Re: [Libguestfs] [PATCH nbdkit 1/9] server: Add libnbdkit.so.

This essentially turns the whole of nbdkit into a library. There is a rump nbdkit program left which simply contains a main() function that forwards to the nbdkit_main() function in the library. The reason for this is to allow nbdkit to be compiled on Windows, because Windows does not allow shared libraries to contain any undefined symbols. nbdkit previously relied on undefined symbols in all plugins and filters (eg. nbdkit_parse_int) which get resolved at run time by the nbdkit program. In order to make this work on Windows we need to have a new library (libnbdkit.so on Linux, but probably called something like LIBNBDKIT.DLL on Windows) which will contain these symbols, and plugins can then be compiled with -lnbdkit so they will link with this library, hence no undefined symbols.

Note this change is backwards compatible. Because the rump nbdkit binary links with -lnbdkit it still contains and reexports all the symbols, so plugins and filters which don't explicitly link with -lnbdkit will still be loadable (on existing platforms). --- server/Makefile.am | 21 ++++++++------ server/main.c | 2 +- server/nbdkit.c | 46 ++++++++++++++++++++++++++++++ server/nbdkit.syms | 1 + tests/test-nbdkit-backend-debug.sh | 24 ++++++++-------- wrapper.c | 10 +++++-- 6 files changed, 80 insertions(+), 24 deletions(-)

-nbdkit_LDFLAGS = \ +libnbdkit_la_LDFLAGS = \ + -shared $(NO_UNDEFINED_ON_WINDOWS) \

+++ b/server/nbdkit.c

+#include <config.h> + +#include <stdio.h> + +extern int nbdkit_main (int argc, char *argv[]);

+ +int +main (int argc, char *argv[]) +{ + /* This does nothing except call into the real main function in + * libnbdkit.so. + */ + return nbdkit_main (argc, argv); +} diff --git a/server/nbdkit.syms b/server/nbdkit.syms index a67669b7..a516cc0f 100644 --- a/server/nbdkit.syms +++ b/server/nbdkit.syms @@ -54,6 +54,7 @@ nbdkit_extents_new; nbdkit_get_extent; nbdkit_is_tls; + nbdkit_main;