/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 1996 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */


#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <libintl.h>
#include "pkglib.h"

/*
 * This is the module responsible for allocating and maintaining lists that
 * require allocation of memory. For certain lists, large chunks are
 * allocated once to contain a large number of entries in each chunk (bl_*
 * for block list). The other approach involves the augmentation of linked
 * lists, each entry of which is alloc'd individually.
 */
#define ERR_CS_ALLOC    "ERROR: Cannot allocate control structure for %s array."
#define ERR_MEM_ALLOC   "ERROR: Cannot allocate memory for %s array."

#define MAX_ARRAYS      50

#define ARRAY_END(x)    (bl_cs_array[x]->cur_segment->avail_ptr)
#define REC_SIZE(x)     (bl_cs_array[x]->struct_size)
#define EOSEG(x)        (bl_cs_array[x]->cur_segment->eoseg_ptr)
#define GET_AVAIL(x)    (ARRAY_END(x) + REC_SIZE(x))

struct alloc_seg {
        char *seg_ptr;          /* ptr to the allocated block */
        char *avail_ptr;        /* ptr to the next available list element */
        char *eoseg_ptr;        /* last byte in the segment */
        int full;               /* segment has no available space */
        struct alloc_seg *next; /* next record */
};

struct blk_list_cs {
        int struct_size;                /* size of a single list element */
        int count_per_block;            /* number of list elements per block */
        int block_size;                 /* just to save time - alloc size */
        int data_handle;                /* list_handle for pointer array */
        struct alloc_seg *alloc_segs;   /* memory pool */

        struct alloc_seg *cur_segment;  /* the current allocated segment */
        int total_elem;                 /* total elements stored */
        int contiguous;                 /* use realloc to grow */
        char *desc;                     /* description of the list */
};

static struct blk_list_cs *bl_cs_array[MAX_ARRAYS];
static int next_array_elem;

/* Support functions */
static int
invalid_handle(int list_handle)
{
        if (list_handle < 0 || list_handle >= next_array_elem)
                return (1);

        return (0);
}

static int
invalid_record(int list_handle, int recno)
{
        if (invalid_handle(list_handle))
                return (1);

        if (recno < 0 || recno > bl_cs_array[list_handle]->total_elem)
                return (1);

        return (0);
}

static void
free_list(int list_handle)
{
        struct blk_list_cs *bl_ptr;
        struct alloc_seg *segstr_ptr, *nextstr_ptr;

        /* Make sure this wasn't free'd earlier */
        if (bl_cs_array[list_handle] == NULL)
                return;

        bl_ptr = bl_cs_array[list_handle];

        /* First free the alloc_seg list. */
        segstr_ptr = bl_ptr->alloc_segs;

        if (segstr_ptr) {
                do {
                        nextstr_ptr = segstr_ptr->next;

                        /* Free the memory block. */
                        free((void *)segstr_ptr->seg_ptr);

                        /* Free the control structure. */
                        free((void *)segstr_ptr);
                        segstr_ptr = nextstr_ptr;
                } while (segstr_ptr);
        }

        /* Free the block control structure. */
        free((void *)bl_ptr->desc);
        free((void *)bl_ptr);

        bl_cs_array[list_handle] = NULL;
}

/* Allocate another alloc_seg structure. */
static int
alloc_next_seg(struct blk_list_cs *bl_ptr)
{
        struct alloc_seg *new_alloc_cs;

        if (bl_ptr->contiguous) {
                int offset_to_avail, seg_size, new_size;
                struct alloc_seg *alloc_segment;

                if (bl_ptr->alloc_segs) {
                        alloc_segment = bl_ptr->alloc_segs;

                        offset_to_avail = (alloc_segment->avail_ptr -
                            alloc_segment->seg_ptr);
                        seg_size = (alloc_segment->eoseg_ptr -
                            alloc_segment->seg_ptr);
                        new_size = (seg_size + bl_ptr->block_size);
                } else {
                        if ((bl_ptr->alloc_segs =
                            (struct alloc_seg *)calloc(1,
                            sizeof (struct alloc_seg))) == NULL) {
                                logerr(gettext(ERR_CS_ALLOC), (bl_ptr->desc ?
                                    bl_ptr->desc : "an unknown"));
                                return (0);
                        }

