[libc] Correct usage of __unix__ and __linux__

[alfredfo]

Here are things still using __unix__, and I'm pretty sure those are correct.

$ grep -rsin '__unix__' -C10 in libc/

gives the following output:

include/llvm-libc-types/once_flag.h-4-// See https://llvm.org/LICENSE.txt for license information.
include/llvm-libc-types/once_flag.h-5-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
include/llvm-libc-types/once_flag.h-6-//
include/llvm-libc-types/once_flag.h-7-//===----------------------------------------------------------------------===//
include/llvm-libc-types/once_flag.h-8-
include/llvm-libc-types/once_flag.h-9-#ifndef __LLVM_LIBC_TYPES_ONCE_FLAG_H__
include/llvm-libc-types/once_flag.h-10-#define __LLVM_LIBC_TYPES_ONCE_FLAG_H__
include/llvm-libc-types/once_flag.h-11-
include/llvm-libc-types/once_flag.h-12-#include <llvm-libc-types/__futex_word.h>
include/llvm-libc-types/once_flag.h-13-
include/llvm-libc-types/once_flag.h:14:#ifdef __unix__
include/llvm-libc-types/once_flag.h-15-typedef __futex_word once_flag;
include/llvm-libc-types/once_flag.h-16-#else
include/llvm-libc-types/once_flag.h-17-#error "Once flag type not defined for the target platform."
include/llvm-libc-types/once_flag.h-18-#endif
include/llvm-libc-types/once_flag.h-19-
include/llvm-libc-types/once_flag.h-20-#endif // __LLVM_LIBC_TYPES_ONCE_FLAG_H__
--
include/llvm-libc-types/pthread_once_t.h-4-// See https://llvm.org/LICENSE.txt for license information.
include/llvm-libc-types/pthread_once_t.h-5-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
include/llvm-libc-types/pthread_once_t.h-6-//
include/llvm-libc-types/pthread_once_t.h-7-//===----------------------------------------------------------------------===//
include/llvm-libc-types/pthread_once_t.h-8-
include/llvm-libc-types/pthread_once_t.h-9-#ifndef __LLVM_LIBC_TYPES_PTHREAD_ONCE_T_H__
include/llvm-libc-types/pthread_once_t.h-10-#define __LLVM_LIBC_TYPES_PTHREAD_ONCE_T_H__
include/llvm-libc-types/pthread_once_t.h-11-
include/llvm-libc-types/pthread_once_t.h-12-#include <llvm-libc-types/__futex_word.h>
include/llvm-libc-types/pthread_once_t.h-13-
include/llvm-libc-types/pthread_once_t.h:14:#ifdef __unix__
include/llvm-libc-types/pthread_once_t.h-15-typedef __futex_word pthread_once_t;
include/llvm-libc-types/pthread_once_t.h-16-#else
include/llvm-libc-types/pthread_once_t.h-17-#error "Once flag type not defined for the target platform."
include/llvm-libc-types/pthread_once_t.h-18-#endif
include/llvm-libc-types/pthread_once_t.h-19-
include/llvm-libc-types/pthread_once_t.h-20-#endif // __LLVM_LIBC_TYPES_PTHREAD_ONCE_T_H__
--
include/llvm-libc-types/__mutex_type.h-12-#include <llvm-libc-types/__futex_word.h>
include/llvm-libc-types/__mutex_type.h-13-
include/llvm-libc-types/__mutex_type.h-14-typedef struct {
include/llvm-libc-types/__mutex_type.h-15-  unsigned char __timed;
include/llvm-libc-types/__mutex_type.h-16-  unsigned char __recursive;
include/llvm-libc-types/__mutex_type.h-17-  unsigned char __robust;
include/llvm-libc-types/__mutex_type.h-18-
include/llvm-libc-types/__mutex_type.h-19-  void *__owner;
include/llvm-libc-types/__mutex_type.h-20-  unsigned long long __lock_count;
include/llvm-libc-types/__mutex_type.h-21-
include/llvm-libc-types/__mutex_type.h:22:#ifdef __unix__
include/llvm-libc-types/__mutex_type.h-23-  __futex_word __ftxw;
include/llvm-libc-types/__mutex_type.h-24-#else
include/llvm-libc-types/__mutex_type.h-25-#error "Mutex type not defined for the target platform."
include/llvm-libc-types/__mutex_type.h-26-#endif
include/llvm-libc-types/__mutex_type.h-27-} __mutex_type;
include/llvm-libc-types/__mutex_type.h-28-
include/llvm-libc-types/__mutex_type.h-29-#endif // __LLVM_LIBC_TYPES___MUTEX_T_H

