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/*
* Copyright (c) 2008 Jakub Jermar
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* - The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/** @addtogroup fs
* @{
*/
/**
* @file vfs_register.c
* @brief
*/
#include <ipc/ipc.h>
#include <ipc/services.h>
#include <async.h>
#include <fibril.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <bool.h>
#include <futex.h>
#include <libadt/list.h>
#include <as.h>
#include <assert.h>
#include <atomic.h>
#include "vfs.h"
atomic_t fs_head_futex = FUTEX_INITIALIZER;
link_t fs_head;
atomic_t fs_handle_next = {
.count = 1
};
/** Verify the VFS info structure.
*
* @param info Info structure to be verified.
*
* @return Non-zero if the info structure is sane, zero otherwise.
*/
static bool vfs_info_sane(vfs_info_t *info)
{
int i;
/*
* Check if the name is non-empty and is composed solely of ASCII
* characters [a-z]+[a-z0-9_-]*.
*/
if (!islower(info->name[0])) {
dprintf("The name doesn't start with a lowercase character.\n");
return false;
}
for (i = 1; i < FS_NAME_MAXLEN; i++) {
if (!(islower(info->name[i]) || isdigit(info->name[i])) &&
(info->name[i] != '-') && (info->name[i] != '_')) {
if (info->name[i] == '\0') {
break;
} else {
dprintf("The name contains illegal "
"characters.\n");
return false;
}
}
}
/*
* This check is not redundant. It ensures that the name is
* NULL-terminated, even if FS_NAME_MAXLEN characters are used.
*/
if (info->name[i] != '\0') {
dprintf("The name is not properly NULL-terminated.\n");
return false;
}
/*
* Check if the FS implements mandatory VFS operations.
*/
if (info->ops[IPC_METHOD_TO_VFS_OP(VFS_LOOKUP)] != VFS_OP_DEFINED) {
dprintf("Operation VFS_LOOKUP not defined by the client.\n");
return false;
}
if (info->ops[IPC_METHOD_TO_VFS_OP(VFS_READ)] != VFS_OP_DEFINED) {
dprintf("Operation VFS_READ not defined by the client.\n");
return false;
}
/*
* Check if each operation is either not defined, defined or default.
*/
for (i = VFS_FIRST; i < VFS_LAST_CLNT; i++) {
if ((info->ops[IPC_METHOD_TO_VFS_OP(i)] != VFS_OP_NULL) &&
(info->ops[IPC_METHOD_TO_VFS_OP(i)] != VFS_OP_DEFAULT) &&
(info->ops[IPC_METHOD_TO_VFS_OP(i)] != VFS_OP_DEFINED)) {
dprintf("Operation info not understood.\n");
return false;
}
}
return true;
}
/** VFS_REGISTER protocol function.
*
* @param rid Hash of the call with the request.
* @param request Call structure with the request.
*/
void vfs_register(ipc_callid_t rid, ipc_call_t *request)
{
ipc_callid_t callid;
ipc_call_t call;
int rc;
size_t size;
dprintf("Processing VFS_REGISTER request received from %p.\n",
request->in_phone_hash);
/*
* The first call has to be IPC_M_DATA_SEND in which we receive the
* VFS info structure from the client FS.
*/
if (!ipc_data_write_receive(&callid, &size)) {
/*
* The client doesn't obey the same protocol as we do.
*/
dprintf("Receiving of VFS info failed.\n");
ipc_answer_0(callid, EINVAL);
ipc_answer_0(rid, EINVAL);
return;
}
dprintf("VFS info received, size = %d\n", size);
/*
* We know the size of the VFS info structure. See if the client
* understands this easy concept too.
*/
if (size != sizeof(vfs_info_t)) {
/*
* The client is sending us something, which cannot be
* the info structure.
*/
dprintf("Received VFS info has bad size.\n");
ipc_answer_0(callid, EINVAL);
ipc_answer_0(rid, EINVAL);
return;
}
/*
* Allocate and initialize a buffer for the fs_info structure.
*/
fs_info_t *fs_info;
fs_info = (fs_info_t *) malloc(sizeof(fs_info_t));
if (!fs_info) {
dprintf("Could not allocate memory for FS info.\n");
ipc_answer_0(callid, ENOMEM);
ipc_answer_0(rid, ENOMEM);
return;
}
link_initialize(&fs_info->fs_link);
futex_initialize(&fs_info->phone_futex, 1);
rc = ipc_data_write_finalize(callid, &fs_info->vfs_info, size);
if (rc != EOK) {
dprintf("Failed to deliver the VFS info into our AS, rc=%d.\n",
rc);
free(fs_info);
ipc_answer_0(callid, rc);
ipc_answer_0(rid, rc);
return;
}
dprintf("VFS info delivered.\n");
if (!vfs_info_sane(&fs_info->vfs_info)) {
free(fs_info);
ipc_answer_0(callid, EINVAL);
ipc_answer_0(rid, EINVAL);
return;
}
futex_down(&fs_head_futex);
/*
* Check for duplicit registrations.
*/
if (fs_name_to_handle(fs_info->vfs_info.name, false)) {
/*
* We already register a fs like this.
*/
dprintf("FS is already registered.\n");
futex_up(&fs_head_futex);
free(fs_info);
ipc_answer_0(callid, EEXISTS);
ipc_answer_0(rid, EEXISTS);
return;
}
/*
* Add fs_info to the list of registered FS's.