                        alloc_segment = bl_ptr->alloc_segs;

                        offset_to_avail = 0;
                        seg_size = 0;
                        new_size = bl_ptr->block_size;
                }

                bl_ptr->cur_segment = alloc_segment;

                if ((alloc_segment->seg_ptr =
                    (char *)realloc((void *)alloc_segment->seg_ptr,
                    (unsigned)new_size)) == NULL) {
                        logerr(gettext(ERR_MEM_ALLOC), (bl_ptr->desc ?
                            bl_ptr->desc : "an unknown"));
                        return (0);
                }

                alloc_segment->next = NULL;

                /* reset the status */
                alloc_segment->full = 0;

                /* readjust the original pointers */
                alloc_segment->avail_ptr = alloc_segment->seg_ptr +
                    offset_to_avail;
                alloc_segment->eoseg_ptr = alloc_segment->seg_ptr + new_size;

                (void) memset(alloc_segment->avail_ptr, '\000',
                    bl_ptr->block_size);
        } else {
                /* Allocate the control structure and link it into the list. */
                if ((new_alloc_cs = (struct alloc_seg *)malloc(
                    sizeof (struct alloc_seg))) == NULL) {
                        logerr(gettext(ERR_CS_ALLOC), (bl_ptr->desc ?
                            bl_ptr->desc : "an unknown"));
                        return (0);
                }

                if (bl_ptr->alloc_segs == NULL) {
                        /*
                         * If this is the first allocation, then initialize
                         * the head pointer and set cur_segment to this first
                         * block of memory.
                         */
                        bl_ptr->alloc_segs = new_alloc_cs;
                } else {
                        /*
                         * Otherwise, point the current cur_segment to the
                         * next one and then point to the new one.
                         */
                        bl_ptr->cur_segment->next = new_alloc_cs;
                }

                new_alloc_cs->next = NULL;
                bl_ptr->cur_segment = new_alloc_cs;

                new_alloc_cs->full = 0;

                /* Now allocate the block of memory that this controls. */
                if ((new_alloc_cs->seg_ptr = calloc(bl_ptr->count_per_block,
                    bl_ptr->struct_size)) == NULL) {
                        logerr(gettext(ERR_MEM_ALLOC), (bl_ptr->desc ?
                            bl_ptr->desc : "an unknown"));
                        return (0);
                }

                new_alloc_cs->avail_ptr = new_alloc_cs->seg_ptr;
                new_alloc_cs->eoseg_ptr = (new_alloc_cs->seg_ptr +
                    bl_ptr->block_size);
        }

        return (1);
}

/*
 * These first functions (beginning with bl_*) manage simple block lists. The
 * pointers returned, may get lost if they aren't assigned to an array or
 * something. While individual records can be obtained by record number, the
 * process isn't very efficient. Look to the array management section
 * (ar_*)for an easily administrable list.
 */

/*
 * Create a block list. Allocate memory for a block list structure and
 * initialize that structure. This doesn't actually allocate memory for the
 * list yet, just the controlling data structure. Returns -1 on failure and a
 * valid block list handle otherwise.
 *
 * NOTE: At the time of writing, it was not seen as important to recover block
 * pointers made available with a bl_free() (two of these at most in
 * pkginstall). If this became important later, we could trade efficiency for
 * speed by ignoring next_array_elem and actually scanning through the array
 * for a NULL pointer and then return that.
 */
int
bl_create(int count_per_block, int struct_size, char *desc)
{
        struct blk_list_cs *bl_ptr;
        int retval;

        if ((bl_cs_array[next_array_elem] =
            (struct blk_list_cs *)calloc(1, sizeof (struct blk_list_cs))) ==
            NULL) {
                logerr(gettext(ERR_CS_ALLOC), (desc ? desc : "an unknown"));
                return (-1);
        }

        bl_ptr = bl_cs_array[next_array_elem];
        retval = next_array_elem++;

        bl_ptr->data_handle = -1;
        bl_ptr->struct_size = struct_size;
        bl_ptr->count_per_block = count_per_block;
        bl_ptr->block_size = (count_per_block * struct_size);
        bl_ptr->desc = strdup((desc ? desc : "unknown"));

        return (retval);
}

/*
 * Get the next available entry in the list. This will allocate memory as
 * required based on the initialization values in bl_create(). Returns a
 * pointer to the allocated memory segment or NULL if operation was not
 * possible.
 */
char *
bl_next_avail(int list_handle)
{
        struct blk_list_cs *bl_ptr;
        char *retval;

        if (invalid_handle(list_handle))
                return (NULL);

        bl_ptr = bl_cs_array[list_handle];