[alfredfo]

another one (__support/threads/mutex.h)

[sivachandra]

LGTM, but...

In D153729#4447435, @alfredfo wrote:

Here are things still using __unix__, and I'm pretty sure those are correct.

All of them seem to be related to the Linux futex word. Wouldn't __linux__ be the most appropriate for them as well?

[alfredfo]

In D153729#4447715, @sivachandra wrote:

LGTM, but...

In D153729#4447435, @alfredfo wrote:

Here are things still using __unix__, and I'm pretty sure those are correct.

All of them seem to be related to the Linux futex word. Wouldn't __linux__ be the most appropriate for them as well?

Oh right, definitely not available on all Unix systems.

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

21

only d_ino (XSI) and d_name are specified by POSIX.

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

15

Apple (__APPLE__) uses 256: https://opensource.apple.com/source/xnu/xnu-201/bsd/sys/utsname.h.auto.html

26

GNU extension

libc/src/__support/File/dir.cpp

43

checked using _DIRENT_HAVE_D_RECLEN, respected by both musl and glibc

ditto _OFF, _TYPE

[alfredfo]

added Linux specific futex word

[alfredfo]

In D153729#4447715, @sivachandra wrote:

LGTM, but...

In D153729#4447435, @alfredfo wrote:

Here are things still using __unix__, and I'm pretty sure those are correct.

All of them seem to be related to the Linux futex word. Wouldn't __linux__ be the most appropriate for them as well?

done! I think there should be something addressing pthread_once_t and once_flag for other Unix platforms though. Both of these would've previously, before this commit, been valid on macOS, as __unix__ is defined and __futex_word is just an aligned 32 bit int. No internal Linux headers were used here before that would've caused an error.

typedef struct {
  _Alignas(sizeof(__UINT32_TYPE__) > _Alignof(__UINT32_TYPE__)
               ? sizeof(__UINT32_TYPE__)
               : _Alignof(__UINT32_TYPE__)) __UINT32_TYPE__ __word;
} __futex_word;

from __futex_word.h

[michaelrj]

LGTM, and if there are spots where both linux and macos should be accepted then we should probably make those #if defined(__linux__) || defined(__APPLE__)

[thesamesam]

In D153729#4450489, @michaelrj wrote:

LGTM, and if there are spots where both linux and macos should be accepted then we should probably make those #if defined(__linux__) || defined(__APPLE__)

Yeah, definitely, or it'll end up biting us later on.

libc/include/llvm-libc-macros/fcntl-macros.h

 #ifndef __LLVM_LIBC_MACROS_FCNTL_MACROS_H
 #define __LLVM_LIBC_MACROS_FCNTL_MACROS_H
 
-#ifdef __unix__
+#ifdef __linux__
 #include "linux/fcntl-macros.h"
 #endif
 
 #endif // __LLVM_LIBC_MACROS_FCNTL_MACROS_H

libc/include/llvm-libc-macros/sched-macros.h

 //===-- Macros defined in sched.h header file -----------------------------===//
 //
 // 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_MACROS_SCHED_MACROS_H
 #define __LLVM_LIBC_MACROS_SCHED_MACROS_H
 
-#ifdef __unix__
+#ifdef __linux__
 #include "linux/sched-macros.h"
 #endif
 
 #endif // __LLVM_LIBC_MACROS_SCHED_MACROS_H

libc/include/llvm-libc-macros/sys-ioctl-macros.h

 //===-- Macros defined in sys/ioctl.h header file -------------------------===//
 //
 // 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_MACROS_SYS_IOCTL_MACROS_H
 #define __LLVM_LIBC_MACROS_SYS_IOCTL_MACROS_H
 
-#ifdef __unix__
+#ifdef __linux__
 #include "linux/sys-ioctl-macros.h"
 #endif
 
 #endif // __LLVM_LIBC_MACROS_SYS_IOCTL_MACROS_H

libc/include/llvm-libc-macros/sys-mman-macros.h

 //===-- Macros defined in sys/mman.h header file --------------------------===//
 //
 // 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_MACROS_SYS_MMAN_MACROS_H
 #define __LLVM_LIBC_MACROS_SYS_MMAN_MACROS_H
 
-#ifdef __unix__
+#ifdef __linux__
 #include "linux/sys-mman-macros.h"
 #endif
 
 #endif // __LLVM_LIBC_MACROS_SYS_MMAN_MACROS_H

libc/include/llvm-libc-macros/sys-random-macros.h

 //===-- Macros defined in sys/random.h header file ------------------------===//
 //
 // 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_MACROS_SYS_RANDOM_MACROS_H
 #define __LLVM_LIBC_MACROS_SYS_RANDOM_MACROS_H
 
-#ifdef __unix__
+#ifdef __linux__
 #include "linux/sys-random-macros.h"
 #endif
 
 #endif // __LLVM_LIBC_MACROS_SYS_RANDOM_MACROS_H

libc/include/llvm-libc-macros/sys-resource-macros.h

 //===-- Macros defined in sys/resource.h header file ----------------------===//
 //
 // 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_MACROS_SYS_RESOURCE_MACROS_H
 #define __LLVM_LIBC_MACROS_SYS_RESOURCE_MACROS_H
 
-#ifdef __unix__
+#ifdef __linux__
 #include "linux/sys-resource-macros.h"
 #endif
 
 #endif // __LLVM_LIBC_MACROS_SYS_RESOURCE_MACROS_H

libc/include/llvm-libc-macros/sys-socket-macros.h

 //===-- Macros defined in sys/socket.h header file ------------------------===//
 //
 // 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_MACROS_SYS_SOCKET_MACROS_H
 #define __LLVM_LIBC_MACROS_SYS_SOCKET_MACROS_H
 
-#ifdef __unix__
+#ifdef __linux__
 #include "linux/sys-socket-macros.h"
 #endif
 
 #endif // __LLVM_LIBC_MACROS_SYS_SOCKET_MACROS_H

libc/include/llvm-libc-macros/sys-stat-macros.h

 //===-- Macros defined in sys/stat.h header file --------------------------===//
 //
 // 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_MACROS_SYS_STAT_MACROS_H
 #define __LLVM_LIBC_MACROS_SYS_STAT_MACROS_H
 
-#ifdef __unix__
+#ifdef __linux__
 #include "linux/sys-stat-macros.h"
 #endif
 
 #endif // __LLVM_LIBC_MACROS_SYS_STAT_MACROS_H

libc/include/llvm-libc-macros/sys-time-macros.h

 //===-- Macros defined in sys/time.h header file --------------------------===//
 //
 // 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_MACROS_SYS_TIME_MACROS_H
 #define __LLVM_LIBC_MACROS_SYS_TIME_MACROS_H
 
-#ifdef __unix__
+#ifdef __linux__
 #include "linux/sys-time-macros.h"
 #endif
 
 #endif // __LLVM_LIBC_MACROS_SYS_TIME_MACROS_H

libc/include/llvm-libc-macros/time-macros.h

 #ifndef __LLVM_LIBC_MACROS_TIME_MACROS_H
 #define __LLVM_LIBC_MACROS_TIME_MACROS_H
 
-#ifdef __unix__
+#ifdef __linux__
 #include "linux/time-macros.h"
 #endif
 
 #endif // __LLVM_LIBC_MACROS_TIME_MACROS_H

libc/include/llvm-libc-macros/unistd-macros.h

 #ifndef __LLVM_LIBC_MACROS_UNISTD_MACROS_H
 #define __LLVM_LIBC_MACROS_UNISTD_MACROS_H
 
-#ifdef __unix__
+#ifdef __linux__
 #include "linux/unistd-macros.h"
 #endif
 
 #endif // __LLVM_LIBC_MACROS_UNISTD_MACROS_H

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

 //===-- Definition of type struct dirent ----------------------------------===//
 //
 // 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_DIRENT_H__
 #define __LLVM_LIBC_TYPES_STRUCT_DIRENT_H__
 
