[PATCH] Fix de-initialization of elf::reader::priv

[Petr Pavlu <petr.pavlu@suse.com>]

Add a destructor for elf::reader::priv which releases any allocated alt
DWARF data and fix the initialize() method to fully reset the object.

The latter fixes a crash observed when handling multiple files. For
instance, when reading the Linux kernel tree, load_vmlinux_corpus()
processes vmlinux and all modules. Member dwarf_handle was never reset
after setting it for the first file which could later result in use of
invalid DWARF data in dwarf::reader::build_die_parent_maps().

	* src/abg-elf-reader.cc (priv::~priv): Release alt debug
	information.
	(priv::initialize): Reset all members.
	(priv::clear_alt_dwarf_debug_info_data): New helper function.

Fixes: 7bd69830 ("Make Front Ends first class citizens")
Signed-off-by: Petr Pavlu <petr.pavlu@suse.com>
---
 src/abg-elf-reader.cc | 38 ++++++++++++++++++++++++++++++++++++--
 1 file changed, 36 insertions(+), 2 deletions(-)

diff --git a/src/abg-elf-reader.cc b/src/abg-elf-reader.cc
index 3b1b5803..4814a70e 100644
--- a/src/abg-elf-reader.cc
+++ b/src/abg-elf-reader.cc
@@ -281,6 +281,11 @@ struct reader::priv
     initialize(debug_info_roots);
   }
 
+  ~priv()
+  {
+    clear_alt_dwarf_debug_info_data();
+  }
+
   /// Reset the private data of @elf elf::reader.
   ///
   /// @param debug_info_roots the vector of new directories where to
@@ -288,11 +293,23 @@ struct reader::priv
   void
   initialize(const vector<char**>& debug_info_roots)
   {
-    debug_info_root_paths = debug_info_roots;
+    clear_alt_dwarf_debug_info_data();
+
+    elf_handle = nullptr;
+    symtab_section = nullptr;
+    elf_architecture.clear();
+    dt_needed.clear();
     symt.reset();
+    debug_info_root_paths = debug_info_roots;
+    offline_callbacks = {};
     dwfl_handle.reset();
     elf_module = nullptr;
-    elf_handle = nullptr;
+    dwarf_handle = nullptr;
+    alt_dwarf_handle = nullptr;
+    alt_dwarf_path.clear();
+    alt_dwarf_fd = 0;
+    ctf_section = nullptr;
+    alt_ctf_section = nullptr;
   }
 
   /// Setup the necessary plumbing to open the ELF file and find all
@@ -348,6 +365,23 @@ struct reader::priv
     return result;
   }
 
+  /// Clear the resources related to the alternate DWARF data.
+  void
+  clear_alt_dwarf_debug_info_data()
+  {
+    if (alt_dwarf_fd)
+      {
+        if (alt_dwarf_handle)
+          {
+            dwarf_end(alt_dwarf_handle);
+            alt_dwarf_handle = nullptr;
+          }
+        close(alt_dwarf_fd);
+        alt_dwarf_fd = 0;
+      }
+    alt_dwarf_path.clear();
+  }
+
   /// Locate the DWARF debug info in the ELF file.
   ///
   /// This also knows how to locate split debug info.
-- 
2.39.0