Re: PRecord sets memory even when it says it did not

Hui Zhu
2009-09-14T04:40:04Z

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On Mon, Sep 14, 2009 at 09:54, Marc Khouzam <marc.khouzam@ericsson.com> wrote:
> Hi Hui,
>
> I'm seeing PRecord changing memory even though I answer
> the query as to not change it.  Please see below.
>
> Thanks
>
> Marc
>
> GNU gdb (GDB) 6.8.50.20090913-cvs
> Copyright (C) 2009 Free Software Foundation, Inc.
> License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
> This is free software: you are free to change and redistribute it.
> There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
> and "show warranty" for details.
> This GDB was configured as "i686-pc-linux-gnu".
> For bug reporting instructions, please see:
> <http://www.gnu.org/software/gdb/bugs/>...
> Reading symbols from /home/marc/testing/a.out...done.
> (gdb) l
> 1       int main() {
> 2           int a = 1;
> 3           int b = 10;
> 4
> 5           a++;
> 6           b++;
> 7
> 8           return a;
> 9       }
> 10
> (gdb) start
> Temporary breakpoint 1 at 0x80483f5: file b.cc, line 2.
> Starting program: /home/marc/testing/a.out
> re
> Temporary breakpoint 1, main () at b.cc:2
> 2           int a = 1;
> (gdb) record
> (gdb) n
> 3           int b = 10;
> (gdb) n
> 5           a++;
> (gdb) n
> 6           b++;
> (gdb) rn
> 5           a++;
> (gdb) p a
> $1 = 1
> (gdb) set var a = 8
> Because GDB is in replay mode, writing to memory will make the execution log unusable from this point onward.  Write memory at address 0xbffff6a0?(y or [n]) n
> Process record canceled the operation.
> (gdb) p a
> $2 = 8
>

Hi Marc,

Thanks for your help.

I just tried change it with "p a=99". I think it must have something
different with "set var a = 8".

This issue is because some value cache about the memory. So I add a
"free_all_values ();" before error.
It looks OK now. Please help me try it.

Thanks,
Hui

2009-09-14 Hui Zhu <teawater@gmail.com>

* record.c (record_xfer_partial): Call free_all_values when
cancel the operation.

---
record.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

--- a/record.c
+++ b/record.c
@@ -1023,7 +1023,10 @@ record_xfer_partial (struct target_ops *
"will make the execution log unusable from this "
"point onward. Write memory at address %s?"),
paddress (target_gdbarch, offset)))
- error (_("Process record canceled the operation."));
+ {
+ free_all_values ();
+ error (_("Process record canceled the operation."));
+ }

/* Destroy the record from here forward. */
record_list_release_next ();

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---
record.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

--- a/record.c
+++ b/record.c
@@ -1023,7 +1023,10 @@ record_xfer_partial (struct target_ops *
"will make the execution log unusable from this "
"point onward. Write memory at address %s?"),
paddress (target_gdbarch, offset)))
- error (_("Process record canceled the operation."));
+ {
+ free_all_values ();
+ error (_("Process record canceled the operation."));
+ }

/* Destroy the record from here forward. */
record_list_release_next ();