Root/lib/argv_split.c

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
11static const char *skip_arg(const char *cp)
12{
13    while (*cp && !isspace(*cp))
14        cp++;
15
16    return cp;
17}
18
19static 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 */
40void argv_free(char **argv)
41{
42    char **p;
43    for (p = argv; *p; p++)
44        kfree(*p);
45
46    kfree(argv);
47}
48EXPORT_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 */
63char **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}
101EXPORT_SYMBOL(argv_split);
102

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