Fix host_file_normalize_mingw

Tom de Vries ran the testsuite on msys2-ucrt64 with mount point map:
...
  /bin C:/msys64/usr/bin
  /c   C:
  /    C:/msys64
...
and ran into the problem that host_file_normalize didn't translate:
...
  /home/user/gdb/build/gdb/testsuite/temp/n/x
...
into:
...
  C:/msys64/home/user/gdb/build/gdb/testsuite/temp/n/x
...

The problem is that host_file_normalize_mingw mishandles a
file/directory under the root mount point.  A simpler reproducer is
"/foo".  If we add that as a test to
gdb.testsuite/mount-point-map.exp, we see:

 input:    /foo
 expected: C:/msys64/foo/
 got:      /foo
 FAIL: gdb.testsuite/mount-point-map.exp: /foo

For a mount point that ends in /, this line in
host_file_normalize_mingw:

  } elseif {[string index $filename $mount_len] eq "/"} {

... is always false, because the character at $mount_len is the one
_after_ the slash.

Notice that the "/" mount point is the only one that ends in "/".
This is even if you try to create one explicitly with a trailing /.

On MSYS2:

 $ mount c:/foo /foo/
 mount: warning - /foo/ does not exist.
 $ mount
 C:/foo on /foo type ntfs (binary,user)
 ...

So fix this by special casing the "/" mount point.

And then... while playing with fixing this, I noticed I had done
something strange with this case:

  if {[string length $filename] == $mount_len} {
      return "$win_filename/"

The intent was to append the slash when the mount is a drive letter,
like 'cygpath -ma' does:

 $ cygpath -ma /c
 C:/

Other cases do not get a trailing slash:

 $ cygpath -ma /c/foo
 C:/foo

I think this is because on Windows, every drive letter has a current
directory, and really "C:" means "current directory of drive letter
C:", not "root of C:".  Resolving it to "C:/" makes it unambiguous.

However, I mishandled that in a63213cd374d ('MSYS2+MinGW testing: Unix
<-> Windows path conversion').  The original version of that patch
when I posted it to the mailing list only supported drive mounts,
which turned out incorrect, and then I generalized it to work with all
mount points before it was merged.  In the process, I inadvertently
made the code append the slash whenever the input filename matches a
mount exactly, any mount.

I also now noticed that TCL's "file normalize" on Linux always removes
the trailing slash, and since host_file_normalize is an abstraction
for it, I think host_file_normalize_mingw should do the same.
Likewise for duplicate slashes, "file normalize" gets rid of them.

Fix all this in host_file_normalize_mingw, and add corresponding tests
to gdb.testsuite/mount-point-map.exp.

I smoke tested this here with a few of the testcases that required
tweaking in the patch that added host_file_normalize, like
gdb.base/source-dir.exp and gdb.base/fullname.exp and they still pass.

Tom ran gdb.testsuite/mount-point-map.exp on both x86_64-linux and
msys2-ucrt64, and it passed in both cases.

Change-Id: I852a8662f0cb8b0ee4e683e9b157618cf6955477

0 files changed, 0 insertions, 0 deletions