mirror of https://github.com/beego/bee.git
115 lines
2.7 KiB
Go
115 lines
2.7 KiB
Go
package reader
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import (
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"errors"
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"debug/dwarf"
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)
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// RelAddr is an address relative to the static base. For normal executables
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// this is just a normal memory address, for PIE it's a relative address.
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type RelAddr uint64
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func ToRelAddr(addr uint64, staticBase uint64) RelAddr {
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return RelAddr(addr - staticBase)
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}
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// VariableReader provides a way of reading the local variables and formal
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// parameters of a function that are visible at the specified PC address.
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type VariableReader struct {
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dwarf *dwarf.Data
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reader *dwarf.Reader
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entry *dwarf.Entry
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depth int
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onlyVisible bool
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pc uint64
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line int
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err error
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}
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// Variables returns a VariableReader for the function or lexical block at off.
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// If onlyVisible is true only variables visible at pc will be returned by
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// the VariableReader.
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func Variables(dwarf *dwarf.Data, off dwarf.Offset, pc RelAddr, line int, onlyVisible bool) *VariableReader {
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reader := dwarf.Reader()
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reader.Seek(off)
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return &VariableReader{dwarf: dwarf, reader: reader, entry: nil, depth: 0, onlyVisible: onlyVisible, pc: uint64(pc), line: line, err: nil}
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}
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// Next reads the next variable entry, returns false if there aren't any.
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func (vrdr *VariableReader) Next() bool {
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if vrdr.err != nil {
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return false
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}
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for {
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vrdr.entry, vrdr.err = vrdr.reader.Next()
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if vrdr.entry == nil || vrdr.err != nil {
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return false
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}
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switch vrdr.entry.Tag {
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case 0:
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vrdr.depth--
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if vrdr.depth == 0 {
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return false
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}
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case dwarf.TagLexDwarfBlock, dwarf.TagSubprogram, dwarf.TagInlinedSubroutine:
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recur := true
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if vrdr.onlyVisible {
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recur, vrdr.err = entryRangesContains(vrdr.dwarf, vrdr.entry, vrdr.pc)
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if vrdr.err != nil {
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return false
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}
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}
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if recur && vrdr.entry.Children {
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vrdr.depth++
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} else {
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if vrdr.depth == 0 {
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return false
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}
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vrdr.reader.SkipChildren()
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}
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default:
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if vrdr.depth == 0 {
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vrdr.err = errors.New("offset was not lexical block or subprogram")
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return false
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}
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if declLine, ok := vrdr.entry.Val(dwarf.AttrDeclLine).(int64); !ok || vrdr.line >= int(declLine) {
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return true
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}
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}
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}
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}
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func entryRangesContains(dwarf *dwarf.Data, entry *dwarf.Entry, pc uint64) (bool, error) {
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rngs, err := dwarf.Ranges(entry)
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if err != nil {
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return false, err
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}
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for _, rng := range rngs {
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if pc >= rng[0] && pc < rng[1] {
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return true, nil
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}
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}
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return false, nil
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}
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// Entry returns the current variable entry.
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func (vrdr *VariableReader) Entry() *dwarf.Entry {
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return vrdr.entry
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}
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// Depth returns the depth of the current scope
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func (vrdr *VariableReader) Depth() int {
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return vrdr.depth
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}
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// Err returns the error if there was one.
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func (vrdr *VariableReader) Err() error {
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return vrdr.err
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}
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