Move dubious file: -> smb: conversion from INetURLObject to file UCP

The Linux-only conversion of file URLs with a non-empty (other than "localhost")
authority to smb URLs had been added in 2010 with
0b9ef81ba5ff08d85f21275222458a5b9b9e484c "tools-urlobj-smb-scheme-patch.diff:
migrated" (applying a Go-oo patch?) but giving no rationale beyond "process
relative SMB paths (in hyperlinks) correctly".  That makes it hard to tell
whether that patch is (still) actively useful for anything, or was just a
misguided hack from the beginning:

* Why make this Linux only?  What about other non-Windows OSs?  (On Windows,
  such URLs can be resolved as UNC pathnames.)  If the reason for Linux-only was
  that it is the only OS where LO can handle smb URLs via GIO, why not make it
  conditional on ENABLE_GIO?

* Why map to smb?  There are various remote file access protocols.  Hardcoding
  smb looks arbitrary here.

Anyway, INetURLObject is arguably at a wrong level for such a patch.  To not
drop the hack wholesale, reimplement it in the file UCP, forwarding to a
potential other UCP that can handle smb URLs any file://<host>/... URLs
(rewritten as smb URLs) that the file UCP cannot handle itself.
(file://localhost/... URLs will already have been normalized to file:///... by
INetURLObject when they reach the file UCP, and even if they were not, the
osl/file.hxx functionality underlying fileaccess::TaskManager::getUnqFromUrl
knows how to handle them, so they will not take the forward-to-smb code branch.)

(The corresponding #ifdef WIN code from 0b9ef81ba5ff08d85f21275222458a5b9b9e484c
has already been removed with 82034b04e81b74a048595b0eac0f73581ecbc9e4
"tdf#119326 crash when adding "Windows Share" File resource".)

(I came across that 2010 patch while looking into
<https://bugs.documentfoundation.org/show_bug.cgi?id=107461> "Does not support
'file://' scheme with actual hostname".  A next step would be to make the file
UCP actually handle any file://<host>/... URLs that denote the local host.)

Change-Id: I77242705dc4c6c1e9cb3a4f32253224ac6cb13cb
Reviewed-on: https://gerrit.libreoffice.org/67372
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

2 files changed, 20 insertions, 0 deletions

diff --git a/ucb/Library_ucpfile1.mk b/ucb/Library_ucpfile1.mk
index 4505708cbac8..f676eacbde3f 100644
--- a/ucb/Library_ucpfile1.mk
+++ b/ucb/Library_ucpfile1.mk
@@ -21,6 +21,7 @@ $(eval $(call gb_Library_use_libraries,ucpfile1,\
 	cppu \
 	cppuhelper \
 	sal \
+	tl \
 	ucbhelper \
 ))
 
diff --git a/ucb/source/ucp/file/prov.cxx b/ucb/source/ucp/file/prov.cxx
index 22b77d8fadaf..a5b4c0d49c1f 100644
--- a/ucb/source/ucp/file/prov.cxx
+++ b/ucb/source/ucp/file/prov.cxx
@@ -21,6 +21,8 @@
 #include <osl/file.hxx>
 #include <osl/socket.h>
 #include <sal/log.hxx>
+#include <tools/urlobj.hxx>
+#include <ucbhelper/content.hxx>
 #include <cppuhelper/queryinterface.hxx>
 #include <comphelper/processfactory.hxx>
 #include <com/sun/star/beans/PropertyAttribute.hpp>
@@ -170,7 +172,24 @@ FileProvider::queryContent(
                                               aUnc );
 
     if(  err )
+    {
+        // Hack to retry file://<host>/... URLs as smb URLs:
+        INetURLObject url(xIdentifier->getContentIdentifier());
+        if (url.GetProtocol() == INetProtocol::File
+            && !url.GetHost(INetURLObject::DecodeMechanism::NONE).isEmpty())
+        {
+            url.changeScheme(INetProtocol::Smb);
+            ucbhelper::Content content;
+            if (ucbhelper::Content::create(
+                    url.GetMainURL(INetURLObject::DecodeMechanism::NONE),
+                    css::uno::Reference<css::ucb::XCommandEnvironment>(), m_xContext, content))
+            {
+                return content.get();
+            }
+        }
+
         throw IllegalIdentifierException( THROW_WHERE );
+    }
 
     return Reference< XContent >( new BaseContent( m_pMyShell.get(), xIdentifier, aUnc ) );
 }