imgtool: Add write to file option

Signed-off-by: Dávid Házi <david.hazi@arm.com>
Signed-off-by: Bence Balogh <bence.balogh@arm.com>
Change-Id: I6028955be5cbcd20d49ef2126dce8d4636b824a6

scripts/imgtool/keys/general.py

@@ -8,7 +8,18 @@ AUTOGEN_MESSAGE = "/* Autogenerated by imgtool.py, do not edit. */"
 
 
 class KeyClass(object):
-    def _emit(self, header, trailer, encoded_bytes, indent, file=sys.stdout, len_format=None):
+    def _emit(self, header, trailer, encoded_bytes, indent, file=sys.stdout,
+              len_format=None):
+        if file and file is not sys.stdout:
+            with open(file, 'w') as file:
+                self._emit_to_output(header, trailer, encoded_bytes, indent,
+                                     file, len_format)
+        else:
+            self._emit_to_output(header, trailer, encoded_bytes, indent,
+                                 sys.stdout, len_format)
+
+    def _emit_to_output(self, header, trailer, encoded_bytes, indent, file,
+                        len_format):
         print(AUTOGEN_MESSAGE, file=file)
         print(header, end='', file=file)
         for count, b in enumerate(encoded_bytes):
@@ -39,7 +50,11 @@ class KeyClass(object):
                 file=file)
 
     def emit_public_pem(self, file=sys.stdout):
+        if file and file is not sys.stdout:
+            with open(file, 'w') as file:
                 print(str(self.get_public_pem(), 'utf-8'), file=file, end='')
+        else:
+            print(str(self.get_public_pem(), 'utf-8'), file=sys.stdout, end='')
 
     def emit_private(self, minimal, format, file=sys.stdout):
         self._emit(

scripts/imgtool/main.py

@@ -128,8 +128,11 @@ def keygen(type, key, password):
               type=click.Choice(valid_encodings),
               help='Valid encodings: {}'.format(', '.join(valid_encodings)))
 @click.option('-k', '--key', metavar='filename', required=True)
+@click.option('-o', '--output', metavar='output', required=False,
+              help='Specify the output file\'s name. \
+                    The stdout is used if it is not provided.')
 @click.command(help='Dump public key from keypair')
-def getpub(key, encoding, lang):
+def getpub(key, encoding, lang, output):
     if encoding and lang:
         raise click.UsageError('Please use only one of `--encoding/-e` '
                                'or `--lang/-l`')
@@ -138,14 +141,17 @@ def getpub(key, encoding, lang):
         # `default=valid_encodings[0]` should be added to `-e` param.
         lang = valid_langs[0]
     key = load_key(key)
+
+    if not output:
+        output = sys.stdout
     if key is None:
         print("Invalid passphrase")
     elif lang == 'c' or encoding == 'lang-c':
-        key.emit_c_public()
+        key.emit_c_public(file=output)
     elif lang == 'rust' or encoding == 'lang-rust':
-        key.emit_rust_public()
+        key.emit_rust_public(file=output)
     elif encoding == 'pem':
-        key.emit_public_pem()
+        key.emit_public_pem(file=output)
     else:
         raise click.UsageError()