lib/posixtm.y

   1 /* Parse dates for touch.
   2    Copyright (C) 1989, 1990, 1991 Free Software Foundation Inc.
   3
   4    This program is free software; you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation; either version 2, or (at your option)
   7    any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program; if not, write to the Free Software
  16    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */
  17
  18 /* Written by Jim Kingdon and David MacKenzie. */
  19 %{
  20 #ifdef __GNUC__
  21 #define alloca __builtin_alloca
  22 #else
  23 #ifdef sparc
  24 #include <alloca.h>
  25 #else
  26 #ifdef _AIX
  27  #pragma alloca
  28 #else
  29 char *alloca ();
  30 #endif
  31 #endif
  32 #endif
  33
  34 #include <stdio.h>
  35 #include <sys/types.h>
  36 #include <time.h>
  37
  38 #define YYDEBUG 1
  39
  40 /* Lexical analyzer's current scan position in the input string. */
  41 static char *curpos;
  42
  43 /* The return value. */
  44 static struct tm t;
  45
  46 time_t mktime ();
  47
  48 #define yyparse posixtime_yyparse
  49 static int yylex ();
  50 static int yyerror ();
  51 %}
  52
  53 %token DIGIT
  54
  55 %%
  56 date :
  57        digitpair /* month */
  58        digitpair /* day */
  59        digitpair /* hours */
  60        digitpair /* minutes */
  61        year
  62        seconds {
  63                  if ($1 >= 1 && $1 <= 12)
  64                    t.tm_mon = $1 - 1;
  65                  else {
  66                    YYABORT;
  67                  }
  68                  if ($2 >= 1 && $2 <= 31)
  69                    t.tm_mday = $2;
  70                  else {
  71                    YYABORT;
  72                  }
  73                  if ($3 >= 0 && $3 <= 23)
  74                    t.tm_hour = $3;
  75                  else {
  76                    YYABORT;
  77                  }
  78                  if ($4 >= 0 && $4 <= 59)
  79                    t.tm_min = $4;
  80                  else {
  81                    YYABORT;
  82                  }
  83                }
  84
  85 year : digitpair {
  86                    t.tm_year = $1;
  87                    /* Deduce the century based on the year.
  88                       See POSIX.2 section 4.63.3.  */
  89                    if ($1 <= 68)
  90                      t.tm_year += 100;
  91                  }
  92     | digitpair digitpair {
  93                             t.tm_year = $1 * 100 + $2;
  94                             if (t.tm_year < 1900) {
  95                               YYABORT;
  96                             } else
  97                               t.tm_year -= 1900;
  98                           }
  99     | /* empty */ {
 100                     time_t now;
 101                     struct tm *tmp;
 102
 103                     /* Use current year.  */
 104                     time (&now);
 105                     tmp = localtime (&now);
 106                     t.tm_year = tmp->tm_year;
 107                   }
 108     ;
 109
 110 seconds : /* empty */ {
 111                         t.tm_sec = 0;
 112                       }
 113         | '.' digitpair {
 114                           if ($2 >= 0 && $2 <= 61)
 115                             t.tm_sec = $2;
 116                           else {
 117                             YYABORT;
 118                           }
 119                         }
 120         ;
 121
 122 digitpair : DIGIT DIGIT {
 123                           $$ = $1 * 10 + $2;
 124                         }
 125           ;
 126 %%
 127 static int
 128 yylex ()
 129 {
 130   char ch = *curpos++;
 131
 132   if (ch >= '0' && ch <= '9')
 133     {
 134       yylval = ch - '0';
 135       return DIGIT;
 136     }
 137   else if (ch == '.' || ch == 0)
 138     return ch;
 139   else
 140     return '?';                 /* Cause an error.  */
 141 }
 142
 143 static int
 144 yyerror ()
 145 {
 146   return 0;
 147 }
 148
 149 /* Parse a POSIX-style date and return it, or (time_t)-1 for an error.  */
 150
 151 time_t
 152 posixtime (s)
 153      char *s;
 154 {
 155   curpos = s;
 156   /* Let mktime decide whether it is daylight savings time.  */
 157   t.tm_isdst = -1;
 158   if (yyparse ())
 159     return (time_t)-1;
 160   else
 161     return mktime (&t);
 162 }
 163
 164 /* Parse a POSIX-style date and return it, or NULL for an error.  */
 165
 166 struct tm *
 167 posixtm (s)
 168      char *s;
 169 {
 170   if (posixtime (s) == -1)
 171     return NULL;
 172   return &t;
 173 }