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diff --git a/README.STREAMS b/README.STREAMS deleted file mode 100644 index 870888a6bc..0000000000 --- a/README.STREAMS +++ /dev/null @@ -1,367 +0,0 @@ -An Overview of the PHP Streams abstraction -========================================== -$Id$ - -Please send comments to: Wez Furlong <wez@thebrainroom.com> - -Why Streams? -============ -You may have noticed a shed-load of issock parameters flying around the PHP -code; we don't want them - they are ugly and cumbersome and force you to -special case sockets and files everytime you need to work with a "user-level" -PHP file pointer. -Streams take care of that and present the PHP extension coder with an ANSI -stdio-alike API that looks much nicer and can be extended to support non file -based data sources. - -Using Streams -============= -Streams use a php_stream* parameter just as ANSI stdio (fread etc.) use a -FILE* parameter. - -The main functions are: - -PHPAPI size_t php_stream_read(php_stream * stream, char * buf, size_t count); -PHPAPI size_t php_stream_write(php_stream * stream, const char * buf, size_t - count); -PHPAPI int php_stream_eof(php_stream * stream); -PHPAPI int php_stream_getc(php_stream * stream); -PHPAPI char *php_stream_gets(php_stream * stream, char *buf, size_t maxlen); -PHPAPI int php_stream_close(php_stream * stream); -PHPAPI int php_stream_flush(php_stream * stream); -PHPAPI int php_stream_seek(php_stream * stream, off_t offset, int whence); -PHPAPI off_t php_stream_tell(php_stream * stream); - -These (should) behave in the same way as the ANSI stdio functions with similar -names: fread, fwrite, feof, fgetc, fgets, fclose, fflush, fseek, ftell. - -Opening Streams -=============== -In most cases, you should use this API: - -PHPAPI php_stream *php_stream_open_wrapper(char *path, char *mode, - int options, char **opened_path TSRMLS_DC); - -Where: - path is the file or resource to open. - mode is the stdio compatible mode eg: "wb", "rb" etc. - options is a combination of the following values: - IGNORE_PATH (default) - don't use include path to search for the file - USE_PATH - use include path to search for the file - IGNORE_URL - do not use plugin wrappers - REPORT_ERRORS - show errors in a standard format if something - goes wrong. - STREAM_MUST_SEEK - If you really need to be able to seek the stream - and don't need to be able to write to the original - file/URL, use this option to arrange for the stream - to be copied (if needed) into a stream that can - be seek()ed. - - opened_path is used to return the path of the actual file opened, - but if you used STREAM_MUST_SEEK, may not be valid. You are - responsible for efree()ing opened_path. opened_path may be (and usually - is) NULL. - -If you need to open a specific stream, or convert standard resources into -streams there are a range of functions to do this defined in php_streams.h. -A brief list of the most commonly used functions: - -PHPAPI php_stream *php_stream_fopen_from_file(FILE *file, const char *mode); - Convert a FILE * into a stream. - -PHPAPI php_stream *php_stream_fopen_tmpfile(void); - Open a FILE * with tmpfile() and convert into a stream. - -PHPAPI php_stream *php_stream_fopen_temporary_file(const char *dir, - const char *pfx, char **opened_path TSRMLS_DC); - Generate a temporary file name and open it. - -There are some network enabled relatives in php_network.h: - -PHPAPI php_stream *php_stream_sock_open_from_socket(int socket, int persistent); - Convert a socket into a stream. - -PHPAPI php_stream *php_stream_sock_open_host(const char *host, unsigned short port, - int socktype, int timeout, int persistent); - Open a connection to a host and return a stream. - -PHPAPI php_stream *php_stream_sock_open_unix(const char *path, int persistent, - struct timeval *timeout); - Open a UNIX domain socket. - - -Stream Utilities -================ - -If you need to copy some data from one stream to another, you will be please -to know that the streams API provides a standard way to do this: - -PHPAPI size_t php_stream_copy_to_stream(php_stream *src, - php_stream *dest, size_t maxlen); - -If you want to copy all remaining data from the src stream, pass -PHP_STREAM_COPY_ALL as the maxlen parameter, otherwise maxlen indicates the -number of bytes to copy. -This function will try to use mmap where available to make the copying more -efficient. - -If you want to read the contents of a stream into an allocated memory buffer, -you should use: - -PHPAPI size_t php_stream_copy_to_mem(php_stream *src, char **buf, - size_t maxlen, int persistent); - -This function will set buf to the address of the buffer that it allocated, -which will be maxlen bytes in length, or will be the entire length of the -data remaining on the stream if you set maxlen to PHP_STREAM_COPY_ALL. -The buffer is allocated using pemalloc(); you need to call pefree() to -release the memory when you are done. -As with copy_to_stream, this