MIME: Make the internal database direct content, not a Qt resource

This saves us from having to bootstrap rcc in regular (non-cross)
compilations, as it can now link to QtCore. Actually un-bootstrapping
rcc is left as an exercise for the reader.

This commit discovered that MSVC cannot handle constexpr arrays bigger
than 256 kB, at which point it simply starts claiming that the constant
expressions using it are not constexpr. ICC has a similar problem at
64 kB, but it tells you why ("note: type "const unsigned char [65537]"
too large for constant-expression evaluation").

Note also that this requires gzip or zstd to be in PATH for compression
to happen. RCC linked to zlib, which is always present due to the
bundled copy. gzip's presence is not likely to be a problem on Unix
systems, but could be for Windows users, especially MSVC ones. If gzip
is not present, QtCore's size will increase by about 1910 kB of
read-only (sharable) data.

Change-Id: I2b1955a995ad40f3b89afffd15a3e65a94670242
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>

1 files changed, 73 insertions, 0 deletions

diff --git a/src/corelib/mimetypes/mime/generate.bat b/src/corelib/mimetypes/mime/generate.bat
new file mode 100644
index 0000000000..f63fc63693
--- /dev/null
+++ b/src/corelib/mimetypes/mime/generate.bat
@@ -0,0 +1,73 @@
+:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
+::
+:: Copyright (C) 2019 Intel Corporation.
+:: Contact: https://www.qt.io/licensing/
+::
+:: This file is part of the tools applications of the Qt Toolkit.
+::
+:: $QT_BEGIN_LICENSE:GPL-EXCEPT$
+:: Commercial License Usage
+:: Licensees holding valid commercial Qt licenses may use this file in
+:: accordance with the commercial license agreement provided with the
+:: Software or, alternatively, in accordance with the terms contained in
+:: a written agreement between you and The Qt Company. For licensing terms
+:: and conditions see https://www.qt.io/terms-conditions. For further
+:: information use the contact form at https://www.qt.io/contact-us.
+::
+:: GNU General Public License Usage
+:: Alternatively, this file may be used under the terms of the GNU
+:: General Public License version 3 as published by the Free Software
+:: Foundation with exceptions as appearing in the file LICENSE.GPL3-EXCEPT
+:: included in the packaging of this file. Please review the following
+:: information to ensure the GNU General Public License requirements will
+:: be met: https://www.gnu.org/licenses/gpl-3.0.html.
+::
+:: $QT_END_LICENSE$
+::
+:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
+
+@echo off
+setlocal ENABLEDELAYEDEXPANSION ENABLEEXTENSIONS
+set me=%~dp0
+
+:: Check if certain tools are in PATH
+for %%C in (gzip.exe zstd.exe perl.exe) do set %%C=%%~$PATH:C
+
+:: If perl is in PATH, just let it do everything
+if not "%perl.exe%" == "" goto PuntToPerl
+
+set COMPRESS=
+set MACRO=MIME_DATABASE_IS_UNCOMPRESSED
+if not "%gzip.exe%" == "" (
+    set COMPRESS=gzip -9
+    set MACRO=MIME_DATABASE_IS_GZIP
+)
+
+:: Check if zstd support was enabled
+if /i "%~1" == "--zstd" (
+    shift
+    if not "%zstd.exe%" == "" (
+        set COMPRESS=zstd -19
+        set MACRO=MIME_DATABASE_IS_ZSTD
+    )
+)
+
+if not "%COMPRESS%" == "" goto CompressedCommon
+
+:: No Compression and no Perl
+:: Just hex-dump with Powershell
+powershell -ExecutionPolicy Bypass %me%hexdump.ps1 %1 %1
+exit /b %errorlevel%
+
+:CompressedCommon
+:: Compress to a temporary file, then hex-dump using Powershell
+echo #define %MACRO%
+set tempfile=generate%RANDOM%.tmp
+%COMPRESS% < %1 > %tempfile%
+powershell -ExecutionPolicy Bypass %me%hexdump.ps1 %tempfile% %1
+del %tempfile%
+exit /b %errorlevel%
+
+:PuntToPerl
+perl %me%generate.pl %*
+exit /b %errorlevel%