int add_sendFile(struct in_addr* sin_addr, char name[]){ struct stat buf; struct sendfile* newFile = NULL; struct sendfile* rear = send_filelist_head; static unsigned int file_num=0; stat(name,&buf); if ( (newFile = (struct sendfile*)malloc(sizeof(struct sendfile))) == NULL ) { printf("newFile failed!\n"); return 1; } newFile->sin_addr.s_addr = sin_addr->s_addr; strncpy(newFile->name, name, 20); newFile->num=file_num; newFile->pkgnum=time(NULL); newFile->size=buf.st_size; newFile->ltime=buf.st_mtime; while (rear->next != NULL) { rear = rear->next; } rear->next = newFile; newFile->next = NULL; return 0;}注释一下程序

好的，下面是对这段代码的注释：

int add_sendFile(struct in_addr* sin_addr, char name[]){
    // 定义变量和指针
    struct stat buf; 
    struct sendfile* newFile = NULL; 
    struct sendfile* rear = send_filelist_head; 
    static unsigned int file_num=0; 

    // 获取文件信息
    stat(name,&buf); 

    // 动态分配一个sendfile结构体
    if ( (newFile = (struct sendfile*)malloc(sizeof(struct sendfile))) == NULL ) {  
        printf("newFile failed!\n");  
        return 1; 
    }

    // 填充结构体信息
    newFile->sin_addr.s_addr = sin_addr->s_addr; 
    strncpy(newFile->name, name, 20); 
    newFile->num=file_num; 
    newFile->pkgnum=time(NULL); 
    newFile->size=buf.st_size; 
    newFile->ltime=buf.st_mtime; 

    // 将结构体加入链表末尾
    while (rear->next != NULL) {  
        rear = rear->next; 
    } 
    rear->next = newFile; 
    newFile->next = NULL; 

    // 返回操作结果
    return 0;
}