// SPDX-License-Identifier: GPL-2.0
/*
 * Helper function for splitting a string into an argv-like array.
 */

#include <linux/kernel.h>
#include <linux/ctype.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/export.h>

static int count_argc(const char *str)
{
        int count = 0;
        bool was_space;

        for (was_space = true; *str; str++) {
                if (isspace(*str)) {
                        was_space = true;
                } else if (was_space) {
                        was_space = false;
                        count++;
                }
        }

        return count;
}

/**
 * argv_free - free an argv
 * @argv: the argument vector to be freed
 *
 * Frees an argv and the strings it points to.
 */
void argv_free(char **argv)
{
        argv--;
        kfree(argv[0]);
        kfree(argv);
}
EXPORT_SYMBOL(argv_free);

/**
 * argv_split - split a string at whitespace, returning an argv
 * @gfp: the GFP mask used to allocate memory
 * @str: the string to be split
 * @argcp: returned argument count
 *
 * Returns: an array of pointers to strings which are split out from
 * @str.  This is performed by strictly splitting on white-space; no
 * quote processing is performed.  Multiple whitespace characters are
 * considered to be a single argument separator.  The returned array
 * is always NULL-terminated.  Returns NULL on memory allocation
 * failure.
 *
 * The source string at `str' may be undergoing concurrent alteration via
 * userspace sysctl activity (at least).  The argv_split() implementation
 * attempts to handle this gracefully by taking a local copy to work on.
 */
char **argv_split(gfp_t gfp, const char *str, int *argcp)
{
        char *argv_str;
        bool was_space;
        char **argv, **argv_ret;
        int argc;

        argv_str = kstrndup(str, KMALLOC_MAX_SIZE - 1, gfp);
        if (!argv_str)
                return NULL;

        argc = count_argc(argv_str);
        argv = kmalloc_array(argc + 2, sizeof(*argv), gfp);
        if (!argv) {
                kfree(argv_str);
                return NULL;
        }

        *argv = argv_str;
        argv_ret = ++argv;
        for (was_space = true; *argv_str; argv_str++) {
                if (isspace(*argv_str)) {
                        was_space = true;
                        *argv_str = 0;
                } else if (was_space) {
                        was_space = false;
                        *argv++ = argv_str;
                }
        }
        *argv = NULL;

        if (argcp)
                *argcp = argc;
        return argv_ret;
}
EXPORT_SYMBOL(argv_split);