osfmk/kern/sscanf.c

   1 /*
   2  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * The contents of this file constitute Original Code as defined in and
   7  * are subject to the Apple Public Source License Version 1.1 (the
   8  * "License").  You may not use this file except in compliance with the
   9  * License.  Please obtain a copy of the License at
  10  * http://www.apple.com/publicsource and read it before using this file.
  11  *
  12  * This Original Code and all software distributed under the License are
  13  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  14  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  15  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
  17  * License for the specific language governing rights and limitations
  18  * under the License.
  19  *
  20  * @APPLE_LICENSE_HEADER_END@
  21  */
  22 /*
  23  * @OSF_FREE_COPYRIGHT@
  24  */
  25 /*
  26  * HISTORY
  27  *
  28  * Revision 1.1.1.1  1998/09/22 21:05:32  wsanchez
  29  * Import of Mac OS X kernel (~semeria)
  30  *
  31  * Revision 1.1.1.1  1998/03/07 02:25:56  wsanchez
  32  * Import of OSF Mach kernel (~mburg)
  33  *
  34  * Revision 1.1.8.2  1997/02/12  12:52:33  stephen
  35  *      New file, reimplemented to be sure of copyright status
  36  *      Initially only supports character matching and '%d'
  37  *      [1997/02/12  12:43:09  stephen]
  38  *
  39  * $EndLog$
  40  */
  41
  42 #include <stdarg.h>
  43 #include <kern/misc_protos.h>
  44
  45 #define isdigit(c) ((unsigned) ((c) - '0') < 10U)
  46
  47 /*
  48  * Scan items from a string in accordance with a format.  This is much
  49  * simpler than the C standard function: it only recognises %d without a
  50  * field width, and does not treat space in the format string or the
  51  * input any differently from other characters.  The return value is the
  52  * number of characters from the input string that were successfully
  53  * scanned, not the number of format items matched as in standard sscanf.
  54  * e.mcmanus@opengroup.org, 12 Feb 97
  55  */
  56 int
  57 sscanf(const char *str, const char *format, ...)
  58 {
  59         const char *start = str;
  60         va_list args;
  61
  62         va_start(args, format);
  63         for ( ; *format != '\0'; format++) {
  64                 if (*format == '%' && format[1] == 'd') {
  65                         int positive;
  66                         int value;
  67                         int *valp;
  68
  69                         if (*str == '-') {
  70                                 positive = 0;
  71                                 str++;
  72                         } else
  73                                 positive = 1;
  74                         if (!isdigit(*str))
  75                                 break;
  76                         value = 0;
  77                         do {
  78                                 value = (value * 10) - (*str - '0');
  79                                 str++;
  80                         } while (isdigit(*str));
  81                         if (positive)
  82                                 value = -value;
  83                         valp = va_arg(args, int *);
  84                         *valp = value;
  85                         format++;
  86                 } else if (*format == *str) {
  87                         str++;
  88                 } else
  89                         break;
  90         }
  91         va_end(args);
  92         return str - start;
  93 }