[PATCH 8/8] winedbg: Offset reported PE base address by 0x1000.

[Zebediah Figura]

On 4/2/20 8:55 AM, Rémi Bernon wrote:
> This is a horrible hack, but without it all gdb computed symbols are
> wrong. There's probably a reason behind it, but it's not clear why.
> 
> Also there's probably a better way to check if a module is PE.
> 
> Signed-off-by: Rémi Bernon <rbernon at codeweavers.com>
> ---
> 
> I'm sending this horrible hack as well because without it gdbproxy
> is still not very usable. I didn't dig very deep into the reasons behind
> it, but I'm suspecting gdb wants to be told about the modules sections,
> and not really the files mappings. Then I couldn't find a simple way to
> iterate over modules sections from another process.
> 
> Using VirtualQueryEx could help iterating over mapped modules but the
> function takes a void* as address, so that won't work if winedbg is
> 32bit and is debugging a 64bit process.

I don't think we need to care about this case. winedbg restarts itself 
as 64-bit for that specific reason.

> 
>   programs/winedbg/gdbproxy.c | 12 ++++++++++++
>   1 file changed, 12 insertions(+)
> 
> diff --git a/programs/winedbg/gdbproxy.c b/programs/winedbg/gdbproxy.c
> index c15a008c656a..79f9634aaeac 100644
> --- a/programs/winedbg/gdbproxy.c
> +++ b/programs/winedbg/gdbproxy.c
> @@ -1476,6 +1476,7 @@ static BOOL CALLBACK packet_query_libraries_cb(PCSTR mod_name, DWORD64 base, PVO
>   {
>       struct gdb_context* gdbctx = ctx;
>       IMAGEHLP_MODULE64 mod;
> +    unsigned int len;
>       DWORD64 addr;
>       BOOL is_wow64;
>       char* tmp;
> @@ -1513,6 +1514,17 @@ static BOOL CALLBACK packet_query_libraries_cb(PCSTR mod_name, DWORD64 base, PVO
>   
>       addr = mod.BaseOfImage;
>   
> +    /* FIXME: This is an ugly hack to make gdb correct about its debug
> +     * info computations with PE files. There's probably a correct way
> +     * to do it. */
> +    len = strlen(mod.LoadedImageName);
> +    if (strcmp(mod.LoadedImageName + len - 4, ".dll") == 0 ||
> +        strcmp(mod.LoadedImageName + len - 4, ".exe") == 0)
> +    {
> +        FIXME("Offsetting %s base address by 0x1000\n", mod.LoadedImageName);
> +        addr += 0x1000;
> +    }
> +
>       packet_reply_add(gdbctx, "\"><segment address=\"0x");
>       packet_reply_val(gdbctx, addr, sizeof(addr));
>       packet_reply_add(gdbctx, "\"/></library>");
>