Support "Preview in Web Browser" in Flatpak mode

...by storing the temporary HTML document in a location that can be accessed by
the browser running outside the Flatpak sandbox.  This reuses and extends the
mechanism already in place for the new HTML-based help in Flatpak mode (see
72b936d70b7eaa6d9f5f911b27e3c955382de967 "Enable --help=html for flatpak").

This fixes <https://github.com/flathub/org.libreoffice.LibreOffice/issues/85>
"“Preview in Web Browser” does not work in Flatpak version".

Change-Id: I5f73fd89139ffe6b8ab0dc501154b4f054a0ae5c
Reviewed-on: https://gerrit.libreoffice.org/71570
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>
(cherry picked from commit c61e7b9940cb30800d6f1000727f9cfd5de9fa5e)
Reviewed-on: https://gerrit.libreoffice.org/71717
Reviewed-by: Michael Stahl <Michael.Stahl@cib.de>

4 files changed, 113 insertions, 73 deletions

diff --git a/sfx2/Library_sfx.mk b/sfx2/Library_sfx.mk
index 97f6f9706e76..750f3b354c73 100644
--- a/sfx2/Library_sfx.mk
+++ b/sfx2/Library_sfx.mk
@@ -94,6 +94,7 @@ $(eval $(call gb_Library_add_exception_objects,sfx,\
     sfx2/source/appl/childwin \
     sfx2/source/appl/childwinimpl \
     sfx2/source/appl/fileobj \
+    sfx2/source/appl/flatpak \
     sfx2/source/appl/fwkhelper \
     sfx2/source/appl/helpdispatch \
     sfx2/source/appl/helpinterceptor \
diff --git a/sfx2/source/appl/flatpak.cxx b/sfx2/source/appl/flatpak.cxx
new file mode 100644
index 000000000000..14411dafc5d0
--- /dev/null
+++ b/sfx2/source/appl/flatpak.cxx
@@ -0,0 +1,99 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4; fill-column: 100 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+#include <sal/config.h>
+
+#include <cassert>
+#include <cstdlib>
+#include <cstring>
+
+#include <osl/file.hxx>
+#include <osl/thread.h>
+#include <rtl/textcvt.h>
+#include <rtl/ustring.h>
+#include <rtl/ustring.hxx>
+#include <sal/log.hxx>
+#include <sfx2/flatpak.hxx>
+#include <tools/debug.hxx>
+#include <unotools/tempfile.hxx>
+#include <unotools/ucbhelper.hxx>
+
+bool flatpak::isFlatpak() {
+    static auto const flatpak = [] { return std::getenv("LIBO_FLATPAK") != nullptr; }();
+    return flatpak;
+}
+
+namespace {
+
+// Must only be accessed with SolarMutex locked:
+struct {
+    bool created = false;
+    OUString url;
+} temporaryHtmlDirectoryStatus;
+
+}
+
+bool flatpak::createTemporaryHtmlDirectory(OUString ** url) {
+    assert(url != nullptr);
+    DBG_TESTSOLARMUTEX();
+    if (!temporaryHtmlDirectoryStatus.created) {
+        auto const env = std::getenv("XDG_CACHE_HOME");
+        if (env == nullptr) {
+            SAL_WARN("sfx.appl", "LIBO_FLATPAK mode but unset XDG_CACHE_HOME");
+            return false;
+        }
+        OUString path;
+        if (!rtl_convertStringToUString(
+                &path.pData, env, std::strlen(env), osl_getThreadTextEncoding(),
+                (RTL_TEXTTOUNICODE_FLAGS_UNDEFINED_ERROR | RTL_TEXTTOUNICODE_FLAGS_MBUNDEFINED_ERROR
+                 | RTL_TEXTTOUNICODE_FLAGS_INVALID_ERROR)))
+        {
+            SAL_WARN(
+                "sfx.appl",
+                "LIBO_FLATPAK mode failure converting XDG_CACHE_HOME \"" << env << "\" encoding");
+            return false;
+        }
+        OUString parent;
+        auto const err = osl::FileBase::getFileURLFromSystemPath(path, parent);
+        if (err != osl::FileBase::E_None) {
+            SAL_WARN(
+                "sfx.appl",
+                "LIBO_FLATPAK mode failure converting XDG_CACHE_HOME \"" << path << "\" to URL: "
+                    << err);
+            return false;
+        }
+        if (!parent.endsWith("/")) {
+            parent += "/";
+        }
+        auto const tmp = utl::TempFile(&parent, true);
+        if (!tmp.IsValid()) {
+            SAL_WARN(
+                "sfx.appl", "LIBO_FLATPAK mode failure creating temp dir at <" << parent << ">");
+            return false;
+        }
+        temporaryHtmlDirectoryStatus.url = tmp.GetURL();
+        temporaryHtmlDirectoryStatus.created = true;
+    }
+    *url = &temporaryHtmlDirectoryStatus.url;
+    return true;
+}
+
+void flatpak::removeTemporaryHtmlDirectory() {
+    DBG_TESTSOLARMUTEX();
+    if (temporaryHtmlDirectoryStatus.created) {
+        if (!utl::UCBContentHelper::Kill(temporaryHtmlDirectoryStatus.url)) {
+            SAL_INFO(
+                "sfx.appl",
+                "LIBO_FLATPAK mode failure removing directory <"
+                    << temporaryHtmlDirectoryStatus.url << ">");
+        }
+    }
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab cinoptions=b1,g0,N-s cinkeys+=0=break: */
diff --git a/sfx2/source/appl/sfxhelp.cxx b/sfx2/source/appl/sfxhelp.cxx
index 03de650df70e..ce59b412d8ce 100644
--- a/sfx2/source/appl/sfxhelp.cxx
+++ b/sfx2/source/appl/sfxhelp.cxx
@@ -56,7 +56,6 @@
 #include <osl/file.hxx>
 #include <unotools/bootstrap.hxx>
 #include <unotools/tempfile.hxx>
-#include <unotools/ucbhelper.hxx>
 #include <rtl/uri.hxx>
 #include <vcl/commandinfoprovider.hxx>
 #include <vcl/layout.hxx>
@@ -73,6 +72,7 @@
 #include "newhelp.hxx"
 #include <sfx2/objsh.hxx>
 #include <sfx2/docfac.hxx>
+#include <sfx2/flatpak.hxx>
 #include <sfx2/sfxresid.hxx>
 #include <helper.hxx>
 #include <sfx2/strings.hrc>
@@ -734,11 +734,6 @@ static bool impl_showOnlineHelp( const OUString& rURL )
 
