Use ULONG_MAX instead of __WORDSIZE to determine native ELF architecture

__WORDSIZE is an internal libc definition. Instead, we can use
ULONG_MAX from limits.h, whose value corresponds to the machine's
native word size.

This allows us to remove the fallback definition of __WORDSIZE in
the Android compatibility headers.

Bug: google-breakpad:631
Change-Id: I7b9e6f3b2121f78ccad9e32bf26acac518aefd8f
Reviewed-on: https://chromium-review.googlesource.com/c/breakpad/breakpad/+/2107100
Reviewed-by: Mike Frysinger <vapier@chromium.org>

src/common/android/include/elf.h

@@ -109,17 +109,6 @@ typedef struct {
 } Elf64_Dyn;
 
 
-// __WORDSIZE is GLibc-specific and used by Google Breakpad on Linux.
-#ifndef __WORDSIZE
-#if defined(__i386__) ||  defined(__ARM_EABI__) || defined(__mips__)
-#define __WORDSIZE 32
-#elif defined(__x86_64__) || defined(__aarch64__)
-#define __WORDSIZE 64
-#else
-#error "Unsupported Android CPU ABI"
-#endif
-#endif
-
 // The Android headers don't always define this constant.
 #ifndef EM_X86_64
 #define EM_X86_64  62

src/common/dwarf/elf_reader.cc

@@ -20,8 +20,8 @@
 // Although most of this code can deal with arbitrary ELF files of
 // either word size, the public ElfReader interface only examines
 // files loaded into the current address space, which must all match
-// __WORDSIZE. This code cannot handle ELF files with a non-native
-// byte ordering.
+// the machine's native word size. This code cannot handle ELF files
+// with a non-native byte ordering.
 //
 // TODO(chatham): It would be nice if we could accomplish this task
 // without using malloc(), so we could use it as the process is dying.
@@ -30,12 +30,13 @@
 #define _GNU_SOURCE  // needed for pread()
 #endif
 
-#include <sys/types.h>
-#include <sys/stat.h>
-#include <sys/mman.h>
-#include <unistd.h>
 #include <fcntl.h>
+#include <limits.h>
 #include <string.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
 
 #include <algorithm>
 #include <map>
@@ -1053,9 +1054,9 @@ ElfReader::~ElfReader() {
 
 
 // The only word-size specific part of this file is IsNativeElfFile().
-#if __WORDSIZE == 32
+#if ULONG_MAX == 0xffffffff
 #define NATIVE_ELF_ARCH Elf32
-#elif __WORDSIZE == 64
+#elif ULONG_MAX == 0xffffffffffffffff
 #define NATIVE_ELF_ARCH Elf64
 #else
 #error "Invalid word size"

src/tools/linux/md2core/minidump-2-core.cc

@@ -33,6 +33,7 @@
 
 #include <elf.h>
 #include <errno.h>
+#include <limits.h>
 #include <link.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -54,7 +55,7 @@
 #include "third_party/lss/linux_syscall_support.h"
 #include "tools/linux/md2core/minidump_memory_range.h"
 
-#if __WORDSIZE == 64
+#if ULONG_MAX == 0xffffffffffffffff
   #define ELF_CLASS ELFCLASS64
 #else
   #define ELF_CLASS ELFCLASS32