Question

大家晚上好。

我现在遇到了一个奇怪的警告，对于我的生活，我无法弄清楚它出了什么问题。我已经尝试了很多我不记得的不同选择。

错误是：

从不兼容的指针类型分配

相关代码：

// Server structure
typedef struct {
    struct addrinfo address;        // Address info
    char buffer[1024];              // Read biffer
    fd_set connections;             // Current connections
    int connections_max;            // Max file descriptor
    int listener;                   // Listener fd
    int port;                       // The port for the server to listen on
    struct addrinfo socket_hints;   // Server's socket hints
    struct timeval socket_timeout;  // When should the socket timeout?
    struct User *users;             // Currently connected users
} Server;

// User structure
typedef struct {
    struct sockaddr_storage address;    // User's address
    socklen_t address_length;           // Length of users address
    int fs_id;                          // ID to the socket they belong to
    char ip_address[INET6_ADDRSTRLEN];  // User's IP address
    char *name;                         // Pointer to the user's name
    struct User *nextUser;              // Next user in the list
} User;

/**
 * Handles sockets on the provided server
 */
void handle_sockets(Server *passed_server) {
    int current_fd;             // Current file descriptor
    int new_connection;         // Socket ID of new connections
    fd_set read_sockets;        // Sockets to read from
    FD_ZERO(&read_sockets);
    struct timeval timeout;     // Sets the timeout for select 

    // See if we have sockets to read
    read_sockets = passed_server->connections;
    timeout = passed_server->socket_timeout;
    if(select(passed_server->connections_max+1, &read_sockets, NULL, NULL, &timeout) == -1) {
        perror("Selecting sockets");
        exit(1);
    }

    // Loop through all of the sockets
    for(current_fd = 0; current_fd <= passed_server->connections_max; current_fd++) {
        if(!FD_ISSET(current_fd, &read_sockets)) {
            continue;
        }

        // Handle new connection
        if(current_fd == passed_server->listener) {
            User *new_user = malloc(sizeof *new_user); 
            memset(&new_user->address, 0, sizeof new_user->address);

            // Get the new address
            new_user->address_length = sizeof new_user->address;
            new_user->fs_id = accept(passed_server->listener, (struct sockaddr *)&new_user->address, &new_user->address_length);

            // Did we have an issue connecting?
            if(new_user->fs_id == -1) {
                free(new_user);
                perror("Accepting new connection");
                continue;
            }

            // Add the user socket to the master list
            FD_SET(new_user->fs_id, &passed_server->connections);
            if(new_user->fs_id > passed_server->connections_max) {
                passed_server->connections_max = new_user->fs_id;
            }

            // Add the user to the list

            //*******************
            // ERRORS IN THE NEXT TWO ASSIGNMENTS
            //*******************

            if(passed_server->users == NULL) {
                passed_server->users = new_user;
            } else {
                new_user->nextUser = passed_server->users;
                passed_server->users = new_user;
            }

            // Let them know we got one!
            printf("Server: New connection from %s on socket %d. Send hello.\n",
                    inet_ntop(
                            new_user->address.ss_family, 
                            get_address((struct sockaddr*)&new_user->address),
                            new_user->ip_address,
                            INET6_ADDRSTRLEN
                    ),
                    new_user->fs_id
            );

            // Can we get to the user from the server?
            //printf("Repeat, the IP address is %s\n", passed_server->users->ip_address);

            // Move on to the next file descriptor
            continue;
        }
    }
}

Full Code

Answer 1

typedef struct User {
    struct sockaddr_storage address;    // User's address
    socklen_t address_length;           // Length of users address
    int fs_id;                          // ID to the socket they belong to
    char ip_address[INET6_ADDRSTRLEN];  // User's IP address
    char *name;                         // Pointer to the user's name
    struct User *nextUser;              // Next user in the list
} User;

在顶部添加“struct User”，以便您可以在结构中引用它。

此外，您需要交换声明的顺序，以便Server结构知道User结构。

Answer 2

声明指针指向某种类型的变量，并且除了void *之外，如果您尝试将声明指向一种类型的指针指定给声明为的指针，则会收到该警告指向其他类型。

指针需要有一个类型才能解释该位置的内存内容。例如，浮点指针需要知道读取四个字节而不是两个或三个字节。此信息在指针类型中提供。

因此，请确保您指定具有兼容类型的指针，或者如果您确定要更改类型，请使用强制转换。

来自不完整指针类型的分配

2 个答案: