Dear list,
I'm trying to understand PHP session handlers and more precisely the
return value of SessionHandlerInterface::read.
The doc [1] states (emphasis mine):
Returns an encoded string of the read data. *If nothing was read, it
must return false*. Note this value is returned internally to PHP
for processing.
However, the example used in the documentation of the SessionHandler
class [2] and other implementations (for instance Symfony's
PdoSessionHandler [3]) seem to return an empty string when nothing can
be read.
If I understand well, the first time you connect to an host, nothing can
be read. My own test seems to indicate that returning false in this case
triggers an error while returning an empty string creates a new session.
Can someone clarify this ? How is the value false used ? More generally,
I haven't found a clear explanation of which method is called at which
time during session creation and how the values are used.
Note that I have posted the same question on SO [4] but I'm not
satisfied by the answers.
Thanks in advance,
Mathieu
[1] https://www.php.net/manual/en/sessionhandlerinterface.read.php
[2] https://www.php.net/manual/en/class.sessionhandler
[3]
https://github.com/symfony/symfony/blob/c71c8727cc665c9e9b56e299fcfcc0adfbf02bac/src/Symfony/Component/HttpFoundation/Session/Storage/Handler/PdoSessionHandler.php#L638
[4] https://stackoverflow.com/questions/68025570
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Mathieu Dubois - IR - UMR 8030 équipe LABGeM
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