Add definitions in ucontext.h in Android for x86

Ref: https://android.googlesource.com/platform/bionic/+/refs/tags/ndk-r20/libc/include/sys/ucontext.h

Author: Yuji Yamamoto

src/unix/linux_like/android/b32/x86/mod.rs

@@ -1,5 +1,144 @@
 pub type c_char = i8;
 pub type wchar_t = i32;
+pub type greg_t = i32;
+
+s! {
+    pub struct _libc_fpreg {
+        pub significand: [u16; 4],
+        pub exponent: u16,
+    }
+
+    pub struct _libc_fpstate {
+        pub cw: ::c_ulong,
+        pub sw: ::c_ulong,
+        pub tag: ::c_ulong,
+        pub ipoff: ::c_ulong,
+        pub cssel: ::c_ulong,
+        pub dataoff: ::c_ulong,
+        pub datasel: ::c_ulong,
+        pub _st: [_libc_fpreg; 8],
+        pub status: ::c_ulong,
+    }
+
+    pub struct mcontext_t {
+        pub gregs: [greg_t; 19],
+        pub fpregs: *mut _libc_fpstate,
+        pub oldmask: ::c_ulong,
+        pub cr2: ::c_ulong,
+    }
+}
+
+cfg_if! {
+    if #[cfg(libc_union)] {
+        s_no_extra_traits! {
+            pub struct __c_anonymous_uc_sigmask_with_padding {
+                pub uc_sigmask: ::sigset_t,
+                /* Android has a wrong (smaller) sigset_t on x86. */
+                __padding_rt_sigset: u32,
+            }
+
+            pub union __c_anonymous_uc_sigmask {
+                uc_sigmask: __c_anonymous_uc_sigmask_with_padding,
+                uc_sigmask64: ::sigset64_t,
+            }
+
+            pub struct ucontext_t {
+                pub uc_flags: ::c_ulong,
+                pub uc_link: *mut ucontext_t,
+                pub uc_stack: ::stack_t,
+                pub uc_mcontext: mcontext_t,
+                pub uc_sigmask__c_anonymous_union: __c_anonymous_uc_sigmask,
+                __padding_rt_sigset: u32,
+                __fpregs_mem: _libc_fpstate,
+            }
+        }
+
+        cfg_if! {
+            if #[cfg(feature = "extra_traits")] {
+                impl PartialEq for __c_anonymous_uc_sigmask_with_padding {
+                    fn eq(
+                        &self, other: &__c_anonymous_uc_sigmask_with_padding
+                    ) -> bool {
+                        self.uc_sigmask == other.uc_sigmask
+                            // Ignore padding
+                    }
+                }
+                impl Eq for __c_anonymous_uc_sigmask_with_padding {}
+                impl ::fmt::Debug for __c_anonymous_uc_sigmask_with_padding {
+                    fn fmt(&self, f: &mut ::fmt::Formatter) -> ::fmt::Result {
+                        f.debug_struct("uc_sigmask_with_padding")
+                            .field("uc_sigmask_with_padding", &self.uc_sigmask)
+                            // Ignore padding
+                            .finish()
+                    }
+                }
+                impl ::hash::Hash for __c_anonymous_uc_sigmask_with_padding {
+                    fn hash<H: ::hash::Hasher>(&self, state: &mut H) {
+                        self.uc_sigmask.hash(state)
+                            // Ignore padding
+                    }
+                }
+
+                impl PartialEq for __c_anonymous_uc_sigmask {
+                    fn eq(&self, other: &__c_anonymous_uc_sigmask) -> bool {
+                        unsafe { self.uc_sigmask == other.uc_sigmask }
+                    }
+                }
+                impl Eq for __c_anonymous_uc_sigmask {}
+                impl ::fmt::Debug for __c_anonymous_uc_sigmask {
+                    fn fmt(&self, f: &mut ::fmt::Formatter) -> ::fmt::Result {
+                        f.debug_struct("uc_sigmask")
+                            .field("uc_sigmask", unsafe { &self.uc_sigmask })
+                            .finish()
+                    }
+                }
+                impl ::hash::Hash for __c_anonymous_uc_sigmask {
+                    fn hash<H: ::hash::Hasher>(&self, state: &mut H) {
+                        unsafe { self.uc_sigmask.hash(state) }
+                    }
+                }
+
+                impl PartialEq for ucontext_t {
+                    fn eq(&self, other: &Self) -> bool {
+                        self.uc_flags == other.uc_flags
+                            && self.uc_link == other.uc_link
+                            && self.uc_stack == other.uc_stack
+                            && self.uc_mcontext == other.uc_mcontext
+                            && self.uc_sigmask__c_anonymous_union
+                                == other.uc_sigmask__c_anonymous_union
+                            // Ignore padding field
+                    }
+                }
+                impl Eq for ucontext_t {}
+                impl ::fmt::Debug for ucontext_t {
+                    fn fmt(&self, f: &mut ::fmt::Formatter) -> ::fmt::Result {
+                        f.debug_struct("ucontext_t")
+                            .field("uc_flags", &self.uc_flags)
+                            .field("uc_link", &self.uc_link)
+                            .field("uc_stack", &self.uc_stack)
+                            .field("uc_mcontext", &self.uc_mcontext)
+                            .field(
+                                "uc_sigmask__c_anonymous_union",
+                                &self.uc_sigmask__c_anonymous_union
+                            )
+                            // Ignore padding field
+                            .finish()
+                    }
+                }
+                impl ::hash::Hash for ucontext_t {
+                    fn hash<H: ::hash::Hasher>(&self, state: &mut H) {
+                        self.uc_flags.hash(state);
+                        self.uc_link.hash(state);
+                        self.uc_stack.hash(state);
+                        self.uc_mcontext.hash(state);
+                        self.uc_sigmask__c_anonymous_union.hash(state);
+                        // Ignore padding field
+                    }
+                }
+            }
+        }
+    }
+}
 
 pub const O_DIRECT: ::c_int = 0x4000;
 pub const O_DIRECTORY: ::c_int = 0x10000;
@@ -414,6 +553,27 @@ pub const EFL: ::c_int = 14;
 pub const UESP: ::c_int = 15;
 pub const SS: ::c_int = 16;
 
+// offsets in mcontext_t.gregs from sys/ucontext.h
+pub const REG_GS: ::c_int = 0;
+pub const REG_FS: ::c_int = 1;
+pub const REG_ES: ::c_int = 2;
+pub const REG_DS: ::c_int = 3;
+pub const REG_EDI: ::c_int = 4;
+pub const REG_ESI: ::c_int = 5;
+pub const REG_EBP: ::c_int = 6;
+pub const REG_ESP: ::c_int = 7;
+pub const REG_EBX: ::c_int = 8;
+pub const REG_EDX: ::c_int = 9;
+pub const REG_ECX: ::c_int = 10;
+pub const REG_EAX: ::c_int = 11;
+pub const REG_TRAPNO: ::c_int = 12;
+pub const REG_ERR: ::c_int = 13;
+pub const REG_EIP: ::c_int = 14;
+pub const REG_CS: ::c_int = 15;
+pub const REG_EFL: ::c_int = 16;
+pub const REG_UESP: ::c_int = 17;
+pub const REG_SS: ::c_int = 18;
+
 cfg_if! {
     if #[cfg(libc_align)] {
         mod align;