[binutils-gdb] [gdb/symtab] Handle failure to open .gnu_debugaltlink file

[binutils-gdb] [gdb/symtab] Handle failure to open .gnu_debugaltlink file

[Tom de Vries]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=05ad0d60341f0933501dc90002da3d4594c30438

commit 05ad0d60341f0933501dc90002da3d4594c30438
Author: Tom de Vries <tdevries@suse.de>
Date:   Sat Nov 26 14:13:06 2022 +0100

    [gdb/symtab] Handle failure to open .gnu_debugaltlink file
    
    If we instrument cc-with-tweaks.sh to remove the .gnu_debugaltlink file after
    dwz has created it, with test-case
    gdb.threads/access-mem-running-thread-exit.exp and target board cc-with-dwz-m
    we run into:
    ...
    (gdb) file access-mem-running-thread-exit^M
    Reading symbols from access-mem-running-thread-exit...^M
    could not find '.gnu_debugaltlink' file for access-mem-running-thread-exit^M
    ...
    followed a bit later by:
    ...
    (gdb) file access-mem-running-thread-exit^M
    Reading symbols from access-mem-running-thread-exit...^M
    gdb/dwarf2/read.c:7284: internal-error: create_all_units: \
      Assertion `per_objfile->per_bfd->all_units.empty ()' failed.^M
    ...
    
    The problem is that create_units does not catch the error thrown by
    dwarf2_get_dwz_file.
    
    Fix this by catching the error and performing the necessary cleanup, getting
    the same result for the first and second file command.
    
    PR symtab/29805
    Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29805

Diff:
---
 gdb/dwarf2/read.c                             | 11 +++++-
 gdb/testsuite/gdb.dwarf2/no-gnu-debuglink.exp | 48 +++++++++++++++++++++++++++
 2 files changed, 58 insertions(+), 1 deletion(-)

diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index 60e120a9d76..53a6a8b5e6d 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -7291,7 +7291,16 @@ create_all_units (dwarf2_per_objfile *per_objfile)
 				  &per_objfile->per_bfd->abbrev, 0,
 				  types_htab, rcuh_kind::TYPE);
 
-  dwz_file *dwz = dwarf2_get_dwz_file (per_objfile->per_bfd);
+  dwz_file *dwz;
+  try
+    {
+      dwz = dwarf2_get_dwz_file (per_objfile->per_bfd);
+    }
+  catch (const gdb_exception_error &)
+    {
+      per_objfile->per_bfd->all_units.clear ();
+      throw;
+    }
   if (dwz != NULL)
     {
       /* Pre-read the sections we'll need to construct an index.  */
diff --git a/gdb/testsuite/gdb.dwarf2/no-gnu-debuglink.exp b/gdb/testsuite/gdb.dwarf2/no-gnu-debuglink.exp
new file mode 100644
index 00000000000..73f7233192e
--- /dev/null
+++ b/gdb/testsuite/gdb.dwarf2/no-gnu-debuglink.exp
@@ -0,0 +1,48 @@
+# Copyright 2022 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU 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 General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# Check that loading a file with a broken .gnu_debugaltlink doesn't crash gdb.
+
+load_lib dwarf.exp
+
+# This test can only be run on targets which support DWARF-2 and use gas.
+if {![dwarf2_support]} {
+    return 0
+}
+
+# No remote host testing either.
+if {[is_remote host]} {
+    return 0
+}
+
+standard_testfile main.c no-gnu-debuglink.S
+
+set asm_file [standard_output_file $srcfile2]
+
+Dwarf::assemble $asm_file {
+    gnu_debugaltlink "file-not-here" "0000000000000000000000000000000000000000"
+}
+
+if { [build_executable $testfile.exp $testfile [list $srcfile $asm_file]] } {
+    return -1
+}
+
+clean_restart
+
+set msg "\r\ncould not find '\.gnu_debugaltlink' file for \[^\r\n\]*"
+gdb_test "file $binfile" "$msg" "file command"
+
+set question "Load new symbol table from .*\? .y or n. "
+gdb_test "file $binfile" "$msg" "file command, again" $question "y"