        /*
         * Allocate more memory if none is allocated yet or our last access
         * filled the allotted segment.
         */
        if (bl_ptr->cur_segment == NULL || bl_ptr->cur_segment->full)
                if (!alloc_next_seg(bl_ptr))
                        return (NULL);

        /* Get the correct pointer. */
        retval = bl_ptr->cur_segment->avail_ptr;

        /* Advance it and mark if full. */
        bl_ptr->cur_segment->avail_ptr += bl_ptr->struct_size;
        bl_ptr->total_elem++;

        if (bl_ptr->cur_segment->avail_ptr >= bl_ptr->cur_segment->eoseg_ptr)
                bl_ptr->cur_segment->full = 1;

        return (retval);
}

char *
bl_get_record(int list_handle, int recno)
{
        struct blk_list_cs *bl_ptr;
        struct alloc_seg *cur_as_ptr;
        int cur_rec = 0;

        if (invalid_record(list_handle, recno))
                return (NULL);

        bl_ptr = bl_cs_array[list_handle];

        cur_as_ptr = bl_ptr->alloc_segs;

        while (recno > (cur_rec + bl_ptr->count_per_block)) {
                cur_as_ptr = cur_as_ptr->next;

                if (cur_as_ptr == NULL)
                        return (NULL);

                cur_rec += bl_ptr->count_per_block;
        }

        /*
         * Now cur_as_ptr points to the allocated segment bearing the
         * intended record and all we do now is move down that by the
         * remaining record lengths.
         */

        return ((char *)cur_as_ptr + ((recno - cur_rec) * bl_ptr->struct_size));
}

void
bl_free(int list_handle)
{
        int cur_handle;

        if (list_handle == -1) {
                for (cur_handle = 0; cur_handle < next_array_elem;
                    cur_handle++) {
                        free_list(cur_handle);
                }
        } else {
                if (invalid_handle(list_handle))
                        return;

                free_list(list_handle);
        }
}

/*
 * These are the array management functions. They insert into (and can return
 * a pointer to) a contiguous list of pointers to stuff. This keeps
 * everything together in a very handy package and is very similar in
 * appearance to the arrays created by the old AT&T code. The method for
 * presenting the interface is entirely different, however.
 */

/*
 * This constructs, maintains and returns pointers into a growable array of
 * pointers to structures of the form
 *      struct something *array[n]
 * The last element in the array is always NULL.
 */
int
ar_create(int count_per_block, int struct_size, char *desc)
{
        int data_handle, retval;
        char ar_desc[60];
        struct blk_list_cs *array_ptr;

        if ((data_handle = bl_create(count_per_block, struct_size, desc)) == -1)
                return (-1);

        sprintf(ar_desc, "%s pointer", desc);
        if ((retval = bl_create(count_per_block, sizeof (char *),
            ar_desc)) == -1)
                return (-1);

        array_ptr = bl_cs_array[retval];

        array_ptr->contiguous = 1;
        array_ptr->data_handle = data_handle;

        return (retval);
}

/* Return a pointer to the first element in the array. */
char **
ar_get_head(int list_handle)
{
        if (invalid_handle(list_handle) ||
            bl_cs_array[list_handle]->alloc_segs == NULL)
                return (NULL);

        return ((char **)bl_cs_array[list_handle]->alloc_segs->seg_ptr);
}

/*
 * Free up the entry in the array indicated by index, but hold onto it for
 * future use.
 */
int
ar_delete(int list_handle, int index)
{
        char **array;
        char *deleted_rec;
        int i;
        struct blk_list_cs *list_ptr, *data_ptr;

        if ((array = ar_get_head(list_handle)) == NULL)
                return (0);

        if (invalid_record(list_handle, index))
                return (0);

