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Ctype wrapper is used to call getnetgrent for #34

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Ctype wrapper is used to call getnetgrent for #34

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41bcc0b
Ctype wrapper is used to call getnetgrent for
Apr 6, 2022
0c9926a
function find_hostname modified to get_hostname
May 30, 2022
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31 changes: 31 additions & 0 deletions src/api/python/hidra/utils/utils_netgroup.py
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from ctypes import *
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@schooft schooft Apr 11, 2022

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Don't use '*' imports in libraries. This has multiple disadvantages.


def get_hostname(netgroup):

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@schooft schooft Apr 11, 2022

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Please add a doctring that describes what the function does, what are the inputs and outputs and any special or surprising behavior one needs to know to use it. Best would be to also add an example.

libc = CDLL("libc.so.6")
if (libc != None):
pass
else:
libc = CDLL("libc.so.7")
Comment on lines +6 to +10
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@schooft schooft Apr 11, 2022

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Is there a better way that going through a fixed list of library names? Why are "libc.so.5" or libc.so.8 not included in that list?

Also it is probably better to not do the lookup at every function call but only once at module load time.



hosts = None
if libc.setnetgrent(netgroup):
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@schooft schooft Apr 11, 2022

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One needs to check that netgroup is of the correct type, otherwise this might cause a segfault.

# returns 1 if successful and 0 otherwise
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@schooft schooft Apr 11, 2022

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The comment should be above or next to the line it refers to.

host = c_char_p()
user = c_char_p()
domain = c_char_p()

hosts = []
while libc.getnetgrent(byref(host), byref(user), byref(domain)):
if host:
# check is host is not a NULL pointer
hosts.append(host.value)
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@schooft schooft Apr 11, 2022

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Is this always safe? What about interleaving calls from multiple threads?
Should this return str instead of bytes?


return(hosts)
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@schooft schooft Apr 11, 2022

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The difference between None and [] might be too subtle. Maybe throw an error instead of returning None?



hosts = get_hostname(b"a3p62-hosts")
print(hosts)
print("done")