1 /* Convert a string representation of time to a time value.
2 Copyright (C) 1997-2023 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19 #include <limits.h>
20 #include <stdio.h>
21 #include <stdio_ext.h>
22 #include <stdlib.h>
23 #include <stdbool.h>
24 #include <string.h>
25 #include <time.h>
26 #include <unistd.h>
27 #include <sys/stat.h>
28 #include <ctype.h>
29
30 #define TM_YEAR_BASE 1900
31
32
33 /* Prototypes for local functions. */
34 static int first_wday (int year, int mon, int wday);
35 static int check_mday (int year, int mon, int mday);
36
37
38 /* Set to one of the following values to indicate an error.
39 1 the DATEMSK environment variable is null or undefined,
40 2 the template file cannot be opened for reading,
41 3 failed to get file status information,
42 4 the template file is not a regular file,
43 5 an error is encountered while reading the template file,
44 6 memory allication failed (not enough memory available),
45 7 there is no line in the template that matches the input,
46 8 invalid input specification Example: February 31 or a time is
47 specified that can not be represented in a time_t (representing
48 the time in seconds since 00:00:00 UTC, January 1, 1970) */
49 int getdate_err;
50
51
52 /* Returns the first weekday WDAY of month MON in the year YEAR. */
53 static int
54 first_wday (int year, int mon, int wday)
55 {
56 struct tm tm;
57
58 if (wday == INT_MIN)
59 return 1;
60
61 memset (&tm, 0, sizeof (struct tm));
62 tm.tm_year = year;
63 tm.tm_mon = mon;
64 tm.tm_mday = 1;
65 mktime (&tm);
66
67 return (1 + (wday - tm.tm_wday + 7) % 7);
68 }
69
70
71 /* Returns 1 if MDAY is a valid day of the month in month MON of year
72 YEAR, and 0 if it is not. */
73 static int
74 check_mday (int year, int mon, int mday)
75 {
76 switch (mon)
77 {
78 case 0:
79 case 2:
80 case 4:
81 case 6:
82 case 7:
83 case 9:
84 case 11:
85 if (mday >= 1 && mday <= 31)
86 return 1;
87 break;
88 case 3:
89 case 5:
90 case 8:
91 case 10:
92 if (mday >= 1 && mday <= 30)
93 return 1;
94 break;
95 case 1:
96 if (mday >= 1 && mday <= (__isleap (year) ? 29 : 28))
97 return 1;
98 break;
99 }
100
101 return 0;
102 }
103
104
105 int
106 __getdate_r (const char *string, struct tm *tp)
107 {
108 FILE *fp;
109 char *line;
110 size_t len;
111 char *datemsk;
112 char *result = NULL;
113 __time64_t timer;
114 struct tm tm;
115 struct __stat64_t64 st;
116 bool mday_ok = false;
117 bool found = false;
118
119 datemsk = getenv ("DATEMSK");
120 if (datemsk == NULL || *datemsk == '\0')
121 return 1;
122
123 if (__stat64_time64 (datemsk, &st) < 0)
124 return 3;
125
126 if (!S_ISREG (st.st_mode))
127 return 4;
128
129 if (__access (datemsk, R_OK) < 0)
130 return 2;
131
132 /* Open the template file. */
133 fp = fopen (datemsk, "rce");
134 if (fp == NULL)
135 return 2;
136
137 /* No threads reading this stream. */
138 __fsetlocking (fp, FSETLOCKING_BYCALLER);
139
140 /* Skip leading whitespace. */
141 while (isspace (*string))
142 string++;
143
144 size_t inlen, oldlen;
145
146 oldlen = inlen = strlen (string);
147
148 /* Skip trailing whitespace. */
149 while (inlen > 0 && isspace (string[inlen - 1]))
150 inlen--;
151
152 char *instr = NULL;
153
154 if (inlen < oldlen)
155 {
156 instr = __strndup(string, inlen);
157 if (instr == NULL)
158 {
159 fclose(fp);
160 return 6;
161 }
162
163 string = instr;
164 }
165
166 line = NULL;
167 len = 0;
168 do
169 {
170 ssize_t n;
171
172 n = __getline (&line, &len, fp);
173 if (n < 0)
