source: trunk/minix/lib/sysutil/env_parse.c@ 20

#include "sysutil.h"
#include <stdlib.h>
#include <string.h>


/*=========================================================================*
 *                              env_parse                                  *
 *=========================================================================*/
PUBLIC int env_parse(env, fmt, field, param, min, max)
char *env;              /* environment variable to inspect */
char *fmt;              /* template to parse it with */
int field;              /* field number of value to return */
long *param;            /* address of parameter to get */
long min, max;          /* minimum and maximum values for the parameter */
{
/* Parse an environment variable setting, something like "DPETH0=300:3".
 * Panic if the parsing fails.  Return EP_UNSET if the environment variable
 * is not set, EP_OFF if it is set to "off", EP_ON if set to "on" or a
 * field is left blank, or EP_SET if a field is given (return value through
 * *param).  Punctuation may be used in the environment and format string,
 * fields in the environment string may be empty, and punctuation may be
 * missing to skip fields.  The format string contains characters 'd', 'o',
 * 'x' and 'c' to indicate that 10, 8, 16, or 0 is used as the last argument
 * to strtol().  A '*' means that a field should be skipped.  If the format
 * string contains something like "\4" then the string is repeated 4 characters
 * to the left.
 */
  char *val, *end;
  char value[EP_BUF_SIZE];
  char PUNCT[] = ":,;.";
  long newpar;
  int s, i, radix, r, keylen;

  if ((s=env_get_param(env, value, sizeof(value))) != 0) { 
      if (s == ESRCH) return(EP_UNSET);         /* only error allowed */ 
      printf("WARNING: get_mon_param() failed in env_parse(): %d\n",s);
      return(EP_EGETKENV);
  }
  val = value;
  if (strcmp(val, "off") == 0) return(EP_OFF);
  if (strcmp(val, "on") == 0) return(EP_ON);

  i = 0;
  r = EP_ON;
  for (;;) {
        while (*val == ' ') val++;      /* skip spaces */
        if (*val == 0) return(r);       /* the proper exit point */
        if (*fmt == 0) break;           /* too many values */

        if (strchr(PUNCT, *val) != NULL) {
                /* Time to go to the next field. */
                if (strchr(PUNCT, *fmt) != NULL) i++;
                if (*fmt++ == *val) val++;
                if (*fmt < 32) fmt -= *fmt;     /* step back? */
        } else {
                /* Environment contains a value, get it. */
                switch (*fmt) {
                case '*':       radix =   -1;   break;
                case 'd':       radix =   10;   break;
                case 'o':       radix =  010;   break;
                case 'x':       radix = 0x10;   break;
                case 'c':       radix =    0;   break;
                default:        goto badenv;
                }
                
                if (radix < 0) {
                        /* Skip. */
                        while (strchr(PUNCT, *val) == NULL) val++;
                        continue;
                } else {
                        /* A number. */
                        newpar = strtol(val, &end, radix);

                        if (end == val) break;  /* not a number */
                        val = end;
                }

                if (i == field) {
                        /* The field requested. */
                        if (newpar < min || newpar > max) break;
                        *param = newpar;
                        r = EP_SET;
                }
        }
  }
badenv:
  env_panic(env);
}