Eric Lee / smarc-fsl-linux-kernel

argv_split.c 2.1 KB
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 
// 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);