diff options
Diffstat (limited to 'trans/fifo.c')
| -rw-r--r-- | trans/fifo.c | 591 |
1 files changed, 591 insertions, 0 deletions
diff --git a/trans/fifo.c b/trans/fifo.c new file mode 100644 index 00000000..3b62cc21 --- /dev/null +++ b/trans/fifo.c @@ -0,0 +1,591 @@ +/* A translator for fifos + + Copyright (C) 1995, 1996, 1997, 1998 Free Software Foundation, Inc. + + Written by Miles Bader <miles@gnu.ai.mit.edu> + + 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 <stdio.h> +#include <errno.h> +#include <unistd.h> +#include <error.h> +#include <string.h> +#include <fcntl.h> +#include <argp.h> + +#include <cthreads.h> +#include <hurd.h> +#include <hurd/ports.h> +#include <hurd/trivfs.h> +#include <hurd/fsys.h> +#include <hurd/pipe.h> + +#include <version.h> + +/* Global options. These defaults are the standard ones, I think... */ +int wait_for_reader = 1, wait_for_writer = 1; +int one_reader = 1; + +/* What kinds of pipes we use. */ +struct pipe_class *fifo_pipe_class; + +/* The current fifo that new opens will see, or NULL if there is none. */ +struct pipe *active_fifo = NULL; + +/* Lock this when changing ACTIVE_FIFO. */ +struct mutex active_fifo_lock; +/* Signal this when ACTIVE_FIFO may have changed. */ +struct condition active_fifo_changed; + +const char *argp_program_version = STANDARD_HURD_VERSION (null); + +static struct argp_option options[] = +{ + { "multiple-readers", 'm', 0, 0, "Allow multiple simultaneous readers" }, + { "noblock", 'n', 0, 0, "Don't block on open" }, + { "dgram", 'd', 0, 0, "Reads reflect write record boundaries" }, + { 0 } +}; + +static error_t +parse_opt (int key, char *arg, struct argp_state *state) +{ + switch (key) + { + case 'm': one_reader = 0; break; + case 'n': wait_for_reader = wait_for_writer = 0; break; + case 'd': fifo_pipe_class = seqpack_pipe_class; break; + default: return ARGP_ERR_UNKNOWN; + } + return 0; +} + +static const struct argp argp = { + options, parse_opt, 0, "Translator for fifos" +}; + +int +main (int argc, char **argv) +{ + error_t err; + mach_port_t bootstrap; + struct trivfs_control *fsys; + + fifo_pipe_class = stream_pipe_class; + + argp_parse (&argp, argc, argv, 0, 0, 0); + + task_get_bootstrap_port (mach_task_self (), &bootstrap); + if (bootstrap == MACH_PORT_NULL) + error (1, 0, "must be started as a translator"); + + /* Reply to our parent */ + err = trivfs_startup (bootstrap, 0, 0, 0, 0, 0, &fsys); + mach_port_deallocate (mach_task_self (), bootstrap); + if (err) + error (3, err, "Contacting parent"); + + /* Launch. */ + do + { + ports_enable_class (fsys->protid_class); + ports_manage_port_operations_multithread (fsys->pi.bucket, + trivfs_demuxer, + 30*1000, 5*60*1000, 0); + } + while (ports_count_class (fsys->protid_class) > 0); + + return 0; +} + +/* ---------------------------------------------------------------- */ + +static error_t +open_hook (struct trivfs_peropen *po) +{ + error_t err = 0; + int flags = po->openmodes; + + if (flags & (O_READ | O_WRITE)) + { + mutex_lock (&active_fifo_lock); + +/* Wait until the active fifo has changed so that CONDITION is true. */ +#define WAIT(condition, noblock_err) \ + while (!err && !(condition)) \ + { \ + if (flags & O_NONBLOCK) \ + { \ + err = noblock_err; \ + break; \ + } \ + else if (hurd_condition_wait (&active_fifo_changed, &active_fifo_lock)) \ + err = EINTR; \ + } + + if (flags & O_READ) + /* When opening for read, what we do depends on what mode this server + is running in. The default (if ONE_READER is set) is to only + allow one reader at a time, with additional opens for read + blocking here until the old reader goes away; otherwise, we allow + multiple readers. If WAIT_FOR_WRITER is true, then once we've + created a fifo, we also block until someone opens it for writing; + otherwise, the first read will block until someone