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