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proc/variables: Large strings & uninitialized memory fixes

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Be more tolerant of unitialized memory, limit length of strings like we
do for array/slices.

Workaround for Issue #189
This commit is contained in:
aarzilli
2015-09-20 08:27:25 +02:00
committed by Derek Parker
parent 7f3ae73471
commit a6391c1f76
1 changed files with 32 additions and 5 deletions
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37
proc/variables.go
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@ -17,6 +17,7 @@ import (
const (
maxVariableRecurse = 1 // How far to recurse when evaluating nested types.
maxArrayValues = 64 // Max value for reading large arrays.
maxErrCount = 3 // Max number of read errors to accept while evaluating slices, arrays and structs
ChanRecv = "chan receive"
ChanSend = "chan send"
@ -540,14 +541,20 @@ func (scope *EvalScope) extractValueInternal(instructions []byte, addr int64, ty
// Recursively call extractValue to grab
// the value of all the members of the struct.
if recurseLevel <= maxVariableRecurse {
errcount := 0
fields := make([]string, 0, len(t.Field))
for _, field := range t.Field {
for i, field := range t.Field {
val, err := scope.extractValueInternal(nil, field.ByteOffset+addr, field.Type, printStructName, recurseLevel+1)
if err != nil {
return "", err
errcount++
val = fmt.Sprintf("<unreadable: %s>", err.Error())
}
fields = append(fields, fmt.Sprintf("%s: %s", field.Name, val))
if errcount > maxErrCount {
fields = append(fields, fmt.Sprintf("...+%d more", len(t.Field)-i))
}
}
if printStructName {
return fmt.Sprintf("%s {%s}", t.StructName, strings.Join(fields, ", ")), nil
@ -595,6 +602,14 @@ func (thread *Thread) readString(addr uintptr) (string, error) {
return "", fmt.Errorf("could not read string len %s", err)
}
strlen := int(binary.LittleEndian.Uint64(val))
if strlen < 0 {
return "", fmt.Errorf("invalid length: %d", strlen)
}
count := strlen
if count > maxArrayValues {
count = maxArrayValues
}
// read addr
val, err = thread.readMemory(addr, thread.dbp.arch.PtrSize())
@ -606,12 +621,18 @@ func (thread *Thread) readString(addr uintptr) (string, error) {
return "", nil
}
val, err = thread.readMemory(addr, strlen)
val, err = thread.readMemory(addr, count)
if err != nil {
return "", fmt.Errorf("could not read string at %#v due to %s", addr, err)
}
return *(*string)(unsafe.Pointer(&val)), nil
retstr := *(*string)(unsafe.Pointer(&val))
if count != strlen {
retstr = retstr + fmt.Sprintf("...+%d more", strlen-count)
}
return retstr, nil
}
func (scope *EvalScope) readSlice(addr uintptr, t *dwarf.StructType, recurseLevel int) (string, error) {
@ -679,6 +700,7 @@ func (scope *EvalScope) readArray(addr uintptr, t *dwarf.ArrayType, recurseLevel
func (scope *EvalScope) readArrayValues(addr uintptr, count int64, stride int64, t dwarf.Type, recurseLevel int) ([]string, error) {
vals := make([]string, 0)
errcount := 0
for i := int64(0); i < count; i++ {
// Cap number of elements
@ -689,9 +711,14 @@ func (scope *EvalScope) readArrayValues(addr uintptr, count int64, stride int64,
val, err := scope.extractValueInternal(nil, int64(addr+uintptr(i*stride)), t, false, recurseLevel+1)
if err != nil {
return nil, err
errcount++
val = fmt.Sprintf("<unreadable: %s>", err.Error())
}
vals = append(vals, val)
if errcount > maxErrCount {
vals = append(vals, fmt.Sprintf("...+%d more", count-i))
break
}
}
return vals, nil
}