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Handle gdb core files better

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Core files created by gdb can have sections missing that would be
present in OS created core files.

We work around this by first reading PT_LOAD entries from the exe and
then reading them from the core.

Fixes #1121
This commit is contained in:
Peter Sanford 2018-06-29 15:02:53 -07:00 committed by Derek Parker
parent 78377cad9d
commit 1d8636cd3d
1 changed files with 23 additions and 11 deletions
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34
pkg/proc/core/linux_amd64_core.go
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@ -256,16 +256,23 @@ func readCore(corePath, exePath string) (*Core, error) {
if err != nil {
return nil, err
}
exeELF, err := elf.NewFile(exe)
if err != nil {
return nil, err
}
if coreFile.Type != elf.ET_CORE {
return nil, fmt.Errorf("%v is not a core file", coreFile)
}
if exeELF.Type != elf.ET_EXEC {
return nil, fmt.Errorf("%v is not an exe file", exeELF)
}
notes, err := readNotes(coreFile)
if err != nil {
return nil, err
}
memory := buildMemory(coreFile, exe, notes)
memory := buildMemory(coreFile, exeELF, exe, notes)
core := &Core{
MemoryReader: memory,
@ -417,7 +424,7 @@ func skipPadding(r io.ReadSeeker, pad int64) error {
return nil
}
func buildMemory(core *elf.File, exe io.ReaderAt, notes []*Note) proc.MemoryReader {
func buildMemory(core, exeELF *elf.File, exe io.ReaderAt, notes []*Note) proc.MemoryReader {
memory := &SplicedMemory{}
// For now, assume all file mappings are to the exe.
@ -434,16 +441,21 @@ func buildMemory(core *elf.File, exe io.ReaderAt, notes []*Note) proc.MemoryRead
}
}
for _, prog := range core.Progs {
if prog.Type == elf.PT_LOAD {
if prog.Filesz == 0 {
continue
// Load memory segments from exe and then from the core file,
// allowing the corefile to overwrite previously loaded segments
for _, elfFile := range []*elf.File{exeELF, core} {
for _, prog := range elfFile.Progs {
if prog.Type == elf.PT_LOAD {
if prog.Filesz == 0 {
continue
}
r := &OffsetReaderAt{
reader: prog.ReaderAt,
offset: uintptr(prog.Vaddr),
}
memory.Add(r, uintptr(prog.Vaddr), uintptr(prog.Filesz))
}
r := &OffsetReaderAt{
reader: prog.ReaderAt,
offset: uintptr(prog.Vaddr),
}
memory.Add(r, uintptr(prog.Vaddr), uintptr(prog.Filesz))
}
}
return memory