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/* A translator for `firmlinks'
Copyright (C) 1997, 1998, 1999 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 <unistd.h>
#include <errno.h>
#include <string.h>
#include <fcntl.h>
#include <argp.h>
#include <error.h>
#include <sys/mman.h>
#include <hurd/trivfs.h>
#include <version.h>
const char *argp_program_version = STANDARD_HURD_VERSION (firmlink);
static const struct argp_option options[] =
{
{ 0 }
};
static const char args_doc[] = "TARGET";
static const char doc[] = "A translator for firmlinks"
"\vA firmlink is sort of half-way between a symbolic link and a hard link;"
"\n"
"\nLike a symbolic link, it is `by name', and contains no actual reference to"
" the target. However, the lookup returns a node which will redirect parent"
" lookups so that attempts to find the cwd that go through the link will"
" reflect the link name, not the target name. The target referenced by the"
" firmlink is looked up in the namespace of the translator, not the client.";
/* Link parameters. */
static char *target = 0; /* What we translate too. */
/* Parse a single option/argument. */
static error_t
parse_opt (int key, char *arg, struct argp_state *state)
{
if (key == ARGP_KEY_ARG && state->arg_num == 0)
target = arg;
else if (key == ARGP_KEY_ARG || key == ARGP_KEY_NO_ARGS)
argp_usage (state);
else
return ARGP_ERR_UNKNOWN;
return 0;
}
static struct argp argp = { options, parse_opt, args_doc, doc };
int
main (int argc, char **argv)
{
error_t err;
mach_port_t bootstrap;
struct trivfs_control *fsys;
/* Parse our options... */
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);
if (err)
error (2, err, "Contacting parent");
/* Launch. */
ports_manage_port_operations_multithread (fsys->pi.bucket, trivfs_demuxer,
2 * 60 * 1000, 0, 0);
return 0;
}
/* Return in LINK the node that TARGET_NAME resolves to, with its parent
replaced by PARENT. FLAGS are the flags to open TARGET_NAME with. */
static error_t
firmlink (mach_port_t parent, const char *target_name, int flags,
mach_port_t *link)
{
error_t err;
file_t authed_link;
file_t target = file_name_lookup (target_name, flags & ~O_CREAT, 0);
if (target == MACH_PORT_NULL)
return errno;
err = file_reparent (target, parent, &authed_link);
mach_port_deallocate (mach_task_self (), target);
mach_port_deallocate (mach_task_self (), parent);
if (! err)
{
err = io_restrict_auth (authed_link, link, 0, 0, 0, 0);
mach_port_deallocate (mach_task_self (), authed_link);
}
return err;
}
/* Trivfs hooks */
int trivfs_fstype = FSTYPE_MISC;
int trivfs_fsid = 0;
int trivfs_support_read = 1;
int trivfs_support_write = 0;
int trivfs_support_exec = 0;
int trivfs_allow_open = O_READ;
/* Return the root node of our file system: A firmlink to TARGET, unless
TARGET doesn't exist, in which case we return a symlink-like node. */
static error_t
getroot (struct trivfs_control *cntl,
mach_port_t reply_port, mach_msg_type_name_t reply_port_type,
mach_port_t dotdot,
uid_t *uids, u_int nuids, uid_t *gids, u_int ngids,
int flags,
retry_type *do_retry, char *retry_name,
mach_port_t *node, mach_msg_type_name_t *node_type)
{
error_t err = firmlink (dotdot, target, flags, node);
if (err == ENOENT)
/* No target? Act like a link. */
return EAGAIN;
if (! err)
{
*node_type = MACH_MSG_TYPE_MOVE_SEND;
*do_retry = FS_RETRY_REAUTH;
retry_name[0] = '\0';
}
return err;
}
/* Called by trivfs_S_fsys_getroot before any other processing takes place;
if the return value is EAGAIN, normal trivfs getroot processing continues,
otherwise the rpc returns with that return value. */
error_t (*trivfs_getroot_hook) () = getroot;
void
trivfs_modify_stat (struct trivfs_protid *cred, struct stat *st)
{
st->st_size = strlen (target);
st->st_blocks = 0;
st->st_mode &= ~S_IFMT;
st->st_mode |= S_IFLNK;
}
/* Shutdown the filesystem. */
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);
}
/* We store the file offset in po->hook (ick!) */
/* 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,
vm_address_t *data, mach_msg_type_number_t *data_len,
off_t offs, mach_msg_type_number_t amount)
{
error_t err = 0;
if (! cred)
err = EOPNOTSUPP;
else if (! (cred->po->openmodes & O_READ))
err = EBADF;
else
{
off_t max = strlen (target);
off_t start = offs >= 0 ? offs : (off_t)cred->po->hook;
if (start < 0)
return EINVAL;
if (start + amount > max)
amount = max - start;
if (amount > *data_len)
*data = mmap (0, amount, PROT_READ|PROT_WRITE, MAP_ANON, 0, 0);
err = (*data == -1) ? errno : 0;
if (!err && amount > 0)
{
memcpy ((char *)(*data + start), target, amount);
if (offs < 0)
cred->po->hook = (void *)(start + amount); /* Update PO offset. */
}
*data_len = amount;
}
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,
mach_msg_type_number_t *amount)
{
if (! cred)
return EOPNOTSUPP;
else if (! (cred->po->openmodes & O_READ))
return EBADF;
else if ((off_t)cred->po->hook < 0)
return EINVAL;
else
*amount = strlen (target) - (off_t)cred->po->hook;
return 0;
}
/* 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)
{
return EOPNOTSUPP;
}
/* 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 *type, int *tag)
{
return EOPNOTSUPP;
}
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