问题描述
我希望能够从客户端向服务器发送文件。我正在使用TCP。我试图使用fseek等获取文件的大小，因为我希望能够处理大文件，然后将一定数量的数据以及文件内容发送到服务器。到目前为止，根据我的printf消息，一切都通过并创建了文件。但是，在服务器上创建的文件为空。我通过参数等发送和接收消息的方式显然存在问题，但我无法弄清楚。有人可以告诉我我哪里出了问题以及如何修复它，因为我是如此接近！
服务器部分：
if(getFile){
char *tmp = buf + 9;
char filename2[MAX_BLOCK_SIZE];
int length,x;
long file_size = 0;
FILE *fp;
strcpy(filename2,tmp);
printf("Server receiving file name...\n");
//first 'read' receives the file name
fp = fopen(filename2,"wb");
if(fp == NULL){
printf("File Could not be opened.\n");
exit(1);
}
printf("Server receiving file...\n");
while((x = read(sd,buf,sizeof(buf)) > 0)){ //second read Now retrieving the file
printf("Server creating new file...\n");
fwrite(buf,1,file_size,fp);
}
fclose(fp);
printf("The server has received the requested document.\n");
}
客户端：
else if(putCommand){
char *tmp = buf + 4;
char filename[MAX_BLOCK_SIZE];
long file_size;
strcpy(filename,"filename ");
strcat(filename,tmp);
FILE *fp;
printf("File name: %s\n",tmp);
fp = fopen(tmp,"rb");
if(fp == NULL){
printf("ERROR: Requested file does not exist.\n");
}
else{
printf("Client sending filename...\n");
if ((nw = write(sd,filename,sizeof(filename)) < nr)){ //sending the file name to the client first
printf("Error sending client's filename.\n");
}
//size_t file_size;
printf("Client sending file...\n");
fseek(fp,SEEK_END);
long filesize = ftell(fp);
fseek(fp,SEEK_SET);
while((file_size = fread(buf,MAX_BLOCK_SIZE,fp)) > 0){ //sending the file
if ((x = write(sd,filesize) < 0)){
printf("Error sending client file.\n");
}
}
fclose(fp);
}
解决方法
这是一个错字。在接收方，您有：
long file_size = 0;
...
while(...)
...
fwrite(buf,1,file_size,fp);
所以您始终写入0字节。
标准方法是：
while((x = read(sd,buf,sizeof(buf)) > 0)){ //second read now retrieving the file
printf("Server creating new file...\n");
fwrite(buf,x,fp); // write the number of bytes returned by previous read
}
最后，我希望buf是一个真实的数组，而不是一个指针...