On Wed, Sep 23, 2009 at 1:38 PM, Mikko Rantalainen < mikko.rantalai...@peda.net> wrote:
> I looked at the patch and it seems that the problem could be caused by
> following code:
>
> > + if (!backup_fp)
> > + {
> > + strcpy(grub_errmsg,"Unable to create the backup file");
> > + goto unable_to_save;
> > + }
> > +
> > + /* 8 bytes for embed_region.start, another 8 for core_size */
> > + int backup_img_size = core_size + GRUB_DISK_SECTOR_SIZE + 8 + 8 + 1
> /* seperation byte 0xff */ ;
> > + backup_img = (char *) xmalloc (backup_img_size);
> ...
> > +save_finish:
> > + fclose (backup_fp);
> > + free(backup_path);
> > + free(backup_img);
>
> Notice that you're using "goto" to skip initialization of backup_img and
> you blindly free()ing it in "save_finish".
>
> I think a nice way to fix this (if you want to use "goto") is to use
> multiple clean up labels. Like this:
>
> +save_cleanup_backup_img:
> + free(backup_img);
> +save_cleanup_backup_fp:
> + fclose (backup_fp);
> +save_cleanup_backup_path:
> + free(backup_path);
>
> Note that you should release the resources in reverse order compared to
> the order of acquiring the resources. If you need to bail out after you
> have acquired the backup_fp but have not yet acquired the backup_img,
> use "goto save_cleanup_backup_fp".
>
Thank you for the help. I followed your suggestion. I thought of putting a
check before freeing, but that did not remove the warning.
ChangeLog entry:
* util/i386/pc/grub-setup.c: Added sections for saving the boot + embed
sector before writing to them. Also added another
section for restoring the boot+embed sectors, given the backup file. The
backup file is relative to the root directory.
* grub-setup takes more options ( -Z to specify the backup file, -z to
restore the backup file )
I did not use indent(1), because it indented many other parts of the code,
which I did not write. I indented only my code.
Thank you,
Kashyap Garimella Jagannadh (irc: garimella )
Undergraduate student,
Department of Computer Science & Eng
Indian Instition of Technology (IIT), Madras.
patch_save_mbr_final
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