threadr.lostcave.ddnss.de/variable_grabbler.py

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#!/usr/bin/env python3
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import os, sys, json, traceback, subprocess
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# Definitions
def stdout(string, end='\n', flush=False):
print(string, end=end, file=sys.stdout, flush=flush)
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def stderr(string, end='\n', flush=False):
print(string, end=end, file=sys.stderr, flush=flush)
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exit_codes = {
"normal exit": 0,
"wrong usage": 1,
"error while processing": 2
}
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stderr("\nVariable Grabbler - version 5.0\n--------------------------------------------------------------------------------")
################################################################################
# Chnages in this version:
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# - complete rewrite in Python 3
# - output to stdout instead of rewriting the file
#===============================================================================
# Full documentation: tbd
#===============================================================================
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# Command line input handling
usage = "Usage: python3 "+sys.argv[0]+" <macro config file> <file to be processed>"
if not len(sys.argv)==3:
stderr("E: Wrong amount of arguments.")
stderr(usage)
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sys.exit(exit_codes["wrong usage"])
if sys.argv[1] == sys.argv[2]:
stderr("E: Both input files are the same.")
stderr(usage)
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sys.exit(exit_codes["wrong usage"])
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# load macros into a dict
stderr("I: Reading macro definitions... ")
macros = {}
try:
if os.path.isfile(sys.argv[1]):
macro_file = open(sys.argv[1], "r")
macros = json.loads(macro_file.read())
macro_file.close()
elif sys.argv[1] == '-':
macros = json.loads(sys.stdin.read())
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else:
stderr("E: Not a valid file: "+sys.argv[1])
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sys.exit(exit_codes["error while processing"])
except:
stderr("E: An exception occurred while trying to read macro definitions:")
traceback.print_exc()
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sys.exit(exit_codes["error while processing"])
# process "file" and "exec" macros
stderr("I: Loading templates and processing commands...")
for macro in macros:
if macros[macro][0] == "file":
if os.path.isfile(macros[macro][1]):
try:
stderr("I: Loading template: " + macro)
template = open(macros[macro][1], "r")
macros[macro] = template.read()
template.close()
except:
stderr("E: An exception occurred while trying to read the template:")
traceback.print_exc()
sys.exit(exit_codes["error while processing"])
else:
stderr("E: Macro \"" + macro + "\": template \"" + macros[macro][1] + "\" is not a valid file.")
sys.exit(exit_codes["error while processing"])
elif macros[macro][0] == "exec":
try:
stderr("I: Running command: " + macro)
process = subprocess.Popen(macros[macro][1], shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
process_stdout, process_stderr = process.communicate()
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macros[macro] = process_stdout.decode("utf-8")
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if len(process_stderr) > 0:
stderr("Output on stderr:\n"+process_stderr)
if not process.returncode == 0:
stderr("E: Command execution failed with exit code "+str(process.returncode))
sys.exit(exit_codes["error while processing"])
except:
stderr("E: An exception occurred while trying to process the command:")
traceback.print_exc()
sys.exit(exit_codes["error while processing"])
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# open file to be processed and iterate over it
stderr("I: Preparing to process input file...")
try:
input_file = sys.stdin
if os.path.isfile(sys.argv[2]):
input_file = open(sys.argv[2], "r")
elif sys.argv[2] == '-':
# nothing to do here bc input_file is already set to sys.stdin
pass
else:
stderr("E: Not a valid file: "+sys.argv[2])
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sys.exit(exit_codes["error while processing"])
# make the magic happen
stderr("I: Processing input file...")
for line in input_file:
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for macro in macros:
line = line.replace("%" + macro + "%", str(macros[macro]))
stdout(line, end="")
# close input file if it's not sys.stdin, assume sys.stdin is being handled for us
if not input_file==sys.stdin:
input_file.close()
except:
stderr("E: An exception occured while processing " + input_file.name + ":")
traceback.print_exc()
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sys.exit(exit_codes["error while processing"])