174 break;
175 if (line[n - 1] == '\n')
176 line[n - 1] = '\0';
177
178 /* Do the conversion. */
179 tp->tm_year = tp->tm_mon = tp->tm_mday = tp->tm_wday = INT_MIN;
180 tp->tm_hour = tp->tm_sec = tp->tm_min = INT_MIN;
181 tp->tm_isdst = -1;
182 tp->tm_gmtoff = 0;
183 tp->tm_zone = NULL;
184 result = strptime (string, line, tp);
185 if ((found = (result && *result == '\0')))
186 break;
187 }
188 while (!__feof_unlocked (fp));
189
190 free (instr);
191
192 /* Free the buffer. */
193 free (line);
194
195 /* Check for errors. */
196 if (__ferror_unlocked (fp))
197 {
198 fclose (fp);
199 return 5;
200 }
201
202 /* Close template file. */
203 fclose (fp);
204
205 if (!found)
206 return 7;
207
208 /* Get current time. */
209 timer = time64_now ();
210 __localtime64_r (&timer, &tm);
211
212 /* If only the weekday is given, today is assumed if the given day
213 is equal to the current day and next week if it is less. */
214 if (tp->tm_wday >= 0 && tp->tm_wday <= 6 && tp->tm_year == INT_MIN
215 && tp->tm_mon == INT_MIN && tp->tm_mday == INT_MIN)
216 {
217 tp->tm_year = tm.tm_year;
218 tp->tm_mon = tm.tm_mon;
219 tp->tm_mday = tm.tm_mday + (tp->tm_wday - tm.tm_wday + 7) % 7;
220 mday_ok = true;
221 }
222
223 /* If only the month is given, the current month is assumed if the
224 given month is equal to the current month and next year if it is
225 less and no year is given (the first day of month is assumed if
226 no day is given. */
227 if (tp->tm_mon >= 0 && tp->tm_mon <= 11 && tp->tm_mday == INT_MIN)
228 {
229 if (tp->tm_year == INT_MIN)
230 tp->tm_year = tm.tm_year + (((tp->tm_mon - tm.tm_mon) < 0) ? 1 : 0);
231 tp->tm_mday = first_wday (tp->tm_year, tp->tm_mon, tp->tm_wday);
232 mday_ok = true;
233 }
234
235 /* If no hour, minute and second are given the current hour, minute
236 and second are assumed. */
237 if (tp->tm_hour == INT_MIN && tp->tm_min == INT_MIN && tp->tm_sec == INT_MIN)
238 {
239 tp->tm_hour = tm.tm_hour;
240 tp->tm_min = tm.tm_min;
241 tp->tm_sec = tm.tm_sec;
242 }
243
244 /* Fill in the gaps. */
245 if (tp->tm_hour == INT_MIN)
246 tp->tm_hour = 0;
247 if (tp->tm_min == INT_MIN)
248 tp->tm_min = 0;
249 if (tp->tm_sec == INT_MIN)
250 tp->tm_sec = 0;
251
252 /* If no date is given, today is assumed if the given hour is
253 greater than the current hour and tomorrow is assumed if
254 it is less. */
255 if (tp->tm_hour >= 0 && tp->tm_hour <= 23
256 && tp->tm_mon == INT_MIN
257 && tp->tm_mday == INT_MIN && tp->tm_wday == INT_MIN)
258 {
259 tp->tm_mon = tm.tm_mon;
260 tp->tm_mday = tm.tm_mday + ((tp->tm_hour - tm.tm_hour) < 0 ? 1 : 0);
261 mday_ok = 1;
262 }
263
264 /* More fillers. */
265 if (tp->tm_year == INT_MIN)
266 tp->tm_year = tm.tm_year;
267 if (tp->tm_mon == INT_MIN)
268 tp->tm_mon = tm.tm_mon;
269
270 /* Check if the day of month is within range, and if the time can be
271 represented in a time_t. We make use of the fact that the mktime
272 call normalizes the struct tm. */
273 if ((!mday_ok && !check_mday (TM_YEAR_BASE + tp->tm_year, tp->tm_mon,
274 tp->tm_mday))
275 || __mktime64 (tp) == (time_t) -1)
276 return 8;
277
278 return 0;
279 }
280 weak_alias (__getdate_r, getdate_r)
281 libc_hidden_def (__getdate_r)
282
283 struct tm *
284 getdate (const char *string)
285 {
286 /* Buffer returned by getdate. */
287 static struct tm tmbuf;
288 int errval = __getdate_r (string, &tmbuf);
289
290 if (errval != 0)
291 {
292 getdate_err = errval;
293 return NULL;
294 }
295
296 return &tmbuf;
297 }