[Crash-utility] [PATCH] Fix for some command-line cases an unintended unlink of a file crash didn't create and a leftover temporary

[Dave Anderson]

----- Original Message -----
> When the crash command line includes two filenames where one is a
> compressed kernel and the other is a debuginfo file and they appear in
> that order then if the uncompressed temporary version of the kernel is
> actually larger than the debuginfo then crash will end with an error but
> will also unlink the debuginfo file and will not clean up the (intended
> temporary) uncompressed copy of the kernel.

Hi Dave,

It's taken me awhile to wrap my head around this, but my first question is: 
how is it possible that the uncompressed stripped kernel can possibly be
larger than the debuginfo file?  

I only have old RHEL3 kernels as examples, but the .debug versions
of the kernel are 5 to 6 times larger than the stripped kernel. 

> This patch at least fixes the unintended unlink and leaving the
> temporary present. It doesn't fix the failure to start but that's
> because the wrong files are assumed the debuginfo and kernel. The size
> case that led to this discovery is probably rare.

Is the unintended unlink() done in the first display_sys_stats() or
in clean_exit()?

And then with your fix applied, why does the crash session still fail?

Dave

 
> The cause is that evidence of a temporary file to unlink is that there
> is a value in pc->namelist and pc->namelist_orig (or pc->namelist_debug
> and pc->namelist_orig_debug) but when the file size test in
> select_namelist() results in the pc->namelist copy to pc->namelist_debug
> the _orig is not copied as well so the implied file to unlink is the one
> set in pc->namelist (the debuginfo filename now).
> 
> The patch causes a populated namelist_orig value to be swapped with
> namelist_debug_orig if the namelist value is copied to namelist_debug.
> 
>     Signed-off-by: David Mair <dmair at suse.com>
> ---
>  symbols.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/symbols.c b/symbols.c
> index 4c6fbf4..e1ed719 100644
> --- a/symbols.c
> +++ b/symbols.c
> @@ -3520,6 +3520,7 @@ int
>  select_namelist(char *new)
>  {
>         struct stat stat1, stat2;
> +       char *namecp;
> 
>         if (pc->server_namelist) {
>                 pc->namelist_debug = new;
> @@ -3533,6 +3534,12 @@ select_namelist(char *new)
> 
>         if (stat1.st_size > stat2.st_size) {
>                 pc->namelist_debug = pc->namelist;
> +               if (pc->namelist_orig)
> +               {
> +                       namecp = pc->namelist_debug_orig;
> +                       pc->namelist_debug_orig = pc->namelist_orig;
> +                       pc->namelist_orig = namecp;
> +               }
>                 pc->namelist = new;
>         } else if (stat2.st_size > stat1.st_size)
>                 pc->namelist_debug = new;
> 
> --
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