 namespace {
 
-bool isFlatpak() {
-    static auto const flatpak = [] { return std::getenv("LIBO_FLATPAK") != nullptr; }();
-    return flatpak;
-}
-
 bool rewriteFlatpakHelpRootUrl(OUString * helpRootUrl) {
     assert(helpRootUrl != nullptr);
     //TODO: This function for now assumes that the passed-in *helpRootUrl references
@@ -905,57 +900,6 @@ bool rewriteFlatpakHelpRootUrl(OUString * helpRootUrl) {
     }
 }
 
-// Must only be accessed with SolarMutex locked:
-static struct {
-    bool created = false;
-    OUString url;
-} flatpakHelpTemporaryDirectoryStatus;
-
-bool createFlatpakHelpTemporaryDirectory(OUString ** url) {
-    assert(url != nullptr);
-    DBG_TESTSOLARMUTEX();
-    if (!flatpakHelpTemporaryDirectoryStatus.created) {
-        auto const env = std::getenv("XDG_CACHE_HOME");
-        if (env == nullptr) {
-            SAL_WARN("sfx.appl", "LIBO_FLATPAK mode but unset XDG_CACHE_HOME");
-            return false;
-        }
-        OUString path;
-        if (!rtl_convertStringToUString(
-                &path.pData, env, std::strlen(env), osl_getThreadTextEncoding(),
-                (RTL_TEXTTOUNICODE_FLAGS_UNDEFINED_ERROR | RTL_TEXTTOUNICODE_FLAGS_MBUNDEFINED_ERROR
-                 | RTL_TEXTTOUNICODE_FLAGS_INVALID_ERROR)))
-        {
-            SAL_WARN(
-                "sfx.appl",
-                "LIBO_FLATPAK mode failure converting XDG_CACHE_HOME \"" << env << "\" encoding");
-            return false;
-        }
-        OUString parent;
-        auto const err = osl::FileBase::getFileURLFromSystemPath(path, parent);
-        if (err != osl::FileBase::E_None) {
-            SAL_WARN(
-                "sfx.appl",
-                "LIBO_FLATPAK mode failure converting XDG_CACHE_HOME \"" << path << "\" to URL: "
-                    << err);
-            return false;
-        }
-        if (!parent.endsWith("/")) {
-            parent += "/";
-        }
-        auto const tmp = utl::TempFile(&parent, true);
-        if (!tmp.IsValid()) {
-            SAL_WARN(
-                "sfx.appl", "LIBO_FLATPAK mode failure creating temp dir at <" << parent << ">");
-            return false;
-        }
-        flatpakHelpTemporaryDirectoryStatus.url = tmp.GetURL();
-        flatpakHelpTemporaryDirectoryStatus.created = true;
-    }
-    *url = &flatpakHelpTemporaryDirectoryStatus.url;
-    return true;
-}
-
 }
 
