Reland: Introduce sys_sigprocmask and sys_sigaction. (patchset #4 id:80001 of https://codereview.ch…

sandbox/linux/system_headers/i386_linux_ucontext.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef SANDBOX_LINUX_SYSTEM_HEADERS_ANDROID_I386_UCONTEXT_H_
 #define SANDBOX_LINUX_SYSTEM_HEADERS_ANDROID_I386_UCONTEXT_H_
 
 // We do something compatible with glibc. Hopefully, at some point Android will
 // provide that for us, and __BIONIC_HAVE_UCONTEXT_T should be defined.
 // This is mostly copied from breakpad (common/android/include/sys/ucontext.h),
 // except we do use sigset_t for uc_sigmask instead of a custom type.
 
 #if !defined(__BIONIC_HAVE_UCONTEXT_T)
+#if !defined(__native_client_nonsfi__)
 #include <asm/sigcontext.h>
+#else
+// In PNaCl toolchain, sigcontext is not defined. So here declare it.
+typedef struct sigaltstack {
+  void* ss_sp;
+  int ss_flags;
+  size_t ss_size;
+} stack_t;
+#endif
 
 /* 80-bit floating-point register */
 struct _libc_fpreg {
   unsigned short significand[4];
   unsigned short exponent;
 };
 
 /* Simple floating-point state, see FNSTENV instruction */
 struct _libc_fpstate {
   unsigned long cw;
@@ skipping 36 matching lines @@
   REG_EFL,
   REG_UESP,
   REG_SS,
 };
 
 typedef struct ucontext {
   uint32_t uc_flags;
   struct ucontext* uc_link;
   stack_t uc_stack;
   mcontext_t uc_mcontext;
-  sigset_t uc_sigmask;
+  // Android and PNaCl toolchain's sigset_t has only 32 bits, though Linux
+  // ABI requires 64 bits.
+  union {
+    sigset_t uc_sigmask;
+    uint32_t kernel_sigmask[2];
+  };
   struct _libc_fpstate __fpregs_mem;
 } ucontext_t;
 
 #else
 #include <sys/ucontext.h>
 #endif  // __BIONIC_HAVE_UCONTEXT_T
 
 #endif  // SANDBOX_LINUX_SYSTEM_HEADERS_ANDROID_I386_UCONTEXT_H_