[Lldb-commits] [PATCH] D152757: [lldb][ObjectFileELF] Set ModuleSpec file offset and size

[Kazuki Sakamoto via Phabricator via lldb-commits]

splhack added inline comments.


================
Comment at: lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp:592
           if (data_sp->GetByteSize() < length)
-            data_sp = MapFileData(file, -1, file_offset);
+            data_sp = MapFileData(file, length, file_offset);
           if (data_sp)
----------------
bulbazord wrote:
> A length of `-1` means "map the whole file", if my understanding is correct. Why do we want to change this to `length` instead of just -1? Or is this `file` the entire zip file?
I'm now updating this diff to add comments to clarify the intention.

For Android zip .so file (D152759),
the ModuleSpec `spec` will have these info with this diff.
- object offset = .so file offset inside the zip file
- object size = .so file size

PlatformAndroid requires this module spec to call DownloadModuleSlice in order to download the .so file from the zip file using adb shell dd.
- file spec = "zip_path!/lib_path"
- file offset = .so file offset inside the zip file == dd skip parameter
- file size = .so file size == dd count parameter

And ObjectFileELF will calculate CRC32 if the ELF does not have GNU BuildID, that will use the `data_sp` size. Which is set by `MapFileData`. Currently `-1` == the whole zip file size. (In fact, lldb-server is crashing due to SIGSEGV.) It is supposed to be the .so file size. 
In the unittest, the test .so file has CRC32 `7D6E4738`. And it should be the same for the file size.

offset-test.bin contains
-1024bytes of '\0'
- liboffset-test.so (file offset = 1024, file size = 3600, CRC32 '7D6E4738')
- 16bytes of '\0'


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D152757/new/

https://reviews.llvm.org/D152757