github.com/liujq9674git/golang-src-1.7@v0.0.0-20230517174348-17f6ec47f3f8/src/runtime/signal_darwin_386.go (about)

     1  // Copyright 2013 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package runtime
     6  
     7  import "unsafe"
     8  
     9  type sigctxt struct {
    10  	info *siginfo
    11  	ctxt unsafe.Pointer
    12  }
    13  
    14  func (c *sigctxt) regs() *regs32   { return &(*ucontext)(c.ctxt).uc_mcontext.ss }
    15  func (c *sigctxt) eax() uint32     { return c.regs().eax }
    16  func (c *sigctxt) ebx() uint32     { return c.regs().ebx }
    17  func (c *sigctxt) ecx() uint32     { return c.regs().ecx }
    18  func (c *sigctxt) edx() uint32     { return c.regs().edx }
    19  func (c *sigctxt) edi() uint32     { return c.regs().edi }
    20  func (c *sigctxt) esi() uint32     { return c.regs().esi }
    21  func (c *sigctxt) ebp() uint32     { return c.regs().ebp }
    22  func (c *sigctxt) esp() uint32     { return c.regs().esp }
    23  func (c *sigctxt) eip() uint32     { return c.regs().eip }
    24  func (c *sigctxt) eflags() uint32  { return c.regs().eflags }
    25  func (c *sigctxt) cs() uint32      { return c.regs().cs }
    26  func (c *sigctxt) fs() uint32      { return c.regs().fs }
    27  func (c *sigctxt) gs() uint32      { return c.regs().gs }
    28  func (c *sigctxt) sigcode() uint32 { return uint32(c.info.si_code) }
    29  func (c *sigctxt) sigaddr() uint32 { return c.info.si_addr }
    30  
    31  func (c *sigctxt) set_eip(x uint32)     { c.regs().eip = x }
    32  func (c *sigctxt) set_esp(x uint32)     { c.regs().esp = x }
    33  func (c *sigctxt) set_sigcode(x uint32) { c.info.si_code = int32(x) }
    34  func (c *sigctxt) set_sigaddr(x uint32) { c.info.si_addr = x }
    35  
    36  func (c *sigctxt) fixsigcode(sig uint32) {
    37  	switch sig {
    38  	case _SIGTRAP:
    39  		// OS X sets c.sigcode() == TRAP_BRKPT unconditionally for all SIGTRAPs,
    40  		// leaving no way to distinguish a breakpoint-induced SIGTRAP
    41  		// from an asynchronous signal SIGTRAP.
    42  		// They all look breakpoint-induced by default.
    43  		// Try looking at the code to see if it's a breakpoint.
    44  		// The assumption is that we're very unlikely to get an
    45  		// asynchronous SIGTRAP at just the moment that the
    46  		// PC started to point at unmapped memory.
    47  		pc := uintptr(c.eip())
    48  		// OS X will leave the pc just after the INT 3 instruction.
    49  		// INT 3 is usually 1 byte, but there is a 2-byte form.
    50  		code := (*[2]byte)(unsafe.Pointer(pc - 2))
    51  		if code[1] != 0xCC && (code[0] != 0xCD || code[1] != 3) {
    52  			// SIGTRAP on something other than INT 3.
    53  			c.set_sigcode(_SI_USER)
    54  		}
    55  	}
    56  }