C code not working in C++ after using inside extern block

Question

This is the code that is working fine when compiling in C:

#include <stdio.h>
#include <unistd.h>
#include <sys/socket.h>
#include <bluetooth/bluetooth.h>
#include <bluetooth/sdp.h>
#include <bluetooth/sdp_lib.h>
#include <bluetooth/rfcomm.h>


sdp_session_t *register_service(uint8_t rfcomm_channel) {
    uint32_t svc_uuid_int[] = { 0x01110000, 0x00100000, 0x80000080, 0xFB349B5F };
    const char *service_name = "Armatus Bluetooth server";
    const char *svc_dsc = "A HERMIT server that interfaces with the Armatus Android app";
    const char *service_prov = "Armatus";

    uuid_t root_uuid, l2cap_uuid, rfcomm_uuid, svc_uuid,
            svc_class_uuid;
    sdp_list_t *l2cap_list = 0,
            *rfcomm_list = 0,
            *root_list = 0,
            *proto_list = 0,
            *access_proto_list = 0,
            *svc_class_list = 0,
            *profile_list = 0;
    sdp_data_t *channel = 0;
    sdp_profile_desc_t profile;
    sdp_record_t record = { 0 };
    sdp_session_t *session = 0;

    // set the general service ID
    sdp_uuid128_create(&svc_uuid, &svc_uuid_int);
    sdp_set_service_id(&record, svc_uuid);

    char str[256] = "";
    sdp_uuid2strn(&svc_uuid, str, 256);
    printf("Registering UUID %s\n", str);

    // set the service class
    sdp_uuid16_create(&svc_class_uuid, SERIAL_PORT_SVCLASS_ID);
    svc_class_list = sdp_list_append(0, &svc_class_uuid);
    sdp_set_service_classes(&record, svc_class_list);

    // set the Bluetooth profile information
    sdp_uuid16_create(&profile.uuid, SERIAL_PORT_PROFILE_ID);
    profile.version = 0x0100;
    profile_list = sdp_list_append(0, &profile);
    sdp_set_profile_descs(&record, profile_list);

    // make the service record publicly browsable
    sdp_uuid16_create(&root_uuid, PUBLIC_BROWSE_GROUP);
    root_list = sdp_list_append(0, &root_uuid);
    sdp_set_browse_groups(&record, root_list);

    // set l2cap information
    sdp_uuid16_create(&l2cap_uuid, L2CAP_UUID);
    l2cap_list = sdp_list_append(0, &l2cap_uuid);
    proto_list = sdp_list_append(0, l2cap_list);

    // register the RFCOMM channel for RFCOMM sockets
    sdp_uuid16_create(&rfcomm_uuid, RFCOMM_UUID);
    channel = sdp_data_alloc(SDP_UINT8, &rfcomm_channel);
    rfcomm_list = sdp_list_append(0, &rfcomm_uuid);
    sdp_list_append(rfcomm_list, channel);
    sdp_list_append(proto_list, rfcomm_list);

    access_proto_list = sdp_list_append(0, proto_list);
    sdp_set_access_protos(&record, access_proto_list);

    // set the name, provider, and description
    sdp_set_info_attr(&record, service_name, service_prov, svc_dsc);

    // connect to the local SDP server, register the service record,
    // and disconnect
    session = sdp_connect(BDADDR_ANY, BDADDR_LOCAL, SDP_RETRY_IF_BUSY);
    sdp_record_register(session, &record, 0);

    // cleanup
    sdp_data_free(channel);
    sdp_list_free(l2cap_list, 0);
    sdp_list_free(rfcomm_list, 0);
    sdp_list_free(root_list, 0);
    sdp_list_free(access_proto_list, 0);
    sdp_list_free(svc_class_list, 0);
    sdp_list_free(profile_list, 0);

    return session;
}

int init_server() {
    int port = 3, result, sock, client, bytes_read, bytes_sent;
    struct sockaddr_rc loc_addr = { 0 }, rem_addr = { 0 };
    char buffer[1024] = { 0 };
    socklen_t opt = sizeof(rem_addr);

    // local bluetooth adapter
    loc_addr.rc_family = AF_BLUETOOTH;
    loc_addr.rc_bdaddr = *BDADDR_ANY;
    loc_addr.rc_channel = (uint8_t) port;

