邮件队列-动态邮件大小-C

/* header */
typedef struct{  
    long type;  
    char data[BUFFER_SIZE];
}msg;

/* main */
msg m;
msgrcv(queueid, &m, BUFFER_SIZE, 0, 0);

// header
typedef struct{  
    long type;  
    char *data;
}msg;

// main
msg m;
m.data = (char*) malloc( BUFFER_SIZE );
msgrcv(queueid, &m, BUFFER_SIZE, 0, 0);

msgsnd()

msgrcv()

typedef struct{  
    long type;  
    char data[1];
}msg;

msg * m = malloc(sizeof(msg) - 1 + NeededSize);
msgrcv(queueid, m, NeededSize, 0, 0);

... // treat m as if the data array was NeededSize elements long
free(m);