/*
 * net/tipc/log.c: TIPC print buffer routines for debugging
 *
 * Copyright (c) 1996-2006, Ericsson AB
 * Copyright (c) 2005-2007, Wind River Systems
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. 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.
 * 3. Neither the names of the copyright holders nor the names of its
 *    contributors may be used to endorse or promote products derived from
 *    this software without specific prior written permission.
 *
 * Alternatively, this software may be distributed under the terms of the
 * GNU General Public License ("GPL") version 2 as published by the Free
 * Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 COPYRIGHT OWNER OR CONTRIBUTORS 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.
 */

#include "core.h"
#include "config.h"
#include "log.h"

/*
 * TIPC pre-defines the following print buffers:
 *
 * TIPC_NULL : null buffer (i.e. print nowhere)
 * TIPC_CONS : system console
 * TIPC_LOG  : TIPC log buffer
 *
 * Additional user-defined print buffers are also permitted.
 */
static struct print_buf null_buf = { NULL, 0, NULL, 0 };
struct print_buf *const TIPC_NULL = &null_buf;

static struct print_buf cons_buf = { NULL, 0, NULL, 1 };
struct print_buf *const TIPC_CONS = &cons_buf;

static struct print_buf log_buf = { NULL, 0, NULL, 1 };
struct print_buf *const TIPC_LOG = &log_buf;

/*
 * Locking policy when using print buffers.
 *
 * 1) tipc_printf() uses 'print_lock' to protect against concurrent access to
 * 'print_string' when writing to a print buffer. This also protects against
 * concurrent writes to the print buffer being written to.
 *
 * 2) tipc_log_XXX() leverages the aforementioned use of 'print_lock' to
 * protect against all types of concurrent operations on their associated
 * print buffer (not just write operations).
 *
 * Note: All routines of the form tipc_printbuf_XXX() are lock-free, and rely
 * on the caller to prevent simultaneous use of the print buffer(s) being
 * manipulated.
 */
static char print_string[TIPC_PB_MAX_STR];
static DEFINE_SPINLOCK(print_lock);

static void tipc_printbuf_move(struct print_buf *pb_to,
                               struct print_buf *pb_from);

#define FORMAT(PTR, LEN, FMT) \
{\
        va_list args;\
        va_start(args, FMT);\
        LEN = vsprintf(PTR, FMT, args);\
        va_end(args);\
        *(PTR + LEN) = '\0';\
}

/**
 * tipc_printbuf_init - initialize print buffer to empty
 * @pb: pointer to print buffer structure
 * @raw: pointer to character array used by print buffer
 * @size: size of character array
 *
 * Note: If the character array is too small (or absent), the print buffer
 * becomes a null device that discards anything written to it.
 */
void tipc_printbuf_init(struct print_buf *pb, char *raw, u32 size)
{
        pb->buf = raw;
        pb->crs = raw;
        pb->size = size;
        pb->echo = 0;

        if (size < TIPC_PB_MIN_SIZE) {
                pb->buf = NULL;
        } else if (raw) {
                pb->buf[0] = 0;
                pb->buf[size - 1] = ~0;
        }
}

/**
 * tipc_printbuf_reset - reinitialize print buffer to empty state
 * @pb: pointer to print buffer structure
 */
static void tipc_printbuf_reset(struct print_buf *pb)
{
        if (pb->buf) {
                pb->crs = pb->buf;
                pb->buf[0] = 0;
                pb->buf[pb->size - 1] = ~0;
        }
}

/**
 * tipc_printbuf_empty - test if print buffer is in empty state
 * @pb: pointer to print buffer structure
 *
 * Returns non-zero if print buffer is empty.
 */
static int tipc_printbuf_empty(struct print_buf *pb)
{
        return !pb->buf || (pb->crs == pb->buf);
}

/**
 * tipc_printbuf_validate - check for print buffer overflow
 * @pb: pointer to print buffer structure
 *
 * Verifies that a print buffer has captured all data written to it.
 * If data has been lost, linearize buffer and prepend an error message
 *
 * Returns length of print buffer data string (including trailing NUL)
 */
int tipc_printbuf_validate(struct print_buf *pb)
{
        char *err = "\n\n*** PRINT BUFFER OVERFLOW ***\n\n";
        char *cp_buf;
        struct print_buf cb;

        if (!pb->buf)
                return 0;

        if (pb->buf[pb->size - 1] == 0) {
                cp_buf = kmalloc(pb->size, GFP_ATOMIC);
                if (cp_buf) {
                        tipc_printbuf_init(&cb, cp_buf, pb->size);
                        tipc_printbuf_move(&cb, pb);
                        tipc_printbuf_move(pb, &cb);
                        kfree(cp_buf);
                        memcpy(pb->buf, err, strlen(err));
                } else {
                        tipc_printbuf_reset(pb);
                        tipc_printf(pb, err);
                }
        }
        return pb->crs - pb->buf + 1;
}

/**
 * tipc_printbuf_move - move print buffer contents to another print buffer
 * @pb_to: pointer to destination print buffer structure
 * @pb_from: pointer to source print buffer structure
 *
 * Current contents of destination print buffer (if any) are discarded.
 * Source print buffer becomes empty if a successful move occurs.
 */
static void tipc_printbuf_move(struct print_buf *pb_to,
                               struct print_buf *pb_from)
{
        int len;

