[Bug symtab/15719] New: watch -l crash

[Bug symtab/15719] New: watch -l crash

[jan.kratochvil at redhat dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=15719

            Bug ID: 15719
           Summary: watch -l crash
           Product: gdb
           Version: HEAD
            Status: NEW
          Severity: normal
          Priority: P2
         Component: symtab
          Assignee: unassigned at sourceware dot org
          Reporter: jan.kratochvil at redhat dot com
            Target: x86_64-unknown-linux-gnu

echo 'struct { struct {} *p; } *v; int main(void) { return 0; }'|gcc -Wall -g
-x c -; gdb ./a.out -ex start -ex 'watch -l v->p->x'

GNU gdb (GDB) 7.6.50.20130704-cvs
[...]
Temporary breakpoint 1, main () at <stdin>:1
1    <stdin>: No such file or directory.
Segmentation fault

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[Bug symtab/15719] watch -l crash

[jan.kratochvil at redhat dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=15719

Jan Kratochvil <jan.kratochvil at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jan.kratochvil at redhat dot com

--- Comment #1 from Jan Kratochvil <jan.kratochvil at redhat dot com> ---
Found by Petr Spacek: https://bugzilla.redhat.com/show_bug.cgi?id=921078

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[Bug symtab/15719] watch -l crash

[tromey at redhat dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=15719

Tom Tromey <tromey at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |tromey at redhat dot com

--- Comment #2 from Tom Tromey <tromey at redhat dot com> ---
I have a patch that changes it to:

(gdb) watch -l v->p->x
Cannot access memory at address 0x0

I'm running it through regression-testing now.
Basically this just amounts to letting fetch_subexp_value pass
through MEMORY_ERROR in this case.

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[Bug symtab/15719] watch -l crash

[tromey at redhat dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=15719

Tom Tromey <tromey at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Assignee|unassigned at sourceware dot org   |tromey at redhat dot com

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[Bug symtab/15719] watch -l crash

[tromey at redhat dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=15719

--- Comment #3 from Tom Tromey <tromey at redhat dot com> ---
It's also weird that this doesn't emit an error about "x"
not being a field.

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[Bug symtab/15719] watch -l crash

[cvs-commit at gcc dot gnu.org]

http://sourceware.org/bugzilla/show_bug.cgi?id=15719

--- Comment #4 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> ---
CVSROOT:    /cvs/src
Module name:    src
Changes by:    tromey@sourceware.org    2013-08-02 16:41:08

Modified files:
    gdb            : ChangeLog breakpoint.c eval.c ppc-linux-nat.c 
                     value.h 
    gdb/testsuite  : ChangeLog 
    gdb/testsuite/gdb.base: watchpoint.c watchpoint.exp 

Log message:
    fix PR symtab/15719

    This patch fixes PR symtab/15719.

    The bug is that "watch -location" crashes on a certain expression.

    The problem is that fetch_subexp_value is catching an exception.
    For ordinary watchpoints this is ok; but for location watchpoints,
    it is better for the exception to propagate.

    Built and regtested on x86-64 Fedora 18.
    New test case included.

    PR symtab/15719:
    * breakpoint.c (update_watchpoint, watchpoint_check)
    (watch_command_1): Update.
    * eval.c (fetch_subexp_value): Add "preserve_errors"
    parameter.
    * ppc-linux-nat.c (check_condition): Update.
    * value.h (fetch_subexp_value): Update.

    * gdb.base/watchpoint.c (struct foo5): New.
    (nullptr): New global.
    * gdb.base/watchpoint.exp (test_watch_location): Add test.

Patches:
http://sourceware.org/cgi-bin/cvsweb.cgi/src/gdb/ChangeLog.diff?cvsroot=src&r1=1.15860&r2=1.15861
http://sourceware.org/cgi-bin/cvsweb.cgi/src/gdb/breakpoint.c.diff?cvsroot=src&r1=1.773&r2=1.774
http://sourceware.org/cgi-bin/cvsweb.cgi/src/gdb/eval.c.diff?cvsroot=src&r1=1.184&r2=1.185
http://sourceware.org/cgi-bin/cvsweb.cgi/src/gdb/ppc-linux-nat.c.diff?cvsroot=src&r1=1.123&r2=1.124
http://sourceware.org/cgi-bin/cvsweb.cgi/src/gdb/value.h.diff?cvsroot=src&r1=1.222&r2=1.223
http://sourceware.org/cgi-bin/cvsweb.cgi/src/gdb/testsuite/ChangeLog.diff?cvsroot=src&r1=1.3757&r2=1.3758
http://sourceware.org/cgi-bin/cvsweb.cgi/src/gdb/testsuite/gdb.base/watchpoint.c.diff?cvsroot=src&r1=1.10&r2=1.11
http://sourceware.org/cgi-bin/cvsweb.cgi/src/gdb/testsuite/gdb.base/watchpoint.exp.diff?cvsroot=src&r1=1.65&r2=1.66

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[Bug symtab/15719] watch -l crash

[tromey at redhat dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=15719

Tom Tromey <tromey at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED
   Target Milestone|---                         |7.7

--- Comment #5 from Tom Tromey <tromey at redhat dot com> ---
Fixed.

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