From f3a88b207e5e2c781374127c81c2924062757613 Mon Sep 17 00:00:00 2001
From: Timotej Lazar <timotej.lazar@fri.uni-lj.si>
Date: Sat, 2 Mar 2019 13:14:38 +0100
Subject: kpov_util: better random strings and filenames

Do not use hard-to-distinguish characters, and use shorter names by
default.
---
 kpov_util.py | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/kpov_util.py b/kpov_util.py
index 8434f85..4acaf79 100755
--- a/kpov_util.py
+++ b/kpov_util.py
@@ -39,11 +39,17 @@ def ssh_test(host, user, password, commands=()):
         results['ssh'] = 'connection to {} as {}/{} failed ({})'.format(host, user, password, e)
     return results
 
-def alnum_gen(r, l=1):
-    s = ""
-    for i in range(l):
-        s += r.choice(string.ascii_letters + string.digits)
-    return s
+# omit i, l, o, I, O, 1, 0 for readability
+uppers = 'ABCDEFGHJKLMNPQRSTUVWXYZ'
+lowers = 'abcdefghjkmnpqrstuvwxyz'
+numbers = '23456789'
+def alnum_gen(r, length=1, lower=True, upper=True):
+    return ''.join(
+        r.choice(
+            numbers +
+            (lowers if lower else '') +
+            (uppers if upper else ''))
+        for i in range(length))
 
 def fortune(r, max_len):
     all_fortunes = []
@@ -112,8 +118,8 @@ def MAC_gen(r):
         [r.choice(s) + r.choice(s) for i in range(5)])
 
 common_file_extensions = ['jpg', 'png', 'txt', 'doc', 'cfg', 'pdf', 'odt', 'cpp', 'c', 'sh', 'java']
-def fname_gen(r, extension = True):
-    s = alnum_gen(r, 8)
+def fname_gen(r, extension=True):
+    s = alnum_gen(r, length=5, upper=False)
     if extension:
         s += '.' + r.choice(common_file_extensions)
     return s
-- 
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