/*
   * net/9p/protocol.c
   *
   * 9P Protocol Support Code
   *
   *  Copyright (C) 2008 by Eric Van Hensbergen <ericvh@gmail.com>
   *
   *  Base on code from Anthony Liguori <aliguori@us.ibm.com>
   *  Copyright (C) 2008 by IBM, Corp.
   *
   *  This program is free software; you can redistribute it and/or modify
   *  it under the terms of the GNU General Public License version 2
   *  as published by the Free Software Foundation.
   *
   *  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:
   *  Free Software Foundation
   *  51 Franklin Street, Fifth Floor
   *  Boston, MA  02111-1301  USA
   *
   */
  
  #include <linux/module.h>
  #include <linux/errno.h>

  #include <linux/kernel.h>

  #include <linux/uaccess.h>

  #include <linux/slab.h>

  #include <linux/sched.h>

  #include <linux/stddef.h>

  #include <linux/types.h>

  #include <net/9p/9p.h>
  #include <net/9p/client.h>
  #include "protocol.h"

  #include <trace/events/9p.h>

  static int

  p9pdu_writef(struct p9_fcall *pdu, int proto_version, const char *fmt, ...);

  
  void p9stat_free(struct p9_wstat *stbuf)
  {
  	kfree(stbuf->name);
  	kfree(stbuf->uid);
  	kfree(stbuf->gid);
  	kfree(stbuf->muid);
  	kfree(stbuf->extension);
  }
  EXPORT_SYMBOL(p9stat_free);

  size_t pdu_read(struct p9_fcall *pdu, void *data, size_t size)

  {

  	size_t len = min(pdu->size - pdu->offset, size);

  	memcpy(data, &pdu->sdata[pdu->offset], len);
  	pdu->offset += len;
  	return size - len;
  }
  
  static size_t pdu_write(struct p9_fcall *pdu, const void *data, size_t size)
  {

  	size_t len = min(pdu->capacity - pdu->size, size);

  	memcpy(&pdu->sdata[pdu->size], data, len);
  	pdu->size += len;
  	return size - len;
  }

  static size_t
  pdu_write_u(struct p9_fcall *pdu, const char __user *udata, size_t size)
  {

  	size_t len = min(pdu->capacity - pdu->size, size);

  	if (copy_from_user(&pdu->sdata[pdu->size], udata, len))
  		len = 0;

  
  	pdu->size += len;
  	return size - len;
  }

  /*
  	b - int8_t
  	w - int16_t
  	d - int32_t
  	q - int64_t
  	s - string
  	S - stat
  	Q - qid
  	D - data blob (int32_t size followed by void *, results are not freed)
  	T - array of strings (int16_t count, followed by strings)
  	R - array of qids (int16_t count, followed by qids)

  	A - stat for 9p2000.L (p9_stat_dotl)

  	? - if optional = 1, continue parsing
  */
  
  static int

  p9pdu_vreadf(struct p9_fcall *pdu, int proto_version, const char *fmt,
  	va_list ap)

  {
  	const char *ptr;
  	int errcode = 0;
  
  	for (ptr = fmt; *ptr; ptr++) {
  		switch (*ptr) {
  		case 'b':{
  				int8_t *val = va_arg(ap, int8_t *);
  				if (pdu_read(pdu, val, sizeof(*val))) {
  					errcode = -EFAULT;
  					break;
  				}
  			}
  			break;
  		case 'w':{
  				int16_t *val = va_arg(ap, int16_t *);

  				__le16 le_val;
  				if (pdu_read(pdu, &le_val, sizeof(le_val))) {

  					errcode = -EFAULT;
  					break;
  				}

  				*val = le16_to_cpu(le_val);

  			}
  			break;
  		case 'd':{
  				int32_t *val = va_arg(ap, int32_t *);

  				__le32 le_val;
  				if (pdu_read(pdu, &le_val, sizeof(le_val))) {

  					errcode = -EFAULT;
  					break;
  				}

  				*val = le32_to_cpu(le_val);

  			}
  			break;
  		case 'q':{
  				int64_t *val = va_arg(ap, int64_t *);

  				__le64 le_val;
  				if (pdu_read(pdu, &le_val, sizeof(le_val))) {

  					errcode = -EFAULT;
  					break;
  				}

  				*val = le64_to_cpu(le_val);

  			}
  			break;
  		case 's':{

  				char **sptr = va_arg(ap, char **);

  				uint16_t len;

  				errcode = p9pdu_readf(pdu, proto_version,
  								"w", &len);

  				if (errcode)
  					break;

