contrib/ntp/libntp/hextoint.c

   1 /*
   2  * hextoint - convert an ascii string in hex to an unsigned
   3  *            long, with error checking
   4  */
   5 #include <config.h>
   6 #include <ctype.h>
   7
   8 #include "ntp_stdlib.h"
   9
  10 int
  11 hextoint(
  12         const char *str,
  13         u_long *pu
  14         )
  15 {
  16         register u_long u;
  17         register const char *cp;
  18
  19         cp = str;
  20
  21         if (*cp == '\0')
  22                 return 0;
  23
  24         u = 0;
  25         while (*cp != '\0') {
  26                 if (!isxdigit((unsigned char)*cp))
  27                         return 0;
  28                 if (u & 0xF0000000)
  29                         return 0;       /* overflow */
  30                 u <<= 4;
  31                 if ('0' <= *cp && *cp <= '9')
  32                         u += *cp++ - '0';
  33                 else if ('a' <= *cp && *cp <= 'f')
  34                         u += *cp++ - 'a' + 10;
  35                 else if ('A' <= *cp && *cp <= 'F')
  36                         u += *cp++ - 'A' + 10;
  37                 else
  38                         return 0;
  39         }
  40         *pu = u;
  41         return 1;
  42 }