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Source file src/runtime/signal_darwin_386.go

Documentation: runtime

  // Copyright 2013 The Go Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style
  // license that can be found in the LICENSE file.
  
  package runtime
  
  import "unsafe"
  
  type sigctxt struct {
  	info *siginfo
  	ctxt unsafe.Pointer
  }
  
  //go:nosplit
  //go:nowritebarrierrec
  func (c *sigctxt) regs() *regs32 { return &(*ucontext)(c.ctxt).uc_mcontext.ss }
  
  func (c *sigctxt) eax() uint32 { return c.regs().eax }
  func (c *sigctxt) ebx() uint32 { return c.regs().ebx }
  func (c *sigctxt) ecx() uint32 { return c.regs().ecx }
  func (c *sigctxt) edx() uint32 { return c.regs().edx }
  func (c *sigctxt) edi() uint32 { return c.regs().edi }
  func (c *sigctxt) esi() uint32 { return c.regs().esi }
  func (c *sigctxt) ebp() uint32 { return c.regs().ebp }
  func (c *sigctxt) esp() uint32 { return c.regs().esp }
  
  //go:nosplit
  //go:nowritebarrierrec
  func (c *sigctxt) eip() uint32 { return c.regs().eip }
  
  func (c *sigctxt) eflags() uint32  { return c.regs().eflags }
  func (c *sigctxt) cs() uint32      { return c.regs().cs }
  func (c *sigctxt) fs() uint32      { return c.regs().fs }
  func (c *sigctxt) gs() uint32      { return c.regs().gs }
  func (c *sigctxt) sigcode() uint32 { return uint32(c.info.si_code) }
  func (c *sigctxt) sigaddr() uint32 { return c.info.si_addr }
  
  func (c *sigctxt) set_eip(x uint32)     { c.regs().eip = x }
  func (c *sigctxt) set_esp(x uint32)     { c.regs().esp = x }
  func (c *sigctxt) set_sigcode(x uint32) { c.info.si_code = int32(x) }
  func (c *sigctxt) set_sigaddr(x uint32) { c.info.si_addr = x }
  
  func (c *sigctxt) fixsigcode(sig uint32) {
  	switch sig {
  	case _SIGTRAP:
  		// OS X sets c.sigcode() == TRAP_BRKPT unconditionally for all SIGTRAPs,
  		// leaving no way to distinguish a breakpoint-induced SIGTRAP
  		// from an asynchronous signal SIGTRAP.
  		// They all look breakpoint-induced by default.
  		// Try looking at the code to see if it's a breakpoint.
  		// The assumption is that we're very unlikely to get an
  		// asynchronous SIGTRAP at just the moment that the
  		// PC started to point at unmapped memory.
  		pc := uintptr(c.eip())
  		// OS X will leave the pc just after the INT 3 instruction.
  		// INT 3 is usually 1 byte, but there is a 2-byte form.
  		code := (*[2]byte)(unsafe.Pointer(pc - 2))
  		if code[1] != 0xCC && (code[0] != 0xCD || code[1] != 3) {
  			// SIGTRAP on something other than INT 3.
  			c.set_sigcode(_SI_USER)
  		}
  	}
  }
  

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