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Fwd: [PHP] proc_open and buffer limit?

php.internals

Mark Krenz

20 years ago
I asked this last night on the general mailing list and also have asked around about it. Nobody seems to know. I normally wouldn't ask a support quesiton on a developers mailing list, but nobody else seems to know so I thought that perhaps a developer knows. Why would I be running into this STDIN data size limit when using proc_open? I've tried setting the limits for apache to unlimited in /etc/security/limits.conf just to see if its a system limit. ----- Forwarded message from Mark Krenz <mark@suso.org> ----- Date: Sun, 22 Jan 2006 00:25:33 +0000 From: Mark Krenz <mark@suso.org> To: php-general@lists.php.net Subject: [PHP] proc_open and buffer limit? I'm using PHP 5.1.1 on Apache 2.0.54 on Gentoo Linux. I've been trying to write a program to pass information to a program using proc_open, however when I do, it only passes the first 65536 bytes of the stream and then cuts off the rest. To make sure its not the program I'm trying to send to, I tries using /bin/cat instead and get the same problem. Below, I've included the code that I'm using, which for the most part is from the proc_open documentation page. For testing, I'm reading from a word dictionary which is over 2MB in size. Is there something I'm missing about using proc_open? ------------------------------------------------------------------------- $program = "/bin/cat"; $descriptorspec = array( 0 => array("pipe", "r"), 1 => array("pipe", "w"), 2 => array("file", "/tmp/error-output.txt", "a") ); $cwd = '/var/www'; $env = array('HOME' => '/var/www'); $process = proc_open($program, $descriptorspec, $pipes, $cwd, $env); if (is_resource($process)) { stream_set_blocking($pipes[0], FALSE); stream_set_blocking($pipes[1], FALSE); $handle = fopen("/usr/share/dict/words", "r"); while (!feof($handle)) { $input .= fread($handle, 8192); } fwrite($pipes[0], $input); fclose($handle); fclose($pipes[0]); while (!feof($pipes[1])) { $output .= fgets($pipes[1], 8192); } fclose($pipes[1]); print "<PRE>$output</PRE><BR><BR>\n"; $return_value = proc_close($process); echo "command returned $return_value\n"; } -------------------------------------------------------------------------
-- Mark S. Krenz IT Director Suso Technology Services, Inc. http://suso.org/ -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php ----- End forwarded message ----- -- Mark S. Krenz IT Director Suso Technology Services, Inc. http://suso.org/

Nicolas Bérard Nault

20 years ago
My guess at first look is that you fill the stdout buffer because you don't read from it untill you stop piping data to stdin. On 1/22/06, Mark Krenz <mark@suso.org> wrote:
> > > I asked this last night on the general mailing list and also have > asked around about it. Nobody seems to know. I normally wouldn't ask a > support quesiton on a developers mailing list, but nobody else seems to > know so I thought that perhaps a developer knows. > > Why would I be running into this STDIN data size limit when using > proc_open? > > I've tried setting the limits for apache to unlimited in > /etc/security/limits.conf just to see if its a system limit. > > ----- Forwarded message from Mark Krenz <mark@suso.org> ----- > > Date: Sun, 22 Jan 2006 00:25:33 +0000 > From: Mark Krenz <mark@suso.org> > To: php-general@lists.php.net > Subject: [PHP] proc_open and buffer limit? > > > I'm using PHP 5.1.1 on Apache 2.0.54 on Gentoo Linux. I've been trying > to write a program to pass information to a program using proc_open, > however when I do, it only passes the first 65536 bytes of the stream > and then cuts off the rest. To make sure its not the program I'm trying > to send to, I tries using /bin/cat instead and get the same problem. > > Below, I've included the code that I'm using, which for the most part is > from the proc_open documentation page. For testing, I'm reading from a > word dictionary which is over 2MB in size. Is there something I'm > missing about using proc_open? > > ------------------------------------------------------------------------- > $program = "/bin/cat"; > > $descriptorspec = array( > 0 => array("pipe", "r"), > 1 => array("pipe", "w"), > 2 => array("file", "/tmp/error-output.txt", "a") > ); > > $cwd = '/var/www'; > $env = array('HOME' => '/var/www'); > > $process = proc_open($program, $descriptorspec, $pipes, $cwd, $env); > > if (is_resource($process)) { > > stream_set_blocking($pipes[0], FALSE); > stream_set_blocking($pipes[1], FALSE); > > $handle = fopen("/usr/share/dict/words", "r"); > while (!feof($handle)) { > $input .= fread($handle, 8192); > } > > fwrite($pipes[0], $input); > fclose($handle); > fclose($pipes[0]); > > while (!feof($pipes[1])) { > $output .= fgets($pipes[1], 8192); > } > fclose($pipes[1]); > > print "<PRE>$output</PRE><BR><BR>\n"; > > $return_value = proc_close($process); > > echo "command returned $return_value\n"; > } > ------------------------------------------------------------------------- > > > > -- > Mark S. Krenz > IT Director > Suso Technology Services, Inc. > http://suso.org/ > > -- > PHP General Mailing List (http://www.php.net/) > To unsubscribe, visit: http://www.php.net/unsub.php > > > ----- End forwarded message ----- > > > -- > Mark S. Krenz > IT Director > Suso Technology Services, Inc. > http://suso.org/ > > -- > PHP Internals - PHP Runtime Development Mailing List > To unsubscribe, visit: http://www.php.net/unsub.php > >
-- Nicolas Bérard Nault (nicobn@gmail.com) Étudiant D.E.C. Sciences, Lettres & Arts Cégep de Sherbrooke Site web: http://www.lapsus-engineer.org "La liberté est un bagne aussi longtemps qu'un seul homme est asservi sur la terre." - Albert Camus, Les Justes.