writes + something. */ + { + if (one_reader) + /* Wait until there isn't any active fifo, so we can make one. */ + WAIT (!active_fifo || !active_fifo->readers, EWOULDBLOCK); + + if (!err && active_fifo == NULL) + /* No other readers, and indeed, no fifo; make one. */ + { + err = pipe_create (fifo_pipe_class, &active_fifo); + if (! err) + active_fifo->flags &= ~PIPE_BROKEN; /* Avoid immediate EOF. */ + } + if (!err) + { + pipe_add_reader (active_fifo); + condition_broadcast (&active_fifo_changed); + /* We'll unlock ACTIVE_FIFO_LOCK below; the writer code won't + make us block because we've ensured that there's a reader + for it. */ + + if (wait_for_writer) + /* Wait until there's a writer. */ + { + WAIT (active_fifo->writers, 0); + if (err) + /* Back out the new pipe creation. */ + { + pipe_remove_reader (active_fifo); + active_fifo = NULL; + condition_broadcast (&active_fifo_changed); + } + } + } + } + + if (!err && (flags & O_WRITE)) + /* Open the active_fifo for writing. If WAIT_FOR_READER is true, + then we block until there's someone to read what we wrote, + otherwise, if there's no fifo, we create one, which we just write + into and leave it for someone to read later. */ + { + if (wait_for_reader) + /* Wait until there's a fifo to write to. */ + WAIT (active_fifo && active_fifo->readers, ENXIO); + if (!err && active_fifo == NULL) + /* No other readers, and indeed, no fifo; make one. */ + { + err = pipe_create (fifo_pipe_class, &active_fifo); + if (!err) + active_fifo->flags &= ~PIPE_BROKEN; + } + if (!err) + { + pipe_add_writer (active_fifo); + condition_broadcast (&active_fifo_changed); + } + } + + po->hook = active_fifo; + + mutex_unlock (&active_fifo_lock); + } + + return err; +} + +static void +close_hook (struct trivfs_peropen *po) +{ + int was_active, detach = 0; + int flags = po->openmodes; + struct pipe *pipe = po->hook; + + if (!pipe) + return; + + mutex_lock (&active_fifo_lock); + was_active = (active_fifo == pipe); + + if (was_active) + /* See if PIPE should cease to be the user-visible face of this fifo. */ + detach = + ((flags & O_READ) && pipe->readers == 1) + || ((flags & O_WRITE) && pipe->writers == 1); + else + /* Let others have their fun. */ + mutex_unlock (&active_fifo_lock); + + if (flags & O_READ) + pipe_remove_reader (pipe); + if (flags & O_WRITE) + pipe_remove_writer (pipe); + /* At this point, PIPE may be gone, so we can't look at it again. */ + + if (was_active) + { + if (detach) + active_fifo = NULL; + condition_broadcast (&active_fifo_changed); + mutex_unlock (&active_fifo_lock); + } +} + +/* Trivfs hooks */ + +int trivfs_fstype = FSTYPE_MISC; +int trivfs_fsid = 0; + +int trivfs_support_read = 1; +int trivfs_support_write = 1; +int trivfs_support_exec = 0; + +int trivfs_allow_open = O_READ | O_WRITE; + +error_t (*trivfs_peropen_create_hook) (struct trivfs_peropen *) = open_hook; +void (*trivfs_peropen_destroy_hook) (struct trivfs_peropen *) = close_hook; + +void +trivfs_modify_stat (struct trivfs_protid *cred, struct stat *st) +{ + struct pipe *pipe = cred->po->hook; + + st->st_mode &= ~S_IFMT; + st->st_mode |= S_IFIFO; + + if (pipe) + { + mutex_lock (&pipe->lock); + st->st_size = pipe_readable (pipe, 1); + st->st_blocks = st->st_size >> 9; + mutex_unlock (&pipe->lock); + } + else + st->st_size = st->st_blocks = 0; + + /* As we try to be clever with large transfers, ask for them. */ + st->st_blksize = vm_page_size * 16; +} + +error_t +trivfs_goaway (struct trivfs_control *cntl, int flags) +{ + error_t err; + int force = (flags & FSYS_GOAWAY_FORCE); + struct port_bucket *bucket = ((struct port_info *)cntl)->bucket; + + err = ports_inhibit_bucket_rpcs (bucket); + if (err == EINTR || (err && !force)) + return err; + + if (ports_count_class (cntl->protid_class) > 0 && !force) + /* Still some opens, and we're not being forced to go