[PATCH] Cygwin: expose all windows volume mount points.

[Jeremy Drake]

Bit of commentary/review on my own patch.

On Fri, 7 Feb 2025, Jeremy Drake via Cygwin-patches wrote:

> diff --git a/winsup/cygwin/local_includes/cygtls.h b/winsup/cygwin/local_includes/cygtls.h
> index d814814b19..ba9e980ec1 100644
> --- a/winsup/cygwin/local_includes/cygtls.h
> +++ b/winsup/cygwin/local_includes/cygtls.h
> @@ -93,10 +93,13 @@ struct _local_storage
>    int dl_error;
>    char dl_buffer[256];
>
> -  /* path.cc */
> +  /* mount.cc */
>    struct mntent mntbuf;
>    int iteration;
> -  unsigned available_drives;
> +  int volumemountpointoffset;
> +  HANDLE volumesearchhandle;
> +  WCHAR *volumemountpoints; // note: malloced
> +  DWORD volumemountpointslen;
>    char mnt_type[80];
>    char mnt_opts[80];
>    char mnt_fsname[CYG_MAX_PATH];

I'm regretting the length of those variable names now...

> diff --git a/winsup/cygwin/local_includes/mount.h b/winsup/cygwin/local_includes/mount.h
> index b2acdf08b4..7120281069 100644
> --- a/winsup/cygwin/local_includes/mount.h
> +++ b/winsup/cygwin/local_includes/mount.h
> @@ -216,6 +216,7 @@ class mount_info
>    bool from_fstab (bool user, WCHAR [], PWCHAR);
>
>    int cygdrive_win32_path (const char *src, char *dst, int& unit);
> +  struct mntent *cygdrive_getmntent ();
>  };
>
>  class dos_drive_mappings

I wasn't sure about making that a member.  The existing code was already
accessing things in mount_info via mount_table->whatever.  This code could
just do that too.

> +      _my_tls.locals.volumemountpoints = (WCHAR *) malloc (NT_MAX_PATH * sizeof (WCHAR));

Forgot to check for NULL return and fail.  Got that in my working copy
now.

>  struct mntent *
>  mount_info::getmntent (int x)
>  {
>    if (x < 0 || x >= nmounts)
> -    return cygdrive_getmntent ();
> -
> +    {
> +      struct mntent *ret;
> +      /* de-duplicate against explicit mount entries */
> +      while ((ret = cygdrive_getmntent ()))
> +	{
> +	  for (int i = 0; i < nmounts; ++i)
> +	    {
> +	      if (!strcmp (ret->mnt_dir, mount[i].posix_path) &&
> +		  strcasematch (ret->mnt_fsname, mount[i].native_path))

This could be improved by using a sorted version, and breaking from the
for loop once past where it could possibly still match.