  				*sptr = kmalloc(len + 1, GFP_NOFS);

  				if (*sptr == NULL) {

  					errcode = -EFAULT;
  					break;
  				}

  				if (pdu_read(pdu, *sptr, len)) {

  					errcode = -EFAULT;

  					kfree(*sptr);
  					*sptr = NULL;

  				} else

  					(*sptr)[len] = 0;

  			}
  			break;
  		case 'Q':{
  				struct p9_qid *qid =
  				    va_arg(ap, struct p9_qid *);

  				errcode = p9pdu_readf(pdu, proto_version, "bdq",

  						      &qid->type, &qid->version,
  						      &qid->path);
  			}
  			break;
  		case 'S':{
  				struct p9_wstat *stbuf =
  				    va_arg(ap, struct p9_wstat *);

  				memset(stbuf, 0, sizeof(struct p9_wstat));

  				stbuf->n_uid = stbuf->n_gid = stbuf->n_muid =

  									-1;

  				errcode =

  				    p9pdu_readf(pdu, proto_version,

  						"wwdQdddqssss?sddd",
  						&stbuf->size, &stbuf->type,
  						&stbuf->dev, &stbuf->qid,
  						&stbuf->mode, &stbuf->atime,
  						&stbuf->mtime, &stbuf->length,
  						&stbuf->name, &stbuf->uid,
  						&stbuf->gid, &stbuf->muid,
  						&stbuf->extension,
  						&stbuf->n_uid, &stbuf->n_gid,
  						&stbuf->n_muid);
  				if (errcode)
  					p9stat_free(stbuf);
  			}
  			break;
  		case 'D':{

  				uint32_t *count = va_arg(ap, uint32_t *);

  				void **data = va_arg(ap, void **);
  
  				errcode =

  				    p9pdu_readf(pdu, proto_version, "d", count);

  				if (!errcode) {
  					*count =

  					    min_t(uint32_t, *count,

  						  pdu->size - pdu->offset);

  					*data = &pdu->sdata[pdu->offset];
  				}
  			}
  			break;
  		case 'T':{

  				uint16_t *nwname = va_arg(ap, uint16_t *);

  				char ***wnames = va_arg(ap, char ***);

  				errcode = p9pdu_readf(pdu, proto_version,
  								"w", nwname);

  				if (!errcode) {
  					*wnames =
  					    kmalloc(sizeof(char *) * *nwname,

  						    GFP_NOFS);

  					if (!*wnames)
  						errcode = -ENOMEM;
  				}
  
  				if (!errcode) {
  					int i;
  
  					for (i = 0; i < *nwname; i++) {
  						errcode =

  						    p9pdu_readf(pdu,
  								proto_version,

  								"s",
  								&(*wnames)[i]);
  						if (errcode)
  							break;
  					}
  				}
  
  				if (errcode) {
  					if (*wnames) {
  						int i;
  
  						for (i = 0; i < *nwname; i++)
  							kfree((*wnames)[i]);
  					}
  					kfree(*wnames);
  					*wnames = NULL;
  				}
  			}
  			break;
  		case 'R':{
  				int16_t *nwqid = va_arg(ap, int16_t *);
  				struct p9_qid **wqids =
  				    va_arg(ap, struct p9_qid **);
  
  				*wqids = NULL;
  
  				errcode =

  				    p9pdu_readf(pdu, proto_version, "w", nwqid);

  				if (!errcode) {
  					*wqids =
  					    kmalloc(*nwqid *
  						    sizeof(struct p9_qid),

  						    GFP_NOFS);

  					if (*wqids == NULL)
  						errcode = -ENOMEM;
  				}
  
  				if (!errcode) {
  					int i;
  
  					for (i = 0; i < *nwqid; i++) {
  						errcode =

  						    p9pdu_readf(pdu,
  								proto_version,

  								"Q",
  								&(*wqids)[i]);
  						if (errcode)
  							break;
  					}
  				}
  
  				if (errcode) {
  					kfree(*wqids);
  					*wqids = NULL;
  				}
  			}
  			break;

  		case 'A': {
  				struct p9_stat_dotl *stbuf =
  				    va_arg(ap, struct p9_stat_dotl *);
  