away, so don't. */ + { + ports_enable_class (cntl->protid_class); + ports_resume_bucket_rpcs (bucket); + return EBUSY; + } + + exit (0); +} + +/* ---------------------------------------------------------------- */ + +/* Return objects mapping the data underlying this memory object. If + the object can be read then memobjrd will be provided; if the + object can be written then memobjwr will be provided. For objects + where read data and write data are the same, these objects will be + equal, otherwise they will be disjoint. Servers are permitted to + implement io_map but not io_map_cntl. Some objects do not provide + mapping; they will set none of the ports and return an error. Such + objects can still be accessed by io_read and io_write. */ +error_t +trivfs_S_io_map(struct trivfs_protid *cred, + memory_object_t *rdobj, + mach_msg_type_name_t *rdtype, + memory_object_t *wrobj, + mach_msg_type_name_t *wrtype) +{ + return EINVAL; +} + +/* ---------------------------------------------------------------- */ + +/* Read data from an IO object. If offset if -1, read from the object + maintained file pointer. If the object is not seekable, offset is + ignored. The amount desired to be read is in AMT. */ +error_t +trivfs_S_io_read (struct trivfs_protid *cred, + mach_port_t reply, mach_msg_type_name_t reply_type, + char **data, size_t *data_len, + off_t offs, size_t amount) +{ + error_t err; + + if (!cred) + err = EOPNOTSUPP; + else if (!(cred->po->openmodes & O_READ)) + err = EBADF; + else + { + struct pipe *pipe = cred->po->hook; + mutex_lock (&pipe->lock); + err = pipe_read (pipe, cred->po->openmodes & O_NONBLOCK, NULL, + data, data_len, amount); + mutex_unlock (&pipe->lock); + } + + return err; +} + +/* ---------------------------------------------------------------- */ + +/* Tell how much data can be read from the object without blocking for + a "long time" (this should be the same meaning of "long time" used + by the nonblocking flag. */ +error_t +trivfs_S_io_readable (struct trivfs_protid *cred, + mach_port_t reply, mach_msg_type_name_t reply_type, + size_t *amount) +{ + error_t err; + + if (!cred) + err = EOPNOTSUPP; + else if (!(cred->po->openmodes & O_READ)) + err = EBADF; + else + { + struct pipe *pipe = cred->po->hook; + mutex_lock (&pipe->lock); + *amount = pipe_readable (pipe, 1); + mutex_unlock (&pipe->lock); + err = 0; + } + + return err; +} + +/* ---------------------------------------------------------------- */ + +/* Change current read/write offset */ +error_t +trivfs_S_io_seek (struct trivfs_protid *cred, + mach_port_t reply, mach_msg_type_name_t reply_type, + off_t offset, int whence, off_t *new_offset) +{ + if (!cred) + return EOPNOTSUPP; + return ESPIPE; +} + +/* ---------------------------------------------------------------- */ + +/* SELECT_TYPE is the bitwise OR of SELECT_READ, SELECT_WRITE, and SELECT_URG. + Block until one of the indicated types of i/o can be done "quickly", and + return the types that are then available. ID_TAG is returned as passed; it + is just for the convenience of the user in matching up reply messages with + specific requests sent. */ +error_t +trivfs_S_io_select (struct trivfs_protid *cred, + mach_port_t reply, mach_msg_type_name_t reply_type, + int *select_type, int *tag) +{ + struct pipe *pipe; + error_t err = 0; + int ready = 0; + + if (!cred) + return EOPNOTSUPP; + + pipe = cred->po->hook; + + if (*select_type & SELECT_READ) + { + if (cred->po->openmodes & O_READ) + { + mutex_lock (&pipe->lock); + if (pipe_wait_readable (pipe, 1, 1) != EWOULDBLOCK) + ready |= SELECT_READ; /* Data immediately readable (or error). */ + mutex_unlock (&pipe->lock); + } + else + ready |= SELECT_READ; /* Error immediately available... */ + } + + if (*select_type & SELECT_WRITE) + { + if (cred->po->openmodes & O_WRITE) + { + mutex_lock (&pipe->lock); + if (pipe_wait_writable (pipe, 1) != EWOULDBLOCK) + ready |= SELECT_WRITE; /* Data immediately writable (or error). */ + mutex_unlock (&pipe->lock); + } + else + ready |= SELECT_WRITE; /* Error immediately available... */ + } + + if (ready) + *select_type = ready; + else + /* Wait for something to change. */ + { + ports_interrupt_self_on_port_death (cred, reply); + err = pipe_pair_select (pipe, pipe, select_type, 1); + } + + return err; +} + +/* ---------------------------------------------------------------- */ + +/* Write data to an IO object. If offset is -1, write at the object + maintained file pointer. If the object is not seekable, offset is + ignored. The amount successfully written is returned in amount. A + given user should not have more than one outstanding io_write on an + object at a time; servers implement congestion control by delaying + responses to io_write. Servers may drop data (returning ENOBUFS) + if they recevie more than one write when not prepared for it. */ +error_t +trivfs_S_io_write (struct trivfs_protid *cred, + mach_port_t reply, mach_msg_type_name_t reply_type, + char *data, size_t data_len, + off_t offs, size_t *amount) +{ + error_t err; + + if (!cred) + err = EOPNOTSUPP; + else + { + int flags = cred->po->openmodes; + struct pipe *pipe = cred->po->hook; + + if (!(flags & O_WRITE)) + err = EBADF; + else + { + mutex_lock (&pipe->lock); + err = pipe_write (pipe, flags & O_NONBLOCK, NULL, + data, data_len, amount); + mutex_unlock (&pipe->lock); + } + } + + return err; +} + +/* ---------------------------------------------------------------- */ + +error_t +trivfs_S_file_set_size (struct trivfs_protid *cred, + mach_port_t reply, mach_msg_type_name_t reply_type, + off_t size) +{ + return size == 0 ? 0 : EINVAL; +} + +/* These four routines modify the O_APPEND, O_ASYNC, O_FSYNC, and + O_NONBLOCK bits for the IO object. In addition, io_get_openmodes + will tell you which of O_READ, O_WRITE, and O_EXEC the object can + be used for. The O_ASYNC bit affects icky async I/O; good async + I/O is done through io_async which is orthogonal to these calls. */ + +error_t +trivfs_S_io_get_openmodes (struct trivfs_protid *cred, + mach_port_t reply, mach_msg_type_name_t reply_type, + int *bits) +{ + if (!cred) + return EOPNOTSUPP; + else + { + *bits = cred->po->openmodes; + return 0; + } +} + +error_t +trivfs_S_io_set_all_openmodes(struct trivfs_protid *cred, + mach_port_t reply, + mach_msg_type_name_t reply_type, + int mode) +{ + if (!cred) + return EOPNOTSUPP; + else + return 0; +} + +error_t +trivfs_S_io_set_some_openmodes (struct trivfs_protid *cred, + mach_port_t reply, + mach_msg_type_name_t reply_type, + int bits) +{ + if (!cred) + return EOPNOTSUPP; + else + return 0; +} + +error_t +trivfs_S_io_clear_some_openmodes (struct trivfs_protid *cred, + mach_port_t reply, + mach_msg_type_name_t reply_type, + int bits) +{ + if (!cred) + return EOPNOTSUPP; + else + return 0; +} + +/* ---------------------------------------------------------------- */ +/* Get/set the owner of the IO object. For terminals, this affects + controlling terminal behavior (see term_become_ctty). For all + objects this affects old-style async IO. Negative values represent + pgrps. This has nothing to do with the owner of a file (as + returned by io_stat, and as used for various permission checks by + filesystems). An owner of 0 indicates that there is no owner. */ + +error_t +trivfs_S_io_get_owner (struct trivfs_protid *cred, + mach_port_t reply, + mach_msg_type_name_t reply_type, + pid_t *owner) +{ + if (!cred) + return EOPNOTSUPP; + *owner = 0; + return 0; +} + +error_t +trivfs_S_io_mod_owner (struct trivfs_protid *cred, + mach_port_t reply, mach_msg_type_name_t reply_type, + pid_t owner) +{ + if (!cred) + return EOPNOTSUPP; + else + return EINVAL; +} |