[PATCH] gdb/jit: fix jit-reader linetable integrity

[Yang Liu <liuyang22@iscas.ac.cn>]

The custom linetable functionality in GDB's JIT Interface has been broken
since commit 1acc9dca423f78e44553928f0de839b618c13766.

In that commit, linetables were made independent from the objfile, which
requires objfile->section_offsets to be initialized. However, section_offsets
were never initialized in objfiles generated by GDB's JIT Interface
with custom jit-readers, leading to GDB crashes when stepping into JITed code
blocks with the following command already executed:

  jit-reader-load libmygdbjitreader.so

This patch fixes the issue by initializing the minimum section_offsets required
for linetable parsing procedures.
---
 gdb/jit.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/gdb/jit.c b/gdb/jit.c
index 77d41bf86ba..7027c84b5bf 100644
--- a/gdb/jit.c
+++ b/gdb/jit.c
@@ -665,6 +665,8 @@ jit_object_close_impl (struct gdb_symbol_callbacks *cb,
 
   objfile *objfile = objfile::make (nullptr, current_program_space,
 				    objfile_name.c_str (), OBJF_NOT_FILENAME);
+  objfile->section_offsets.assign (1, 0);
+  objfile->sect_index_text = 0;
   objfile->per_bfd->gdbarch = priv_data->gdbarch;
 
   for (gdb_symtab &symtab : obj->symtabs)
-- 
2.42.0