Handle IOError exceptions

[guidoiaquinti]

If the entire service or the control/status files do not exist or we are not able to read/write the files, raise an exception instead of failing with IOError

I don't know if this is a good solution as it's not backward compatible with the implementation that are already catching the exception. Suggestions are welcome

[fmoo]

This is kind of sketchy because of the write fails, we still want to close the file.

Probably initialize f = None outside of the try block and do a conditional close in a finally:

[guidoiaquinti]

You mean something like this?

f = None
try:
    f = open(self._control,"w+")
    f.write(signal)
except IOError as e:
    if f is not None:
      try:
        f.close()
       except IOError:
        pass
    raise ServiceControlError("Unable to write service control file '{0}'".format(e.filename))

What about splitting the 2 operations in different try/exc blocks?

try:
    f = open(self._control,"w+")
except IOError as e:
    raise ServiceControlError("Unable to open service control file '{0}'".format(e.filename))
try:
    f.write(signal)
except IOError as e:
    raise ServiceControlError("Unable to write service control file '{0}'".format(e.filename))
finally:
    f.close()   

[fmoo]

I was thinking:

f = None
try:
    f = open(...)
    f.write(...)
except IOError as e:
    raise SuperviseControlError(...)
finally:
    if f is not None:
        f.close()

Splitting and the extra try around the close is probably overkill, but I'm not used to weird scenarios that you can't close fds on.

[fmoo]

Since this is a breaking change, please update VERSION to 2.0.0

[guidoiaquinti]

While doing some GitHub cleanup 🧹 I found this old PR from 2016.

After 6 years waiting, I think I'm good to close this. Thank you anyway @fmoo !