[libc] Add limits.h

[alfredfo]

Summary

Also adds macros SSIZE_MAX and LONG_MAX

is it okay to open revisions like this with multiple commits?

libc/config/linux/x86_64/headers.txt

 set(TARGET_PUBLIC_HEADERS
     libc.include.assert
     libc.include.ctype
     libc.include.dirent
     libc.include.errno
     libc.include.fcntl
     libc.include.fenv
     libc.include.inttypes
+    libc.include.limits
     libc.include.math
     libc.include.pthread
     libc.include.sched
     libc.include.signal
     libc.include.spawn
     libc.include.setjmp
     libc.include.stdio
     libc.include.stdlib

libc/include/CMakeLists.txt

add_gen_header(
   DEF_FILE inttypes.h.def
   GEN_HDR inttypes.h
   DEPENDS
     .llvm_libc_common_h
     .llvm-libc-types.imaxdiv_t
 )
 
 add_gen_header(
+  limits
+  DEF_FILE limits.h.def
+  GEN_HDR limits.h
+  DEPENDS
+    .llvm_libc_common_h
+    .llvm-libc-macros.limits_macros
+)
+
+add_gen_header(
   math
   DEF_FILE math.h.def
   GEN_HDR math.h
   DEPENDS
     .llvm_libc_common_h
     .llvm-libc-macros.math_macros
     .llvm-libc-types.double_t
     .llvm-libc-types.float_t

libc/include/limits.h.def

+//===-- C standard library header limits.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_LIMITS_H
+#define LLVM_LIBC_LIMITS_H
+
+#include <__llvm-libc-common.h>
+#include <llvm-libc-macros/limits-macros.h>
+
+%%public_api()
+
+#endif // LLVM_LIBC_LIMITS_H

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

DEPENDS
     .linux.unistd_macros
 )
 
 add_header(
   wchar_macros
   HDR
     wchar-macros.h
 )
+
+add_header(
+  limits_macros
+  HDR
+    limits-macros.h
+)

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

+#ifndef __LLVM_LIBC_MACROS_LIMITS_MACROS_H
+#define __LLVM_LIBC_MACROS_LIMITS_MACROS_H
+
+#ifdef __linux__
+#include <linux/limits.h>
+#endif
+
+#if __LP64__
+#define __LONG_MAX 0x7fffffffffffffffL
+#else
+#define __LONG_MAX 0x7fffffffL
+#endif // __LP64__
+
+#define LONG_MAX __LONG_MAX
+#define SSIZE_MAX LONG_MAX
+
+#endif // __LLVM_LIBC_MACROS_LIMITS_MACROS_H

libc/spec/posix.td

[
       FunctionSpec<
           "openat",
           RetValSpec<IntType>,
           [ArgSpec<IntType>, ArgSpec<ConstCharPtr>, ArgSpec<IntType>, ArgSpec<VarArgType>]
       >,
     ]
   >;
 
+  HeaderSpec Limits = HeaderSpec<
+    "limits.h",
+    [
+        Macro<"SSIZE_MAX">,
+    ],
+    [], // Types
+    [], // Enumerations
+    [] // Functions
+  >;
+
   HeaderSpec SysMMan = HeaderSpec<
       "sys/mman.h",
       [
         // TODO: Add a facility to bunch macros into bitwise-or-able groups.
         // POSIX requires it, so such thing should be captured in this spec.
         Macro<"PROT_EXEC">,
         Macro<"PROT_NONE">,
         Macro<"PROT_READ">,

   >;
 
   let Headers = [
     ArpaInet,
     CType,
     Dirent,
     Errno,
     FCntl,
+    Limits,
     PThread,
     Sched,
     Signal,
     Spawn,
     StdIO,
     StdLib,
+    String,
     SysIOctl,
     SysMMan,
     SysResource,
     SysSelect,
     SysSocket,
     SysStat,
     SysTypes,
     SysUtsName,
     SysWait,
-    Time,
     Termios,
-    UniStd,
-    String
+    Time,
+    UniStd
   ];
 }

libc/spec/stdc.td

HeaderSpec IntTypes = HeaderSpec<
       [
           FunctionSpec<"imaxabs", RetValSpec<IntMaxTType>, [ArgSpec<IntMaxTType>]>,
           FunctionSpec<"imaxdiv", RetValSpec<IMaxDivTType>, [ArgSpec<IntMaxTType>, ArgSpec<IntMaxTType>]>,
           FunctionSpec<"strtoimax", RetValSpec<IntMaxTType>, [ArgSpec<ConstCharRestrictedPtr>, ArgSpec<CharRestrictedPtrPtr>, ArgSpec<IntType>]>,
           FunctionSpec<"strtoumax", RetValSpec<UIntMaxTType>, [ArgSpec<ConstCharRestrictedPtr>, ArgSpec<CharRestrictedPtrPtr>, ArgSpec<IntType>]>,
       ]
   >;
 
+  HeaderSpec Limits = HeaderSpec<
+      "limits.h",
+      [
+        Macro<"LONG_MAX">,
+      ],
+      [], // Types
+      [], // Enumerations
+      [] // Functions
+  >;
+
   HeaderSpec Errno = HeaderSpec<
       "errno.h",
       [
         Macro<"errno">,
         Macro<"EDOM">,
         Macro<"EILSEQ">,
         Macro<"ERANGE">,
       ]
let Headers = [
     CType,
     Errno,
     Fenv,
     Math,
     String,
     StdIO,
     StdLib,
     IntTypes,
+    Limits,
     SetJmp,
     Signal,
     Threads,
     Time,
     WChar,
   ];
 }