breakpoints/2457: Incorrect handling of erroneous breakpoint conditions

[fchouinard at gmail dot com]

>Number:         2457
>Category:       breakpoints
>Synopsis:       Incorrect handling of erroneous breakpoint conditions
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue May 13 21:58:01 UTC 2008
>Closed-Date:
>Last-Modified:
>Originator:     Francois Chouinard
>Release:        GNU gdb 6.8-debian
>Organization:
>Environment:
Ubuntu 8.04 (Hardy Heron)
>Description:
When setting a condition on an existing breakpoint, GDB performs essentially the following steps (I skip the multi-location handling):

- Clear any existing condition
- Attach the new condition on the breakpoint
- Validate the condition (in context) using the parser

The problem occurs when the condition fails the validation: an exception is thrown and the subsequent longjmp() unrolls the stack beyond condition_command(). This prevents the caller from recovering from the error and leaves the breakpoint in an undesirable state (IMHO).

See the attached trace for an example.

>How-To-Repeat:
Follow the steps in the attached file.
>Fix:
Ideally, the exception should be caught and handled properly but this is a real pain in C.

There is a very simple solution (2 lines of code!) which I could provide if you want.
>Release-Note:
>Audit-Trail:
>Unformatted:
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