lib/common/var.c

/*
 * Copyright (C) 1993-2005  by Darren Reed.
 * See the IPFILTER.LICENCE file for details on licencing.
 */

#include <ctype.h>

#include "ipf.h"

typedef struct  variable    {
    struct  variable    *v_next;
    char    *v_name;
    char    *v_value;
} variable_t;

static  variable_t  *vtop = NULL;

static variable_t *find_var __P((char *));
static char *expand_string __P((char *, int));


static variable_t *find_var(name)
char *name;
{
    variable_t *v;

    for (v = vtop; v != NULL; v = v->v_next)
        if (!strcmp(name, v->v_name))
            return v;
    return NULL;
}


char *get_variable(string, after, line)
char *string, **after;
int line;
{
    char c, *s, *t, *value;
    variable_t *v;

    s = string;

    if (*s == '{') {
        s++;
        for (t = s; *t != '\0'; t++)
            if (*t == '}')
                break;
        if (*t == '\0') {
            fprintf(stderr, "%d: { without }\n", line);
            return NULL;
        }
    } else if (ISALPHA(*s)) {
        for (t = s + 1; *t != '\0'; t++)
            if (!ISALPHA(*t) && !ISDIGIT(*t) && (*t != '_'))
                break;
    } else {
        fprintf(stderr, "%d: variables cannot start with '%c'\n",
            line, *s);
        return NULL;
    }

    if (after != NULL)
        *after = t;
    c = *t;
    *t = '\0';
    v = find_var(s);
    *t = c;
    if (v == NULL) {
        fprintf(stderr, "%d: unknown variable '%s'\n", line, s);
        return NULL;
    }

    s = strdup(v->v_value);
    value = expand_string(s, line);
    if (value != s)
        free(s);
    return value;
}


static char *expand_string(oldstring, line)
char *oldstring;
int line;
{
    char c, *s, *p1, *p2, *p3, *newstring, *value;
    int len;

    p3 = NULL;
    newstring = oldstring;

    for (s = oldstring; *s != '\0'; s++)
        if (*s == '$') {
            *s = '\0';
            s++;

            switch (*s)
            {
            case '$' :
                bcopy(s, s - 1, strlen(s));
                break;
            default :
                c = *s;
                if (c == '\0')
                    return newstring;

                value = get_variable(s, &p3, line);
                if (value == NULL)
                    return NULL;

                p2 = expand_string(value, line);
                if (p2 == NULL)
                    return NULL;

                len = strlen(newstring) + strlen(p2);
                if (p3 != NULL) {
                    if (c == '{' && *p3 == '}')
                        p3++;
                    len += strlen(p3);
                }
                p1 = malloc(len + 1);
                if (p1 == NULL)
                    return NULL;

                *(s - 1) = '\0';
                strcpy(p1, newstring);
                strcat(p1, p2);
                if (p3 != NULL)
                    strcat(p1, p3);

                s = p1 + len - strlen(p3) - 1;
                if (newstring != oldstring)
                    free(newstring);
                newstring = p1;
                break;
            }
        }
    return newstring;
}


void set_variable(name, value)
char *name;
char *value;
{
    variable_t *v;
    int len;

    if (name == NULL || value == NULL || *name == '\0')
        return;

    v = find_var(name);
    if (v != NULL) {
        free(v->v_value);
        v->v_value = strdup(value);
        return;
    }

    len = strlen(value);

    if ((*value == '"' && value[len - 1] == '"') ||
        (*value == '\'' && value[len - 1] == '\'')) {
        value[len - 1] = '\0';
        value++;
        len -=2;
    }

    v = (variable_t *)malloc(sizeof(*v));
    if (v == NULL)
        return;
    v->v_name = strdup(name);
    v->v_value = strdup(value);
    v->v_next = vtop;
    vtop = v;
}