Implement segfault handler in Crystal

Required adding some C bindings for various signal structures,
based on rust's fairly comprehensive libc bindings.

This removes the need to build and link a separate C library and
reduces the complexity of cross-compiling (at build-time), with
some added complexity when porting to a new platform.

`siginfo_t` can be fairly complex, involving large context-dependent
unions that vary across architecture and platform. In Crystal's
case, we only care about the segfault version of the structure,
so we omit the others.

.gitignore

@@ -14,5 +14,3 @@ all_spec
 /src/llvm/ext/llvm_ext.o
 /src/llvm/ext/llvm_ext.obj
 /src/llvm/ext/llvm_ext.dwo
-/src/ext/*.o
-/src/ext/libcrystal.a

CONTRIBUTING.md

@@ -91,8 +91,6 @@ Additionally, all official documentation can be found on [the Crystal website](h
 1. Fork it ( https://github.com/crystal-lang/crystal/fork )
 2. Clone it
 
-Be sure to execute `make libcrystal` inside the cloned repository.
-
 Once in the cloned directory, and once you [installed Crystal](https://crystal-lang.org/install/),
 you can execute `bin/crystal` instead of `crystal`. This is a wrapper that will use the cloned repository
 as the standard library. Otherwise the barebones `crystal` executable uses the standard library that comes in

Makefile

@@ -42,11 +42,7 @@ SHELL = sh
 LLVM_CONFIG := $(shell src/llvm/ext/find-llvm-config)
 LLVM_EXT_DIR = src/llvm/ext
 LLVM_EXT_OBJ = $(LLVM_EXT_DIR)/llvm_ext.o
-LIB_CRYSTAL_SOURCES = $(shell find src/ext -name '*.c')
-LIB_CRYSTAL_OBJS = $(subst .c,.o,$(LIB_CRYSTAL_SOURCES))
-LIB_CRYSTAL_TARGET = src/ext/libcrystal.a
-DEPS = $(LLVM_EXT_OBJ) $(LIB_CRYSTAL_TARGET)
-CFLAGS += -fPIC $(if $(debug),-g -O0)
+DEPS = $(LLVM_EXT_OBJ)
 CXXFLAGS += $(if $(debug),-g -O0)
 CRYSTAL_VERSION ?= $(shell cat src/VERSION)
 
@@ -99,11 +95,9 @@ docs: ## Generate standard library documentation
 .PHONY: crystal
 crystal: $(O)/crystal ## Build the compiler
 
-.PHONY: deps llvm_ext libcrystal
+.PHONY: deps llvm_ext
 deps: $(DEPS) ## Build dependencies
-
 llvm_ext: $(LLVM_EXT_OBJ)
-libcrystal: $(LIB_CRYSTAL_TARGET)
 
 $(O)/all_spec: $(DEPS) $(SOURCES) $(SPEC_SOURCES)
 	@mkdir -p $(O)
@@ -124,13 +118,9 @@ $(O)/crystal: $(DEPS) $(SOURCES)
 $(LLVM_EXT_OBJ): $(LLVM_EXT_DIR)/llvm_ext.cc
 	$(CXX) -c $(CXXFLAGS) -o $@ $< $(shell $(LLVM_CONFIG) --cxxflags)
 
-$(LIB_CRYSTAL_TARGET): $(LIB_CRYSTAL_OBJS)
-	$(AR) -rcs $@ $^
-
 .PHONY: clean
 clean: clean_crystal ## Clean up built directories and files
 	rm -rf $(LLVM_EXT_OBJ)
-	rm -rf $(LIB_CRYSTAL_OBJS) $(LIB_CRYSTAL_TARGET)
 
 .PHONY: clean_crystal
 clean_crystal: ## Clean up crystal built files

shell.nix

@@ -146,6 +146,5 @@ pkgs.stdenv.mkDerivation rec {
 
   LLVM_CONFIG = "${llvm_suite.llvm}/bin/llvm-config";
 