    // register service
    sdp_session_t *session = register_service(port);

    // allocate socket
    sock = socket(AF_BLUETOOTH, SOCK_STREAM, BTPROTO_RFCOMM);
    printf("socket() returned %d\n", sock);

    // bind socket to port 3 of the first available
    result = bind(sock, (struct sockaddr *)&loc_addr, sizeof(loc_addr));
    printf("bind() on channel %d returned %d\n", port, result);

    // put socket into listening mode
    result = listen(sock, 1);
    printf("listen() returned %d\n", result);

    //sdpRegisterL2cap(port);

    // accept one connection
    printf("calling accept()\n");
    client = accept(sock, (struct sockaddr *)&rem_addr, &opt);
    printf("accept() returned %d\n", client);

    ba2str(&rem_addr.rc_bdaddr, buffer);
    fprintf(stderr, "accepted connection from %s\n", buffer);
    memset(buffer, 0, sizeof(buffer));

    return client;
}
int main(){
    return init_server();
}

But when I copy this code in C++ like this:

#include <iostream>
extern "C"{
#include <stdio.h>
#include <unistd.h>
#include <sys/socket.h>
#include <bluetooth/bluetooth.h>
#include <bluetooth/sdp.h>
#include <bluetooth/sdp_lib.h>
#include <bluetooth/rfcomm.h>
    uint32_t svc_uuid_int[] = { 0x01110000, 0x00100000, 0x80000080, 0xFB349B5F };
    const char *service_name = "Armatus Bluetooth server";
    const char *svc_dsc = "A HERMIT server that interfaces with the Armatus Android app";
    const char *service_prov = "Armatus";

    uuid_t root_uuid, l2cap_uuid, rfcomm_uuid, svc_uuid,
            svc_class_uuid;
    sdp_list_t *l2cap_list = 0,
            *rfcomm_list = 0,
            *root_list = 0,
            *proto_list = 0,
            *access_proto_list = 0,
            *svc_class_list = 0,
            *profile_list = 0;
    sdp_data_t *channel = 0;
    sdp_profile_desc_t profile;
    sdp_record_t record = { 0 };
    sdp_session_t *session = 0;

    // set the general service ID
    sdp_uuid128_create(&svc_uuid, &svc_uuid_int);
    sdp_set_service_id(&record, svc_uuid);

    char str[256] = "";
    sdp_uuid2strn(&svc_uuid, str, 256);
    printf("Registering UUID %s\n", str);

    // set the service class
    sdp_uuid16_create(&svc_class_uuid, SERIAL_PORT_SVCLASS_ID);
    svc_class_list = sdp_list_append(0, &svc_class_uuid);
    sdp_set_service_classes(&record, svc_class_list);

    // set the Bluetooth profile information
    sdp_uuid16_create(&profile.uuid, SERIAL_PORT_PROFILE_ID);
    profile.version = 0x0100;
    profile_list = sdp_list_append(0, &profile);
    sdp_set_profile_descs(&record, profile_list);

    // make the service record publicly browsable
    sdp_uuid16_create(&root_uuid, PUBLIC_BROWSE_GROUP);
    root_list = sdp_list_append(0, &root_uuid);
    sdp_set_browse_groups(&record, root_list);

    // set l2cap information
    sdp_uuid16_create(&l2cap_uuid, L2CAP_UUID);
    l2cap_list = sdp_list_append(0, &l2cap_uuid);
    proto_list = sdp_list_append(0, l2cap_list);

    // register the RFCOMM channel for RFCOMM sockets
    sdp_uuid16_create(&rfcomm_uuid, RFCOMM_UUID);
    channel = sdp_data_alloc(SDP_UINT8, &rfcomm_channel);
    rfcomm_list = sdp_list_append(0, &rfcomm_uuid);
    sdp_list_append(rfcomm_list, channel);
    sdp_list_append(proto_list, rfcomm_list);

    access_proto_list = sdp_list_append(0, proto_list);
    sdp_set_access_protos(&record, access_proto_list);

    // set the name, provider, and description
    sdp_set_info_attr(&record, service_name, service_prov, svc_dsc);

    // connect to the local SDP server, register the service record,
    // and disconnect
    session = sdp_connect(BDADDR_ANY, BDADDR_LOCAL, SDP_RETRY_IF_BUSY);
    sdp_record_register(session, &record, 0);

