问题描述
static int cwd(int ctrlfd,char *cmdline){
printf ("cmdline:%s\n",cmdline);
char temp[200];
char * space = strtok(cmdline," \n");
printf ("cwd to :%s\n",cmdline);
space[strlen(space)+1]='\0';
if(chdir(space)==0) {
getcwd(space,sizeof(space));
printf("changing directory succesfull %s\n",space);
return ftp_send_resp(ctrlfd,250);
}
else{
space = *explain_chdir(const char *pathname);
printf("changing directory failed %s\n",space);
return ftp_send_resp(ctrlfd,550);
}
}
我的尝试：
大家好我在unix下用c实现一个ftp服务器，
i am working在我的cwd或更改工作目录功能，
我在这个函数中唯一的问题是chdir没有改变工作目录
我认为问题在于我给它的字符串路径，虽然我尝试了一切不起作用请帮帮我！
ftp_send_resp用于发送对filezilla的回复
和strtok用于剪切来自filezilla的字符串作为新路径
先谢谢大家
What I have tried:
hello everyone I am implementing an ftp server in c under unix ,
i am working on my cwd or change working directory function ,
my only problem in this function is that chdir is not changing the working directory
I think the problem is in the string path i am giving to it although I tried everything its not working please help me !
ftp_send_resp is used to send response to filezilla
and strtok is used to cut the string coming from filezilla as new path
thank you all in advance
推荐答案
space[strlen(space)+1]='\0';
惊讶没有人注意到它是错误的我不认为需要...但是对于记录
数组是基于零的AKA它从ZERO开始。 ..存储在数组[0] ... [strlen-1] ...所以它将是
Surprised noone noticed it is wrong and I don't think needed ... however for record
The array is zero based AKA it starts at ZERO ... Stores in array [0]...[strlen-1] ... so it would be
space[strlen(space)]='\0';
这条线更令人着迷
Even more fascinating is this line
getcwd(space,sizeof(space));
空格是一个字符* AKA指针
指针大小为4字节（32位）或8字节（64位）
我在想这个函数可能要求缓冲区的大小是strlen（空格）+1
但是我仍然认为这不是问题我的怀疑是你的程序没有权限的目录，只需要检查错误的errno值。我怀疑你会得到EACCES。所以尝试更简单的代码并打印错误。显然改变你正在使用的命令行的目录路径
Space is a char* AKA a pointer
sizeof the pointer will be 4 bytes (32 bits) or 8 bytes (64 bits)
I am thinking that function is probably asking for the size of the buffer being strlen(Space)+1
However I still think that isn't the issue my suspicion is your program doesn't have permissions for the directory which simply needs to check the value of errno on error. I suspect you will be getting EACCES. So try simpler code and print errno. Obviously change the directory path to your command line you are using
const char * const path = "/home/Public/test";
if (chdir(path) != 0){
printf ("chdir failed - %s\n", strerror (errno));
}
char * space = strtok(cmdline," \n");
否则你的程序将崩溃。
这将在字符串后面写一个 NULL char（在现有的<$ c $之后） c> NULL char）：
Otherwise your program will crash.
This will write a NULL char behind the string (behind the existing NULL char):
space[strlen(space)+1]='\0';
我想你想在这里删除一个尾随换行符。因为这会让系统 chdir 命令失败。所以它应该是这样的：
I guess you want to remove a trailing line feed here. Because that would let the system chdir command fail. So it should be something like this:
// Skip space characters
while (*space == ' ')
space++;
// Remove trailing line feed
int len = strlen(space);
if (space[len-1] == '\n')
space[len-1] = '\0';
但是，更好的实现会检查多个换行符和回车符。
只需使用现有命令查看会发生什么：
However, a better implementation would check for multiple line feeds and also carriage returns.
Just use an existing command to see what happens:
cmdline = "cwd directory\n"
然后空格将指向directory \ n。将其传递给 chdir 当然会失败。因此，跳过前导空格并删除尾随换行符以获取目录。
Then space would point to " directory\n". Passing that to chdir will off course fail. So skip the leading space(s) and remove the trailing line feed to get "directory".
这篇关于Chdir无法更改我的工作目录的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！