allow "hwi signtx -"

hwilib/_cli.py

@@ -160,7 +160,7 @@ def get_parser() -> HWIArgumentParser:
  getmasterxpub_parser.set_defaults(func=getmasterxpub_handler)
 
  signtx_parser = subparsers.add_parser('signtx', help='Sign a PSBT')
- signtx_parser.add_argument('psbt', help='The Partially Signed Bitcoin Transaction to sign')
+ signtx_parser.add_argument('psbt', help='The Partially Signed Bitcoin Transaction to sign or special charater "-" to read the PSBT from standard input')
  signtx_parser.set_defaults(func=signtx_handler)
 
  getxpub_parser = subparsers.add_parser('getxpub', help='Get an extended public key')

hwilib/commands.py

@@ -58,6 +58,8 @@
 from .psbt import PSBT
 
 from itertools import count
+from select import select
+from sys import stdin
 from typing import (
  Any,
  Dict,
@@ -183,6 +185,74 @@ def getmasterxpub(client: HardwareWalletClient, addrtype: AddressType = AddressT
  """
  return {"xpub": client.get_master_xpub(addrtype, account).to_string()}
 
+def get_psbt_from_pipe() -> str:
+ """Read b64-encoded PSBT from stdin pipe if available.
+
+ Return string read from pipe if input is availble and is non-binary
+ data.
+ Raises an exception otherwise (e.g. no data, bad data, error).
+ """
+ stdin_ready = select( # select.select
+ [
+ stdin, # sys.stdin
+ ],
+ [],
+ [],
+ 0.0,
+ )[ # noqa
+ 0
+ ] # noqa
+ if not stdin_ready:
+ logging.debug(
+ "stdin is not ready for reading. "
+ "A pipe could be used, but pipe could be empty "
+ "or stdin is a keyboard."
+ )
+ else:
+ logging.debug(
+ "stdin is ready. Something "
+ "is definitely piped into program from stdin. "
+ "Reading input from stdin pipe."
+ )
+ if ((not stdin_ready) and (not stdin.isatty())) or stdin_ready:
+ if not stdin.isatty(): # sys.stdin
+ logging.debug(
+ "Pipe was definitely used, but pipe might be empty. "
+ "Trying to read from pipe in any case."
+ )
+ ret = ""
+ try:
+ for line in stdin: # sys.stdin
+ ret += line
+ logging.debug(f"Reading data from stdin pipe. Read text '{ret}'.")
+ # be tolerant, cleanup string
+ ret = ret.replace("\n", "").strip()
+ logging.debug(f"Cleaned up text is '{ret}'.")
+ return ret
+ except EOFError: # EOF when reading a line
+ logging.debug(
+ "Reading from stdin resulted in EOF. This can happen "
+ "when a pipe was used, but the pipe is empty. "
+ "No input will be generated."
+ )
+ raise BadArgumentError(
+ "Stdin input pipe is empty. Pipe PSBT into command."
+ )
+ except UnicodeDecodeError:
+ logging.info(
+ "Reading from stdin resulted in UnicodeDecodeError. This "
+ "can happen if you try to pipe binary data for a "
+ "base64-encoded PSBT. For a base64-encoded PSBT only pipe "
+ "text via stdin, not binary data. Input will be rejected."
+ )
+ raise BadArgumentError(
+ "Stdin input pipe must not contain binary data. "
+ "Send a base64-encoded PSBT into the pipe instead."
+ )
+ raise BadArgumentError(
+ "Stdin input pipe is not ready. Pipe PSBT into command."
+ )
+
 def signtx(client: HardwareWalletClient, psbt: str) -> Dict[str, Union[bool, str]]:
  """
  Sign a Partially Signed Bitcoin Transaction (PSBT) with the client.
@@ -192,6 +262,9 @@ def signtx(client: HardwareWalletClient, psbt: str) -> Dict[str, Union[bool, str
  :return: A dictionary containing the processed PSBT serialized in Base64.
  Returned as ``{"psbt": <base64 psbt string>}``.
  """
+ if psbt == "-":
+ # special char "-" to indicate stdin pipe, read everything in pipe as one PSBT
+ psbt = get_psbt_from_pipe()
  # Deserialize the transaction
  tx = PSBT()
  tx.deserialize(psbt)