lib/cmdline.c

   1 /*
   2  * linux/lib/cmdline.c
   3  * Helper functions generally used for parsing kernel command line
   4  * and module options.
   5  *
   6  * Code and copyrights come from init/main.c and arch/i386/kernel/setup.c.
   7  *
   8  * This source code is licensed under the GNU General Public License,
   9  * Version 2.  See the file COPYING for more details.
  10  *
  11  * GNU Indent formatting options for this file: -kr -i8 -npsl -pcs
  12  *
  13  */
  14
  15 #include <linux/export.h>
  16 #include <linux/kernel.h>
  17 #include <linux/string.h>
  18
  19 /*
  20  *      If a hyphen was found in get_option, this will handle the
  21  *      range of numbers, M-N.  This will expand the range and insert
  22  *      the values[M, M+1, ..., N] into the ints array in get_options.
  23  */
  24
  25 static int get_range(char **str, int *pint, int n)
  26 {
  27         int x, inc_counter, upper_range;
  28
  29         (*str)++;
  30         upper_range = simple_strtol((*str), NULL, 0);
  31         inc_counter = upper_range - *pint;
  32         for (x = *pint; n && x < upper_range; x++, n--)
  33                 *pint++ = x;
  34         return inc_counter;
  35 }
  36
  37 /**
  38  *      get_option - Parse integer from an option string
  39  *      @str: option string
  40  *      @pint: (output) integer value parsed from @str
  41  *
  42  *      Read an int from an option string; if available accept a subsequent
  43  *      comma as well.
  44  *
  45  *      Return values:
  46  *      0 - no int in string
  47  *      1 - int found, no subsequent comma
  48  *      2 - int found including a subsequent comma
  49  *      3 - hyphen found to denote a range
  50  */
  51
  52 int get_option(char **str, int *pint)
  53 {
  54         char *cur = *str;
  55
  56         if (!cur || !(*cur))
  57                 return 0;
  58         *pint = simple_strtol(cur, str, 0);
  59         if (cur == *str)
  60                 return 0;
  61         if (**str == ',') {
  62                 (*str)++;
  63                 return 2;
  64         }
  65         if (**str == '-')
  66                 return 3;
  67
  68         return 1;
  69 }
  70 EXPORT_SYMBOL(get_option);
  71
  72 /**
  73  *      get_options - Parse a string into a list of integers
  74  *      @str: String to be parsed
  75  *      @nints: size of integer array
  76  *      @ints: integer array
  77  *
  78  *      This function parses a string containing a comma-separated
  79  *      list of integers, a hyphen-separated range of _positive_ integers,
  80  *      or a combination of both.  The parse halts when the array is
  81  *      full, or when no more numbers can be retrieved from the
  82  *      string.
  83  *
  84  *      Return value is the character in the string which caused
  85  *      the parse to end (typically a null terminator, if @str is
  86  *      completely parseable).
  87  */
  88
  89 char *get_options(const char *str, int nints, int *ints)
  90 {
  91         int res, i = 1;
  92
  93         while (i < nints) {
  94                 res = get_option((char **)&str, ints + i);
  95                 if (res == 0)
  96                         break;
  97                 if (res == 3) {
  98                         int range_nums;
  99                         range_nums = get_range((char **)&str, ints + i, nints - i);
 100                         if (range_nums < 0)
 101                                 break;
 102                         /*
 103                          * Decrement the result by one to leave out the
 104                          * last number in the range.  The next iteration
 105                          * will handle the upper number in the range
 106                          */
 107                         i += (range_nums - 1);
 108                 }
 109                 i++;
 110                 if (res == 1)
 111                         break;
 112         }
 113         ints[0] = i - 1;
 114         return (char *)str;
 115 }
 116 EXPORT_SYMBOL(get_options);
 117
 118 /**
 119  *      memparse - parse a string with mem suffixes into a number
 120  *      @ptr: Where parse begins
 121  *      @retptr: (output) Optional pointer to next char after parse completes
 122  *
 123  *      Parses a string into a number.  The number stored at @ptr is
 124  *      potentially suffixed with K, M, G, T, P, E.
 125  */
 126
 127 unsigned long long memparse(const char *ptr, char **retptr)
 128 {
 129         char *endptr;   /* local pointer to end of parsed string */
 130
 131         unsigned long long ret = simple_strtoull(ptr, &endptr, 0);
 132
 133         switch (*endptr) {
 134         case 'E':
 135         case 'e':
 136                 ret <<= 10;
 137         case 'P':
 138         case 'p':
 139                 ret <<= 10;
 140         case 'T':
 141         case 't':
 142                 ret <<= 10;
 143         case 'G':
 144         case 'g':
 145                 ret <<= 10;
 146         case 'M':
 147         case 'm':
 148                 ret <<= 10;
 149         case 'K':
 150         case 'k':
 151                 ret <<= 10;
 152                 endptr++;
 153         default:
 154                 break;
 155         }
 156
 157         if (retptr)
 158                 *retptr = endptr;
 159
 160         return ret;
 161 }
 162 EXPORT_SYMBOL(memparse);
 163
 164 /**
 165  *      parse_option_str - Parse a string and check an option is set or not
 166  *      @str: String to be parsed
 167  *      @option: option name
 168  *
 169  *      This function parses a string containing a comma-separated list of
 170  *      strings like a=b,c.
 171  *
 172  *      Return true if there's such option in the string, or return false.
 173  */
 174 bool parse_option_str(const char *str, const char *option)
 175 {
 176         while (*str) {
 177                 if (!strncmp(str, option, strlen(option))) {
 178                         str += strlen(option);
 179                         if (!*str || *str == ',')
 180                                 return true;
 181                 }
 182
 183                 while (*str && *str != ',')
 184                         str++;
 185
 186                 if (*str == ',')
 187                         str++;
 188         }
 189
 190         return false;
 191 }