/
context.go
58 lines (52 loc) · 1.24 KB
/
context.go
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package tracer
import (
"os"
"syscall"
)
// Context is the context for current syscall trap
// used to retrive syscall number and arguments
type Context struct {
// Pid is current context process pid
Pid int
// current reg context (platform dependent)
regs syscall.PtraceRegs
}
var (
// UseVMReadv determine whether use ProcessVMReadv syscall to read str
// initial true and becomes false if tried and failed with ENOSYS
UseVMReadv = true
pageSize = 4 << 10
)
func init() {
pageSize = os.Getpagesize()
}
func getTrapContext(pid int) (*Context, error) {
var regs syscall.PtraceRegs
//err := syscall.PtraceGetRegs(pid, ®s)
err := ptraceGetRegSet(pid, ®s)
if err != nil {
return nil, err
}
return &Context{
Pid: pid,
regs: regs,
}, nil
}
// GetString get the string from process data segment
func (c *Context) GetString(addr uintptr) string {
buff := make([]byte, syscall.PathMax)
if UseVMReadv {
if err := vmReadStr(c.Pid, addr, buff); err != nil {
// if ENOSYS, then disable this function
if no, ok := err.(syscall.Errno); ok {
if no == syscall.ENOSYS {
UseVMReadv = false
}
}
} else {
return string(buff[:clen(buff)])
}
}
syscall.PtracePeekData(c.Pid, addr, buff)
return string(buff[:clen(buff)])
}