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

PMC *new_io_pmc: Creates and returns a new ParrotIO PMC.
STRING *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.
ParrotIO *PIO_new: Creates a new IO stream.; The values of flags and mode are set in the returned ParrotIO.; Currently iotype is unused.
PMC *PIO_dup: Duplicates an IO stream.
void PIO_destroy: Destroys the IO stream. At the moment, this only frees the memory and removes the pointers from the PMC.
void PIO_init: Sets up the interpreter's layer stack and creates the STD* handles.; Called when creating an interpreter.
void PIO_finish: Closes the interpreter's IO resourses. Called during its interpreter destruction.
void PIO_internal_shutdown: IO system destructor, called on destruction of the last interpreter.
INTVAL PIO_init_stacks: Initializes the interpreter's default IO stack by pushing on the IO layers (OS-specific first).
INTVAL 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

INTVAL 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?
INTVAL PIO_peek: Iterates down the stack to the first layer implementing "Peek" API.
INTVAL 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
INTVAL PIO_setbuf: Sets the buffer size for *pmc to bufsize. Returns 0 if the buffering was enabled.
INTVAL PIO_setlinebuf: Enables line buffering for *pmc. Returns 0 if line buffering was successfully set, or already enabled.
PMC *PIO_open: Creates and returns a ParrotIO PMC for *spath.
PMC *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).
INTVAL PIO_close: Flushes, closes, and destroys the ParrotIO PMC *pmc.
void PIO_flush: Flushes the ParrotIO PMC *pmc.
STRING *PIO_reads: Return a new STRING* holding up to len bytes.
INTVAL PIO_read: Reads up to len bytes from *pmc and copies them into *buffer.
INTVAL PIO_write: Writes len bytes from *buffer to *pmc.
PIOOFF_T 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.
PIOOFF_T PIO_tell: Returns the current read/write position of *pmc.
INTVAL PIO_eof: Returns a boolean value indication whether *pmc's current read/write position is EOF.
INTVAL PIO_puts: Writes *s tp *pmc. C string version.
INTVAL PIO_putps: Writes *s to *pmc. Parrot string version.
INTVAL PIO_fprintf: Writes a C string format with varargs to *pmc.
INTVAL PIO_printf: Writes a C string format with varargs to stdout.
INTVAL PIO_eprintf: Writes a C string format with varargs to stderr.
PIOHANDLE PIO_getfd: Returns *pmc's file descriptor, or 0 if it is not defined.

`PIO_STD*` Functions

PMC *PIO_STDIN: Returns the ParrotIO PMC for stdin.
PMC *PIO_STDOUT: Returns the ParrotIO PMC for stdout.
PMC *PIO_STDERR: Returns the ParrotIO PMC for stderr.

DOD-related Functions

void 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.

PIOOFF_T PIO_make_offset: Returns offset.
PIOOFF_T 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.
PIOOFF_T PIO_make_offset_pmc: Returns the return value of the get_integer vtable method on *pmc.

Networking Functions

INTVAL PIO_poll: Polls *pmc for the events in which every sec seconds + usec microseconds.
PMC *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.
INTVAL PIO_recv: Receives a message from the connected socket *pmc in *buf. Returns -1 if it fails.
INTVAL PIO_send: Sends the message *buf to the connected socket *pmc. Returns -1 if it cannot send the message.
INTVAL PIO_connect: Connects *pmc to *address. Returns -1 on failure.
INTVAL PIO_bind: Binds *pmc's socket to the local address and port specified by *address. Returns -1 on failure.
INTVAL PIO_listen: Listens for new connections on socket *pmc. Returns -1 on failure.
PMC *PIO_accept: Accepts a new connection and returns a newly created ParrotIO socket. Returns NULL on failure.
INTVAL 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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