/*
 * (C) Copyright 2012
 * Joe Hershberger, National Instruments, joe.hershberger@ni.com
 *
 * SPDX-License-Identifier:     GPL-2.0+
 */

#ifdef USE_HOSTCC /* Eliminate "ANSI does not permit..." warnings */
#include <stdint.h>
#include <stdio.h>
#include <linux/linux_string.h>
#else
#include <common.h>
#include <slre.h>
#endif

#include <env_attr.h>
#include <errno.h>
#include <linux/string.h>
#include <malloc.h>

/*
 * Iterate through the whole list calling the callback for each found element.
 * "attr_list" takes the form:
 *      attributes = [^,:\s]*
 *      entry = name[:attributes]
 *      list = entry[,list]
 */
int env_attr_walk(const char *attr_list,
        int (*callback)(const char *name, const char *attributes, void *priv),
        void *priv)
{
        const char *entry, *entry_end;
        char *name, *attributes;

        if (!attr_list)
                /* list not found */
                return 1;

        entry = attr_list;
        do {
                char *entry_cpy = NULL;

                entry_end = strchr(entry, ENV_ATTR_LIST_DELIM);
                /* check if this is the last entry in the list */
                if (entry_end == NULL) {
                        int entry_len = strlen(entry);

                        if (entry_len) {
                                /*
                                 * allocate memory to copy the entry into since
                                 * we will need to inject '\0' chars and squash
                                 * white-space before calling the callback
                                 */
                                entry_cpy = malloc(entry_len + 1);
                                if (entry_cpy)
                                        /* copy the rest of the list */
                                        strcpy(entry_cpy, entry);
                                else
                                        return -ENOMEM;
                        }
                } else {
                        int entry_len = entry_end - entry;

                        if (entry_len) {
                                /*
                                 * allocate memory to copy the entry into since
                                 * we will need to inject '\0' chars and squash
                                 * white-space before calling the callback
                                 */
                                entry_cpy = malloc(entry_len + 1);
                                if (entry_cpy) {
                                        /* copy just this entry and null term */
                                        strncpy(entry_cpy, entry, entry_len);
                                        entry_cpy[entry_len] = '\0';
                                } else
                                        return -ENOMEM;
                        }
                }

                /* check if there is anything to process (e.g. not ",,,") */
                if (entry_cpy != NULL) {
                        attributes = strchr(entry_cpy, ENV_ATTR_SEP);
                        /* check if there is a ':' */
                        if (attributes != NULL) {
                                /* replace the ':' with '\0' to term name */
                                *attributes++ = '\0';
                                /* remove white-space from attributes */
                                attributes = strim(attributes);
                        }
                        /* remove white-space from name */
                        name = strim(entry_cpy);

                        /* only call the callback if there is a name */
                        if (strlen(name) != 0) {
                                int retval = 0;

                                retval = callback(name, attributes, priv);
                                if (retval) {
                                        free(entry_cpy);
                                        return retval;
                                }
                        }
                }

                free(entry_cpy);
                entry = entry_end + 1;
        } while (entry_end != NULL);

        return 0;
}

#if defined(CONFIG_REGEX)
struct regex_callback_priv {
        const char *searched_for;
        char *regex;
        char *attributes;
};

static int regex_callback(const char *name, const char *attributes, void *priv)
{
        int retval = 0;
        struct regex_callback_priv *cbp = (struct regex_callback_priv *)priv;
        struct slre slre;
        char regex[strlen(name) + 3];

        /* Require the whole string to be described by the regex */
        sprintf(regex, "^%s$", name);
        if (slre_compile(&slre, regex)) {
                struct cap caps[slre.num_caps + 2];

                if (slre_match(&slre, cbp->searched_for,
                               strlen(cbp->searched_for), caps)) {
                        free(cbp->regex);
                        if (!attributes) {
                                retval = -EINVAL;
                                goto done;
                        }
                        cbp->regex = malloc(strlen(regex) + 1);
                        if (cbp->regex) {
                                strcpy(cbp->regex, regex);
                        } else {
                                retval = -ENOMEM;
                                goto done;
                        }

