chdir does not work with/crashes when given relative paths

[shinyquagsire23]

While reworking my gpsp port's file code I found that chdir has a borked behavior in that it cannot chdir to relative file locations. As an example, doing a chdir("."); will actually cause ctrulib to crash to home. Same with chdir("..");. Even if you try to chdir to an exiting directory within the current working directory, it will crash. A simple test to check against this bug is just a chdir(".") after initializing sdmc.

Also, getcwd seems to return "/" initially rather than "sdmc:/", up until you explicitly chdir("sdmc:/"). Doesn't seem to affect anything, but it's there. I believe @mtheall is the one I should be talking with on this issue.

[mtheall]

The newlib code is supposed to handle relative path components before passing a path down to the driver's code. It would be interesting to see what path is passed to sdmc_chdir().

[mtheall]

So this is what I have found:

https://github.com/devkitPro/buildscripts/blob/master/dkarm-eabi/patches/newlib-2.2.0.patch#L779
We get here because the _current_working_directory is "/"

https://github.com/devkitPro/buildscripts/blob/master/dkarm-eabi/patches/newlib-2.2.0.patch#L782
pathPosition is assigned the value 0x1 because there is no ":" in "/"

https://github.com/devkitPro/buildscripts/blob/master/dkarm-eabi/patches/newlib-2.2.0.patch#L785
Obviously a segfault.

[mtheall]

I think this would probably work:

        strncpy (temp_cwd, _current_working_directory, PATH_MAX);
    }

-   pathPosition = strchr (temp_cwd , ':') + 1;
+   pathPosition = strchr (temp_cwd , ':');
+   if (pathPosition == NULL)
+       pathPosition = temp_cwd;
+   else
+       ++pathPosition;

    /* Make sure the path starts in the root directory */
    if (pathPosition[0] != DIRECTORY_SEPARATOR_CHAR) {

[mtheall]

For what it's worth, this has nothing to do with relative directories. You can recreate it by simply performing the first chdir() with any path which does not have a colon ":".