    // cleanup
    sdp_data_free(channel);
    sdp_list_free(l2cap_list, 0);
    sdp_list_free(rfcomm_list, 0);
    sdp_list_free(root_list, 0);
    sdp_list_free(access_proto_list, 0);
    sdp_list_free(svc_class_list, 0);
    sdp_list_free(profile_list, 0);

    return session;
}

int init_server() {
    int port = 3, result, sock, client, bytes_read, bytes_sent;
    struct sockaddr_rc loc_addr = { 0 }, rem_addr = { 0 };
    char buffer[1024] = { 0 };
    socklen_t opt = sizeof(rem_addr);

    // local bluetooth adapter
    loc_addr.rc_family = AF_BLUETOOTH;
    loc_addr.rc_bdaddr = *BDADDR_ANY;
    loc_addr.rc_channel = (uint8_t) port;

    // register service
    sdp_session_t *session = register_service(port);

    // allocate socket
    sock = socket(AF_BLUETOOTH, SOCK_STREAM, BTPROTO_RFCOMM);
    printf("socket() returned %d\n", sock);

    // bind socket to port 3 of the first available
    result = bind(sock, (struct sockaddr *)&loc_addr, sizeof(loc_addr));
    printf("bind() on channel %d returned %d\n", port, result);

    // put socket into listening mode
    result = listen(sock, 1);
    printf("listen() returned %d\n", result);

    //sdpRegisterL2cap(port);

    // accept one connection
    printf("calling accept()\n");
    client = accept(sock, (struct sockaddr *)&rem_addr, &opt);
    printf("accept() returned %d\n", client);

    ba2str(&rem_addr.rc_bdaddr, buffer);
    fprintf(stderr, "accepted connection from %s\n", buffer);
    memset(buffer, 0, sizeof(buffer));

    return client;
}
}
int main()
{
    init_server();
}

It gives the following compile time error:

In file included from test.cpp:9:0: test.cpp: In function ‘sdp_session_t* register_service(uint8_t)’: test.cpp:115:27: error:taking address of temporary [-fpermissive] session = sdp_connect(BDADDR_ANY, BDADDR_LOCAL, SDP_RETRY_IF_BUSY); ^ test.cpp:115:39: error: taking address of temporary [-fpermissive] session = sdp_connect(BDADDR_ANY, BDADDR_LOCAL, SDP_RETRY_IF_BUSY); ^ test.cpp: In function ‘int init_server()’: test.cpp:138:27: error: taking address of temporary [-fpermissive] loc_addr.rc_bdaddr = *BDADDR_ANY;

What can I do?? Please help.

Are you compiling C or C++? Remove the other language tag, it is misplaced here. Also, you really need to extract a [mcve]. There's way too much code here. — Ulrich Eckhardt, Dec 04 '18 at 19:36
C++ and C are *not* the same language. And the subset of C that has equivalent semantics in C++ is getting smaller every year (but lots of syntax remains that is both valid C and C++ but has *completely different* semantics). You need to decide whether you are writing C or C++. It matters; things that look the same in source code may behave *very* different depending on your language choice. — Jesper Juhl, Dec 04 '18 at 19:39
Why do you think the `extern "C"` block has anything to do with it? Did you try without it and succeed? — molbdnilo, Dec 04 '18 at 19:41
@molbdnilo "This is the code that is working fine when compiling in C:" .. i think the two codes are the same apart from adding `extern "C"` — 463035818_is_not_an_ai, Dec 04 '18 at 19:43
you misunderstand what `extern "C" {... }` is good for. I cannot explain either, but in a nutshell: It lets you declare functions than can be called from a C program. It is not to copy past C code and compile it as C++ — 463035818_is_not_an_ai, Dec 04 '18 at 19:47
to answer your question literally: If you have code in one language and you need code in a different lanuguage you have to a) understand what the code does b) rewrite it in the other language. Writing lots of test can help and a sound understanding of both languages is probably inevitable. — 463035818_is_not_an_ai, Dec 04 '18 at 19:52
ok sorry guys...i searched but maybe not well...also i am not a C/C++ expert. It's just the code I have to write to test my Android app. — Ryosuke, Dec 04 '18 at 20:17

C code not working in C++ after using inside extern block

0 Answers0