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[glibc.git] / time / getdate.c
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1 /* Convert a string representation of time to a time value.
2 Copyright (C) 1997, 1998 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4 Contributed by Mark Kettenis <kettenis@phys.uva.nl>, 1997.
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Library General Public License as
8 published by the Free Software Foundation; either version 2 of the
9 License, or (at your option) any later version.
11 The GNU C Library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Library General Public License for more details.
16 You should have received a copy of the GNU Library General Public
17 License along with the GNU C Library; see the file COPYING.LIB. If not,
18 write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
19 Boston, MA 02111-1307, USA. */
21 #include <limits.h>
22 #include <stdio.h>
23 #include <stdlib.h>
24 #include <string.h>
25 #include <time.h>
26 #include <sys/stat.h>
29 /* Prototypes for local functions. */
30 static int first_wday (int year, int mon, int wday);
31 static int check_mday (int year, int mon, int mday);
34 /* Set to one of the following values to indicate an error.
35 1 the DATEMSK environment variable is null or undefined,
36 2 the template file cannot be opened for reading,
37 3 failed to get file status information,
38 4 the template file is not a regular file,
39 5 an error is encountered while reading the template file,
40 6 memory allication failed (not enough memory available),
41 7 there is no line in the template that matches the input,
42 8 invalid input specification Example: February 31 or a time is
43 specified that can not be represented in a time_t (representing
44 the time in seconds since 00:00:00 UTC, January 1, 1970) */
45 int getdate_err = 0;
48 /* Returns the first weekday WDAY of month MON in the year YEAR. */
49 static int
50 first_wday (int year, int mon, int wday)
52 struct tm tm;
54 if (wday == INT_MIN)
55 return 1;
57 memset (&tm, 0, sizeof (struct tm));
58 tm.tm_year = year;
59 tm.tm_mon = mon;
60 tm.tm_mday = 1;
61 mktime (&tm);
63 return (1 + (wday - tm.tm_wday + 7) % 7);
67 /* Returns 1 if MDAY is a valid day of the month in month MON of year
68 YEAR, and 0 if it is not. */
69 static int
70 check_mday (int year, int mon, int mday)
72 switch (mon)
74 case 0:
75 case 2:
76 case 4:
77 case 6:
78 case 7:
79 case 9:
80 case 11:
81 if (mday >= 1 && mday <= 31)
82 return 1;
83 break;
84 case 3:
85 case 5:
86 case 8:
87 case 10:
88 if (mday >= 1 && mday <= 30)
89 return 1;
90 break;
91 case 1:
92 if (mday >= 1 && mday < (__isleap (year) ? 29 : 28))
93 return 1;
94 break;
97 return 0;
102 __getdate_r (const char *string, struct tm *tp)
104 FILE *fp;
105 char *line;
106 size_t len;
107 char *datemsk;
108 char *result = NULL;
109 time_t timer;
110 struct tm tm;
111 struct stat st;
112 int mday_ok = 0;
114 datemsk = getenv ("DATEMSK");
115 if (datemsk == NULL || *datemsk == '\0')
116 return 1;
118 if (stat (datemsk, &st) < 0)
119 return 3;
121 if (!S_ISREG (st.st_mode))
122 return 4;
124 /* Open the template file. */
125 fp = fopen (datemsk, "r");
126 if (fp == NULL)
127 return 2;
129 line = NULL;
130 len = 0;
133 ssize_t n;
135 n = __getline (&line, &len, fp);
136 if (n < 0)
137 break;
138 if (line[n - 1] == '\n')
139 line[n - 1] = '\0';
141 /* Do the conversion. */
142 tp->tm_year = tp->tm_mon = tp->tm_mday = tp->tm_wday = INT_MIN;
143 tp->tm_hour = tp->tm_sec = tp->tm_min = INT_MIN;
144 result = strptime (string, line, tp);
145 if (result && *result == '\0')
146 break;
148 while (!feof_unlocked (fp));
150 /* Free the buffer. */
151 free (line);
153 /* Check for errors. */
154 if (ferror_unlocked (fp))
156 fclose (fp);
157 return 5;
160 /* Close template file. */
161 fclose (fp);
163 if (result == NULL || *result != '\0')
164 return 7;
166 /* Get current time. */
167 time (&timer);
168 __localtime_r (&timer, &tm);
170 /* If only the weekday is given, today is assumed if the given day
171 is equal to the current day and next week if it is less. */
172 if (tp->tm_wday >= 0 && tp->tm_wday <= 6 && tp->tm_year == INT_MIN
173 && tp->tm_mon == INT_MIN && tp->tm_mday == INT_MIN)
175 tp->tm_year = tm.tm_year;
176 tp->tm_mon = tm.tm_mon;
177 tp->tm_mday = tm.tm_mday + (tp->tm_wday - tm.tm_wday + 7) % 7;
178 mday_ok = 1;
181 /* If only the month is given, the current month is assumed if the
182 given month is equal to the current month and next year if it is
183 less and no year is given (the first day of month is assumed if
184 no day is given. */
185 if (tp->tm_mon >= 0 && tp->tm_mon <= 11 && tp->tm_mday == INT_MIN)
187 if (tp->tm_year == INT_MIN)
188 tp->tm_year = tm.tm_year + (((tp->tm_mon - tm.tm_mon) < 0) ? 1 : 0);
189 tp->tm_mday = first_wday (tp->tm_year, tp->tm_mon, tp->tm_wday);
190 mday_ok = 1;
193 /* If no hour, minute and second are given the current hour, minute
194 and second are assumed. */
195 if (tp->tm_hour == INT_MIN && tp->tm_min == INT_MIN && tp->tm_sec == INT_MIN)
197 tp->tm_hour = tm.tm_hour;
198 tp->tm_min = tm.tm_min;
199 tp->tm_sec = tm.tm_sec;
202 /* If no date is given, today is assumed if the given hour is
203 greater than the current hour and tomorrow is assumed if
204 it is less. */
205 if (tp->tm_hour >= 0 && tp->tm_hour <= 23
206 && tp->tm_year == INT_MIN && tp->tm_mon == INT_MIN
207 && tp->tm_mday == INT_MIN && tp->tm_wday == INT_MIN)
209 tp->tm_year = tm.tm_year;
210 tp->tm_mon = tm.tm_mon;
211 tp->tm_mday = tm.tm_mday + ((tp->tm_hour - tm.tm_hour) < 0 ? 1 : 0);
212 mday_ok = 1;
215 /* Fill in the gaps. */
216 if (tp->tm_year == INT_MIN)
217 tp->tm_year = tm.tm_year;
218 if (tp->tm_hour == INT_MIN)
219 tp->tm_hour = 0;
220 if (tp->tm_min == INT_MIN)
221 tp->tm_min = 0;
222 if (tp->tm_sec == INT_MIN)
223 tp->tm_sec = 0;
225 /* Check if the day of month is within range, and if the time can be
226 represented in a time_t. We make use of the fact that the mktime
227 call normalizes the struct tm. */
228 if ((!mday_ok && !check_mday (tp->tm_year, tp->tm_mon, tp->tm_mday))
229 || mktime (tp) == (time_t) -1)
230 return 8;
232 return 0;
234 #ifdef weak_alias
235 weak_alias (__getdate_r, getdate_r)
236 #endif
239 struct tm *
240 getdate (const char *string)
242 /* Buffer returned by getdate. */
243 static struct tm tmbuf;
244 int errval = __getdate_r (string, &tmbuf);
246 if (errval != 0)
248 getdate_err = errval;
249 return NULL;
252 return &tmbuf;