[Yang Yang]

Hi all, hello Yutaka, long time no see! Today I bump into a problem that the External Tool function fails to serve document content to the external tool. I’ve tested it with 32-bit v10.1.1 and 16.2.1, both on Windows 7 64 Simplified Chinese Edition. Here is the detail.

For several years I’ve configured an external tool to run Python snippets on the fly. The external tool is actually a Go binary to call Python with document content as stdin, but here I’ll use an equivalent Python script for clarity:

# PythonToolForEmEditor.py

import subprocess
import sys

def main():
    PYTHON_CMD = r'D:\Tools\Python\python.exe -'
    ENCODING = 'utf-8'

    content = sys.stdin.buffer.read()  # read binary data; use ioutil.ReadAll() in Go

    # Should not happen: even an empty file has a newline to read.
    if not content:
        print(">>> Empty content! Debugging time. <<<", file=sys.stderr)
        return

    if content[-1] == 0x1a:  # strip possible trailing Ctrl-Z
        content = content[:-1]
    output = subprocess.run(PYTHON_CMD,
                            input=content,
                            stdout=subprocess.PIPE,
                            stderr=subprocess.STDOUT).stdout
    sys.stdout.buffer.write(output.decode(sys.stdout.encoding).encode(ENCODING))

if __name__ == '__main__':
    main()

It reads binary data from stdin, feeds it to the Python interpreter, and write the output to stdout. Both stdin and stdout are UTF-8 encoded.

The External Tool is configured like this:

This has worked wonderfully for years without any issue (encoding related in particular). But with some documents, the “Should not happen” part does happen: nothing is read at all. A minimal example, min.py, is uploaded here (not pasted because space or encoding varieties may scare this issue away): https://ufile.io/78d15.

Note that what really matters is the multi-line string in min.py. Removing any line from it will make the External Tool work. In contrast, type min.py | python PythonToolForEmEditor.py always works well.

By the way, I’m using Python 3, so an encoding comment line is not strictly required.

Any suggestion is appreciated. Thanks a lot!

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