From 760c406afd447f94677ee207e20f52ddcb8fbf18 Mon Sep 17 00:00:00 2001 From: Miles Bader Date: Wed, 26 Jul 1995 20:09:37 +0000 Subject: Initial revision --- libpipe/pipe.c | 246 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 246 insertions(+) create mode 100644 libpipe/pipe.c (limited to 'libpipe/pipe.c') diff --git a/libpipe/pipe.c b/libpipe/pipe.c new file mode 100644 index 00000000..73463acd --- /dev/null +++ b/libpipe/pipe.c @@ -0,0 +1,246 @@ +/* Generic one-way pipes + + Copyright (C) 1995 Free Software Foundation, Inc. + + Written by Miles Bader + + This program is free software; you can redistribute it and/or + modify it under the terms of the GNU General Public License as + published by the Free Software Foundation; either version 2, or (at + your option) any later version. + + This program is distributed in the hope that it will be useful, but + WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program; if not, write to the Free Software + Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ + +#include /* For bzero() */ + +#include +#include + +#include "pipe.h" + +static inline void +timestamp (time_value_t *stamp) +{ + host_get_time (mach_host_self (), stamp); +} + +/* ---------------------------------------------------------------- */ + +/* Creates a new pipe of class CLASS and returns it in RESULT. */ +error_t +pipe_create (struct pipe_class *class, struct pipe **pipe) +{ + struct pipe *new = malloc (sizeof (struct pipe)); + + if (new == NULL) + return ENOMEM; + + new->refs = 0; + new->flags = 0; + new->class = class; + + bzero (&new->read_time, sizeof (new->read_time)); + bzero (&new->write_time, sizeof (new->write_time)); + + condition_init (&new->pending_reads); + condition_init (&new->pending_selects); + mutex_init (&new->lock); + + new->interrupt_seq_num = 0; + pq_create (&new->queue); + + *pipe = new; + return 0; +} + +/* Free PIPE and any resources it holds. */ +void +pipe_free (struct pipe *pipe) +{ + pq_free (pipe->queue); + free (pipe); +} + +/* Wake up all threads waiting on PIPE, which should be locked. */ +inline void +pipe_kick (struct pipe *pipe) +{ + /* Now wake them all up for the bad news... */ + condition_broadcast (&pipe->pending_reads); + mutex_unlock (&pipe->lock); + condition_broadcast (&pipe->pending_selects); + mutex_lock (&pipe->lock); /* Get back the lock on PIPE. */ +} + +/* Discard a reference to PIPE, which should be unlocked, being sure to make + users aware of this. */ +void +pipe_break (struct pipe *pipe) +{ + mutex_lock (&pipe->lock); + + /* As there may be multiple writers on a connectionless socket, we + never allow EOF to be signaled on the reader. */ + if (! (pipe->class->flags & PIPE_CLASS_CONNECTIONLESS)) + pipe->flags |= PIPE_BROKEN; + + if (pipe->refs > 1) + /* Other references to PIPE besides ours? Wake 'em up. */ + pipe_kick (pipe); + + pipe_release (pipe); +} + +/* Writes up to LEN bytes of DATA, to PIPE, which should be locked, and + returns the amount written in AMOUNT. If present, the information in + CONTROL & PORTS is written in a preceding control packet. If an error is + returned, nothing is done. */ +error_t +pipe_send (struct pipe *pipe, void *source, + char *data, size_t data_len, + char *control, size_t control_len, + mach_port_t *ports, size_t num_ports, + size_t *amount) +{ + error_t err = 0; + + if (pipe->flags & PIPE_BROKEN) + return EPIPE; + + if (control || ports) + /* Write a control packet. */ + { + struct packet *control_packet = + pq_queue (pipe->queue, PACKET_TYPE_CONTROL, source); + if (control_packet == NULL) + err = ENOBUFS; + else + { + err = packet_write (control_packet, control, control_len, NULL); + if (!err) + err = packet_set_ports (control_packet, ports, num_ports); + if (err) + /* Trash CONTROL_PACKET somehow XXX */; + } + } + + if (!err) + err = (*pipe->class->write)(pipe->queue, source, data, data_len, amount); + + if (!err) + { + timestamp (&pipe->write_time); + + /* And wakeup anyone that might be interested in it. */ + condition_signal (&pipe->pending_reads); + mutex_unlock (&pipe->lock); + + mutex_lock (&pipe->lock); /* Get back the lock on PIPE. */ + /* Only wakeup selects if there's still data available. */ + if (pipe_is_readable (pipe, 0)) + { + condition_signal (&pipe->pending_selects); + /* We leave PIPE locked here, assuming the caller will soon unlock + it and allow others access. */ + } + } + + return err; +} + +/* Reads up to AMOUNT bytes from PIPE, which should be locked, into DATA, and + returns the amount read in DATA_LEN. If NOBLOCK is true, EWOULDBLOCK is + returned instead of block when no data is immediately available. If an + error is returned, nothing is done. If source isn't NULL, the address of + the socket from which the data was sent is returned in it; this may be + NULL if it wasn't specified by the sender (which is usually the case with + connection-oriented protcols). + + If there is control data waiting (before any data), then the behavior + depends on whether this is an `ordinary read' (when CONTROL and PORTS are + both NULL), in which case any control data is skipped, or a `msg read', in + which case the contents of the first control packet is returned (in + CONTROL and PORTS), as well as the first data packet following that (if + the control packet is followed by another control packet or no packet in + this case, a zero length data buffer is returned; the user should be + careful to distinguish this case from EOF (when no control or ports data + is returned either). */ +error_t +pipe_recv (struct pipe *pipe, int noblock, unsigned *flags, void **source, + char **data, size_t *data_len, size_t amount, + char **control, size_t *control_len, + mach_port_t **ports, size_t *num_ports) +{ + error_t err; + struct packet *packet; + struct pq *pq = pipe->queue; + /* True if the user isn't asking for any `control' data. */ + int data_only = (control == NULL && ports == NULL); + + err = pipe_wait (pipe, noblock, data_only); + if (err) + return err; + + packet = pq_head (pq, PACKET_TYPE_ANY, 0); + + if (data_only) + /* The user doesn't want to know about control info, so skip any... */ + while (packet && packet->type == PACKET_TYPE_CONTROL) + packet = pq_next (pq, PACKET_TYPE_ANY, 0); + else if (packet && packet->type == PACKET_TYPE_CONTROL) + /* Read this control packet first, before looking for a data packet. */ + { + void *control_source; + + if (control != NULL) + packet_read (packet, control, control_len, packet_readable (packet)); + if (ports != NULL) + /* Copy out the port rights being sent. */ + packet_read_ports (packet, ports, num_ports); + + packet_read_source (packet, &control_source); + packet = pq_next (pq, PACKET_TYPE_DATA, control_source); + if (!packet && source) + /* Since there is no data, say where the control data came from. */ + *source = control_source; + else if (control_source) + /* Otherwise be sure to get rid of our reference to the address. */ + pipe_dealloc_addr (control_source); + } + else + /* No control data... */ + { + if (control_len) + *control_len = 0; + if (num_ports) + *num_ports = 0; + } + + if (!err) + if (packet) + /* Read some data (PACKET must be a data packet at this point). */ + { + int dq = 1; /* True if we should dequeue this packet. */ + + if (source) + packet_read_source (packet, source); + err = (*pipe->class->read)(packet, &dq, flags, data, data_len, amount); + if (dq) + pq_dequeue (pq); + } + else + /* Return EOF. */ + *data_len = 0; + + if (!err && packet) + timestamp (&pipe->read_time); + + return err; +} -- cgit v1.2.3