[binutils-gdb] When getting the locno of a bpstat, handle the case of bp with null locations.

[binutils-gdb] When getting the locno of a bpstat, handle the case of bp with null locations.

[Philippe Waroquiers]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=28a072f4af84ad295d37f8aa70c5fec9d36a274c

commit 28a072f4af84ad295d37f8aa70c5fec9d36a274c
Author: Philippe Waroquiers <philippe.waroquiers@skynet.be>
Date:   Sun Nov 20 17:42:12 2022 +0100

    When getting the locno of a bpstat, handle the case of bp with null locations.
    
    The test py-objfile.exp unloads the current file while debugging the process.
    This results in bpstat bs->b->loc to become nullptr.
    Handle this case in breakpoint.c:bpstat_locno.
    
    Note: GDB crashes on this problem with an internal error,
    but the end of gdb summary shows:
      ...
                      === gdb Summary ===
    
      # of expected passes          36
    
    The output also does not contain a 'FAIL:'.
    After the fix, the nr of expected passes increased.
    
    In the gdb.log output, one can see:
      ...
      Fatal signal: Segmentation fault
      ----- Backtrace -----
      0x55698905c5b9 gdb_internal_backtrace_1
              ../../binutils-gdb/gdb/bt-utils.c:122
      0x55698905c5b9 _Z22gdb_internal_backtracev
      ...
    
      ERROR: Couldn't send python print(objfile.filename) to GDB.
      ERROR: : spawn id exp9 not open
          while executing
      "expect {
      -i exp9 -timeout 10
              -re ".*A problem internal to GDB has been detected" {
                  fail "$message (GDB internal error)"
                  gdb_internal_error..."
          ("uplevel" body line 1)
          invoked from within
      ....
    
    Wondering if it might be possible to improve gdb_test to have
      gdb_test "python print(objfile.filename)" "None" \
          "objfile.filename after objfile is unloaded"
    reporting a failed result instead of just producing the internal error.

Diff:
---
 gdb/breakpoint.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/gdb/breakpoint.c b/gdb/breakpoint.c
index 5b691673a0e..a161b78a8aa 100644
--- a/gdb/breakpoint.c
+++ b/gdb/breakpoint.c
@@ -4486,7 +4486,7 @@ bpstat_locno (const bpstat *bs)
 
   int locno = 0;
 
-  if (b != nullptr && b->loc->next != nullptr)
+  if (b != nullptr && b->loc != nullptr && b->loc->next != nullptr)
     {
       const bp_location *bl_i;