PHP/resource/stream

stream-type "resource" demiobjects in PHP

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About

Although there are a lot of functions that handle streams in PHP, how to properly use these functions is often not explained very well. I'm having to reverse-engineer a lot through trial and error.

Tentative Conclusions

• If a stream is set to blocking mode (with stream_set_blocking(<stream resource>, TRUE);), then EoS (end-of-stream) is indicated by the return of an empty string.
  • Questions about how it works in non-blocking mode:
    • How do we detect EoS in non-blocking mode? Some tentative leads:
      • We could set the stream with an event-callback (see stream_notification_callback) and look for STREAM_NOTIFY_COMPLETED events. PROBLEM: docs say this is only supported for http and ftp.
      • Maybe feof() would work? PROBLEM: although docs say this can be used on a stream, they also say it has to have been opened with fopen() or fsockopen(), which rules out process-fed streams created with functions like ssh2_exec().
    • Does empty-string still correctly signal that the process has completed?
      • I think we have to assume that this is true for stream_get_contents(): it will never return empty as long as the process is active. (Maybe in non-blocking mode, it blocks until there is at least one byte, or something?)
    • What happens if the process has not completed (so there's no new data yet) -- how can we tell that there might be more?

Links

Reference

• Stream Functions