-  # ld: warning: object file (.../src/ext/libcrystal.a(sigfault.o)) was built for newer OSX version (10.14) than being linked (10.12)
   MACOSX_DEPLOYMENT_TARGET = "10.11";
 }

src/kernel.cr

@@ -535,7 +535,7 @@ end
   end
 
   Signal.setup_default_handlers
-  LibExt.setup_sigfault_handler
+  Signal.setup_sigfault_handler
 {% end %}
 
 {% if !flag?(:win32) %}

src/lib_c/aarch64-darwin/c/signal.cr

@@ -33,6 +33,7 @@ lib LibC
   SIGEMT    =  7
   SIGINFO   = 29
   SIGWINCH  = 28
+  SIGSTKSZ  = 131072
 
   SIG_SETMASK = 3
 
@@ -42,9 +43,41 @@ lib LibC
   SIG_DFL = SighandlerT.new(Pointer(Void).new(0_u64), Pointer(Void).null)
   SIG_IGN = SighandlerT.new(Pointer(Void).new(1_u64), Pointer(Void).null)
 
+  SA_ONSTACK = 0x0001
+  SA_SIGINFO = 0x0040
+
+  struct SiginfoT
+    si_signo : Int
+    si_errno : Int
+    si_code : Int
+    si_pid : PidT
+    si_uid : UidT
+    si_status : Int
+    si_addr : Void*
+    _pad : StaticArray(SizeT, 9)
+  end
+
+  alias SigactionHandlerT = (Int, SiginfoT*, Void*) ->
+
+  struct Sigaction
+    # Technically a union, but only one can be valid and we only use sa_sigaction
+    # and not sa_handler (which would be a SighandlerT)
+    sa_sigaction : SigactionHandlerT
+    sa_mask : SigsetT
+    sa_flags : Int
+  end
+
+  struct StackT
+    ss_sp : Void*
+    ss_size : SizeT
+    ss_flags : Int
+  end
+
   fun kill(x0 : PidT, x1 : Int) : Int
   fun pthread_sigmask(Int, SigsetT*, SigsetT*) : Int
   fun signal(x0 : Int, x1 : Int -> Void) : Int -> Void
+  fun sigaction(x0 : Int, x1 : Sigaction*, x2 : Sigaction*) : Int
+  fun sigaltstack(x0 : StackT*, x1 : StackT*) : Int
   fun sigemptyset(SigsetT*) : Int
   fun sigfillset(SigsetT*) : Int
   fun sigaddset(SigsetT*, Int) : Int

src/lib_c/aarch64-linux-gnu/c/signal.cr

@@ -35,6 +35,7 @@ lib LibC
   SIGPWR    = 30
   SIGSTKFLT = 16
   SIGUNUSED = 31
+  SIGSTKSZ  = 16384
 
   SIG_SETMASK = 2
 
@@ -46,9 +47,38 @@ lib LibC
     val : ULong[32] # (1024 / (8 * sizeof(long)))
   end
 
+  SA_ONSTACK = 0x08000000
+  SA_SIGINFO = 0x00000004
+
+  struct SiginfoT
+    si_signo : Int
+    si_errno : Int
+    si_code : Int
+    __pad0 : Int
+    si_addr : Void* # Assuming the sigfault form of siginfo_t
+    __pad1 : StaticArray(Int, 20) # __SI_PAD_SIZE (28) - sizeof(void*) (8) = 20
+  end
+
+  alias SigactionHandlerT = (Int, SiginfoT*, Void*) ->
+
+  struct Sigaction
+    sa_sigaction : SigactionHandlerT
+    sa_mask : SigsetT
+    sa_flags : Int
+    sa_restorer : Void*
+  end
+
+  struct StackT
+    ss_sp : Void*
+    ss_flags : Int
+    ss_size : SizeT
+  end
+
   fun kill(pid : PidT, sig : Int) : Int
   fun pthread_sigmask(Int, SigsetT*, SigsetT*) : Int
   fun signal(sig : Int, handler : Int -> Void) : Int -> Void
+  fun sigaction(x0 : Int, x1 : Sigaction*, x2 : Sigaction*) : Int
+  fun sigaltstack(x0 : StackT*, x1 : StackT*) : Int
   fun sigemptyset(SigsetT*) : Int
   fun sigfillset(SigsetT*) : Int
   fun sigaddset(SigsetT*, Int) : Int

