在C中制作pwd类型的函数

Question

I'm pulling my hair out here. Its been about 1.5 years since I've done any c programming so bear with me.

I need to make a function in c that does what the pwd function does in linux. I have a struct of nodes that represent a folder. Each one has a pointer back to its parent so it should be pretty easy but I'm dying here. I thought I could just keep using strcat to append the name of a nodes parent to the path name. But, even if I was able to get this to work I would be left with a list that is in reverse, which is fine I guess. I could at least deal with that. But if I'm in directory c whose parent is b whose parent is a whose parent is root I should be able to use pwd to output the string "/a/b/c". I'm stuck. Any ideas? When I try to use strcat I get segmentation faults up the ying yang.

void pwd( ){  

    char *thePath;
    NODE *nodePtr;
    nodePtr = cwd;

    while( nodePtr != root ){

    }
    printf("%s\n", thePath);
    return;
}   

Answer 1

If all you want to do is print out the path, this should be pretty easy with recursion.

void pwd_recurse (NODE *nodePtr)
{
    if (nodePtr == root)
    {
         return;
    }
    pwd_recurse(nodePtr->parent);
    printf("/%s",nodePtr->name);
}

void pwd()
{
    ///however you get the nodePtr;
    pwd_recurse(nodePtr);
    printf("\n");
}

This nicely sidesteps having to deal with memory allocations (though it does mean if you have a degenerate filesystem with loops (insert obligatory XKCD cartoon here), you'll have a stackoverflow, which is arguable better than an infinite loop.)