xref: /openbmc/linux/lib/argv_split.c (revision 36ee98b5)
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