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
count_argc(const char * str)12 static 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 */
argv_free(char ** argv)35 void argv_free(char **argv)
36 {
37 argv--;
38 kfree(argv[0]);
39 kfree(argv);
40 }
41 EXPORT_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 */
argv_split(gfp_t gfp,const char * str,int * argcp)60 char **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 }
95 EXPORT_SYMBOL(argv_split);
96