/*======================================================================
 FILE: icalmemory.c
 CREATOR: eric 30 June 1999

 Copyright (C) 2000 Eric Busboom <eric@softwarestudio.org>
   http://www.softwarestudio.org

 The contents of this file are subject to the Mozilla Public License
 Version 1.0 (the "License"); you may not use this file except in
 compliance with the License. You may obtain a copy of the License at
 http://www.mozilla.org/MPL/

 Software distributed under the License is distributed on an "AS IS"
 basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
 the License for the specific language governing rights and
 limitations under the License.

 This program is free software; you can redistribute it and/or modify
 it under the terms of either:

    The LGPL as published by the Free Software Foundation, version
    2.1, available at: http://www.gnu.org/licenses/lgpl-2.1.html

 Or:

    The Mozilla Public License Version 1.0. You may obtain a copy of
    the License at http://www.mozilla.org/MPL/
======================================================================*/

/**
 * @file icalmemory.c
 * @brief Common memory management routines.
 *
 * libical often passes strings back to the caller. To make these
 * interfaces simple, I did not want the caller to have to pass in a
 * memory buffer, but having libical pass out newly allocated memory
 * makes it difficult to de-allocate the memory.
 *
 * The ring buffer in this scheme makes it possible for libical to pass
 * out references to memory which the caller does not own, and be able
 * to de-allocate the memory later. The ring allows libical to have
 * several buffers active simultaneously, which is handy when creating
 * string representations of components.
 */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include "icalmemory.h"
#include "icalerror.h"

#include <stdlib.h>

#define BUFFER_RING_SIZE 2500
#define MIN_BUFFER_SIZE 200

/* HACK. Not threadsafe */

typedef struct
{
    int pos;
    void *ring[BUFFER_RING_SIZE];
} buffer_ring;

#if !defined(HAVE_PTHREAD)
static buffer_ring *global_buffer_ring = 0;
#endif

/** get rid of this buffer ring */
static void icalmemory_free_ring_byval(buffer_ring * br)
{
    int i;

    for (i = 0; i < BUFFER_RING_SIZE; i++) {
        if (br->ring[i] != 0) {
            free(br->ring[i]);
        }
    }
    free(br);
}

#if defined(HAVE_PTHREAD)
#include <pthread.h>

static pthread_key_t ring_key;
static pthread_once_t ring_key_once = PTHREAD_ONCE_INIT;

static void ring_destroy(void *buf)
{
    if (buf)
        icalmemory_free_ring_byval((buffer_ring *) buf);

    pthread_setspecific(ring_key, NULL);
}

static void ring_key_alloc(void)
{
    pthread_key_create(&ring_key, ring_destroy);
}

#endif

#if 0
/*keep for historical sake*/
static void icalmemory_free_tmp_buffer(void *buf)
{
    if (buf == 0) {
        return;
    }

    free(buf);
}

#endif

static buffer_ring *buffer_ring_new(void)
{
    buffer_ring *br;
    int i;

    br = (buffer_ring *) malloc(sizeof(buffer_ring));

    for (i = 0; i < BUFFER_RING_SIZE; i++) {
        br->ring[i] = 0;
    }
    br->pos = 0;
    return (br);
}

#if defined(HAVE_PTHREAD)
static buffer_ring *get_buffer_ring_pthread(void)
{
    buffer_ring *br;

    pthread_once(&ring_key_once, ring_key_alloc);

    br = pthread_getspecific(ring_key);

    if (!br) {
        br = buffer_ring_new();
        pthread_setspecific(ring_key, br);
    }
    return (br);
}

#else
/* get buffer ring via a single global for a non-threaded program */
static buffer_ring *get_buffer_ring_global(void)
{
    if (global_buffer_ring == 0) {
        global_buffer_ring = buffer_ring_new();
    }
    return (global_buffer_ring);
}

#endif

static buffer_ring *get_buffer_ring(void)
{
#if defined(HAVE_PTHREAD)
    return (get_buffer_ring_pthread());
#else
    return get_buffer_ring_global();
#endif
}

/** Add an existing buffer to the buffer ring */
void icalmemory_add_tmp_buffer(void *buf)
{
    buffer_ring *br = get_buffer_ring();

    /* Wrap around the ring */
    if (++(br->pos) == BUFFER_RING_SIZE) {
        br->pos = 0;
    }