 #define SHTML1 "<!DOCTYPE HTML><html lang=\"en-US\"><head><meta charset=\"UTF-8\">"
@@ -968,7 +912,7 @@ static bool impl_showOfflineHelp( const OUString& rURL )
     OUString aBaseInstallPath = getHelpRootURL();
     // For the flatpak case, find the pathname outside the flatpak sandbox that corresponds to
     // aBaseInstallPath, because that is what needs to be stored in aTempFile below:
-    if (isFlatpak() && !rewriteFlatpakHelpRootUrl(&aBaseInstallPath)) {
+    if (flatpak::isFlatpak() && !rewriteFlatpakHelpRootUrl(&aBaseInstallPath)) {
         return false;
     }
 
@@ -981,7 +925,7 @@ static bool impl_showOfflineHelp( const OUString& rURL )
     // technical reasons, so that it can be accessed by the browser running outside the sandbox):
     OUString const aExtension(".html");
     OUString * parent = nullptr;
-    if (isFlatpak() && !createFlatpakHelpTemporaryDirectory(&parent)) {
+    if (flatpak::isFlatpak() && !flatpak::createTemporaryHtmlDirectory(&parent)) {
         return false;
     }
     ::utl::TempFile aTempFile("NewHelp", true, &aExtension, parent, false );
@@ -1375,16 +1319,4 @@ bool SfxHelp::IsHelpInstalled()
     return impl_hasHelpInstalled();
 }
 
-void SfxHelp::removeFlatpakHelpTemporaryDirectory() {
-    DBG_TESTSOLARMUTEX();
-    if (flatpakHelpTemporaryDirectoryStatus.created) {
-        if (!utl::UCBContentHelper::Kill(flatpakHelpTemporaryDirectoryStatus.url)) {
-            SAL_INFO(
-                "sfx.appl",
-                "LIBO_FLATPAK mode failure removing directory <"
-                    << flatpakHelpTemporaryDirectoryStatus.url << ">");
-        }
-    }
-}
-
 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */
diff --git a/sfx2/source/view/viewsh.cxx b/sfx2/source/view/viewsh.cxx
index 04733ec20cfb..f7b3d2166b8b 100644
--- a/sfx2/source/view/viewsh.cxx
+++ b/sfx2/source/view/viewsh.cxx
@@ -61,6 +61,7 @@
 
 #include <officecfg/Setup.hxx>
 #include <sfx2/app.hxx>
+#include <sfx2/flatpak.hxx>
 #include <sfx2/viewsh.hxx>
 #include "viewimp.hxx"
 #include <sfx2/sfxresid.hxx>
@@ -618,8 +619,15 @@ void SfxViewShell::ExecMisc_Impl( SfxRequest &rReq )
                 OSL_ASSERT( !aFilterName.isEmpty() );
                 OSL_ASSERT( !aFileName.isEmpty() );
 
-                // Creates a temporary directory to store our predefined file into it.
-                ::utl::TempFile aTempDir( nullptr, true );
+                // Creates a temporary directory to store our predefined file into it (for the
+                // flatpak case, create it in XDG_CACHE_HOME instead of /tmp for technical reasons,
+                // so that it can be accessed by the browser running outside the sandbox):
+                OUString * parent = nullptr;
+                if (flatpak::isFlatpak() && !flatpak::createTemporaryHtmlDirectory(&parent))
+                {
+                    SAL_WARN("sfx.view", "cannot create Flatpak html temp dir");
+                }
+                ::utl::TempFile aTempDir( parent, true );
 
                 INetURLObject aFilePathObj( aTempDir.GetURL() );
                 aFilePathObj.insertName( aFileName );