src/lib_c/aarch64-linux-musl/c/signal.cr

@@ -34,6 +34,7 @@ lib LibC
   SIGPWR    = 30
   SIGSTKFLT = 16
   SIGUNUSED = LibC::SIGSYS
+  SIGSTKSZ  = 12288
 
   SIG_SETMASK = 2
 
@@ -45,9 +46,38 @@ lib LibC
     val : ULong[16] # 128 / sizeof(long)
   end
 
+  SA_ONSTACK = 0x08000000
+  SA_SIGINFO = 0x00000004
+
+  struct SiginfoT
+    si_signo : Int
+    si_errno : Int
+    si_code : Int
+    __pad0 : Int
+    si_addr : Void* # Assuming the sigfault form of siginfo_t
+    __pad1 : StaticArray(Int, 20) # __SI_PAD_SIZE (28) - sizeof(void*) (8) = 20
+  end
+
+  alias SigactionHandlerT = (Int, SiginfoT*, Void*) ->
+
+  struct Sigaction
+    sa_sigaction : SigactionHandlerT
+    sa_mask : SigsetT
+    sa_flags : Int
+    sa_restorer : Void*
+  end
+
+  struct StackT
+    ss_sp : Void*
+    ss_flags : Int
+    ss_size : SizeT
+  end
+
   fun kill(x0 : PidT, x1 : Int) : Int
   fun pthread_sigmask(Int, SigsetT*, SigsetT*) : Int
   fun signal(x0 : Int, x1 : Int -> Void) : Int -> Void
+  fun sigaction(x0 : Int, x1 : Sigaction*, x2 : Sigaction*) : Int
+  fun sigaltstack(x0 : StackT*, x1 : StackT*) : Int
   fun sigemptyset(SigsetT*) : Int
   fun sigfillset(SigsetT*) : Int
   fun sigaddset(SigsetT*, Int) : Int

src/lib_c/arm-linux-gnueabihf/c/signal.cr

@@ -35,6 +35,7 @@ lib LibC
   SIGPWR    = 30
   SIGSTKFLT = 16
   SIGUNUSED = 31
+  SIGSTKSZ  = 8192
 
   SIG_SETMASK = 2
 
@@ -46,9 +47,37 @@ lib LibC
     val : ULong[32] # (1024 / (8 * sizeof(long)))
   end
 
+  SA_ONSTACK = 0x08000000
+  SA_SIGINFO = 0x00000004
+
+  struct SiginfoT
+    si_signo : Int
+    si_errno : Int
+    si_code : Int
+    si_addr : Void* # Assuming the sigfault form of siginfo_t
+    __pad : StaticArray(Int, 25) # __SI_PAD_SIZE (29) - sizeof(void*) (4) = 25
+  end
+
+  alias SigactionHandlerT = (Int, SiginfoT*, Void*) ->
+
+  struct Sigaction
+    sa_sigaction : SigactionHandlerT
+    sa_mask : SigsetT
+    sa_flags : Int
+    sa_restorer : Void*
+  end
+
+  struct StackT
+    ss_sp : Void*
+    ss_flags : Int
+    ss_size : SizeT
+  end
+
   fun kill(pid : PidT, sig : Int) : Int
   fun pthread_sigmask(Int, SigsetT*, SigsetT*) : Int
   fun signal(sig : Int, handler : Int -> Void) : Int -> Void
+  fun sigaction(x0 : Int, x1 : Sigaction*, x2 : Sigaction*) : Int
+  fun sigaltstack(x0 : StackT*, x1 : StackT*) : Int
   fun sigemptyset(SigsetT*) : Int
   fun sigfillset(SigsetT*) : Int
   fun sigaddset(SigsetT*, Int) : Int

