1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Helper function for splitting a string into an argv-like array.
4 */
5
6#include <linux/kernel.h>
7#include <linux/ctype.h>
8#include <linux/string.h>
9#include <linux/slab.h>
10#include <linux/export.h>
11
12static int count_argc(const char *str)
13{
14	int count = 0;
15	bool was_space;
16
17	for (was_space = true; *str; str++) {
18		if (isspace(*str)) {
19			was_space = true;
20		} else if (was_space) {
21			was_space = false;
22			count++;
23		}
24	}
25
26	return count;
27}
28
29/**
30 * argv_free - free an argv
31 * @argv: the argument vector to be freed
32 *
33 * Frees an argv and the strings it points to.
34 */
35void argv_free(char **argv)
36{
37	argv--;
38	kfree(argv[0]);
39	kfree(argv);
40}
41EXPORT_SYMBOL(argv_free);
42
43/**
44 * argv_split - split a string at whitespace, returning an argv
45 * @gfp: the GFP mask used to allocate memory
46 * @str: the string to be split
47 * @argcp: returned argument count
48 *
49 * Returns: an array of pointers to strings which are split out from
50 * @str.  This is performed by strictly splitting on white-space; no
51 * quote processing is performed.  Multiple whitespace characters are
52 * considered to be a single argument separator.  The returned array
53 * is always NULL-terminated.  Returns NULL on memory allocation
54 * failure.
55 *
56 * The source string at `str' may be undergoing concurrent alteration via
57 * userspace sysctl activity (at least).  The argv_split() implementation
58 * attempts to handle this gracefully by taking a local copy to work on.
59 */
60char **argv_split(gfp_t gfp, const char *str, int *argcp)
61{
62	char *argv_str;
63	bool was_space;
64	char **argv, **argv_ret;
65	int argc;
66
67	argv_str = kstrndup(str, KMALLOC_MAX_SIZE - 1, gfp);
68	if (!argv_str)
69		return NULL;
70
71	argc = count_argc(argv_str);
72	argv = kmalloc_array(argc + 2, sizeof(*argv), gfp);
73	if (!argv) {
74		kfree(argv_str);
75		return NULL;
76	}
77
78	*argv = argv_str;
79	argv_ret = ++argv;
80	for (was_space = true; *argv_str; argv_str++) {
81		if (isspace(*argv_str)) {
82			was_space = true;
83			*argv_str = 0;
84		} else if (was_space) {
85			was_space = false;
86			*argv++ = argv_str;
87		}
88	}
89	*argv = NULL;
90
91	if (argcp)
92		*argcp = argc;
93	return argv_ret;
94}
95EXPORT_SYMBOL(argv_split);
96