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Greg Kroah-Hartmanb2441312017-11-01 15:07:57 +01001// SPDX-License-Identifier: GPL-2.0
Jeremy Fitzhardinged84d1cc2007-07-17 18:37:02 -07002/*
3 * Helper function for splitting a string into an argv-like array.
4 */
5
6#include <linux/kernel.h>
7#include <linux/ctype.h>
André Goddard Rosae7d28602009-12-14 18:01:06 -08008#include <linux/string.h>
Robert P. J. Day5a56db12007-10-20 00:25:12 +02009#include <linux/slab.h>
Paul Gortmaker8bc3bcc2011-11-16 21:29:17 -050010#include <linux/export.h>
Jeremy Fitzhardinged84d1cc2007-07-17 18:37:02 -070011
Jeremy Fitzhardinged84d1cc2007-07-17 18:37:02 -070012static int count_argc(const char *str)
13{
14 int count = 0;
Oleg Nesterov095d1412013-04-29 16:18:10 -070015 bool was_space;
Jeremy Fitzhardinged84d1cc2007-07-17 18:37:02 -070016
Oleg Nesterov095d1412013-04-29 16:18:10 -070017 for (was_space = true; *str; str++) {
18 if (isspace(*str)) {
19 was_space = true;
20 } else if (was_space) {
21 was_space = false;
Jeremy Fitzhardinged84d1cc2007-07-17 18:37:02 -070022 count++;
Jeremy Fitzhardinged84d1cc2007-07-17 18:37:02 -070023 }
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{
Oleg Nesterov095d1412013-04-29 16:18:10 -070037 argv--;
38 kfree(argv[0]);
Jeremy Fitzhardinged84d1cc2007-07-17 18:37:02 -070039 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.
Oleg Nesterov095d1412013-04-29 16:18:10 -070055 *
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.
Jeremy Fitzhardinged84d1cc2007-07-17 18:37:02 -070059 */
60char **argv_split(gfp_t gfp, const char *str, int *argcp)
61{
Oleg Nesterov095d1412013-04-29 16:18:10 -070062 char *argv_str;
63 bool was_space;
64 char **argv, **argv_ret;
65 int argc;
Jeremy Fitzhardinged84d1cc2007-07-17 18:37:02 -070066
Oleg Nesterov095d1412013-04-29 16:18:10 -070067 argv_str = kstrndup(str, KMALLOC_MAX_SIZE - 1, gfp);
68 if (!argv_str)
69 return NULL;
70
71 argc = count_argc(argv_str);
Kees Cook6da2ec52018-06-12 13:55:00 -070072 argv = kmalloc_array(argc + 2, sizeof(*argv), gfp);
Oleg Nesterov095d1412013-04-29 16:18:10 -070073 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;
Jeremy Fitzhardinged84d1cc2007-07-17 18:37:02 -070090
Neil Horman8e2b7052007-10-16 23:26:33 -070091 if (argcp)
92 *argcp = argc;
Oleg Nesterov095d1412013-04-29 16:18:10 -070093 return argv_ret;
Jeremy Fitzhardinged84d1cc2007-07-17 18:37:02 -070094}
95EXPORT_SYMBOL(argv_split);