/* bijou HTTP server for plan 9 by sean caron (scaron@umich.edu) */

#include "main.h"

// if this returns 0 then the path tries to go below the root
int check_directory_path(char *path) {
    int i, d;
	
    d = 0;    // path depth counter
    i = 1;    // position-within-path-string counter

    while (1) {
        /* hit end of string; stop */
        if (i >= strlen(path)) {
            break;
        }

        // doing this lookbehind should catch the case of multiple concurrent slashes in the path
        if ((path[i] == '/') && (path[i-1] != '/' )) {
            d = d + 1;
            i = i + 1;
        }

        /* handle .. in middle of string */
        else if ((path[i] == '.') && (path[i-1] == '/') && (path[i+1] == '.') && (path[i+2] == '/')) {
            i = i + 3;
            d = d - 1;
        }

        /* handle special case .. at end of string */
        else if ((path[i] == '.') && (path[i-1] == '/') && (path[i+1] == '.') && ( (i+2) == strlen(path))) {
            i = i + 3;
            d = d - 1;
        }

        /* regular character */
        else {
            i = i + 1;
        }

        /* fallen below the root; stop */
        if (d < 0) {
            break;
        }
    }

    return d;
}