        /* Get the pointer to the array control structure. */
        list_ptr = bl_cs_array[list_handle];

        if (!(list_ptr->contiguous))
                return (0);     /* This isn't an array. */

        data_ptr = bl_cs_array[list_ptr->data_handle];

        /*
         * Since this looks just like an array. Record the pointer being
         * deleted for insertion into the avail list at the end and move all
         * elements below it up one.
         */
        deleted_rec = array[index];

        for (i = index; array[i] != NULL; i++)
                array[i] = array[i+1];

        /*
         * Now insert the deleted entry into the avails list after the NULL
         * and adjust the avail_ptr to point to the NULL again.
         */
        array[i] = deleted_rec;
        list_ptr->alloc_segs->avail_ptr -= list_ptr->struct_size;

        /* Adjust other entries in the control structure. */
        list_ptr->alloc_segs->full = 0;
        list_ptr->total_elem -= 1;

        /* Clear the deleted data area. */
        (void) memset(deleted_rec, '\000', data_ptr->struct_size);

        return (1);
}

/*
 * Return a new pointer to a structure pointer. Find an available element in
 * the array and point it at an available element in the data pool
 * constructed of block lists. Allocate new memory as necessary.
 */
char **
ar_next_avail(int list_handle)
{
        struct blk_list_cs *array_ptr;
        char *data_area, **pointer_area;

        if (invalid_handle(list_handle) ||
            !(bl_cs_array[list_handle]->contiguous) ||
            invalid_handle(bl_cs_array[list_handle]->data_handle))
                return (NULL);

        array_ptr = bl_cs_array[list_handle];

        /*
         * First see if an avail has already been allocated (it will be right
         * after the NULL termination of the array if it exists). Return
         * that, if found.
         */
        if ((bl_cs_array[list_handle]->cur_segment != NULL) &&
            (ARRAY_END(list_handle) + REC_SIZE(list_handle) <
            EOSEG(list_handle)) &&
            (*(pointer_area = (char **) GET_AVAIL(list_handle)) != NULL)) {
                /* We can reclaim a previous deletion. */
                data_area = *pointer_area;

                *(char **)(ARRAY_END(list_handle)) = data_area; /* reactivate */
                *pointer_area-- = NULL; /* new end */

                array_ptr->cur_segment->avail_ptr += array_ptr->struct_size;
                array_ptr->total_elem++;
        } else {
                /*
                 * Get the data area first. This is the record we're pointing
                 * to from the array.
                 */
                data_area = bl_next_avail(array_ptr->data_handle);

                /* Now get the next pointer from the pointer array. */
                pointer_area = (char **) bl_next_avail(list_handle);

                *pointer_area = data_area;

                /*
                 * The array must be NULL terminated. So, if the block list
                 * structure is full, we have to grow it without resetting
                 * the avail pointer. NOTE: This will only work for a
                 * contiguous list!
                 */
                if (bl_cs_array[list_handle]->alloc_segs->full) {
                        char **old_list_pointer, **new_list_pointer;

                        /*
                         * First grab the old numbers in case realloc() moves
                         * everything.
                         */
                        old_list_pointer = ar_get_head(list_handle);

                        /*
                         * Now allocate additional contiguous memory, moving
                         * the original block if necessary.
                         */
                        if (!alloc_next_seg(array_ptr))
                                return (NULL);

                        /*
                         * Now determine if everything moved and readjust the
                         * pointer_area if required.
                         */
                        new_list_pointer = ar_get_head(list_handle);

                        if (old_list_pointer != new_list_pointer) {
                                pointer_area += (new_list_pointer -
                                    old_list_pointer);
                        }
                }
        }

        return (pointer_area);
}

/*
 * Relinquish the array back to the memory pool. Note that there is no method
 * provided to free *all* arrays.
 */
void
ar_free(int list_handle)
{
        if (invalid_handle(list_handle))
                return;

        bl_free(bl_cs_array[list_handle]->data_handle);
        bl_free(list_handle);
}