While RPM packages have a robust ecosystem around them for programmatically retrieving information about package metadata, the Debian package management system is sorely lacking in this respect.
Here is a simple C example which demonstrates how to programmatically list all installed Debian packages.
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <dpkg/dpkg.h>
#include <dpkg/dpkg-db.h>
#include <dpkg/pkg-array.h>
#include "filesdb.h"
const char thisname[] = "example1";
int
main(int argc, const char *const *argv)
{
struct pkg_array array;
struct pkginfo *pkg;
int i;
enum modstatdb_rw msdb_status;
standard_startup();
filesdbinit();
msdb_status = modstatdb_open(msdbrw_readonly);
pkg_infodb_init(msdb_status);
pkg_array_init_from_db(&array);
pkg_array_sort(&array, pkg_sorter_by_name);
for (i = 0; i < array.n_pkgs; i++) {
pkg = array.pkgs[i];
if (pkg->status == stat_notinstalled)
continue;
printf("Package --> %sn", pkg->set->name);
}
pkg_array_destroy(&array);
modstatdb_shutdown();
standard_shutdown();
}
You also need the following files from the dpkg source code:
config.h strnlen.h ehandle.h filesdb.h infodb.h main.h filesdb.c infodb.c libdpkg.a
Here is how to build the example:
gcc -c -DLIBDPKG_VOLATILE_API -I. example.c infodb.c filesdb.c gcc -DLIBDPKG_VOLATILE_API -o example example.o filesdb.o infodb.o ./libdpkg.a
In case you were wondering, there is no dynamic version of libdpkg and neither is there a published API for this library.
If you need a complete solution to programmatically interacting with the Debian package management system using C or C++, please contact me for details.
