[Libguestfs] [PATCH nbdkit 2/2] vddk: Drive library loading from libdir parameter.

[Richard W.M. Jones]

On Thu, Feb 13, 2020 at 08:23:32AM -0600, Eric Blake wrote:
> On 2/13/20 8:01 AM, Richard W.M. Jones wrote:
> >Do not use LD_LIBRARY_PATH to locate the VDDK library.  Setting this
> >always causes problems because VDDK comes bundled with broken
> >replacements for system libraries, such as libcrypto.so and
> >libstdc++.so.  Two problems this causes which we have seen in the real
> >world:
> >
> >(1) User does ‘export LD_LIBRARY_PATH=vmware-vix-disklib-distrib’ and
> >that breaks lots of ordinary utilities on their system.
> >
> >(2) nbdkit vddk --run subcommand inherits the LD_LIBRARY_PATH
> >environment variable from nbdkit, and common commands such as
> >'qemu-img' break, relying on complex workarounds like saving and
> >restoring the original LD_LIBRARY_PATH in the subcommand.
> >
> >Instead rely on a relatively undocumented feature of dlopen which is
> >that when we pass in a full path it will try to load dependent
> >libraries from the same directory.
> >
> >Note this may break some callers who are not using libdir and
> >expecting LD_LIBRARY_PATH to work, so it's a change in behaviour which
> >we will have to highlight prominently in the 1.18 release notes.
> >
> >Thanks: Dan Berrange, Ming Xie, Eric Blake.
> 
> Do you want to use Dan's preferred UTF-8 spelling?

I'll fix this.  Hope mxie doesn't mind being "romanized" :-)

> >+    if (asprintf (&path, "%s/lib%d/%s",
> >+                  libdir ? : VDDK_LIBDIR, 8*SIZEOF_LONG, sonames[i]) == -1) {
> 
> could you just spell this sizeof(long)*CHAR_BITS?
> 
> I'm guessing that the vddk files always ship with a dir/lib32/xxx.so
> and a dir/lib64/xxx.so convention?
> 
> Or, can we just hard-code the name '/lib64/', since...

It uses lib32/ or lib64/.  i386 support was dropped in VDDK > 5.1.1,
but in theory we support it.

> But the idea looks sane to me. I don't have VDDK libraries installed
> so I can't readily test it, but assume this helps.

There's a larger problem with this patch as we discussed on IRC, so
I'll try to spin a second version.

Rich.

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