c - segmentation fault while using fread and not able to read the data from the file -

here want copy data file enter_data , pass function insert(key,keys) segmentation fault , more on not able read data file

here classifier structure, , packet_filter has structure of ip , udp in want enter src , dst ip adddress , src , dst port number

    struct classifier     {         int key_node;         struct packet_filter pktfltr;         struct classifier *next;     }__attribute__((packed));         void addrule(struct classifier keys)     {             int key;             file *fp;             fp = fopen("enter_data","r");             fread(&keys, sizeof (struct classifier), 3, fp);             insert(key,keys);             fclose(fp);     } 

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                    file: enter_data          key = 822;         keys.key_node = 822;         inet_aton("172.28.6.137", &(keys.pktfltr.ip.ip_src));         inet_aton("172.28.6.10",&(keys.pktfltr.ip.ip_dst));         keys.pktfltr.protocol.proto.uh_sport = ntohs(1032);         keys.pktfltr.protocol.proto.uh_dport = ntohs(5000);         keys.next = null;           key = 522 ;         keys.key_node = 522;         inet_aton("172.28.6.87", &(keys.pktfltr.ip.ip_src));         inet_aton("172.28.6.110",&(keys.pktfltr.ip.ip_dst));         keys.pktfltr.protocol.proto.uh_sport = ntohs(1032);         keys.pktfltr.protocol.proto.uh_dport = ntohs(5010);         keys.next = null;          key = 522 ;         keys.key_node = 522;         inet_aton("172.28.6.87", &(keys.pktfltr.ip.ip_src));         inet_aton("172.28.6.110",&(keys.pktfltr.ip.ip_dst));         keys.pktfltr.protocol.proto.uh_sport = ntohs(1032);         keys.pktfltr.protocol.proto.uh_dport = ntohs(5011);         keys.next = null; 

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this not work, because try read binary file, while file text.

second - need check if fp null after trying open file - advice.

third - if file binary, wouldn't work,

fread(&keys, sizeof (struct classifier), 3, fp); 

should

//                                      vvv fread(&keys, sizeof (struct classifier), 1, fp); 

as keys not array , need read on block.