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:; 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.

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.

parrotcode: Generic IO
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