From 609fad38b5818806323757d816d9fac5ba3c8a4c Mon Sep 17 00:00:00 2001
From: Olivier Gayot <olivier.gayot@sigexec.com>
Date: Fri, 20 Mar 2020 19:58:03 +0100
Subject: Add first version capable of parsing very simple commands

The script is able to parse very simple commands that don't wrap multiple
lines.

Signed-off-by: Olivier Gayot <olivier.gayot@sigexec.com>
---
 vish.py | 57 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 57 insertions(+)
 create mode 100755 vish.py

(limited to 'vish.py')

diff --git a/vish.py b/vish.py
new file mode 100755
index 0000000..a8febc3
--- /dev/null
+++ b/vish.py
@@ -0,0 +1,57 @@
+#!/usr/bin/env python3
+
+import os
+import re
+import argparse
+
+class EOFException(Exception):
+    pass
+
+
+class Instruction():
+    def __init__(self, string: str):
+        # TODO handle quoting and escapments
+        keywords = string.split()
+        self.prog = keywords[0]
+        self.arguments = keywords[1:]
+
+
+    def execute(self):
+        cpid = os.fork()
+        if cpid == 0:
+            os.execvp(self.prog, [self.prog] + self.arguments)
+        else:
+            os.waitpid(cpid, 0)
+
+
+def read_instruction(fh):
+    # TODO We should be reading an instruction, not a line.
+    while True:
+        line = fh.readline()
+        if line == "":
+            raise EOFException()
+
+        line = line.strip()
+        # We ignore empty lines and lines which start with #
+        if not line.startswith("#") and not line == "":
+            break
+
+    return Instruction(line)
+
+
+def main(arguments):
+    for script in arguments["<script>"]:
+        with open(script, mode="r", encoding="utf-8") as fh:
+            while True:
+                try:
+                    instruction = read_instruction(fh)
+                    instruction.execute()
+
+                except EOFException:
+                    break
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser(description="Command interpreter written in Python.")
+    parser.add_argument("<script>", action="store", nargs="+", help="Script to run")
+    args = parser.parse_args()
+    main(vars(args))
-- 
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