Mark Krenz

20 years ago
Well, the program that I'm really doing this with has a -o option to write its data out to a file and when I use that option I have the same problem with it only taking the first 64KB on stdin. On Mon, Jan 23, 2006 at 04:48:12AM GMT, Nicolas Bérard Nault [nicobn@gmail.com] said the following:
> My guess at first look is that you fill the stdout buffer because you don't > read from it untill you stop piping data to stdin. >
-- Mark S. Krenz IT Director Suso Technology Services, Inc. http://suso.org/

Wez Furlong

20 years ago
There are quite a few bad streams usages there. I'd rewrite your code like this: $words = fopen('/usr/share/dict/words', 'r'); stream_copy_to_stream($words, $pipes[0]); fclose($pipes[0]); fclose($words); $output = stream_get_contents($pipes[1]); fclose($pipes[1]); proc_close($process); My guess at the cause of the problem was that you're tying to write 2MB into a pipe, and the underlying write() syscall could only write 64k; since you're ignoring the return code from fwrite(), you're missing this vital fact. Using the streams functions in PHP 5 helps you to write code that "does what I mean", and makes for shorter, more readable code. --Wez. PS: http://netevil.org/talks/PHP-Streams-Lucky-Dip.pdf has some tips and insider knowledge on using streams in PHP. On 1/23/06, Mark Krenz <mark@suso.org> wrote:

Mark Krenz

20 years ago
Thanks for your help. stream_copy_to_stream does seem like a better way to go. However I still have the same problem. Only 65536 bytes are written to /tmp/output.txt. Here is the new source code based on your ideas: -------------------------------------------------------------------------- $program = "/usr/bin/dd of=/tmp/output.txt"; $descriptorspec = array( 0 => array("pipe", "r"), 1 => array("pipe", "w"), 2 => array("file", "/tmp/error-output.txt", "a") ); $cwd = '/var/www'; $env = array('HOME' => '/var/www'); $process = proc_open($program, $descriptorspec, $pipes, $cwd, $env); if (is_resource($process)) { stream_set_blocking($pipes[0], FALSE); stream_set_blocking($pipes[1], FALSE); $handle = fopen("/usr/share/dict/words", "r"); stream_copy_to_stream($handle, $pipes[0]); fclose($pipes[0]); fclose($handle); $output = stream_get_contents($pipes[1]); fclose($pipes[1]); print "<PRE>$output</PRE><BR><BR>\n"; $return_value = proc_close($process); echo "command returned $return_value\n"; } -------------------------------------------------------------------------- I switched to using dd instead of cat because using cat made the situation more complex (because it sends back data as it gets it). The program I'm going to eventually do this with doesn't do that. On Mon, Jan 23, 2006 at 02:08:55PM GMT, Wez Furlong [kingwez@gmail.com] said the following:
> There are quite a few bad streams usages there. > > I'd rewrite your code like this: > > $words = fopen('/usr/share/dict/words', 'r'); > stream_copy_to_stream($words, $pipes[0]); > fclose($pipes[0]); > fclose($words); > $output = stream_get_contents($pipes[1]); > fclose($pipes[1]); > proc_close($process); > > My guess at the cause of the problem was that you're tying to write > 2MB into a pipe, and the underlying write() syscall could only write > 64k; since you're ignoring the return code from fwrite(), you're > missing this vital fact. > > Using the streams functions in PHP 5 helps you to write code that > "does what I mean", and makes for shorter, more readable code. > > --Wez. > > PS: http://netevil.org/talks/PHP-Streams-Lucky-Dip.pdf > has some tips and insider knowledge on using streams in PHP. > > > > On 1/23/06, Mark Krenz <mark@suso.org> wrote: > > stream_set_blocking($pipes[0], FALSE); > > stream_set_blocking($pipes[1], FALSE); > > > > $handle = fopen("/usr/share/dict/words", "r"); > > while (!feof($handle)) { > > $input .= fread($handle, 8192); > > } > > > > fwrite($pipes[0], $input); > > fclose($handle); > > fclose($pipes[0]); > > > > while (!feof($pipes[1])) { > > $output .= fgets($pipes[1], 8192); > > } > > fclose($pipes[1]); > > > > print "<PRE>$output</PRE><BR><BR>\n"; > > > > $return_value = proc_close($process); > > > > echo "command returned $return_value\n"; > > } >
-- Mark S. Krenz IT Director Suso Technology Services, Inc. http://suso.org/

Wez Furlong

20 years ago
I suggest running the script using strace: strace -e trace=file php myscript.php and taking a look to see what the underlying read/write syscalls are up to. --Wez. On 1/23/06, Mark Krenz <mark@suso.org> wrote: