osfmk/kern/sscanf.c

   1 /*
   2  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
   7  *
   8  * This file contains Original Code and/or Modifications of Original Code
   9  * as defined in and that are subject to the Apple Public Source License
  10  * Version 2.0 (the 'License'). You may not use this file except in
  11  * compliance with the License. Please obtain a copy of the License at
  12  * http://www.opensource.apple.com/apsl/ and read it before using this
  13  * file.
  14  *
  15  * The Original Code and all software distributed under the License are
  16  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  17  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  18  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  20  * Please see the License for the specific language governing rights and
  21  * limitations under the License.
  22  *
  23  * @APPLE_LICENSE_HEADER_END@
  24  */
  25 /*
  26  * @OSF_FREE_COPYRIGHT@
  27  */
  28 /*
  29  * HISTORY
  30  *
  31  * Revision 1.1.1.1  1998/09/22 21:05:32  wsanchez
  32  * Import of Mac OS X kernel (~semeria)
  33  *
  34  * Revision 1.1.1.1  1998/03/07 02:25:56  wsanchez
  35  * Import of OSF Mach kernel (~mburg)
  36  *
  37  * Revision 1.1.8.2  1997/02/12  12:52:33  stephen
  38  *      New file, reimplemented to be sure of copyright status
  39  *      Initially only supports character matching and '%d'
  40  *      [1997/02/12  12:43:09  stephen]
  41  *
  42  * $EndLog$
  43  */
  44
  45 #include <stdarg.h>
  46 #include <kern/misc_protos.h>
  47
  48 #define isdigit(c) ((unsigned) ((c) - '0') < 10U)
  49
  50 /*
  51  * Scan items from a string in accordance with a format.  This is much
  52  * simpler than the C standard function: it only recognises %d without a
  53  * field width, and does not treat space in the format string or the
  54  * input any differently from other characters.  The return value is the
  55  * number of characters from the input string that were successfully
  56  * scanned, not the number of format items matched as in standard sscanf.
  57  * e.mcmanus@opengroup.org, 12 Feb 97
  58  */
  59 int
  60 sscanf(const char *str, const char *format, ...)
  61 {
  62         const char *start = str;
  63         va_list args;
  64
  65         va_start(args, format);
  66         for ( ; *format != '\0'; format++) {
  67                 if (*format == '%' && format[1] == 'd') {
  68                         int positive;
  69                         int value;
  70                         int *valp;
  71
  72                         if (*str == '-') {
  73                                 positive = 0;
  74                                 str++;
  75                         } else
  76                                 positive = 1;
  77                         if (!isdigit(*str))
  78                                 break;
  79                         value = 0;
  80                         do {
  81                                 value = (value * 10) - (*str - '0');
  82                                 str++;
  83                         } while (isdigit(*str));
  84                         if (positive)
  85                                 value = -value;
  86                         valp = va_arg(args, int *);
  87                         *valp = value;
  88                         format++;
  89                 } else if (*format == *str) {
  90                         str++;
  91                 } else
  92                         break;
  93         }
  94         va_end(args);
  95         return str - start;
  96 }