Re: GHC static binaries with glibc-2.12?

11 Oct 2010

      On 10/10/2010 05:22, Alexander Dunlap wrote:
...
On Fri, Oct 8, 2010 at 12:46 AM, Simon Marlow  wrote:
...
On 08/10/2010 03:23, Alexander Dunlap wrote:
...
I recently upgraded my Arch Linux system to glibc 2.12 and static
binaries compiled with GHC 6.12.3 all fail with the message
"mkTextEncoding: invalid argument (Invalid argument)". This did not
happen with glibc 2.11. Has anyone else had this problem? Does anyone
have any advice for debugging it?
Probably something to do with iconv.  Doesn't iconv need to load its codec
modules dynamically at runtime?
Cheers,
        Simon
Yes, it does, but strace seems to show that the program is looking in
the right place for the iconv libraries. Is there some way to step
through the code of a statically-linked program? I'm not sure how to
proceed debugging a Haskell-originated error that only occurs with
static linking (so I can't use the GHCi debugger).
The error is almost certainly being returned by iconv(), which is called 
via this wrapper in base/cbits/iconv.c:

size_t hs_iconv(iconv_t cd,
		const char* * inbuf, size_t * inbytesleft,
		char* * outbuf, size_t * outbytesleft)
{
     // (void*) cast avoids a warning.  Some iconvs use (const
     // char**inbuf), other use (char **inbuf).
     return iconv(cd, (void*)inbuf, inbytesleft, outbuf, outbytesleft);
}

you could run the program in gdb and set a breakpoint on hs_iconv, or 
iconv itself.  Since it will be compiled without debugging information 
you'll have to poke around on the C stack yourself to find the arguments.

Alternatively get a GHC build and instrument the code in 
libraries/base/GHC/IO/Encoding/IConv.hs to see what's going on.

Cheers,
	Simon