[libc][errno] Use macro instead of system header (#91150)

## Why
Currently, the system header `errno.h` is included in `libc_errno.h`,
which is supposed to be consumed by internal implementations only. As
unit and hermetic tests should never use `#include <errno.h>` but
instead use `#include "src/errno/libc_errno.h"`, we do not want to
implicitly include `errno.h`. In order to have a clear seperation
between those two, we want to pull out the definitions of errno numbers
from `errno.h`.

## What
* Extract the definitions of errno numbers from
[include/errno.h.def](https://github.com/llvm/llvm-project/pull/91150/files#diff-ed38ed463ed50571b498a5b69039cab58dc9d145da7f751a24da9d77f07781cd)
and place it under
[include/llvm-libc-macros/linux/error-number-macros.h](https://github.com/llvm/llvm-project/pull/91150/files#diff-d6192866629690ebb7cefa1f0a90b6675073e9642f3279df08a04dcdb05fd892)
* Provide mips-specific errno numbers in
[include/llvm-libc-macros/linux/mips/error-number-macros.h](https://github.com/llvm/llvm-project/pull/91150/files#diff-3fd35a4c94e0cc359933e497b10311d857857b2e173e8afebc421b04b7527743)
* Find definition of mips errno numbers in glibc
[here](https://github.com/bminor/glibc/blob/ea73eb5f581ef5931fd67005aa0c526ba43366c9/sysdeps/unix/sysv/linux/mips/bits/errno.h#L32-L50)
(equally defined in the Linux kernel)
* Provide sparc-specific errno numbers in
[include/llvm-libc-macros/linux/sparc/error-number-macros.h](https://github.com/llvm/llvm-project/pull/91150/files#diff-5f16ffb2a51a6f72ebd4403aca7e1edea48289c99dd5978a1c84385bec4f226b)
* Find definition of sparc errno numbers in glibc
[here](https://github.com/bminor/glibc/blob/ea73eb5f581ef5931fd67005aa0c526ba43366c9/sysdeps/unix/sysv/linux/sparc/bits/errno.h#L33-L51)
(equally defined in the Linux kernel)
* Include proxy header `errno_macros.h` instead of the system header
`errno.h` in `libc_errno.h`/`libc_errno.cpp`

Closes #80172

Author: robincaloudis

libc/hdr/CMakeLists.txt

@@ -32,6 +32,16 @@ add_proxy_header_library(
     libc.include.math
 )
 
+add_proxy_header_library(
+  errno_macros
+  HDRS
+    errno_macros.h
+  FULL_BUILD_DEPENDS
+    libc.include.errno
+    libc.include.llvm-libc-macros.error_number_macros
+    libc.include.llvm-libc-macros.generic_error_number_macros
+)
+
 add_proxy_header_library(
   fcntl_macros
   HDRS

libc/hdr/errno_macros.h

@@ -0,0 +1,26 @@
+//===-- Definition of macros from errno.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_HDR_ERRNO_MACROS_H
+#define LLVM_LIBC_HDR_ERRNO_MACROS_H
+
+#ifdef LIBC_FULL_BUILD
+
+#ifdef __linux__
+#include "llvm-libc-macros/error-number-macros.h"
+#else // __linux__
+#include "llvm-libc-macros/generic-error-number-macros.h"
+#endif
+
+#else // Overlay mode
+
+#include <errno.h>
+
+#endif // LLVM_LIBC_FULL_BUILD
+
+#endif // LLVM_LIBC_HDR_ERRNO_MACROS_H

libc/include/errno.h.def

@@ -15,29 +15,11 @@
 
 #include <linux/errno.h>
 
-#ifndef ERFKILL
-#define ERFKILL 132
-#endif // ERFKILL
-
-#ifndef EOWNERDEAD
-#define EOWNERDEAD 130
-#endif // EOWNERDEAD
-
-#ifndef EHWPOISON
-#define EHWPOISON 133
-#endif // EHWPOISON
-
-#ifndef ECANCELED
-#define ECANCELED 125
-#endif // ECANCELED
-
 #ifndef ENOTSUP
 #define ENOTSUP EOPNOTSUPP
 #endif // ENOTSUP
 
-#ifndef ENOTRECOVERABLE
-#define ENOTRECOVERABLE 131
-#endif // ENOTRECOVERABLE
+#include "llvm-libc-macros/linux/error-number-macros.h"
 
 #else // __linux__
 #include "llvm-libc-macros/generic-error-number-macros.h"

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

@@ -37,6 +37,12 @@ add_macro_header(
     assert-macros.h
 )
 
+add_macro_header(
+  error_number_macros
+  HDR
+    error-number-macros.h
+)
+
 add_macro_header(
   generic_error_number_macros
   HDR

libc/include/llvm-libc-macros/error-number-macros.h

@@ -0,0 +1,8 @@
+#ifndef LLVM_LIBC_MACROS_ERROR_NUMBER_MACROS_H
+#define LLVM_LIBC_MACROS_ERROR_NUMBER_MACROS_H
+
+#ifdef __linux__
+#include "linux/error-number-macros.h"
+#endif
+
+#endif // LLVM_LIBC_MACROS_ERROR_NUMBER_MACROS_H

libc/include/llvm-libc-macros/generic-error-number-macros.h

@@ -44,5 +44,7 @@
 #define EDOM 33
 #define ERANGE 34
 #define EILSEQ 35
+#define ENAMETOOLONG 36
+#define EOVERFLOW 75
 
