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References: <518e7f86-c4b6-c4f5-8e99-8a51ce049738@gmail.com>
 <CAJmy8YH42tD5O9d6pZCb0NFLP0TEhp+go=-cVTtWAa_tQbP25Q@mail.gmail.com> <dad6f99d-1b85-0e9e-7311-6170e781a007@cubiclesoft.com>
In-Reply-To: <dad6f99d-1b85-0e9e-7311-6170e781a007@cubiclesoft.com>
Date: Sun, 12 Feb 2023 15:59:21 +0100
Message-ID: <CAJmy8YF1d9SSZ49mKtrRktBoAud3nRZ85rB9Ux+pdrTY0sqofQ@mail.gmail.com>
To: Thomas Hruska <thruska@cubiclesoft.com>
Cc: Niels Dossche <dossche.niels@gmail.com>, PHP internals <internals@lists.php.net>
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Subject: Re: [PHP-DEV] RFC karma request
From: divinity76@gmail.com (Hans Henrik Bergan)

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Good point, and come to think of it, people wishing to $offset can fseek()
before before fpassthru() anyway. Nevermind the $offset thing, it's more
trouble than it's worth ^^

On Sun, Feb 12, 2023, 15:46 Thomas Hruska <thruska@cubiclesoft.com> wrote:

> On 2/12/2023 5:47 AM, Hans Henrik Bergan wrote:
> > Fwiw I would also find an $offset argument useful. fpassthru's lack of
> both
> > $length and $offset made my life harder when implementing "HTTP 206
> Partial
> > Content" / "HTTP range requests",
>
> I was going to suggest this myself until I realized that an $offset
> parameter would be rather problematic.  What happens if the offset is
> negative?  Does a negative offset mean seek backwards from the current
> position OR start at that many bytes from the end of the stream?  Is the
> offset a seek operation or a read operation?  Not all streams are
> seekable and reading is generally a fairly slow, blocking I/O operation.
>   Also, not all stream lengths are known.  A negative offset in
> non-seekable scenarios would almost certainly have to throw an error.
> fseek()/fread() are more flexible and consistent for getting to the
> desired starting point in a source stream.
>
> A negative $length would also present some issues.  Again, not all
> stream lengths are known.  Correctly handling negative values would
> require managing an internally, temporarily allocated buffer of
> sufficient size to be able to backtrack streams of unknown length.  And
> might even have to cache the entire stream in RAM, which would be
> problematic for 1GB+ streams.  Or just throw an error for such streams.
> Or just restrict $length to non-negative values only.
>
> In short, a non-negative, nullable $length parameter is the only
> well-defined operation for fpassthru().
>
> fpassthru() is largely a convenience wrapper around fread()/unbuffered
> echo in a loop with some extra output buffer management and is subject
> to PHP max_execution_time.  For large files and/or slow/high latency
> networks, PHP can timeout before delivering all content.
>
> There are several web server extensions available (X-Sendfile and
> X-Accel-Redirect) where, for local files, the rest of the request can be
> handed off from PHP to the web server to completely avoid writing any
> file output to the output buffer and also avoid timeout issues.  The
> existence of modern web server extensions for all major web servers
> limits the overall usefulness of fpassthru().  IMO, $length should be
> added for language-level completeness/convenience but it might also be a
> good idea to mention X-Sendfile/X-Accel-Redirect in the documentation
> for fpassthru() so that users are encouraged to leverage
> resource-efficient technologies wherever possible.
>
>
> > Ended up with a
> > $output = fopen('php://output', 'wb'); + stream_copy_to_stream()
> > hack because of fpassthru's shortcomings (Thanks to cmb for that hack, by
> > the way)
> >
> >
> > On Sat, Feb 11, 2023, 15:26 Niels Dossche <dossche.niels@gmail.com>
> wrote:
> >
> >> Dear internals
> >>
> >> I would like to gain RFC karma for creating and proposing an RFC:
> >> "Implement GH-9673: $length argument for fpassthru".
> >> Account name: nielsdos
> >>
> >> Thanks in advance
> >> Kind regards
> >> Niels
>
>
> --
> Thomas Hruska
> CubicleSoft President
>
> CubicleSoft has over 80 original open source projects and counting.
> Plus a couple of commercial/retail products.
>
> What software are you looking to build?
>
>

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