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/bug.h>
   8
   9 static const char *skip_sep(const char *cp)
  10 {
  11         while (*cp && isspace(*cp))
  12                 cp++;
  13
  14         return cp;
  15 }
  16
  17 static const char *skip_arg(const char *cp)
  18 {
  19         while (*cp && !isspace(*cp))
  20                 cp++;
  21
  22         return cp;
  23 }
  24
  25 static int count_argc(const char *str)
  26 {
  27         int count = 0;
  28
  29         while (*str) {
  30                 str = skip_sep(str);
  31                 if (*str) {
  32                         count++;
  33                         str = skip_arg(str);
  34                 }
  35         }
  36
  37         return count;
  38 }
  39
  40 /**
  41  * argv_free - free an argv
  42  * @argv - the argument vector to be freed
  43  *
  44  * Frees an argv and the strings it points to.
  45  */
  46 void argv_free(char **argv)
  47 {
  48         char **p;
  49         for (p = argv; *p; p++)
  50                 kfree(*p);
  51
  52         kfree(argv);
  53 }
  54 EXPORT_SYMBOL(argv_free);
  55
  56 /**
  57  * argv_split - split a string at whitespace, returning an argv
  58  * @gfp: the GFP mask used to allocate memory
  59  * @str: the string to be split
  60  * @argcp: returned argument count
  61  *
  62  * Returns an array of pointers to strings which are split out from
  63  * @str.  This is performed by strictly splitting on white-space; no
  64  * quote processing is performed.  Multiple whitespace characters are
  65  * considered to be a single argument separator.  The returned array
  66  * is always NULL-terminated.  Returns NULL on memory allocation
  67  * failure.
  68  */
  69 char **argv_split(gfp_t gfp, const char *str, int *argcp)
  70 {
  71         int argc = count_argc(str);
  72         char **argv = kzalloc(sizeof(*argv) * (argc+1), gfp);
  73         char **argvp;
  74
  75         if (argv == NULL)
  76                 goto out;
  77
  78         *argcp = argc;
  79         argvp = argv;
  80
  81         while (*str) {
  82                 str = skip_sep(str);
  83
  84                 if (*str) {
  85                         const char *p = str;
  86                         char *t;
  87
  88                         str = skip_arg(str);
  89
  90                         t = kstrndup(p, str-p, gfp);
  91                         if (t == NULL)
  92                                 goto fail;
  93                         *argvp++ = t;
  94                 }
  95         }
  96         *argvp = NULL;
  97
  98   out:
  99         return argv;
 100
 101   fail:
 102         argv_free(argv);
 103         return NULL;
 104 }
 105 EXPORT_SYMBOL(argv_split);