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/module.h>
10 
skip_arg(const char * cp)11 static const char *skip_arg(const char *cp)
12 {
13 	while (*cp && !isspace(*cp))
14 		cp++;
15 
16 	return cp;
17 }
18 
count_argc(const char * str)19 static int count_argc(const char *str)
20 {
21 	int count = 0;
22 
23 	while (*str) {
24 		str = skip_spaces(str);
25 		if (*str) {
26 			count++;
27 			str = skip_arg(str);
28 		}
29 	}
30 
31 	return count;
32 }
33 
34 /**
35  * argv_free - free an argv
36  * @argv - the argument vector to be freed
37  *
38  * Frees an argv and the strings it points to.
39  */
argv_free(char ** argv)40 void argv_free(char **argv)
41 {
42 	char **p;
43 	for (p = argv; *p; p++)
44 		kfree(*p);
45 
46 	kfree(argv);
47 }
48 EXPORT_SYMBOL(argv_free);
49 
50 /**
51  * argv_split - split a string at whitespace, returning an argv
52  * @gfp: the GFP mask used to allocate memory
53  * @str: the string to be split
54  * @argcp: returned argument count
55  *
56  * Returns an array of pointers to strings which are split out from
57  * @str.  This is performed by strictly splitting on white-space; no
58  * quote processing is performed.  Multiple whitespace characters are
59  * considered to be a single argument separator.  The returned array
60  * is always NULL-terminated.  Returns NULL on memory allocation
61  * failure.
62  */
argv_split(gfp_t gfp,const char * str,int * argcp)63 char **argv_split(gfp_t gfp, const char *str, int *argcp)
64 {
65 	int argc = count_argc(str);
66 	char **argv = kzalloc(sizeof(*argv) * (argc+1), gfp);
67 	char **argvp;
68 
69 	if (argv == NULL)
70 		goto out;
71 
72 	if (argcp)
73 		*argcp = argc;
74 
75 	argvp = argv;
76 
77 	while (*str) {
78 		str = skip_spaces(str);
79 
80 		if (*str) {
81 			const char *p = str;
82 			char *t;
83 
84 			str = skip_arg(str);
85 
86 			t = kstrndup(p, str-p, gfp);
87 			if (t == NULL)
88 				goto fail;
89 			*argvp++ = t;
90 		}
91 	}
92 	*argvp = NULL;
93 
94   out:
95 	return argv;
96 
97   fail:
98 	argv_free(argv);
99 	return NULL;
100 }
101 EXPORT_SYMBOL(argv_split);
102