Add imgtool publishing support

This adds initial support for publishing imgtool to pypi.org.

The main imgtool.py was moved to imgtool package and made into the main
file, and a new imgtool.py that calls into the package, was added allowing
for the old usage behavior to remain functional.

Signed-off-by: Fabio Utzig <utzig@apache.org>
diff --git a/scripts/imgtool.py b/scripts/imgtool.py
index dbb3334..7861474 100755
--- a/scripts/imgtool.py
+++ b/scripts/imgtool.py
@@ -14,188 +14,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import click
-import getpass
-from imgtool import keys
-from imgtool import image
-from imgtool.version import decode_version
-
-
-def gen_rsa2048(keyfile, passwd):
-    keys.RSA2048.generate().export_private(path=keyfile, passwd=passwd)
-
-
-def gen_ecdsa_p256(keyfile, passwd):
-    keys.ECDSA256P1.generate().export_private(keyfile, passwd=passwd)
-
-
-def gen_ecdsa_p224(keyfile, passwd):
-    print("TODO: p-224 not yet implemented")
-
-
-valid_langs = ['c', 'rust']
-keygens = {
-    'rsa-2048':   gen_rsa2048,
-    'ecdsa-p256': gen_ecdsa_p256,
-    'ecdsa-p224': gen_ecdsa_p224,
-}
-
-
-def load_key(keyfile):
-    # TODO: better handling of invalid pass-phrase
-    key = keys.load(keyfile)
-    if key is not None:
-        return key
-    passwd = getpass.getpass("Enter key passphrase: ").encode('utf-8')
-    return keys.load(keyfile, passwd)
-
-
-def get_password():
-    while True:
-        passwd = getpass.getpass("Enter key passphrase: ")
-        passwd2 = getpass.getpass("Reenter passphrase: ")
-        if passwd == passwd2:
-            break
-        print("Passwords do not match, try again")
-
-    # Password must be bytes, always use UTF-8 for consistent
-    # encoding.
-    return passwd.encode('utf-8')
-
-
-@click.option('-p', '--password', is_flag=True,
-              help='Prompt for password to protect key')
-@click.option('-t', '--type', metavar='type', required=True,
-              type=click.Choice(keygens.keys()))
-@click.option('-k', '--key', metavar='filename', required=True)
-@click.command(help='Generate pub/private keypair')
-def keygen(type, key, password):
-    password = get_password() if password else None
-    keygens[type](key, password)
-
-
-@click.option('-l', '--lang', metavar='lang', default=valid_langs[0],
-              type=click.Choice(valid_langs))
-@click.option('-k', '--key', metavar='filename', required=True)
-@click.command(help='Get public key from keypair')
-def getpub(key, lang):
-    key = load_key(key)
-    if key is None:
-        print("Invalid passphrase")
-    elif lang == 'c':
-        key.emit_c()
-    elif lang == 'rust':
-        key.emit_rust()
-    else:
-        raise ValueError("BUG: should never get here!")
-
-
-def validate_version(ctx, param, value):
-    try:
-        decode_version(value)
-        return value
-    except ValueError as e:
-        raise click.BadParameter("{}".format(e))
-
-
-def validate_header_size(ctx, param, value):
-    min_hdr_size = image.IMAGE_HEADER_SIZE
-    if value < min_hdr_size:
-        raise click.BadParameter(
-            "Minimum value for -H/--header-size is {}".format(min_hdr_size))
-    return value
-
-
-class BasedIntParamType(click.ParamType):
-    name = 'integer'
-
-    def convert(self, value, param, ctx):
-        try:
-            if value[:2].lower() == '0x':
-                return int(value[2:], 16)
-            elif value[:1] == '0':
-                return int(value, 8)
-            return int(value, 10)
-        except ValueError:
-            self.fail('%s is not a valid integer' % value, param, ctx)
-
-
-@click.argument('outfile')
-@click.argument('infile')
-@click.option('-E', '--encrypt', metavar='filename',
-              help='Encrypt image using the provided public key')
-@click.option('-e', '--endian', type=click.Choice(['little', 'big']),
-              default='little', help="Select little or big endian")
-@click.option('--overwrite-only', default=False, is_flag=True,
-              help='Use overwrite-only instead of swap upgrades')
-@click.option('-M', '--max-sectors', type=int,
-              help='When padding allow for this amount of sectors (defaults to 128)')
-@click.option('--pad', default=False, is_flag=True,
-              help='Pad image to --slot-size bytes, adding trailer magic')
-@click.option('-S', '--slot-size', type=BasedIntParamType(), required=True,
-              help='Size of the slot where the image will be written')
-@click.option('--pad-header', default=False, is_flag=True,
-              help='Add --header-size zeroed bytes at the beginning of the image')
-@click.option('-H', '--header-size', callback=validate_header_size,
-              type=BasedIntParamType(), required=True)
-@click.option('-v', '--version', callback=validate_version,  required=True)
-@click.option('--align', type=click.Choice(['1', '2', '4', '8']),
-              required=True)
-@click.option('-k', '--key', metavar='filename')
-@click.command(help='Create a signed or unsigned image')
-def sign(key, align, version, header_size, pad_header, slot_size, pad,
-         max_sectors, overwrite_only, endian, encrypt, infile, outfile):
-    img = image.Image.load(infile, version=decode_version(version),
-                           header_size=header_size, pad_header=pad_header,
-                           pad=pad, align=int(align), slot_size=slot_size,
-                           max_sectors=max_sectors,
-                           overwrite_only=overwrite_only,
-                           endian=endian)
-    key = load_key(key) if key else None
-    enckey = load_key(encrypt) if encrypt else None
-    if enckey:
-        if not isinstance(enckey, (keys.RSA2048, keys.RSA2048Public)):
-            raise Exception("Encryption only available with RSA")
-        if key and not isinstance(key, (keys.RSA2048, keys.RSA2048Public)):
-            raise Exception("Encryption with sign only available with RSA")
-    img.create(key, enckey)
-
-    if pad:
-        img.pad_to(slot_size)
-
-    img.save(outfile)
-
-
-class AliasesGroup(click.Group):
-
-    _aliases = {
-        "create": "sign",
-    }
-
-    def list_commands(self, ctx):
-        cmds = [k for k in self.commands]
-        aliases = [k for k in self._aliases]
-        return sorted(cmds + aliases)
-
-    def get_command(self, ctx, cmd_name):
-        rv = click.Group.get_command(self, ctx, cmd_name)
-        if rv is not None:
-            return rv
-        if cmd_name in self._aliases:
-            return click.Group.get_command(self, ctx, self._aliases[cmd_name])
-        return None
-
-
-@click.command(cls=AliasesGroup,
-               context_settings=dict(help_option_names=['-h', '--help']))
-def imgtool():
-    pass
-
-
-imgtool.add_command(keygen)
-imgtool.add_command(getpub)
-imgtool.add_command(sign)
-
+from imgtool import main
 
 if __name__ == '__main__':
-    imgtool()
+    main.imgtool()