 #endif // LLVM_LIBC_MACROS_GENERIC_ERROR_NUMBER_MACROS_H

libc/include/llvm-libc-macros/linux/CMakeLists.txt

@@ -1,3 +1,15 @@
+add_subdirectory(${CMAKE_CURRENT_SOURCE_DIR}/mips)
+add_subdirectory(${CMAKE_CURRENT_SOURCE_DIR}/sparc)
+
+add_header(
+  error_number_macros
+  HDR
+    error-number-macros.h
+  DEPENDS
+    .mips.error_number_macros
+    .sparc.error_number_macros
+)
+
 add_header(
   fcntl_macros
   HDR

libc/include/llvm-libc-macros/linux/error-number-macros.h

@@ -0,0 +1,32 @@
+#ifndef LLVM_LIBC_MACROS_LINUX_ERROR_NUMBER_MACROS_H
+#define LLVM_LIBC_MACROS_LINUX_ERROR_NUMBER_MACROS_H
+
+#if defined(__mips__)
+#include "mips/error-number-macros.h"
+
+#elif defined(__sparc__)
+#include "sparc/error-number-macros.h"
+
+#else
+#ifndef ECANCELED
+#define ECANCELED 125
+#endif // ECANCELED
+
+#ifndef EOWNERDEAD
+#define EOWNERDEAD 130
+#endif // EOWNERDEAD
+
+#ifndef ENOTRECOVERABLE
+#define ENOTRECOVERABLE 131
+#endif // ENOTRECOVERABLE
+
+#ifndef ERFKILL
+#define ERFKILL 132
+#endif // ERFKILL
+
+#ifndef EHWPOISON
+#define EHWPOISON 133
+#endif // EHWPOISON
+#endif
+
+#endif // LLVM_LIBC_MACROS_LINUX_ERROR_NUMBER_MACROS_H

libc/include/llvm-libc-macros/linux/mips/CMakeLists.txt

@@ -0,0 +1,5 @@
+add_header(
+  error_number_macros
+  HDR
+    error-number-macros.h
+)

libc/include/llvm-libc-macros/linux/mips/error-number-macros.h

@@ -0,0 +1,24 @@
+#ifndef LLVM_LIBC_MACROS_LINUX_MIPS_ERROR_NUMBER_MACROS_H
+#define LLVM_LIBC_MACROS_LINUX_MIPS_ERROR_NUMBER_MACROS_H
+
+#ifndef ECANCELED
+#define ECANCELED 158
+#endif // ECANCELED
+
+#ifndef EOWNERDEAD
+#define EOWNERDEAD 165
+#endif // EOWNERDEAD
+
+#ifndef ENOTRECOVERABLE
+#define ENOTRECOVERABLE 166
+#endif // ENOTRECOVERABLE
+
+#ifndef ERFKILL
+#define ERFKILL 167
+#endif // ERFKILL
+
+#ifndef EHWPOISON
+#define EHWPOISON 168
+#endif // EHWPOISON
+
+#endif // LLVM_LIBC_MACROS_LINUX_MIPS_ERROR_NUMBER_MACROS_H

libc/include/llvm-libc-macros/linux/sparc/CMakeLists.txt

@@ -0,0 +1,5 @@
+add_header(
+  error_number_macros
+  HDR
+    error-number-macros.h
+)

libc/include/llvm-libc-macros/linux/sparc/error-number-macros.h

@@ -0,0 +1,24 @@
+#ifndef LLVM_LIBC_MACROS_LINUX_SPARC_ERROR_NUMBER_MACROS_H
+#define LLVM_LIBC_MACROS_LINUX_SPARC_ERROR_NUMBER_MACROS_H
+
+#ifndef ECANCELED
+#define ECANCELED 127
+#endif // ECANCELED
+
+#ifndef EOWNERDEAD
+#define EOWNERDEAD 132
+#endif // EOWNERDEAD
+
+#ifndef ENOTRECOVERABLE
+#define ENOTRECOVERABLE 133
+#endif // ENOTRECOVERABLE
+
+#ifndef ERFKILL
+#define ERFKILL 134
+#endif // ERFKILL
+
+#ifndef EHWPOISON
+#define EHWPOISON 135
+#endif // EHWPOISON
+
+#endif // LLVM_LIBC_MACROS_LINUX_SPARC_ERROR_NUMBER_MACROS_H

libc/src/errno/CMakeLists.txt

@@ -18,6 +18,6 @@ add_entrypoint_object(
   COMPILE_OPTIONS
     ${full_build_flag}
   DEPENDS
-    libc.include.errno
+    libc.hdr.errno_macros
     libc.src.__support.common
 )

libc/src/errno/libc_errno.cpp

@@ -37,7 +37,7 @@ LIBC_NAMESPACE::Errno::operator int() { return __llvmlibc_errno; }
 
 #else
 // In overlay mode, we simply use the system errno.
-#include <errno.h>
+#include "hdr/errno_macros.h"
 
 void LIBC_NAMESPACE::Errno::operator=(int a) { errno = a; }
 LIBC_NAMESPACE::Errno::operator int() { return errno; }

libc/src/errno/libc_errno.h

@@ -12,11 +12,7 @@
 #include "src/__support/macros/attributes.h"
 #include "src/__support/macros/properties/architectures.h"
 
-// TODO: https://github.com/llvm/llvm-project/issues/80172
-// Separate just the definition of errno numbers in
-// include/llvm-libc-macros/* and only include that instead of the system
-// <errno.h>.
-#include <errno.h>
+#include "hdr/errno_macros.h"
 
 // This header is to be consumed by internal implementations, in which all of
 // them should refer to `libc_errno` instead of using `errno` directly from