/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 *
 * Simple property list handling code.
 *
 * Copyright (c) 1998
 *      Jordan Hubbard.  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,
 *    verbatim and that no modifications are made prior to this
 *    point in the file.
 * 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.
 *
 * 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 OR HIS PETS 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, LIFE 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 <sys/types.h>
#include <ctype.h>
#include <err.h>
#include <libutil.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

static properties
property_alloc(char *name, char *value)
{
    properties n;

    if ((n = (properties)malloc(sizeof(struct _property))) == NULL)
        return (NULL);
    n->next = NULL;
    if (name != NULL) {
        if ((n->name = strdup(name)) == NULL) {
            free(n);
            return (NULL);
        }
    } else
        n->name = NULL;
    if (value != NULL) {
        if ((n->value = strdup(value)) == NULL) {
            free(n->name);
            free(n);
            return (NULL);
        }
    } else
        n->value = NULL;
    return (n);
}

properties
properties_read(int fd)
{
    properties head, ptr;
    char hold_n[PROPERTY_MAX_NAME + 1];
    char hold_v[PROPERTY_MAX_VALUE + 1];
    char buf[BUFSIZ * 4];
    int bp, n, v, max;
    enum { LOOK, COMMENT, NAME, VALUE, MVALUE, COMMIT, FILL, STOP } state, last_state;
    int ch = 0, blevel = 0;

    n = v = bp = max = 0;
    head = ptr = NULL;
    state = last_state = LOOK;
    while (state != STOP) {
        if (state != COMMIT) {
            if (bp == max) {
                last_state = state;
                state = FILL;
            } else
                ch = buf[bp++];
        }
        switch(state) {
        case FILL:
            if ((max = read(fd, buf, sizeof buf)) < 0) {
                properties_free(head);
                return (NULL);
            }
            if (max == 0) {
                state = STOP;
            } else {
                /*
                 * Restore the state from before the fill (which will be
                 * initialised to LOOK for the first FILL). This ensures that
                 * if we were part-way through eg., a VALUE state, when the
                 * buffer ran out, that the previous operation will be allowed
                 * to complete.
                 */
                state = last_state;
                ch = buf[0];
                bp = 0;
            }
            continue;

        case LOOK:
            if (isspace((unsigned char)ch))
                continue;
            /* Allow shell or lisp style comments */
            else if (ch == '#' || ch == ';') {
                state = COMMENT;
                continue;
            }
            else if (isalnum((unsigned char)ch) || ch == '_') {
                if (n >= PROPERTY_MAX_NAME) {
                    n = 0;
                    state = COMMENT;
                }
                else {
                    hold_n[n++] = ch;
                    state = NAME;
                }
            }
            else
                state = COMMENT;        /* Ignore the rest of the line */
            break;

        case COMMENT:
            if (ch == '\n')
                state = LOOK;
            break;

        case NAME:
            if (ch == '\n' || !ch) {
                hold_n[n] = '\0';
                hold_v[0] = '\0';
                v = n = 0;
                state = COMMIT;
            }
            else if (isspace((unsigned char)ch))
                continue;
            else if (ch == '=') {
                hold_n[n] = '\0';
                v = n = 0;
                state = VALUE;
            }
            else
                hold_n[n++] = ch;
            break;

        case VALUE:
            if (v == 0 && ch == '\n') {
                hold_v[v] = '\0';
                v = n = 0;
                state = COMMIT;
            } 
            else if (v == 0 && isspace((unsigned char)ch))
                continue;
            else if (ch == '{') {
                state = MVALUE;
                ++blevel;
            }
            else if (ch == '\n' || !ch) {
                hold_v[v] = '\0';
                v = n = 0;
                state = COMMIT;
            }
            else {
                if (v >= PROPERTY_MAX_VALUE) {
                    state = COMMENT;
                    v = n = 0;
                    break;
                }
                else
                    hold_v[v++] = ch;
            }
            break;

        case MVALUE:
            /* multiline value */
            if (v >= PROPERTY_MAX_VALUE) {
                warn("properties_read: value exceeds max length");
                state = COMMENT;
                n = v = 0;
            }
            else if (ch == '}' && !--blevel) {
                hold_v[v] = '\0';
                v = n = 0;
                state = COMMIT;
            }
            else {
                hold_v[v++] = ch;
                if (ch == '{')
                    ++blevel;
            }
            break;

        case COMMIT:
            if (head == NULL) {
                if ((head = ptr = property_alloc(hold_n, hold_v)) == NULL)
                    return (NULL);
            } else {
                if ((ptr->next = property_alloc(hold_n, hold_v)) == NULL) {
                    properties_free(head);
                    return (NULL);
                }
                ptr = ptr->next;
            }
            state = LOOK;
            v = n = 0;
            break;

        case STOP:
            /* we don't handle this here, but this prevents warnings */
            break;
        }
    }
    if (head == NULL && (head = property_alloc(NULL, NULL)) == NULL)
        return (NULL);

    return (head);
}

char *
property_find(properties list, const char *name)
{
    if (list == NULL || name == NULL || !name[0])
        return (NULL);
    while (list != NULL) {
        if (list->name != NULL && strcmp(list->name, name) == 0)
            return (list->value);
        list = list->next;
    }
    return (NULL);
}

void
properties_free(properties list)
{
    properties tmp;

    while (list) {
        tmp = list->next;
        if (list->name)
            free(list->name);
        if (list->value)
            free(list->value);
        free(list);
        list = tmp;
    }
}