  				memset(stbuf, 0, sizeof(struct p9_stat_dotl));
  				errcode =
  				    p9pdu_readf(pdu, proto_version,
  					"qQdddqqqqqqqqqqqqqqq",
  					&stbuf->st_result_mask,
  					&stbuf->qid,
  					&stbuf->st_mode,
  					&stbuf->st_uid, &stbuf->st_gid,
  					&stbuf->st_nlink,
  					&stbuf->st_rdev, &stbuf->st_size,
  					&stbuf->st_blksize, &stbuf->st_blocks,
  					&stbuf->st_atime_sec,
  					&stbuf->st_atime_nsec,
  					&stbuf->st_mtime_sec,
  					&stbuf->st_mtime_nsec,
  					&stbuf->st_ctime_sec,
  					&stbuf->st_ctime_nsec,
  					&stbuf->st_btime_sec,
  					&stbuf->st_btime_nsec,
  					&stbuf->st_gen,
  					&stbuf->st_data_version);
  			}
  			break;

  		case '?':

  			if ((proto_version != p9_proto_2000u) &&
  				(proto_version != p9_proto_2000L))

  				return 0;
  			break;
  		default:
  			BUG();
  			break;
  		}
  
  		if (errcode)
  			break;
  	}
  
  	return errcode;
  }
  
  int

  p9pdu_vwritef(struct p9_fcall *pdu, int proto_version, const char *fmt,
  	va_list ap)

  {
  	const char *ptr;
  	int errcode = 0;
  
  	for (ptr = fmt; *ptr; ptr++) {
  		switch (*ptr) {
  		case 'b':{
  				int8_t val = va_arg(ap, int);
  				if (pdu_write(pdu, &val, sizeof(val)))
  					errcode = -EFAULT;
  			}
  			break;
  		case 'w':{

  				__le16 val = cpu_to_le16(va_arg(ap, int));

  				if (pdu_write(pdu, &val, sizeof(val)))
  					errcode = -EFAULT;
  			}
  			break;
  		case 'd':{

  				__le32 val = cpu_to_le32(va_arg(ap, int32_t));

  				if (pdu_write(pdu, &val, sizeof(val)))
  					errcode = -EFAULT;
  			}
  			break;
  		case 'q':{

  				__le64 val = cpu_to_le64(va_arg(ap, int64_t));

  				if (pdu_write(pdu, &val, sizeof(val)))
  					errcode = -EFAULT;
  			}
  			break;
  		case 's':{

  				const char *sptr = va_arg(ap, const char *);

  				uint16_t len = 0;

  				if (sptr)

  					len = min_t(uint16_t, strlen(sptr),
  								USHRT_MAX);

  				errcode = p9pdu_writef(pdu, proto_version,
  								"w", len);

  				if (!errcode && pdu_write(pdu, sptr, len))

  					errcode = -EFAULT;
  			}
  			break;
  		case 'Q':{
  				const struct p9_qid *qid =
  				    va_arg(ap, const struct p9_qid *);
  				errcode =

  				    p9pdu_writef(pdu, proto_version, "bdq",

  						 qid->type, qid->version,
  						 qid->path);
  			} break;
  		case 'S':{
  				const struct p9_wstat *stbuf =
  				    va_arg(ap, const struct p9_wstat *);
  				errcode =

  				    p9pdu_writef(pdu, proto_version,

  						 "wwdQdddqssss?sddd",
  						 stbuf->size, stbuf->type,

  						 stbuf->dev, &stbuf->qid,

  						 stbuf->mode, stbuf->atime,
  						 stbuf->mtime, stbuf->length,
  						 stbuf->name, stbuf->uid,
  						 stbuf->gid, stbuf->muid,
  						 stbuf->extension, stbuf->n_uid,
  						 stbuf->n_gid, stbuf->n_muid);
  			} break;
  		case 'D':{

  				uint32_t count = va_arg(ap, uint32_t);

  				const void *data = va_arg(ap, const void *);

  				errcode = p9pdu_writef(pdu, proto_version, "d",
  									count);

  				if (!errcode && pdu_write(pdu, data, count))
  					errcode = -EFAULT;
  			}
  			break;

  		case 'U':{
  				int32_t count = va_arg(ap, int32_t);
  				const char __user *udata =

  						va_arg(ap, const void __user *);

  				errcode = p9pdu_writef(pdu, proto_version, "d",
  									count);

  				if (!errcode && pdu_write_u(pdu, udata, count))
  					errcode = -EFAULT;
  			}
  			break;

  		case 'T':{

  				uint16_t nwname = va_arg(ap, int);

  				const char **wnames = va_arg(ap, const char **);

  				errcode = p9pdu_writef(pdu, proto_version, "w",
  									nwname);

  				if (!errcode) {
  					int i;
  
  					for (i = 0; i < nwname; i++) {
  						errcode =

  						    p9pdu_writef(pdu,
  								proto_version,

  								 "s",
  								 wnames[i]);
  						if (errcode)
  							break;
  					}
  				}
  			}
  			break;
  		case 'R':{
  				int16_t nwqid = va_arg(ap, int);
  				struct p9_qid *wqids =
  				    va_arg(ap, struct p9_qid *);