function will try use mmap where it can. - -If you have an existing stream and need to be able to seek() it, you -can use this function to copy the contents into a new stream that can -be seek()ed: - -PHPAPI int php_stream_make_seekable(php_stream *origstream, php_stream **newstream); - -It returns one of the following values: -#define PHP_STREAM_UNCHANGED 0 /* orig stream was seekable anyway */ -#define PHP_STREAM_RELEASED 1 /* newstream should be used; origstream is no longer valid */ -#define PHP_STREAM_FAILED 2 /* an error occurred while attempting conversion */ -#define PHP_STREAM_CRITICAL 3 /* an error occurred; origstream is in an unknown state; you should close origstream */ - -make_seekable will always set newstream to be the stream that is valid -if the function succeeds. -When you have finished, remember to close the stream. - -NOTE: If you only need to seek forwards, there is no need to call this -function, as the php_stream_seek can emulate forward seeking when the -whence parameter is SEEK_CUR. - -NOTE: Writing to the stream may not affect the original source, so it -only makes sense to use this for read-only use. - -NOTE: If the origstream is network based, this function will block -until the whole contents have been downloaded. - -NOTE: Never call this function with an origstream that is referenced -as a resource! It will close the origstream on success, and this -can lead to a crash when the resource is later used/released. - -NOTE: If you are opening a stream and need it to be seekable, use the -STREAM_MUST_SEEK option to php_stream_open_wrapper(); - -Casting Streams -=============== -What if your extension needs to access the FILE* of a user level file pointer? -You need to "cast" the stream into a FILE*, and this is how you do it: - -FILE * fp; -php_stream * stream; /* already opened */ - -if (php_stream_cast(stream, PHP_STREAM_AS_STDIO, (void*)&fp, REPORT_ERRORS) == FAILURE) { - RETURN_FALSE; -} - -The prototype is: - -PHPAPI int php_stream_cast(php_stream * stream, int castas, void ** ret, int - show_err); - -The show_err parameter, if non-zero, will cause the function to display an -appropriate error message of type E_WARNING if the cast fails. - -castas can be one of the following values: -PHP_STREAM_AS_STDIO - a stdio FILE* -PHP_STREAM_AS_FD - a generic file descriptor -PHP_STREAM_AS_SOCKETD - a socket descriptor - -If you ask a socket stream for a FILE*, the abstraction will use fdopen to -create it for you. Be warned that doing so may cause buffered data to be lost -if you mix ANSI stdio calls on the FILE* with php stream calls on the stream. - -If your system has the fopencookie function, php streams can synthesize a -FILE* on top of any stream, which is useful for SSL sockets, memory based -streams, data base streams etc. etc. - -In situations where this is not desireable, you should query the stream -to see if it naturally supports FILE *. You can use this code snippet -for this purpose: - - if (php_stream_is(stream, PHP_STREAM_IS_STDIO)) { - /* can safely cast to FILE* with no adverse side effects */ - } - -You can use: - -PHPAPI int php_stream_can_cast(php_stream * stream, int castas) - -to find out if a stream can be cast, without actually performing the cast, so -to check if a stream is a socket you might use: - -if (php_stream_can_cast(stream, PHP_STREAM_AS_SOCKETD) == SUCCESS) { - /* it can be a socket */ -} - -Please note the difference between php_stream_is and php_stream_can_cast; -stream_is tells you if the stream is a particular type of stream, whereas -can_cast tells you if the stream can be forced into the form you request. -The former doesn't change anything, while the later *might* change some -state in the stream. - -Stream Internals -================ - -There are two main structures associated with a stream - the php_stream -itself, which holds some state information (and possibly a buffer) and a -php_stream_ops structure, which holds the "virtual method table" for the -underlying implementation. - -The php_streams ops struct consists of pointers to methods that implement -read, write, close, flush, seek, gets and cast operations. Of these, an -implementation need only implement write, read, close and flush. The gets -method is intended to be used for streams if there is an underlying method -that can efficiently behave as fgets. The ops struct also contains a label -for the implementation that will be used when printing error messages - the -stdio implementation has a label of "STDIO" for example. - -The idea is that a stream implementation defines a php_stream_ops struct, and -associates it with a php_stream using php_stream_alloc. - -As an example, the php_stream_fopen() function looks like this: - -PHPAPI php_stream * php_stream_fopen(const char * filename, const char * mode) -{ - FILE * fp = fopen(filename, mode); - php_stream * ret; - - if (fp) { - ret = php_stream_alloc(&php_stream_stdio_ops, fp, 0, 0, mode); - if (ret) - return ret; - - fclose(fp); - } - return NULL; -} - -php_stream_stdio_ops is a php_stream_ops structure that can be used to handle -FILE* based streams. - -A socket based stream would use code similar to that above to create a stream -to be passed back to fopen_wrapper (or it's yet to be implemented successor). - -The prototype for php_stream_alloc is this: - -PHPAPI php_stream * php_stream_alloc(php_stream_ops * ops, void * abstract, - size_t bufsize, int persistent, const char * mode) - -ops is a pointer to the implementation, -abstract holds implementation specific data that is relevant to this instance -of the stream, -bufsize is the size of the buffer to use - if 0, then buffering at the stream -level will be disabled (recommended for underlying sources that implement -their own buffering - such a FILE*), -persistent controls how the memory is to be allocated - persistently so that -it lasts across requests, or non-persistently so that it is freed at the end -of a request (it uses pemalloc), -mode is the stdio-like mode of operation - php streams places no real meaning -in the mode parameter, except that it checks for a 'w' in the string when -attempting to write (this may change). - -The mode parameter is passed on to fdopen/fopencookie when the stream is cast -into a FILE*, so it should be compatible with the mode parameter of fopen(). - -Writing your own stream implementation -====================================== - -!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! -RULE #1: when writing your own streams: make sure you have configured PHP with ---enable-debug. -I've taken some great pains to hook into the zend memory manager to help track -down allocation problems. It will also help you spot incorrect use of the -STREAMS_DC, STREAMS_CC and the semi-private STREAMS_REL_CC macros for function -definitions. -!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! - -RULE #2: Please use the stdio stream as a reference; it will help you -understand the semantics of the stream operations, and it will always -be more up to date than these docs :-) - -First, you need to figure out what data you need to associate with the -php_stream. For example, you might need a pointer to some memory for memory -based streams, or if you were making a stream to read data from an RDBMS like -mysql, you might want to store the connection and rowset handles. - -The stream has a field called abstract that you can use to hold this data. -If you need to store more than a single field of data, define a structure to -hold it, allocate it (use pemalloc with the persistent flag set -appropriately), and use the abstract pointer to refer to it. - -For structured state you might have this: - -struct my_state { - MYSQL conn; - MYSQL_RES * result; -}; - -struct my_state * state = pemalloc(sizeof(struct my_state), persistent); - -/* initialize the connection, and run a query, using the fields in state to - * hold the results */ - -state->result = mysql_use_result(&state->conn); - -/* now allocate the stream itself */ -stream = php_stream_alloc(&my_ops, state, 0, persistent, "r"); - -/* now stream->abstract == state */ - -Once you have that part figured out, you can write your implementation and -define the your own php_stream_ops struct (we called it my_ops in the above -example). - -For example, for reading from this wierd mysql stream: - -static size_t php_mysqlop_read(php_stream * stream, char * buf, size_t count) -{ - struct my_state * state = (struct my_state*)stream->abstract; - - if (buf == NULL && count == 0) { - /* in this special case, php_streams is asking if we have reached the - * end of file */ - if (... at end of file ...) - return EOF; - else - return 0; - } - - /* pull out some data from the stream and put it in buf */ - ... mysql_fetch_row(state->result) ... - /* we could do something strange, like format the data as XML here, - and place that in the buf, but that brings in some complexities, - such as coping with a buffer size too small to hold the data, - so I won't even go in to how to do that here */ -} - -Implement the other operations - remember that write, read, close and flush -are all mandatory. The rest are optional. Declare your stream ops struct: - -php_stream_ops my_ops = { - php_mysqlop_write, php_mysqlop_read, php_mysqlop_close, - php_mysqlop_flush, NULL, NULL, NULL, - "Strange mySQL example" -} - -Thats it! - -Take a look at the STDIO implementation in streams.c for more information -about how these operations work. -The main thing to remember is that in your close operation you need to release -and free the resources you allocated for the abstract field. In the case of -the example above, you need to use mysql_free_result on the rowset, close the -connection and then use pefree to dispose of the struct you allocated. -You may read the stream->persistent field to determine if your struct was -allocated in persistent mode or not. - -vim:tw=78:et |