Line data    Source code

       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             : 
      12           0 : static int count_argc(const char *str)
      13             : {
      14           0 :         int count = 0;
      15           0 :         bool was_space;
      16             : 
      17           0 :         for (was_space = true; *str; str++) {
      18           0 :                 if (isspace(*str)) {
      19             :                         was_space = true;
      20           0 :                 } else if (was_space) {
      21           0 :                         was_space = false;
      22           0 :                         count++;
      23             :                 }
      24             :         }
      25             : 
      26           0 :         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             :  */
      35           0 : void argv_free(char **argv)
      36             : {
      37           0 :         argv--;
      38           0 :         kfree(argv[0]);
      39           0 :         kfree(argv);
      40           0 : }
      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             :  */
      60           0 : char **argv_split(gfp_t gfp, const char *str, int *argcp)
      61             : {
      62           0 :         char *argv_str;
      63           0 :         bool was_space;
      64           0 :         char **argv, **argv_ret;
      65           0 :         int argc;
      66             : 
      67           0 :         argv_str = kstrndup(str, KMALLOC_MAX_SIZE - 1, gfp);
      68           0 :         if (!argv_str)
      69             :                 return NULL;
      70             : 
      71           0 :         argc = count_argc(argv_str);
      72           0 :         argv = kmalloc_array(argc + 2, sizeof(*argv), gfp);
      73           0 :         if (!argv) {
      74           0 :                 kfree(argv_str);
      75           0 :                 return NULL;
      76             :         }
      77             : 
      78           0 :         *argv = argv_str;
      79           0 :         argv_ret = ++argv;
      80           0 :         for (was_space = true; *argv_str; argv_str++) {
      81           0 :                 if (isspace(*argv_str)) {
      82           0 :                         was_space = true;
      83           0 :                         *argv_str = 0;
      84           0 :                 } else if (was_space) {
      85           0 :                         was_space = false;
      86           0 :                         *argv++ = argv_str;
      87             :                 }
      88             :         }
      89           0 :         *argv = NULL;
      90             : 
      91           0 :         if (argcp)
      92           0 :                 *argcp = argc;
      93             :         return argv_ret;
      94             : }
      95             : EXPORT_SYMBOL(argv_split);