  				errcode = p9pdu_writef(pdu, proto_version, "w",
  									nwqid);

  				if (!errcode) {
  					int i;
  
  					for (i = 0; i < nwqid; i++) {
  						errcode =

  						    p9pdu_writef(pdu,
  								proto_version,

  								 "Q",
  								 &wqids[i]);
  						if (errcode)
  							break;
  					}
  				}
  			}
  			break;

  		case 'I':{
  				struct p9_iattr_dotl *p9attr = va_arg(ap,
  							struct p9_iattr_dotl *);
  
  				errcode = p9pdu_writef(pdu, proto_version,
  							"ddddqqqqq",
  							p9attr->valid,
  							p9attr->mode,
  							p9attr->uid,
  							p9attr->gid,
  							p9attr->size,
  							p9attr->atime_sec,
  							p9attr->atime_nsec,
  							p9attr->mtime_sec,
  							p9attr->mtime_nsec);
  			}
  			break;

  		case '?':

  			if ((proto_version != p9_proto_2000u) &&
  				(proto_version != p9_proto_2000L))

  				return 0;
  			break;
  		default:
  			BUG();
  			break;
  		}
  
  		if (errcode)
  			break;
  	}
  
  	return errcode;
  }

  int p9pdu_readf(struct p9_fcall *pdu, int proto_version, const char *fmt, ...)

  {
  	va_list ap;
  	int ret;
  
  	va_start(ap, fmt);

  	ret = p9pdu_vreadf(pdu, proto_version, fmt, ap);

  	va_end(ap);
  
  	return ret;
  }
  
  static int

  p9pdu_writef(struct p9_fcall *pdu, int proto_version, const char *fmt, ...)

  {
  	va_list ap;
  	int ret;
  
  	va_start(ap, fmt);

  	ret = p9pdu_vwritef(pdu, proto_version, fmt, ap);

  	va_end(ap);
  
  	return ret;
  }

  int p9stat_read(struct p9_client *clnt, char *buf, int len, struct p9_wstat *st)

  {
  	struct p9_fcall fake_pdu;

  	int ret;

  
  	fake_pdu.size = len;
  	fake_pdu.capacity = len;
  	fake_pdu.sdata = buf;
  	fake_pdu.offset = 0;

  	ret = p9pdu_readf(&fake_pdu, clnt->proto_version, "S", st);

  	if (ret) {

  		p9_debug(P9_DEBUG_9P, "<<< p9stat_read failed: %d
  ", ret);

  		trace_9p_protocol_dump(clnt, &fake_pdu);

  	}
  
  	return ret;

  }
  EXPORT_SYMBOL(p9stat_read);

  int p9pdu_prepare(struct p9_fcall *pdu, int16_t tag, int8_t type)
  {

  	pdu->id = type;

  	return p9pdu_writef(pdu, 0, "dbw", 0, type, tag);
  }

  int p9pdu_finalize(struct p9_client *clnt, struct p9_fcall *pdu)

  {
  	int size = pdu->size;
  	int err;
  
  	pdu->size = 0;
  	err = p9pdu_writef(pdu, 0, "d", size);
  	pdu->size = size;

  	trace_9p_protocol_dump(clnt, pdu);

  	p9_debug(P9_DEBUG_9P, ">>> size=%d type: %d tag: %d
  ",
  		 pdu->size, pdu->id, pdu->tag);

  	return err;
  }
  
  void p9pdu_reset(struct p9_fcall *pdu)
  {
  	pdu->offset = 0;
  	pdu->size = 0;
  }

  int p9dirent_read(struct p9_client *clnt, char *buf, int len,
  		  struct p9_dirent *dirent)

  {
  	struct p9_fcall fake_pdu;
  	int ret;
  	char *nameptr;
  
  	fake_pdu.size = len;
  	fake_pdu.capacity = len;
  	fake_pdu.sdata = buf;
  	fake_pdu.offset = 0;

  	ret = p9pdu_readf(&fake_pdu, clnt->proto_version, "Qqbs", &dirent->qid,
  			  &dirent->d_off, &dirent->d_type, &nameptr);

  	if (ret) {

  		p9_debug(P9_DEBUG_9P, "<<< p9dirent_read failed: %d
  ", ret);

  		trace_9p_protocol_dump(clnt, &fake_pdu);

  		goto out;
  	}
  
  	strcpy(dirent->d_name, nameptr);

  	kfree(nameptr);

  
  out:
  	return fake_pdu.offset;
  }
  EXPORT_SYMBOL(p9dirent_read);