iscsi_session_to_json.md

Converts a series of "assignments" to a "JSON" dict.

It was intended to parse /var/lib/iscsi/nodes/$TARGET/$PORTAL/default files of iSCSI initiator node (where one have ran iscsiadm command). The path is for CentOS 7 based machines -- your mileage may vary.

Syntax of input files

• line ::= entry? [ # comment ] \n

• comment ::= .* # ignored

• entry ::= space* name space* = space* value space*

• name ::= simpleName | simpleName . name

• simpleName ::= identifier | indexed

• indexed ::= identifier [ index ]

• index ::= int

• identifier ::= .* # actually, no restrictions other than lack of '[9]' suffix applied

• value ::= null | bool | float | int | string

• null ::= None

• bool ::= Yes | No

• float ::= int . [ int ] # actually, anything that has a '.' and can be parsed with float()

• int ::= digit | digit int # actually, anything that has no '.' and can be parsed with int()

• string ::= .* # actually, anything else, i.e. not null, bool, float, or int.

Caveats

1. Indexed names are mapped to dicts, not lists!
2. Comments and empty lines are just ignored.

iscsi_session_to_json.py

#!/usr/bin/python
'''
# Converts a series of "assignments" to a "JSON" dict.

It was intended to parse `/var/lib/iscsi/nodes/$TARGET/$PORTAL/default` files
of iSCSI initiator node (where one have ran `iscsiadm` command). The path is
for CentOS 7 based machines -- your mileage may vary.

## Syntax of input files

line ::= [ entry ] [ '#' comment ] '\n'

comment ::= .*                  # ignored

entry ::= space* name space* '=' space* value space*

name ::= simpleName | simpleName '.' name
simpleName ::= identifier | indexed
indexed ::= identifier '[' index ']'
index ::= int
identifier ::=  .*              # actually, no restrictions other than lack of '[9]' suffix applied

value ::= null | bool | float | int | string
null ::= 'None'
bool ::= 'Yes' | 'No'
float ::= int '.' [ int ]       # actually, anything that has a '.' and can be parsed with float()
int ::= digit | digit int       # actually, anything that has no '.' and can be parsed with int()
string ::= .*                   # actually, anything else, i.e. not null, bool, float, or int.

## Caveats

Indexed names are mapped to dicts, not lists!

Comments and empty lines are just ignored.
'''

import logging
logging.basicConfig(datefmt='%F %T %z', level=logging.INFO)
logger = logging.getLogger('py2json')

import sys
import json

def convert_value(s):
    if s == 'None':
        return None
    if s in ('No',):
        return False
    if s in ('Yes',):
        return True
    if '.' in s:
        try:
            return float(s)
        except ValueError:
            return s.decode('utf-8')
    try:
        return int(s)
    except ValueError:
        return s.decode('utf-8')

def convert_name(s):
    r = []
    for item in s.split('.'):
        if item.endswith(']'):
            nm, idx = item.split('[', 1)
            idx = int(idx.split(']', 1).pop(0))
            idx = str(idx).decode('utf-8') # we make use of dicts instead of lists here
            r.append((nm.decode('utf-8'), idx))
        else:
            r.append((item.decode('utf-8'), None))
    return r

def set_value(r, name, value, was):
    logger.debug('set_value(r={}, name={}, value={})'.format(`r`, `name`, `value`))
    if name:
        (n, i) = name[0]
        logger.debug('set_value: n={} i={}'.format(`n`, `i`))
        if i is None:
            r[n] = r.get(n, {})
            r[n] = set_value(r[n], name[1:], value, i)
        else:
            r[n] = r.get(n, {i: {}}) # it should be a list, but...
            r[n][i] = set_value(r[n][i], name[1:], value, i)
        return r
    return value

def convert(fin=sys.stdin, fout=sys.stdout):
    r, n = {}, 0
    for line in fin.xreadlines():
        n += 1
        logger.debug('{}: {}'.format(n, `line`))
        line, comment = map(lambda s: s.strip(), line.split('#', 1) + ['',''])[:2]
        if not line:
            continue
        name, value = map(lambda s: s.strip(), line.split('=', 1))
        name, value = convert_name(name), convert_value(value)

        set_value(r, name, value, None)
                
        logger.debug('{}: {}={}'.format(n, `name`, `value`))
    return r

def compare(d1, d2):
    if type(d1) is not type(d2):
        logger.info('compare({}, {}): type'.format(`d1`, `d2`))
        return False
    if type(d1) is not dict:
        if d1 != d2:
            logger.info('compare({}, {}): non-dict'.format(`d1`, `d2`))
        return d1 == d2
    keys = d1.keys()
    if sorted(keys) == sorted(d2.keys()):
        for k in keys:
            if not compare(d1[k], d2[k]):
                return False
        return True
    else:
        logger.info('compare({}, {}): keys {} != {}'.format(`d1`, `d2`, `keys`, `d2.keys()`))
        return False

def main():
    import pprint
    d = convert()
    pprint.pprint(d)
    print
    json.dump(d, fp=sys.stdout, indent=2)
    print
    s = json.dumps(d)
    d2 = json.loads(s)
    assert compare(d, d2)
    return 0

if __name__ == '__main__':
    sys.exit(main())

# EOF #