* Neal H. Walfield: > Hi Florian, > > On Tue, 10 May 2022 12:04:52 +0200, > Florian Weimer wrote: >> * Neal H. Walfield: >> >> > There are two major constraints. Because rpm's OpenPGP API is public, >> > it must be preserved until the next soname bump. And, the OpenPGP >> > backend should be pluggable. >> >> How is this plug-in mechanism supposed to work? Via RPM configuration >> files? > > It is a build-time configuration option. When you configure rpm, you > can do: > > ./configure --with-crypto=sequoia > > to get the Sequoia backend. --with-crypto defaults to libgcrypt, > which uses the internal OpenPGP implementation with libgcrypt. (There > is also --with-crypto=openssl, which uses the internal OpenPGP > implementation with OpenSSL.)
That's a very limited form of pluggability. I expect the most portable approach (for ELF targets) is to use a stub shared object that contains all symbols, including those provided by dependencies. (librpmio.so should probably be a linker script referencing the actual object, to prevent accidental loading of librpmio.so via dlopen.) That approach keeps the run-time DT_NEEDED value an implementation detail. I don't know if libtool supports that out of the box. On non-ELF targets, you may need forwarder functions, and the plug-in library cannot use the same symbols. Thanks, Florian
