Change 7zip default to external utility

Signed-off-by: Hiroshi Miura <miurahr@linux.com>

README.rst

@@ -33,7 +33,7 @@ This is an utility replacing the official graphical Qt installer. It can
 automatically download prebuilt Qt binaries for any target (you're not bound to
 Linux binaries on Linux; you could also download iOS binaries).
 It's working with Python > 3.5 on Linux, OS X and Windows.
-
+It is required to install 7zip utility in your platform.
 
 Install
 -------
@@ -52,19 +52,20 @@ General usage looks like this:
 .. code-block:: bash
 
     aqt [-h][--help][-O | --outputdir <directory>][-b | --base <mirror url>][-E | --external <7zip command>] \
-        install <qt-version> <host> <target> [<arch>]
+        [--internal] install <qt-version> <host> <target> [<arch>]
 
 .. code-block:: bash
 
-    python -m aqt [-h][--help][-O | --outputdir <directory>][-b | --base <mirror url>] \
-        install <qt-version> <host> <target> [<arch>]
+    python -m aqt [-h][--help][-O | --outputdir <directory>][-b | --base <mirror url>][-E | --external <7zip command>] \
+        [--internal] install <qt-version> <host> <target> [<arch>]
 
 * The Qt version is formatted like this: `5.11.3`
 * Host is one of: `linux`, `mac`, `windows`
 * Target is one of: `desktop`, `android`, `ios` (iOS only works with mac host)
 * For android and windows you also need to specify an arch: `win64_msvc2017_64`,
   `win64_msvc2015_64`, `win32_msvc2015`, `win32_mingw53`, `win64_mingw73`, `android_x86`, `android_armv7`
-* You can also use external 7zip command instead of internal extration function.
+* You can also use internal 7zip extractor instead of external 7zip command.
+* You can specify external 7zip command path.
 
 
 The Qt packages are installed under current directory as such `Qt<ver>/<ver>/gcc_64/`

aqt/cli.py

@@ -66,21 +66,20 @@ class Cli():
         os_name = args.host
         output_dir = args.outputdir
         mirror = args.base
+        use_py7zr = args.internal
+        sevenzip = None
+        if not use_py7zr:
             sevenzip = args.external
-        if sevenzip is not None:
-            if sevenzip == '_auto':
+            if sevenzip is None:
                 if platform.system() == 'Windows':
                     sevenzip = r'C:\Program Files\7-Zip\7z.exe'
                 else:
                     sevenzip = r'7zr'
-            elif not os.path.exists(sevenzip):
-                print('Specified unexist external command in option -E')
+            elif os.path.exists(sevenzip):
+                pass
+            else:
+                print('Specified external 7zip command is not exist.')
                 exit(1)
-        elif sys.version_info.major == 2:
-            if platform.system() == 'Windows':
-                sevenzip = r'C:\Program Files\7-Zip\7z.exe'
-            else:
-                sevenzip = r'7zr'
         if arch is None:
             if os_name == "linux" and target == "desktop":
                 arch = "gcc_64"
@@ -140,8 +139,8 @@ class Cli():
         install_parser.add_argument('-b', '--base', nargs='?',
                                     help="Specify mirror base url such as http://mirrors.ocf.berkeley.edu/qt/, "
                                          "where 'online' folder exist.")
-        install_parser.add_argument('-E', '--external', nargs='?', const='_auto',
-                                    help='Use external 7zip command instead of internal extractor.')
+        install_parser.add_argument('-E', '--external', nargs=1, help='Specify external 7zip command path.')
+        install_parser.add_argument('--internal', action='store_true', help='Use internal extractor.')
         list_parser = subparsers.add_parser('list')
         list_parser.set_defaults(func=self.run_list)
         list_parser.add_argument("qt_version", help="Qt version in the format of \"5.X.Y\"")

ci/steps.yml

@@ -24,7 +24,7 @@ steps:
     inputs:
       scriptSource: filePath
       scriptPath: $(Build.SourcesDirectory)/bin/aqt
-      arguments: install $(QT_VERSION) $(HOST) $(TARGET) $(ARCH) -E
+      arguments: install $(QT_VERSION) $(HOST) $(TARGET) $(ARCH)
       workingDirectory: $(Build.BinariesDirectory)
     condition: not(variables['QT_BASE_MIRROR'])
     displayName: Run Aqt (No Base URL Set)
@@ -32,7 +32,7 @@ steps:
     inputs:
       scriptSource: filePath
       scriptPath: $(Build.SourcesDirectory)/bin/aqt
-      arguments: install $(QT_VERSION) $(HOST) $(TARGET) $(ARCH) -b $(QT_BASE_MIRROR) -E
+      arguments: install $(QT_VERSION) $(HOST) $(TARGET) $(ARCH) -b $(QT_BASE_MIRROR)
       workingDirectory: $(Build.BinariesDirectory)
     condition: variables['QT_BASE_MIRROR']
     displayName: Run Aqt (Base URL Set)