Read binary data (from file) into a struct

I'm reading binary data from a file, specifically from a zip file. (To know more about the zip format structure see http://en.wikipedia.org/wiki/ZIP_%28file_format%29)

I've created a struct that stores the data:

typedef struct {
                                            /*Start Size            Description                                 */
    int signatute;                          /*   0  4   Local file header signature = 0x04034b50                */
    short int version;                      /*   4  2   Version needed to extract (minimum)                     */
    short int bit_flag;                     /*   6  2   General purpose bit flag                                */
    short int compression_method;           /*   8  2   Compression method                                      */
    short int time;                         /*  10  2   File last modification time                             */
    short int date;                         /*  12  2   File last modification date                             */
    int crc;                                /*  14  4   CRC-32                                                  */
    int compressed_size;                    /*  18  4   Compressed size                                         */
    int uncompressed_size;                  /*  22  4   Uncompressed size                                       */
    short int name_length;                  /*  26  2   File name length (n)                                    */
    short int extra_field_length;           /*  28  2   Extra field length (m)                                  */
    char *name;                             /*  30  n   File name                                               */
    char *extra_field;                      /*30+n  m   Extra field                                             */

} ZIP_local_file_header;

The size returned by sizeof(ZIP_local_file_header) is 40, but if the sum of each field is calculated with sizeof operator the total size is 38.

If we have the next struct:

typedef struct {
    short int x;
    int y;
} FOO;

sizeof(FOO) returns 8 because the memory is allocated with 4 bytes every time. So, to allocate x are reserved 4 bytes (but the real size is 2 bytes). If we need another short int it will fill the resting 2 bytes of the previous allocation. But as we have an int it will be allocated plus 4 bytes and the empty 2 bytes are wasted.

To read data from file, we can use the function fread:

ZIP_local_file_header p;
fread(&p,sizeof(ZIP_local_file_header),1,file);

But as there're empty bytes in the middle, it isn't read correctly.

What can I do to sequentially and efficiently store data with ZIP_local_file_header wasting no bytes?