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Merge pull request #69 from monoidic/develop
tweaks, basic DWARF-based info
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,178 @@ | ||
| // This file is part of GoRE. | ||
| // | ||
| // Copyright (C) 2019-2024 GoRE Authors | ||
| // | ||
| // This program is free software: you can redistribute it and/or modify | ||
| // it under the terms of the GNU Affero General Public License as published by | ||
| // the Free Software Foundation, either version 3 of the License, or | ||
| // (at your option) any later version. | ||
| // | ||
| // This program is distributed in the hope that it will be useful, | ||
| // but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
| // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | ||
| // GNU General Public License for more details. | ||
| // | ||
| // You should have received a copy of the GNU Affero General Public License | ||
| // along with this program. If not, see <http://www.gnu.org/licenses/>. | ||
|
|
||
| package gore | ||
|
|
||
| import ( | ||
| "bytes" | ||
| "debug/dwarf" | ||
| "encoding/binary" | ||
| ) | ||
|
|
||
| const ( | ||
| // official DWARF language ID for Go | ||
| // https://dwarfstd.org/languages.html | ||
| dwLangGo int64 = 0x0016 | ||
|
|
||
| // DWARF operation; used to encode type offsets | ||
| dwOpAddr = 0x03 | ||
| ) | ||
|
|
||
| func getGoRootFromDwarf(fh fileHandler) (string, bool) { | ||
| return getDwarfString(fh, getDwarfStringCheck("runtime.defaultGOROOT")) | ||
| } | ||
|
|
||
| func getBuildVersionFromDwarf(fh fileHandler) (string, bool) { | ||
| return getDwarfString(fh, getDwarfStringCheck("runtime.buildVersion")) | ||
| } | ||
|
|
||
| // DWARF entry plus any associated children | ||
| type dwarfEntryPlus struct { | ||
| entry *dwarf.Entry | ||
| children []*dwarfEntryPlus | ||
| } | ||
|
|
||
| type dwarfwalkStatus uint8 | ||
|
|
||
| const ( | ||
| dwStop dwarfwalkStatus = iota + 1 | ||
| dwContinue | ||
| dwFound | ||
| ) | ||
|
|
||
| func getDwarfString(fh fileHandler, check func(fh fileHandler, entry *dwarfEntryPlus) (string, dwarfwalkStatus)) (string, bool) { | ||
| data, err := fh.getDwarf() | ||
| if err != nil { | ||
| return "", false | ||
| } | ||
|
|
||
| r := data.Reader() | ||
| // walk through compilation units | ||
| getValOuter: | ||
| for cu := dwarfReadEntry(r); cu != nil; cu = dwarfReadEntry(r) { | ||
| if langField := cu.entry.AttrField(dwarf.AttrLanguage); langField == nil || langField.Val != dwLangGo { | ||
| continue | ||
| } | ||
| getValInner: | ||
| for _, entry := range cu.children { | ||
| ret, status := check(fh, entry) | ||
| switch status { | ||
| case dwStop: | ||
| break getValOuter | ||
| case dwFound: | ||
| return ret, true | ||
| case dwContinue: | ||
| continue getValInner | ||
| } | ||
| } | ||
| } | ||
| return "", false | ||
| } | ||
|
|
||
| // get, by name, a DWARF entry corresponding to a string constant | ||
| func getDwarfStringCheck(name string) func(fh fileHandler, entry *dwarfEntryPlus) (string, dwarfwalkStatus) { | ||
| return func(fh fileHandler, d *dwarfEntryPlus) (string, dwarfwalkStatus) { | ||
| entry := d.entry | ||
| nameField := entry.AttrField(dwarf.AttrName) | ||
| if nameField == nil { | ||
| return "", dwContinue | ||
| } | ||
|
|
||
| if fieldName := nameField.Val.(string); fieldName != name { | ||
| return "", dwContinue | ||
| } | ||
|
|
||
| return commonStringCheck(fh, entry) | ||
| } | ||
| } | ||
|
|
||
| func commonStringCheck(fh fileHandler, entry *dwarf.Entry) (string, dwarfwalkStatus) { | ||
| locationField := entry.AttrField(dwarf.AttrLocation) | ||
| if locationField == nil { | ||
| // unexpected failure | ||
| return "", dwStop | ||
| } | ||
| location := locationField.Val.([]byte) | ||
| // DWARF address operation followed by the machine byte order encoded address | ||
| if location[0] != dwOpAddr { | ||
| return "", dwStop | ||
| } | ||
| var addr uint64 | ||
| if fh.getFileInfo().WordSize == intSize32 { | ||
| addr = uint64(fh.getFileInfo().ByteOrder.Uint32(location[1:])) | ||
| } else { | ||
| addr = fh.getFileInfo().ByteOrder.Uint64(location[1:]) | ||
| } | ||
|
|
||
| sectionBase, data, err := fh.getSectionDataFromAddress(addr) | ||
| if err != nil { | ||
| return "", dwStop | ||
| } | ||
| off := addr - sectionBase | ||
| r := bytes.NewReader(data[off:]) | ||
| var stringData [2]uint64 | ||
| if fh.getFileInfo().WordSize == intSize32 { | ||
| var stringData32 [2]uint32 | ||
| err = binary.Read(r, fh.getFileInfo().ByteOrder, &stringData32) | ||
| if err != nil { | ||
| return "", dwStop | ||
| } | ||
| stringData[0] = uint64(stringData32[0]) | ||
| stringData[1] = uint64(stringData32[1]) | ||
| } else { | ||
| err = binary.Read(r, fh.getFileInfo().ByteOrder, &stringData) | ||
| if err != nil { | ||
| return "", dwStop | ||
| } | ||
| } | ||
| addr = stringData[0] | ||
| stringLen := stringData[1] | ||
| sectionBase, data, err = fh.getSectionDataFromAddress(addr) | ||
| if err != nil { | ||
| return "", dwStop | ||
| } | ||
| off = addr - sectionBase | ||
| raw := data[off : off+stringLen] | ||
| return string(raw), dwFound | ||
| } | ||
|
|
||
| func dwarfReadEntry(r *dwarf.Reader) *dwarfEntryPlus { | ||
| entry, _ := r.Next() | ||
| if entry == nil { | ||
| return nil | ||
| } | ||
| var children []*dwarfEntryPlus | ||
| if entry.Children { | ||
| children = dwarfReadChildren(r) | ||
| } | ||
| return &dwarfEntryPlus{ | ||
| entry: entry, | ||
| children: children, | ||
| } | ||
| } | ||
|
|
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| func dwarfReadChildren(r *dwarf.Reader) []*dwarfEntryPlus { | ||
| var ret []*dwarfEntryPlus | ||
|
|
||
| for { | ||
| e := dwarfReadEntry(r) | ||
| if e.entry.Tag == 0 { | ||
| return ret | ||
| } | ||
| ret = append(ret, e) | ||
| } | ||
| } |
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