*/
dprintf("Inserting FS into the list of registered file systems.\n");
list_append(&fs_info->fs_link, &fs_head);
/*
* Now we want the client to send us the IPC_M_CONNECT_TO_ME call so
* that a callback connection is created and we have a phone through
* which to forward VFS requests to it.
*/
callid = async_get_call(&call);
if (IPC_GET_METHOD(call) != IPC_M_CONNECT_TO_ME) {
dprintf("Unexpected call, method = %d\n", IPC_GET_METHOD(call));
list_remove(&fs_info->fs_link);
futex_up(&fs_head_futex);
free(fs_info);
ipc_answer_0(callid, EINVAL);
ipc_answer_0(rid, EINVAL);
return;
}
fs_info->phone = IPC_GET_ARG5(call);
ipc_answer_0(callid, EOK);
dprintf("Callback connection to FS created.\n");
/*
* The client will want us to send him the address space area with PLB.
*/
if (!ipc_share_in_receive(&callid, &size)) {
dprintf("Unexpected call, method = %d\n", IPC_GET_METHOD(call));
list_remove(&fs_info->fs_link);
futex_up(&fs_head_futex);
ipc_hangup(fs_info->phone);
free(fs_info);
ipc_answer_0(callid, EINVAL);
ipc_answer_0(rid, EINVAL);
return;
}
/*
* We can only send the client address space area PLB_SIZE bytes long.
*/
if (size != PLB_SIZE) {
dprintf("Client suggests wrong size of PFB, size = %d\n", size);
list_remove(&fs_info->fs_link);
futex_up(&fs_head_futex);
ipc_hangup(fs_info->phone);
free(fs_info);
ipc_answer_0(callid, EINVAL);
ipc_answer_0(rid, EINVAL);
return;
}
/*
* Commit to read-only sharing the PLB with the client.
*/
(void) ipc_share_in_finalize(callid, plb,
AS_AREA_READ | AS_AREA_CACHEABLE);
dprintf("Sharing PLB.\n");
/*
* That was it. The FS has been registered.
* In reply to the VFS_REGISTER request, we assign the client file
* system a global file system handle.
*/
fs_info->fs_handle = (int) atomic_postinc(&fs_handle_next);
ipc_answer_1(rid, EOK, (ipcarg_t) fs_info->fs_handle);
futex_up(&fs_head_futex);
dprintf("\"%.*s\" filesystem successfully registered, handle=%d.\n",
FS_NAME_MAXLEN, fs_info->vfs_info.name, fs_info->fs_handle);
}
/** For a given file system handle, implement policy for allocating a phone.
*
* @param handle File system handle.
*
* @return Phone over which a multi-call request can be safely
* sent. Return 0 if no phone was found.
*/
int vfs_grab_phone(int handle)
{
/*
* For now, we don't try to be very clever and very fast.
* We simply lookup the phone in the fs_head list. We currently don't
* open any additional phones (even though that itself would be pretty
* straightforward; housekeeping multiple open phones to a FS task would
* be more demanding). Instead, we simply take the respective
* phone_futex and keep it until vfs_release_phone().
*/
futex_down(&fs_head_futex);
link_t *cur;
fs_info_t *fs;
for (cur = fs_head.next; cur != &fs_head; cur = cur->next) {
fs = list_get_instance(cur, fs_info_t, fs_link);
if (fs->fs_handle == handle) {
futex_up(&fs_head_futex);
/*
* For now, take the futex unconditionally.
* Oh yeah, serialization rocks.
* It will be up'ed in vfs_release_phone().
*/
futex_down(&fs->phone_futex);
/*
* Avoid deadlock with other fibrils in the same thread
* by disabling fibril preemption.
*/
fibril_inc_sercount();
return fs->phone;
}
}
futex_up(&fs_head_futex);
return 0;
}
/** Tell VFS that the phone is in use for any request.
*
* @param phone Phone to FS task.
*/
void vfs_release_phone(int phone)
{
bool found = false;
/*
* Undo the fibril_inc_sercount() done in vfs_grab_phone().
*/
fibril_dec_sercount();
futex_down(&fs_head_futex);
link_t *cur;
for (cur = fs_head.next; cur != &fs_head; cur = cur->next) {
fs_info_t *fs = list_get_instance(cur, fs_info_t, fs_link);
if (fs->phone == phone) {
found = true;
futex_up(&fs_head_futex);
futex_up(&fs->phone_futex);
return;
}
}
futex_up(&fs_head_futex);
/*
* Not good to get here.
*/
assert(found == true);
}
/** Convert file system name to its handle.
*
* @param name File system name.
* @param lock If true, the function will down and up the
* fs_head_futex.
*
* @return File system handle or zero if file system not found.
*/
int fs_name_to_handle(char *name, bool lock)
{
int handle = 0;
if (lock)
futex_down(&fs_head_futex);
link_t *cur;
for (cur = fs_head.next; cur != &fs_head; cur = cur->next) {
fs_info_t *fs = list_get_instance(cur, fs_info_t, fs_link);
if (strncmp(fs->vfs_info.name, name,
sizeof(fs->vfs_info.name)) == 0) {
handle = fs->fs_handle;
break;
}
}
if (lock)
futex_up(&fs_head_futex);
return handle;
}
/**
* @}
*/