Simple setup implementation

gaps_channel_setup.c

#include <libpirate/primitives.h>
#include <linux/limits.h>
#include <stdlib.h>
#include <string.h>

#include "gaps_resources.h"
// ^ declares resource and resource_parameter structs, as well as communication
// functions gaps_request_resource() and gaps_signal_failure()

extern struct gaps_resource *__gaps_channel_gaps_resources;
// ^ defined by the linker as
//     struct resource __<resource_type>_gaps_resources;
// for each declared resource type
//
// by convention, maybe terminated by a resource with all zero fields

struct gaps_channel_config {
    char path[PATH_MAX];
    int flags;
    // more fields here, obviously
};

__attribute__((constructor))
void setup_gaps_channels_auto(void) {
    char *fdstr = getenv("__GAPS_RUN_FD");
    if(!fdstr)
        exit(1);
    int fd = atoi(fdstr);

    int i;
    for(i = 0; __gaps_channel_gaps_resources[i].gr_name; ++i) {
        struct gaps_resource const *r = &__gaps_channel_gaps_resources[i];
        struct gaps_channel_config cfg;

        // check parameter list to we whether resource should be automatically
        // initialized
        int j, manual_init = 0;
        for(j = 0; r->gr_params[j].grp_name; ++j) {
            struct gaps_resource_param *rp = &r->gr_params[j];

            if(!strcmp(rp->grp_name, "init") && !strcmp(rp->grp_value, "manual"))
                ++manual_init;
        }
        if(manual_init)
            continue;

        // request resource config
        if(gaps_request_resource(r->gr_obj, &cfg, r->gr_name, r->gr_type, fd)) {
            gaps_signal_failure(fd, "no configuration for channel %s", r->gr_name);
            exit(1);
        }

        // perform configuration
        if(pirate_set_pathname(*(int*)r->gr_obj, cfg.path)) {
            gaps_signal_failure(fd, "unable to set path channel %s", r->gr_name);
            exit(1);
        }
        // more config ...
        if(pirate_open(fd, cfg.flags)) {
            gaps_signal_failure(fd, "unable to open channel %s", r->gr_name);
            exit(1);
        }
    }
}

gaps_resources.h

struct gaps_resource_param {
    char *grp_name;
    char *grp_value;
};

struct gaps_resource {
    char *gr_name;
    char *gr_type;
    void *gr_obj;
    struct gaps_resource_param *gr_params;
};

int gaps_request_resource(void *obj, void *cfg, char *name, char *type, int fd);

int gaps_signal_failure(int fd, char *fmt, ...);