minix/lib/libsys/env_parse.c

   1 #include "sysutil.h"
   2 #include <stdlib.h>
   3 #include <string.h>
   4 #include <minix/param.h>
   5
   6
   7 /*=========================================================================*
   8  *                              env_parse                                  *
   9  *=========================================================================*/
  10 int env_parse(const char *env, const char *fmt,
  11         int field, long *param, long min, long max)
  12 {
  13 /* Parse an environment variable setting, something like "DPETH0=300:3".
  14  * Panic if the parsing fails.  Return EP_UNSET if the environment variable
  15  * is not set, EP_OFF if it is set to "off", EP_ON if set to "on" or a
  16  * field is left blank, or EP_SET if a field is given (return value through
  17  * *param).  Punctuation may be used in the environment and format string,
  18  * fields in the environment string may be empty, and punctuation may be
  19  * missing to skip fields.  The format string contains characters 'd', 'o',
  20  * 'x' and 'c' to indicate that 10, 8, 16, or 0 is used as the last argument
  21  * to strtol().  A '*' means that a field should be skipped.  If the format
  22  * string contains something like "\4" then the string is repeated 4 characters
  23  * to the left.
  24  */
  25   char *val, *end;
  26   char value[EP_BUF_SIZE];
  27   char PUNCT[] = ":,;.";
  28   long newpar;
  29   int s, i, radix, r;
  30
  31   if ((s=env_get_param(env, value, sizeof(value))) != 0) {
  32       if (s == ESRCH) return(EP_UNSET);         /* only error allowed */
  33       printf("WARNING: env_get_param() failed in env_parse(): %d\n",s);
  34       return(EP_EGETKENV);
  35   }
  36   val = value;
  37   if (strcmp(val, "off") == 0) return(EP_OFF);
  38   if (strcmp(val, "on") == 0) return(EP_ON);
  39
  40   i = 0;
  41   r = EP_ON;
  42   for (;;) {
  43         while (*val == ' ') val++;      /* skip spaces */
  44         if (*val == 0) return(r);       /* the proper exit point */
  45         if (*fmt == 0) break;           /* too many values */
  46
  47         if (strchr(PUNCT, *val) != NULL) {
  48                 /* Time to go to the next field. */
  49                 if (strchr(PUNCT, *fmt) != NULL) i++;
  50                 if (*fmt++ == *val) val++;
  51                 if (*fmt < 32) fmt -= *fmt;     /* step back? */
  52         } else {
  53                 /* Environment contains a value, get it. */
  54                 switch (*fmt) {
  55                 case '*':       radix =   -1;   break;
  56                 case 'd':       radix =   10;   break;
  57                 case 'o':       radix =  010;   break;
  58                 case 'x':       radix = 0x10;   break;
  59                 case 'c':       radix =    0;   break;
  60                 default:        goto badenv;
  61                 }
  62
  63                 if (radix < 0) {
  64                         /* Skip. */
  65                         while (strchr(PUNCT, *val) == NULL) val++;
  66                         continue;
  67                 } else {
  68                         /* A number. */
  69                         newpar = strtol(val, &end, radix);
  70
  71                         if (end == val) break;  /* not a number */
  72                         val = end;
  73                 }
  74
  75                 if (i == field) {
  76                         /* The field requested. */
  77                         if (newpar < min || newpar > max) break;
  78                         *param = newpar;
  79                         r = EP_SET;
  80                 }
  81         }
  82   }
  83 badenv:
  84   env_panic(env);
  85   return -1;
  86 }