check --ssl-cert and --ssl-key to be files

httpie/cli.py

@@ -19,6 +19,7 @@ from .input import (Parser, AuthCredentialsArgType, KeyValueArgType,
                     OUT_REQ_HEAD, OUT_REQ_BODY, OUT_RESP_HEAD,
                     OUT_RESP_BODY, OUTPUT_OPTIONS, OUTPUT_OPTIONS_DEFAULT,
                     PRETTY_MAP, PRETTY_STDOUT_TTY_ONLY, SessionNameValidator)
+from .utils import existing_file
 
 
 class HTTPieHelpFormatter(RawDescriptionHelpFormatter):
@@ -468,6 +469,7 @@ network.add_argument(
 network.add_argument(
     '--ssl-cert',
     default=None,
+    type=existing_file,
     help="""
     You can specify a local cert to use as client side SSL certificate.
     This file may either contain both private key and certificate or you may
@@ -479,6 +481,7 @@ network.add_argument(
 network.add_argument(
     '--ssl-key',
     default=None,
+    type=existing_file,
     help="""
     The private key to use with SSL. Only needed if --ssl-cert is given and the
     certificate file does not contain the private key.

httpie/utils.py

@@ -1,4 +1,5 @@
 from __future__ import division
+import argparse
 
 
 def humanize_bytes(n, precision=2):
@@ -44,3 +45,12 @@ def humanize_bytes(n, precision=2):
             break
 
     return '%.*f %s' % (precision, n / factor, suffix)
+
+
+def existing_file(filename):
+    try:
+        open(filename, 'rb')
+    except IOError as ex:
+        raise argparse.ArgumentTypeError(
+            '%s: %s' % (filename, ex.args[1]))
+    return filename