    /* Free buffers as their slots are overwritten */
    if (br->ring[br->pos] != 0) {
        free(br->ring[br->pos]);
    }

    /* Assign the buffer to a slot */
    br->ring[br->pos] = buf;
}

/**
 * Create a new temporary buffer on the ring. Libical owns these and
 * will deallocate them.
 */

void *icalmemory_tmp_buffer(size_t size)
{
    char *buf;

    if (size < MIN_BUFFER_SIZE) {
        size = MIN_BUFFER_SIZE;
    }

    buf = (void *)malloc(size);

    if (buf == 0) {
        icalerror_set_errno(ICAL_NEWFAILED_ERROR);
        return 0;
    }

    memset(buf, 0, size);

    icalmemory_add_tmp_buffer(buf);

    return buf;
}

void icalmemory_free_ring()
{
    buffer_ring *br;

    br = get_buffer_ring();

    icalmemory_free_ring_byval(br);
#if defined(HAVE_PTHREAD)
    pthread_setspecific(ring_key, 0);
#else
    global_buffer_ring = 0;
#endif
}

/** Like strdup, but the buffer is on the ring. */
char *icalmemory_tmp_copy(const char *str)
{
    char *b = icalmemory_tmp_buffer(strlen(str) + 1);

    strcpy(b, str);

    return b;
}

char *icalmemory_strdup(const char *s)
{
    return strdup(s);
}

/*
 * These buffer routines create memory the old fashioned way -- so the
 * caller will have to deallocate the new memory
 */

void *icalmemory_new_buffer(size_t size)
{
    void *b = malloc(size);

    if (b == 0) {
        icalerror_set_errno(ICAL_NEWFAILED_ERROR);
        return 0;
    }

    memset(b, 0, size);

    return b;
}

void *icalmemory_resize_buffer(void *buf, size_t size)
{
    void *b = realloc(buf, size);

    if (b == 0) {
        icalerror_set_errno(ICAL_NEWFAILED_ERROR);
        return 0;
    }

    return b;
}

void icalmemory_free_buffer(void *buf)
{
    free(buf);
}

void icalmemory_append_string(char **buf, char **pos, size_t *buf_size, const char *string)
{
    char *new_buf;
    char *new_pos;

    size_t data_length, final_length, string_length;

#if !defined(ICAL_NO_INTERNAL_DEBUG)
    icalerror_check_arg_rv((buf != 0), "buf");
    icalerror_check_arg_rv((*buf != 0), "*buf");
    icalerror_check_arg_rv((pos != 0), "pos");
    icalerror_check_arg_rv((*pos != 0), "*pos");
    icalerror_check_arg_rv((buf_size != 0), "buf_size");
    icalerror_check_arg_rv((*buf_size != 0), "*buf_size");
    icalerror_check_arg_rv((string != 0), "string");
#endif

    string_length = strlen(string);
    data_length = (size_t) * pos - (size_t) * buf;
    final_length = data_length + string_length;

    if (final_length >= (size_t) * buf_size) {

        *buf_size = (*buf_size) * 2 + final_length;

        new_buf = realloc(*buf, *buf_size);

        new_pos = (void *)((size_t) new_buf + data_length);

        *pos = new_pos;
        *buf = new_buf;
    }

    strcpy(*pos, string);

    *pos += string_length;
}

void icalmemory_append_char(char **buf, char **pos, size_t *buf_size, char ch)
{
    char *new_buf;
    char *new_pos;

    size_t data_length, final_length;

#if !defined(ICAL_NO_INTERNAL_DEBUG)
    icalerror_check_arg_rv((buf != 0), "buf");
    icalerror_check_arg_rv((*buf != 0), "*buf");
    icalerror_check_arg_rv((pos != 0), "pos");
    icalerror_check_arg_rv((*pos != 0), "*pos");
    icalerror_check_arg_rv((buf_size != 0), "buf_size");
    icalerror_check_arg_rv((*buf_size != 0), "*buf_size");
#endif

    data_length = (size_t) * pos - (size_t) * buf;

    final_length = data_length + 2;

    if (final_length > (size_t) * buf_size) {

        *buf_size = (*buf_size) * 2 + final_length + 1;

        new_buf = realloc(*buf, *buf_size);

        new_pos = (void *)((size_t) new_buf + data_length);

        *pos = new_pos;
        *buf = new_buf;
    }

    **pos = ch;
    *pos += 1;
    **pos = 0;
}