                        free(cbp->attributes);
                        cbp->attributes = malloc(strlen(attributes) + 1);
                        if (cbp->attributes) {
                                strcpy(cbp->attributes, attributes);
                        } else {
                                retval = -ENOMEM;
                                free(cbp->regex);
                                cbp->regex = NULL;
                                goto done;
                        }
                }
        } else {
                printf("Error compiling regex: %s\n", slre.err_str);
                retval = -EINVAL;
        }
done:
        return retval;
}

/*
 * Retrieve the attributes string associated with a single name in the list
 * There is no protection on attributes being too small for the value
 */
int env_attr_lookup(const char *attr_list, const char *name, char *attributes)
{
        if (!attributes)
                /* bad parameter */
                return -EINVAL;
        if (!attr_list)
                /* list not found */
                return -EINVAL;

        struct regex_callback_priv priv;
        int retval;

        priv.searched_for = name;
        priv.regex = NULL;
        priv.attributes = NULL;
        retval = env_attr_walk(attr_list, regex_callback, &priv);
        if (retval)
                return retval; /* error */

        if (priv.regex) {
                strcpy(attributes, priv.attributes);
                free(priv.attributes);
                free(priv.regex);
                /* success */
                return 0;
        }
        return -ENOENT; /* not found in list */
}
#else

/*
 * Search for the last exactly matching name in an attribute list
 */
static int reverse_name_search(const char *searched, const char *search_for,
        const char **result)
{
        int result_size = 0;
        const char *cur_searched = searched;

        if (result)
                *result = NULL;

        if (*search_for == '\0') {
                if (result)
                        *result = searched;
                return strlen(searched);
        }

        for (;;) {
                const char *match = strstr(cur_searched, search_for);
                const char *prevch;
                const char *nextch;

                /* Stop looking if no new match is found */
                if (match == NULL)
                        break;

                prevch = match - 1;
                nextch = match + strlen(search_for);

                /* Skip spaces */
                while (*prevch == ' ' && prevch >= searched)
                        prevch--;
                while (*nextch == ' ')
                        nextch++;

                /* Start looking past the current match so last is found */
                cur_searched = match + 1;
                /* Check for an exact match */
                if (match != searched &&
                    *prevch != ENV_ATTR_LIST_DELIM &&
                    prevch != searched - 1)
                        continue;
                if (*nextch != ENV_ATTR_SEP &&
                    *nextch != ENV_ATTR_LIST_DELIM &&
                    *nextch != '\0')
                        continue;

                if (result)
                        *result = match;
                result_size = strlen(search_for);
        }

        return result_size;
}

/*
 * Retrieve the attributes string associated with a single name in the list
 * There is no protection on attributes being too small for the value
 */
int env_attr_lookup(const char *attr_list, const char *name, char *attributes)
{
        const char *entry = NULL;
        int entry_len;

        if (!attributes)
                /* bad parameter */
                return -EINVAL;
        if (!attr_list)
                /* list not found */
                return -EINVAL;

        entry_len = reverse_name_search(attr_list, name, &entry);
        if (entry != NULL) {
                int len;

                /* skip the name */
                entry += entry_len;
                /* skip spaces */
                while (*entry == ' ')
                        entry++;
                if (*entry != ENV_ATTR_SEP)
                        len = 0;
                else {
                        const char *delim;
                        static const char delims[] = {
                                ENV_ATTR_LIST_DELIM, ' ', '\0'};

                        /* skip the attr sep */
                        entry += 1;
                        /* skip spaces */
                        while (*entry == ' ')
                                entry++;

                        delim = strpbrk(entry, delims);
                        if (delim == NULL)
                                len = strlen(entry);
                        else
                                len = delim - entry;
                        memcpy(attributes, entry, len);
                }
                attributes[len] = '\0';

                /* success */
                return 0;
        }

        /* not found in list */
        return -ENOENT;
}
#endif