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
  11 static const char *skip_arg(const char *cp)
  12 {
  13         while (*cp && !isspace(*cp))
  14                 cp++;
  15
  16         return cp;
  17 }
  18
  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  */
  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  */
  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);