NAME ^

src/io/io.c - Generic IO

DESCRIPTION ^

The Parrot IO subsystem uses a per-interpreter stack to provide a layer-based approach to IO. Each layer implements a subset of the ParrotIOLayerAPI vtable. To find an IO function, Parrot searches the layer stack downwards until it finds a non-NULL function pointer for that particular slot.

This file implements the generic functionality. Specific layers are in separate files: src/io/io_buf.c, src/io/io_stdio.c, src/io/io_unix.c, src/io/io_win32.c, and src/io/io_layers.c.

The ParrotIO PMC provides the class-based interface that is used in Parrot ops. The ParrotIO struct is defined in src/io/io_private.h.

Resource Functions ^

new_io_pmc

Creates and returns a new ParrotIO PMC.

PIO_make_io_string

Creates a STRING* suitable for returning results from IO read functions. The passed in buf parameter can:

  1. Point to a NULL STRING
  2. Point to a real STRING
  3. Point to a fake STRING with (strstart, bufused) holding the *buffer information.
In the third case, the buffer or STRING must be able to hold the required amount of data. For cases 1 and 2, a NULL strstart tells this function to allocate the STRING memory.

PIO_new

Creates a new IO stream.

The values of flags and mode are set in the returned ParrotIO.

Currently iotype is unused.

PIO_destroy

Destroys the IO stream. At the moment, this only frees the memory and removes the pointers from the PMC.

PIO_init

Sets up the interpreter's layer stack and creates the STD* handles.

Called when creating an interpreter.

PIO_finish

Closes the interpreter's IO resourses. Called during its interpreter destruction.

PIO_internal_shutdown

IO system destructor, called on destruction of the last interpreter.

PIO_init_stacks

Initializes the interpreter's default IO stack by pushing on the IO layers (OS-specific first).

PIO_base_init

Init routine called once for each layer at interpreter creation time. This is similar to a Perl module INIT {} block.

This default implementation does nothing and returns 0.

Generic top-level ParrotIO interface ^

PIO_parse_open_flags

Parses *flagstr for Perl-style file open mode flags (<, >, >>, +<, +>) and returns the combined generic bit flags.

The low level OS layers may then interpret the generic bits differently depending on platform.

XXX BD Should this be static?

PIO_peek

Iterates down the stack to the first layer implementing "Peek" API.

PIO_pioctl

General purpose interface for manipulating IO objects and layer attributes.

Refer to the PIOCTL* values in include/parrot/io.h.

All set operations return 0 on success and a negative value on error. get operations use the return value as the value requested, but should always be >= 0. A negative value indicates an error. This may be too limited, but we will see. --Melvin

PIO_setbuf

Sets the buffer size for *pmc to bufsize. Returns 0 if the buffering was enabled.

PIO_setlinebuf

Enables line buffering for *pmc. Returns 0 if line buffering was successfully set, or already enabled.

PIO_open

Creates and returns a ParrotIO PMC for *spath.

PIO_fdopen

Creates and returns a ParrotIO PMC for *spath on an existing, open file descriptor.

This is used particularly to initialize the STD* IO handles onto the OS IO handles (0,1,2).

PIO_close

Flushes, closes, and destroys the ParrotIO PMC *pmc.

PIO_flush

Flushes the ParrotIO PMC *pmc.

PIO_reads

Return a new STRING* holding up to len bytes.

PIO_read

Reads up to len bytes from *pmc and copies them into *buffer.

PIO_write

Writes len bytes from *buffer to *pmc.

PIO_seek

Moves the read/write position of *pmc to offset bytes from the position indicated by w. Typically w will be 0 for the start of the file, 1 for the current position, and 2 for the end.

PIO_tell

Returns the current read/write position of *pmc.

PIO_eof

Returns a boolean value indication whether *pmc's current read/write position is EOF.

PIO_puts

Writes *s tp *pmc. C string version.

PIO_putps

Writes *s to *pmc. Parrot string version.

PIO_fprintf

Writes a C string format with varargs to *pmc.

PIO_printf

Writes a C string format with varargs to stdout.

PIO_eprintf

Writes a C string format with varargs to stderr.

PIO_getfd

Returns *pmc's file descriptor, or 0 if it is not defined.

PIO_STD* Functions ^

PIO_STDIN

Returns the ParrotIO PMC for stdin.

PIO_STDOUT

Returns the ParrotIO PMC for stdout.

PIO_STDERR

Returns the ParrotIO PMC for stderr.

DOD-related Functions ^

Parrot_IOData_mark

Called from trace_active_PMCs() to mark the IO data live.

Offset Functions ^

These are used to create offsets for the seek op.

PIO_make_offset

Returns offset.

PIO_make_offset32

hi is shifted 32 bytes to the left and ored together with lo. This allows 64-bit seeks with only 32-bit INTVALS.

PIO_make_offset_pmc

Returns the return value of the get_integer vtable method on *pmc.

Networking Functions ^

PIO_poll

Polls *pmc for the events in which every sec seconds + usec microseconds.

PIO_socket

Creates and returns a socket using the specified address family, socket type, and protocol number. Check the returned PMC with a boolean test to see whether the socket was successfully created.

PIO_recv

Receives a message from the connected socket *pmc in *buf. Returns -1 if it fails.

PIO_send

Sends the message *buf to the connected socket *pmc. Returns -1 if it cannot send the message.

PIO_connect

Connects *pmc to *address. Returns -1 on failure.

PIO_bind

Binds *pmc's socket to the local address and port specified by *address. Returns -1 on failure.

PIO_listen

Listens for new connections on socket *pmc. Returns -1 on failure.

PIO_accept

Accepts a new connection and returns a newly created ParrotIO socket. Returns NULL on failure.

PIO_isatty

Returns a boolean value indicating whether *pmc is a console/tty.

SEE ALSO ^

io/io_buf.c, io/io_passdown.c, io/io_stdio.c, io/io_unix.c, io/io_win32.c, io/io_private.h.

HISTORY ^

Initially written by Melvin Smith.

Some ideas and goals from Perl 5.7 and Nick Ing-Simmons' work.

TODO ^

Rework to use copy-on-write IO stacks rather than creating a new stack for each IO stream.

Add support for loadable layers in Parrot bytecode.


parrot