        /* Handle the cases where contents can't be moved */
        if (!pb_to->buf)
                return;

        if (!pb_from->buf) {
                tipc_printbuf_reset(pb_to);
                return;
        }

        if (pb_to->size < pb_from->size) {
                strcpy(pb_to->buf, "*** PRINT BUFFER MOVE ERROR ***");
                pb_to->buf[pb_to->size - 1] = ~0;
                pb_to->crs = strchr(pb_to->buf, 0);
                return;
        }

        /* Copy data from char after cursor to end (if used) */
        len = pb_from->buf + pb_from->size - pb_from->crs - 2;
        if ((pb_from->buf[pb_from->size - 1] == 0) && (len > 0)) {
                strcpy(pb_to->buf, pb_from->crs + 1);
                pb_to->crs = pb_to->buf + len;
        } else
                pb_to->crs = pb_to->buf;

        /* Copy data from start to cursor (always) */
        len = pb_from->crs - pb_from->buf;
        strcpy(pb_to->crs, pb_from->buf);
        pb_to->crs += len;

        tipc_printbuf_reset(pb_from);
}

/**
 * tipc_printf - append formatted output to print buffer
 * @pb: pointer to print buffer
 * @fmt: formatted info to be printed
 */
void tipc_printf(struct print_buf *pb, const char *fmt, ...)
{
        int chars_to_add;
        int chars_left;
        char save_char;

        spin_lock_bh(&print_lock);

        FORMAT(print_string, chars_to_add, fmt);
        if (chars_to_add >= TIPC_PB_MAX_STR)
                strcpy(print_string, "*** PRINT BUFFER STRING TOO LONG ***");

        if (pb->buf) {
                chars_left = pb->buf + pb->size - pb->crs - 1;
                if (chars_to_add <= chars_left) {
                        strcpy(pb->crs, print_string);
                        pb->crs += chars_to_add;
                } else if (chars_to_add >= (pb->size - 1)) {
                        strcpy(pb->buf, print_string + chars_to_add + 1
                               - pb->size);
                        pb->crs = pb->buf + pb->size - 1;
                } else {
                        strcpy(pb->buf, print_string + chars_left);
                        save_char = print_string[chars_left];
                        print_string[chars_left] = 0;
                        strcpy(pb->crs, print_string);
                        print_string[chars_left] = save_char;
                        pb->crs = pb->buf + chars_to_add - chars_left;
                }
        }

        if (pb->echo)
                printk("%s", print_string);

        spin_unlock_bh(&print_lock);
}

/**
 * tipc_log_resize - change the size of the TIPC log buffer
 * @log_size: print buffer size to use
 */
int tipc_log_resize(int log_size)
{
        int res = 0;

        spin_lock_bh(&print_lock);
        kfree(TIPC_LOG->buf);
        TIPC_LOG->buf = NULL;
        if (log_size) {
                if (log_size < TIPC_PB_MIN_SIZE)
                        log_size = TIPC_PB_MIN_SIZE;
                res = TIPC_LOG->echo;
                tipc_printbuf_init(TIPC_LOG, kmalloc(log_size, GFP_ATOMIC),
                                   log_size);
                TIPC_LOG->echo = res;
                res = !TIPC_LOG->buf;
        }
        spin_unlock_bh(&print_lock);

        return res;
}

/**
 * tipc_log_resize_cmd - reconfigure size of TIPC log buffer
 */
struct sk_buff *tipc_log_resize_cmd(const void *req_tlv_area, int req_tlv_space)
{
        u32 value;

        if (!TLV_CHECK(req_tlv_area, req_tlv_space, TIPC_TLV_UNSIGNED))
                return tipc_cfg_reply_error_string(TIPC_CFG_TLV_ERROR);

        value = ntohl(*(__be32 *)TLV_DATA(req_tlv_area));
        if (value > 32768)
                return tipc_cfg_reply_error_string(TIPC_CFG_INVALID_VALUE
                                                   " (log size must be 0-32768)");
        if (tipc_log_resize(value))
                return tipc_cfg_reply_error_string(
                        "unable to create specified log (log size is now 0)");
        return tipc_cfg_reply_none();
}

/**
 * tipc_log_dump - capture TIPC log buffer contents in configuration message
 */
struct sk_buff *tipc_log_dump(void)
{
        struct sk_buff *reply;

        spin_lock_bh(&print_lock);
        if (!TIPC_LOG->buf) {
                spin_unlock_bh(&print_lock);
                reply = tipc_cfg_reply_ultra_string("log not activated\n");
        } else if (tipc_printbuf_empty(TIPC_LOG)) {
                spin_unlock_bh(&print_lock);
                reply = tipc_cfg_reply_ultra_string("log is empty\n");
        } else {
                struct tlv_desc *rep_tlv;
                struct print_buf pb;
                int str_len;

                str_len = min(TIPC_LOG->size, 32768u);
                spin_unlock_bh(&print_lock);
                reply = tipc_cfg_reply_alloc(TLV_SPACE(str_len));
                if (reply) {
                        rep_tlv = (struct tlv_desc *)reply->data;
                        tipc_printbuf_init(&pb, TLV_DATA(rep_tlv), str_len);
                        spin_lock_bh(&print_lock);
                        tipc_printbuf_move(&pb, TIPC_LOG);
                        spin_unlock_bh(&print_lock);
                        str_len = strlen(TLV_DATA(rep_tlv)) + 1;
                        skb_put(reply, TLV_SPACE(str_len));
                        TLV_SET(rep_tlv, TIPC_TLV_ULTRA_STRING, NULL, str_len);
                }
        }
        return reply;
}