PHP: php://
php://
php:// — Accessing various I/O streams
Description
PHP provides a number of miscellaneous I/O streams that allow access to
PHP's own input and output streams, the standard input, output and error
file descriptors, in-memory and disk-backed temporary file streams, and
filters that can manipulate other file resources as they are read from and
written to.
php://stdin, php://stdout and php://stderr
php://stdin, php://stdout and
php://stderr allow direct access to the corresponding
input or output stream of the PHP process. The stream references a
duplicate file descriptor, so if you open php://stdin
and later close it, you close only your copy of the descriptor-the actual
stream referenced by STDIN is unaffected. Note that
PHP exhibited buggy behavior in this regard until PHP 5.2.1. It is
recommended that you simply use the constants STDIN,
STDOUT and STDERR instead of
manually opening streams using these wrappers.
php://stdin is read-only, whereas
php://stdout and php://stderr are
write-only.
php://input
php://input is a read-only stream that allows you to
read raw data from the request body. In the case of POST requests, it is
preferable to use php://input instead of $HTTP_RAW_POST_DATA as it does not depend
on special php.ini directives. Moreover, for those cases where
$HTTP_RAW_POST_DATA is not populated by default, it is a
potentially less memory intensive alternative to activating .
php://input is not available with
enctype="multipart/form-data".
Note:
A stream opened with php://input can only be read
once; the stream does not support seek operations. However, depending on
the SAPI implementation, it may be possible to open another
php://input stream and restart reading. This is only
possible if the request body data has been saved. Typically, this is the
case for POST requests, but not other request methods, such as PUT or
PROPFIND.
php://output
php://output is a write-only stream that allows you to
write to the output buffer mechanism in the same way as
print and echo.
php://fd
php://fd allows direct access to the given file
descriptor. For example, php://fd/3 refers to file
descriptor 3.
php://memory and php://temp
php://memory and php://temp are
read-write streams that allow temporary data to be stored in a file-like
wrapper. The only difference between the two is that
php://memory will always store its data in memory,
whereas php://temp will use a temporary file once the
amount of data stored hits a predefined limit (the default is 2 MB). The
location of this temporary file is determined in the same way as the
sys_get_temp_dir() function.
The memory limit of php://temp can be controlled by
appending /maxmemory:NN, where NN is
the maximum amount of data to keep in memory before using a temporary
file, in bytes.
php://filter
php://filter is a kind of meta-wrapper designed to
permit the application of filters to a
stream at the time of opening. This is useful with all-in-one file
functions such as readfile(),
file(), and file_get_contents()
where there is otherwise no opportunity to apply a filter to the stream
prior the contents being read.
The php://filter target takes the following parameters
as part of its path. Multiple filter chains can be specified on one path.
Please refer to the examples for specifics on using these parameters.
resource=<stream to be filtered>
This parameter is required. It specifies the stream that you would
like to filter.
read=<filter list to apply to read chain>
This parameter is optional. One or more filter names can be provided
here, separated by the pipe character (|).
write=<filter list to apply to write chain>
This parameter is optional. One or more filter names can be provided
here, separated by the pipe character (|).
<filter list to apply to both chains>
Any filter lists which are not prefixed by read=
or write= will be applied to both the read and
write chains as appropriate.
Options
Wrapper Summary (for php://filter, refer to the
summary of the wrapper being filtered)
Restricted by
No
Restricted by
php://input,
php://stdin,
php://memory and
php://temp only.
Allows Reading
php://stdin,
php://input,
php://fd,
php://memory and
php://temp only.
Allows Writing
php://stdout,
php://stderr,
php://output,
php://fd,
php://memory and
php://temp only.
Allows Appending
php://stdout,
php://stderr,
php://output,
php://fd,
php://memory and
php://temp only. (Equivalent to writing)
Allows Simultaneous Reading and Writing
php://fd,
php://memory and
php://temp only.
Supports stat()
php://memory and
php://temp only.
Supports unlink()
No
Supports rename()
No
Supports mkdir()
No
Supports rmdir()
No
Supports stream_select()
php://stdin,
php://stdout,
php://stderr,
php://fd and
php://temp only.
Changelog
5.3.6
php://fd was added.
5.1.0
php://memory and php://temp
were added.
5.0.0
php://filter was added.
Examples
Example #1 php://temp/maxmemory
This optional parameter allows setting the memory limit before
php://temp starts using a temporary file.
Example #2 php://filter/resource=<stream to be filtered>
This parameter must be located at
the end of your php://filter specification and
should point to the stream which you want filtered.
Example #3 php://filter/read=<filter list to apply to read chain>
This parameter takes one or more
filternames separated by the pipe character |.
Example #4 php://filter/write=<filter list to apply to write chain>
This parameter takes one or more
filternames separated by the pipe character |.