src/lib_c/i386-linux-gnu/c/signal.cr

@@ -35,6 +35,7 @@ lib LibC
   SIGPWR    = 30
   SIGSTKFLT = 16
   SIGUNUSED = 31
+  SIGSTKSZ  = 8192
 
   SIG_SETMASK = 2
 
@@ -46,9 +47,37 @@ lib LibC
     val : ULong[32] # (1024 / (8 * sizeof(long)))
   end
 
+  SA_ONSTACK = 0x08000000
+  SA_SIGINFO = 0x00000004
+
+  struct SiginfoT
+    si_signo : Int
+    si_errno : Int
+    si_code : Int
+    si_addr : Void* # Assuming the sigfault form of siginfo_t
+    __pad : StaticArray(Int, 25) # __SI_PAD_SIZE (29) - sizeof(void*) (4) = 25
+  end
+
+  alias SigactionHandlerT = (Int, SiginfoT*, Void*) ->
+
+  struct Sigaction
+    sa_sigaction : SigactionHandlerT
+    sa_mask : SigsetT
+    sa_flags : Int
+    sa_restorer : Void*
+  end
+
+  struct StackT
+    ss_sp : Void*
+    ss_flags : Int
+    ss_size : SizeT
+  end
+
   fun kill(pid : PidT, sig : Int) : Int
   fun pthread_sigmask(Int, SigsetT*, SigsetT*) : Int
   fun signal(sig : Int, handler : Int -> Void) : Int -> Void
+  fun sigaction(x0 : Int, x1 : Sigaction*, x2 : Sigaction*) : Int
+  fun sigaltstack(x0 : StackT*, x1 : StackT*) : Int
   fun sigemptyset(SigsetT*) : Int
   fun sigfillset(SigsetT*) : Int
   fun sigaddset(SigsetT*, Int) : Int

src/lib_c/i386-linux-musl/c/signal.cr

@@ -34,6 +34,7 @@ lib LibC
   SIGPWR    = 30
   SIGSTKFLT = 16
   SIGUNUSED = LibC::SIGSYS
+  SIGSTKSZ  = 8192
 
   SIG_SETMASK = 2
 
@@ -45,9 +46,37 @@ lib LibC
     bits : ULong[32] # 128 / sizeof(long)
   end
 
+  SA_ONSTACK = 0x08000000
+  SA_SIGINFO = 0x00000004
+
+  struct SiginfoT
+    si_signo : Int
+    si_errno : Int
+    si_code : Int
+    si_addr : Void* # Assuming the sigfault form of siginfo_t
+    __pad : StaticArray(Int, 25) # __SI_PAD_SIZE (29) - sizeof(void*) (4) = 25
+  end
+
+  alias SigactionHandlerT = (Int, SiginfoT*, Void*) ->
+
+  struct Sigaction
+    sa_sigaction : SigactionHandlerT
+    sa_mask : SigsetT
+    sa_flags : Int
+    sa_restorer : Void*
+  end
+
+  struct StackT
+    ss_sp : Void*
+    ss_flags : Int
+    ss_size : SizeT
+  end
+
   fun kill(x0 : PidT, x1 : Int) : Int
   fun pthread_sigmask(Int, SigsetT*, SigsetT*) : Int
   fun signal(x0 : Int, x1 : Int -> Void) : Int -> Void
+  fun sigaction(x0 : Int, x1 : Sigaction*, x2 : Sigaction*) : Int
+  fun sigaltstack(x0 : StackT*, x1 : StackT*) : Int
   fun sigemptyset(SigsetT*) : Int
   fun sigfillset(SigsetT*) : Int
   fun sigaddset(SigsetT*, Int) : Int