 #include <llvm-libc-types/ino_t.h>
 #include <llvm-libc-types/off_t.h>
 
 struct dirent {
   ino_t d_ino;
-#ifdef __unix__
+#ifdef __linux__
   off_t d_off;
   unsigned short d_reclen;
 #endif
   unsigned char d_type;
   // The user code should use strlen to determine actual the size of d_name.
   // Likewise, it is incorrect and prohibited by the POSIX standard to detemine
   // the size of struct dirent type using sizeof. The size should be got using
   // a different method, for example, from the d_reclen field on Linux.
   char d_name[1];
 };
 
 #endif // __LLVM_LIBC_TYPES_STRUCT_DIRENT_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__
+#ifdef __linux__
 #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__
+#ifdef __linux__
   char domainname[__UTS_NAME_LENGTH];
 #endif
 };
 
 #undef __UTS_NAME_LENGTH
 
 #endif // __LLVM_LIBC_TYPES_STRUCT_UTSNAME_H__

libc/src/__support/File/dir.cpp

if (!readsize)
       return __llvm_libc::Error(readsize.error());
     fillsize = readsize.value();
     readptr = 0;
   }
   if (fillsize == 0)
     return nullptr;
 
   struct ::dirent *d = reinterpret_cast<struct ::dirent *>(buffer + readptr);
-#ifdef __unix__
+#ifdef __linux__
   // The d_reclen field is available on Linux but not required by POSIX.
   readptr += d->d_reclen;
 #else
   // Other platforms have to implement how the read pointer is to be updated.
 #error "DIR read pointer update is missing."
 #endif
   return d;
 }
 

libc/src/__support/OSUtil/io.h

 #define LLVM_LIBC_SRC_SUPPORT_OSUTIL_IO_H
 
 #include "src/__support/macros/properties/architectures.h"
 
 #if defined(LIBC_TARGET_ARCH_IS_GPU)
 #include "gpu/io.h"
 #elif defined(__APPLE__)
 #include "darwin/io.h"
-#elif defined(__unix__)
+#elif defined(__linux__)
 #include "linux/io.h"
 #elif defined(__Fuchsia__)
 #include "fuchsia/io.h"
 #endif
 
 #endif // LLVM_LIBC_SRC_SUPPORT_OSUTIL_IO_H

libc/src/__support/OSUtil/quick_exit.h

 #define LLVM_LIBC_SRC_SUPPORT_OSUTIL_QUICK_EXIT_H
 
 #include "src/__support/macros/properties/architectures.h"
 
 #if defined(LIBC_TARGET_ARCH_IS_GPU)
 #include "gpu/quick_exit.h"
 #elif defined(__APPLE__)
 #include "darwin/quick_exit.h"
-#elif defined(__unix__)
+#elif defined(__linux__)
 #include "linux/quick_exit.h"
 #endif
 
 #endif // LLVM_LIBC_SRC_SUPPORT_OSUTIL_QUICK_EXIT_H

libc/src/__support/OSUtil/syscall.h

 //===--------------- Internal syscall declarations --------------*- 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_SYSCALL_H
 #define LLVM_LIBC_SRC_SUPPORT_OSUTIL_SYSCALL_H
 
 #ifdef __APPLE__
 #include "darwin/syscall.h"
-#elif defined(__unix__)
+#elif defined(__linux__)
 #include "linux/syscall.h"
 #endif
 
 #endif // LLVM_LIBC_SRC_SUPPORT_OSUTIL_SYSCALL_H