stream_filter_append(3) [php man page]
STREAM_FILTER_APPEND(3) 1 STREAM_FILTER_APPEND(3) stream_filter_append - Attach a filter to a stream SYNOPSIS
resource stream_filter_append (resource $stream, string $filtername, [int $read_write], [mixed $params]) DESCRIPTION
Adds $filtername to the list of filters attached to $stream. PARAMETERS
o $stream - The target stream. o $filtername - The filter name. o $read_write - By default, stream_filter_append(3) will attach the filter to the read filter chain if the file was opened for reading (i.e. File Mode: r, and/or +). The filter will also be attached to the write filter chain if the file was opened for writing (i.e. File Mode: w, a, and/or +). STREAM_FILTER_READ, STREAM_FILTER_WRITE, and/or STREAM_FILTER_ALL can also be passed to the $read_write parameter to override this behavior. o $params - This filter will be added with the specified $params to the end of the list and will therefore be called last during stream operations. To add a filter to the beginning of the list, use stream_filter_prepend(3). RETURN VALUES
Returns a resource which can be used to refer to this filter instance during a call to stream_filter_remove(3). CHANGELOG
+--------+---------------------------------------------------+ |Version | | | | | | | Description | | | | +--------+---------------------------------------------------+ | 5.1.0 | | | | | | | Prior to PHP 5.1.0, this function returns TRUE | | | on success or FALSE on failure. | | | | +--------+---------------------------------------------------+ EXAMPLES
Example #1 Controlling where filters are applied <?php /* Open a test file for reading and writing */ $fp = fopen('test.txt', 'w+'); /* Apply the ROT13 filter to the * write filter chain, but not the * read filter chain */ stream_filter_append($fp, "string.rot13", STREAM_FILTER_WRITE); /* Write a simple string to the file * it will be ROT13 transformed on the * way out */ fwrite($fp, "This is a test "); /* Back up to the beginning of the file */ rewind($fp); /* Read the contents of the file back out. * Had the filter been applied to the * read filter chain as well, we would see * the text ROT13ed back to its original state */ fpassthru($fp); fclose($fp); /* Expected Output --------------- Guvf vf n grfg */ ?> NOTES
Note When using custom (user) filters stream_filter_register(3) must be called first in order to register the desired user filter to $filtername. Note Stream data is read from resources (both local and remote) in chunks, with any unconsumed data kept in internal buffers. When a new filter is appended to a stream, data in the internal buffers is processed through the new filter at that time. This differs from the behavior of stream_filter_prepend(3). Note When a filter is added for read and write, two instances of the filter are created. stream_filter_append(3) must be called twice with STREAM_FILTER_READ and STREAM_FILTER_WRITE to get both filter resources. SEE ALSO
stream_filter_register(3), stream_filter_prepend(3), stream_get_filters(3). PHP Documentation Group STREAM_FILTER_APPEND(3)
Check Out this Related Man Page
EvmFilterCreate(3) Library Functions Manual EvmFilterCreate(3) NAME
EvmFilterCreate(), EvmFilterDestroy(), EvmFilterIsFile(), EvmFilterReadFile(), EvmFilterSet(), EvmFilterTest() - event filter evaluator routines SYNOPSIS
Library EVM Support Library Parameters filter_evaluator For filter_evaluator is the return handle of an established filter evaluator. For filter_evaluator , identifies the filter evaluator that uses the filter_string in subsequent matches. For filter_evaluator identifies the filter evaluator that compares the supplied event with the filter string. For filter_evaluator identifies the filter evaluator to be destroyed. filter_string The filter string used by the filter evaluator in subsequent matches. See the EvmFilter(5) manpage for the syntax. event The event to be compared with the filter string currently associated with the filter evaluator. matchFlag The result obtained when the supplied event is compared with the filter string currently associated with the filter evalu- ator. Possible return values are as follows: The event matches the filter_string. The event does not match the filter_string. DESCRIPTION
The filter evaluation routines check whether an event matches a given event filter. These functions are useful to clients that pass a com- plex filter to the EVM daemon. Then the clients test incoming events against subcomponents of the filter to determine the appropriate action. The routine establishes an instance of a filter evaluator, returning a handle in filter_evaluator. The routine passes a filter_string to the filter_evaluator for subsequent matches. The routine compares the supplied event with the filter_string currently associated with the filter_evaluator. The result is returned in matchFlag. Possible return values are as follows: The event matches the filter_string. The event does not match the filter_string. The indirect filter syntax, is supported by the and routines. Programs which support indirect filters may use to determine whether a user- supplied filter string is indirect. If so, then use to expand the file to a regular filter string. returns if the supplied filter_string uses indirect filter notation, and returns otherwise. interprets the supplied filter_string, and attempts to open and read the referenced file. returns a pointer to heap space memory contain- ing the expanded filter string. The caller is responsible for freeing the memory when it is no longer needed. NULL is returned if an error occurs while reading the file. Note that does not attempt to validate the filter string contained in the file. The routine destroys the filter_evaluator, freeing all associated resources. RETURN VALUE
The operation completed without error. A filter string that is syntactically invalid passed to the filter evaluator. One of the arguments to the function is invalid. A value in a structure member is invalid. An operation failed because an attempt to acquire heap memory failed. An attempt was made to use a filter evaluator without first calling which provides an initial filter string. An attempt to read a filter file failed. ERRORS
The value of is not set. SEE ALSO
Event Management EVM(5). EVM Events EvmEvent(5). Event Filter EvmFilter(5). EvmFilterCreate(3)