system/core/svchost/svchost.cpp

// Copyright 2018 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include <lib/async-loop/cpp/loop.h>
#include <lib/process-launcher/launcher.h>
#include <lib/svc/outgoing.h>
#include <zircon/status.h>

// An instance of a zx_service_provider_t.
//
// Includes the |ctx| pointer for the zx_service_provider_t.
typedef struct zx_service_provider_instance {
    // The service provider for which this structure is an instance.
    const zx_service_provider_t* provider;

    // The |ctx| pointer returned by the provider's |init| function, if any.
    void* ctx;
} zx_service_provider_instance_t;

static zx_status_t provider_init(zx_service_provider_instance_t* instance) {
    if (instance->provider->ops->init) {
        zx_status_t status = instance->provider->ops->init(&instance->ctx);
        if (status != ZX_OK)
            return status;
    }
    return ZX_OK;
}

static zx_status_t provider_publish(zx_service_provider_instance_t* instance,
                                    async_t* async, const fbl::RefPtr<fs::PseudoDir>& dir) {
    const zx_service_provider_t* provider = instance->provider;

    if (!provider->services || !provider->ops->connect)
        return ZX_ERR_INVALID_ARGS;

    for (size_t i = 0; provider->services[i]; ++i) {
        const char* service_name = provider->services[i];
        zx_status_t status = dir->AddEntry(
            service_name,
            fbl::MakeRefCounted<fs::Service>([instance, async, service_name](zx::channel request) {
                return instance->provider->ops->connect(instance->ctx, async, service_name, request.release());
            }));
        if (status != ZX_OK) {
            for (size_t j = 0; j < i; ++j)
                dir->RemoveEntry(provider->services[j]);
            return status;
        }
    }

    return ZX_OK;
}

static void provider_release(zx_service_provider_instance_t* instance) {
    if (instance->provider->ops->release)
        instance->provider->ops->release(instance->ctx);
    instance->ctx = nullptr;
}

static zx_status_t provider_load(zx_service_provider_instance_t* instance,
                                 async_t* async, const fbl::RefPtr<fs::PseudoDir>& dir) {
    if (instance->provider->version != SERVICE_PROVIDER_VERSION) {
        return ZX_ERR_INVALID_ARGS;
    }

    zx_status_t status = provider_init(instance);
    if (status != ZX_OK) {
        return status;
    }

    status = provider_publish(instance, async, dir);
    if (status != ZX_OK) {
        provider_release(instance);
        return status;
    }

    return ZX_OK;
}

int main(int argc, char** argv) {
    async::Loop loop;
    async_t* async = loop.async();
    svc::Outgoing outgoing(async);

    zx_status_t status = outgoing.ServeFromStartupInfo();
    if (status != ZX_OK) {
        fprintf(stderr, "svchost: error: Failed to serve outgoing directory: %d (%s).\n",
                status, zx_status_get_string(status));
        return 1;
    }

    zx_service_provider_instance_t launcher = {
        .provider = launcher_get_service_provider(),
        .ctx = nullptr,
    };

    status = provider_load(&launcher, async, outgoing.public_dir());
    if (status != ZX_OK) {
        fprintf(stderr, "svchost: error: Failed to load launcher service: %d (%s).\n",
                status, zx_status_get_string(status));
        return 1;
    }

    status = loop.Run();
    provider_release(&launcher);
    return status;
}