x/i 0x204c5ac. seg fault

x/i 0x204c5ac. seg fault

[Shaun Jackman]

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The following typo caused a seg fault:

GNU gdb 6.4.50.20060206-cvs
...
(gdb) x/i 0x204c5ac.
Segmentation fault

Sorry that I haven't tested a more recent version than 6.4.50.20060206-cvs.

Cheers,
Shaun
\x16º&ÖëzÛ«ŸntßÉb²Ö«r\x18\x1d

Re: x/i 0x204c5ac. seg fault

[Daniel Jacobowitz]

On Fri, Apr 28, 2006 at 11:25:20AM +0100, Dave Korn wrote:
> (gdb) x/i 0x204c5ac
> 0x204c5ac:      Cannot access memory at address 0x204c5ac

You missed the trailing ".".

The problem arises for two reasons.

1.  c-exp.y:parse_number fails to handle sscanf errors; it doesn't
    issue an error, but leaves the type unset.

2.  The system sscanf in glibc apparently rejects hex float.

-- 
Daniel Jacobowitz
CodeSourcery

RE: x/i 0x204c5ac. seg fault

[Dave Korn]

On 28 April 2006 14:13, Daniel Jacobowitz wrote:

> On Fri, Apr 28, 2006 at 11:25:20AM +0100, Dave Korn wrote:
>> (gdb) x/i 0x204c5ac
>> 0x204c5ac:      Cannot access memory at address 0x204c5ac
> 
> You missed the trailing ".".

  Oooops!  Copy'n'paste error -vs- word-selection.  Nonetheless:

dk@rainbow /usr/build/obj-gdb/gdb> ./gdb
GNU gdb 6.4.50.20060329-cvs
Copyright (C) 2006 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for details.
This GDB was configured as "i686-pc-cygwin".
Setting up the environment for debugging gdb.
No symbol table is loaded.  Use the "file" command.
No symbol table is loaded.  Use the "file" command.
/usr/build/obj-gdb/gdb/.gdbinit:8: Error in sourced command file:
No breakpoint number 0.
(gdb) x/i 0x204c5ac.
Invalid number "0x204c5ac.".
(gdb)

  :-)

> The problem arises for two reasons.
> 
> 1.  c-exp.y:parse_number fails to handle sscanf errors; it doesn't
>     issue an error, but leaves the type unset.
> 
> 2.  The system sscanf in glibc apparently rejects hex float.

  That'll be the reason I can't reproduce it.  I'm on cygwin, hence newlib
rather than glibc.


    cheers,
      DaveK
-- 
Can't think of a witty .sigline today....

Re: x/i 0x204c5ac. seg fault

[Andreas Schwab]

Daniel Jacobowitz <drow@false.org> writes:

> 2.  The system sscanf in glibc apparently rejects hex float.

A valid hex float constant always contains a 'p' or 'P'.

Andreas.

-- 
Andreas Schwab, SuSE Labs, schwab@suse.de
SuSE Linux Products GmbH, Maxfeldstraße 5, 90409 Nürnberg, Germany
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