Server ensure path exists

Question

In server.c to ensure the path exists I use this code:

if (access(path, F_OK) == -1)
{
    error(404);
    continue;
}

This leads to a 404 error even when the path exists. For example, if the request (using telnet) is

GET /cat.html HTTP/1.1

Using gdb or printf statements, path is:

/home/jharvard/Dropbox/pset6/public/cat.html

Yet the return value of access (if stored in a variable and printed) is -1. What is causing this?

UPDATE: This is how I form path:

// concatenate root and absolute-path
        char path[strlen(root) + rt_l + 1];
        strcpy(path, root);
        if (qptr == NULL)
        {
            strcpy(path + strlen(root), request_target);
        }
        else
        {
            strncpy(path + strlen(root), request_target, qptr - space1 - 1);
            path[qptr - space1] = '\0';
        }

rt_l is is simply the length of the request target

Answer 1

Turns out I had lots of errors sprinkled throughout my code. I basically debugged my code line by line on paper and checking how strings and pointers were updating. I had many errors in my pointer arithmetic where I was subtracting pointers to dynamically determine string lengths such as the length of the method string. For example, I was subtracting a pointer in the request-target string from a pointer in the original line string or copying strings in the same manner and it would result in random behavior and errors.