------------------------------------------===//
+//
+// 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/CPP/string_view.h"
+#include "src/__support/architectures.h"
+#include "src/sys/utsname/uname.h"
+#include "test/ErrnoSetterMatcher.h"
+#include "utils/UnitTest/Test.h"
+
+#include <errno.h>
+#include <sys/utsname.h>
+
+TEST(LlvmLibcUnameTest, GetMachineName) {
+  struct utsname names;
+  ASSERT_GE(__llvm_libc::uname(&names), 0);
+#ifdef LLVM_LIBC_ARCH_X86_64
+  ASSERT_STREQ(names.machine, "x86_64");
+#elif defined(LLVM_LIBC_ARCH_AARCH64)
+  ASSERT_STREQ(names.machine, "aarch64");
+#endif
+}