src/lib/wallclock/time_to_tm.c

   1 /* Copyright (c) 2003-2004, Roger Dingledine
   2  * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
   3  * Copyright (c) 2007-2021, The Tor Project, Inc. */
   4 /* See LICENSE for licensing information */
   5
   6 /**
   7  * \file time_to_tm.c
   8  * \brief Convert to struct tm, portably.
   9  **/
  10
  11 #include "orconfig.h"
  12 #include "lib/cc/torint.h"
  13 #include "lib/cc/compat_compiler.h"
  14 #include "lib/wallclock/time_to_tm.h"
  15 #include "lib/string/printf.h"
  16 #include "lib/err/torerr.h"
  17
  18 #include <errno.h>
  19 #include <time.h>
  20 #include <string.h>
  21 #include <stdlib.h>
  22
  23 #if !defined(_WIN32)
  24 /** Defined iff we need to add locks when defining fake versions of reentrant
  25  * versions of time-related functions. */
  26 #define TIME_FNS_NEED_LOCKS
  27 #endif
  28
  29 /** Helper: Deal with confused or out-of-bounds values from localtime_r and
  30  * friends.  (On some platforms, they can give out-of-bounds values or can
  31  * return NULL.)  If <b>islocal</b>, this is a localtime result; otherwise
  32  * it's from gmtime.  The function returns <b>r</b>, when given <b>timep</b>
  33  * as its input. If we need to store new results, store them in
  34  * <b>resultbuf</b>. */
  35 static struct tm *
  36 correct_tm(int islocal, const time_t *timep, struct tm *resultbuf,
  37            struct tm *r, char **err_out)
  38 {
  39   const char *outcome;
  40
  41   if (PREDICT_LIKELY(r)) {
  42     /* We can't strftime dates after 9999 CE, and we want to avoid dates
  43      * before 1 CE (avoiding the year 0 issue and negative years). */
  44     if (r->tm_year > 8099) {
  45       r->tm_year = 8099;
  46       r->tm_mon = 11;
  47       r->tm_mday = 31;
  48       r->tm_yday = 364;
  49       r->tm_wday = 6;
  50       r->tm_hour = 23;
  51       r->tm_min = 59;
  52       r->tm_sec = 59;
  53     } else if (r->tm_year < (1-1900)) {
  54       r->tm_year = (1-1900);
  55       r->tm_mon = 0;
  56       r->tm_mday = 1;
  57       r->tm_yday = 0;
  58       r->tm_wday = 0;
  59       r->tm_hour = 0;
  60       r->tm_min = 0;
  61       r->tm_sec = 0;
  62     }
  63     return r;
  64   }
  65
  66   /* If we get here, gmtime or localtime returned NULL. It might have done
  67    * this because of overrun or underrun, or it might have done it because of
  68    * some other weird issue. */
  69   if (timep) {
  70     if (*timep < 0) {
  71       r = resultbuf;
  72       r->tm_year = 70; /* 1970 CE */
  73       r->tm_mon = 0;
  74       r->tm_mday = 1;
  75       r->tm_yday = 0;
  76       r->tm_wday = 0;
  77       r->tm_hour = 0;
  78       r->tm_min = 0 ;
  79       r->tm_sec = 0;
  80       outcome = "Rounding up to 1970";
  81       goto done;
  82     } else if (*timep >= INT32_MAX) {
  83       /* Rounding down to INT32_MAX isn't so great, but keep in mind that we
  84        * only do it if gmtime/localtime tells us NULL. */
  85       r = resultbuf;
  86       r->tm_year = 137; /* 2037 CE */
  87       r->tm_mon = 11;
  88       r->tm_mday = 31;
  89       r->tm_yday = 364;
  90       r->tm_wday = 6;
  91       r->tm_hour = 23;
  92       r->tm_min = 59;
  93       r->tm_sec = 59;
  94       outcome = "Rounding down to 2037";
  95       goto done;
  96     }
  97   }
  98
  99   /* If we get here, then gmtime/localtime failed without getting an extreme
 100    * value for *timep */
 101   /* LCOV_EXCL_START */
 102   r = resultbuf;
 103   memset(resultbuf, 0, sizeof(struct tm));
 104   outcome="can't recover";
 105   /* LCOV_EXCL_STOP */
 106  done:
 107   if (err_out) {
 108     tor_asprintf(err_out, "%s(%"PRId64") failed with error %s: %s",
 109                  islocal?"localtime":"gmtime",
 110                  timep?((int64_t)*timep):0,
 111                  strerror(errno),
 112                  outcome);
 113   }
 114   return r;
 115 }
 116
 117 /** @{ */
 118 /** As localtime_r, but defined for platforms that don't have it:
 119  *
 120  * Convert *<b>timep</b> to a struct tm in local time, and store the value in
 121  * *<b>result</b>.  Return the result on success, or NULL on failure.
 122  */
 123 #ifdef HAVE_LOCALTIME_R
 124 struct tm *
 125 tor_localtime_r_msg(const time_t *timep, struct tm *result, char **err_out)
 126 {
 127   struct tm *r;
 128   r = localtime_r(timep, result);
 129   return correct_tm(1, timep, result, r, err_out);
 130 }
 131 #elif defined(TIME_FNS_NEED_LOCKS)
 132 struct tm *
 133 tor_localtime_r_msg(const time_t *timep, struct tm *result, char **err_out)
 134 {
 135   struct tm *r;
 136   static tor_mutex_t *m=NULL;
 137   if (!m) { m=tor_mutex_new(); }
 138   raw_assert(result);
 139   tor_mutex_acquire(m);
 140   r = localtime(timep);
 141   if (r)
 142     memcpy(result, r, sizeof(struct tm));
 143   tor_mutex_release(m);
 144   return correct_tm(1, timep, result, r, err_out);
 145 }
 146 #else
 147 struct tm *
 148 tor_localtime_r_msg(const time_t *timep, struct tm *result, char **err_out)
 149 {
 150   struct tm *r;
 151   raw_assert(result);
 152   r = localtime(timep);
 153   if (r)
 154     memcpy(result, r, sizeof(struct tm));
 155   return correct_tm(1, timep, result, r, err_out);
 156 }
 157 #endif /* defined(HAVE_LOCALTIME_R) || ... */
 158 /** @} */
 159
 160 /** @{ */
 161 /** As gmtime_r, but defined for platforms that don't have it:
 162  *
 163  * Convert *<b>timep</b> to a struct tm in UTC, and store the value in
 164  * *<b>result</b>.  Return the result on success, or NULL on failure.
 165  */
 166 #ifdef HAVE_GMTIME_R
 167 struct tm *
 168 tor_gmtime_r_msg(const time_t *timep, struct tm *result, char **err_out)
 169 {
 170   struct tm *r;
 171   r = gmtime_r(timep, result);
 172   return correct_tm(0, timep, result, r, err_out);
 173 }
 174 #elif defined(TIME_FNS_NEED_LOCKS)
 175 struct tm *
 176 tor_gmtime_r_msg(const time_t *timep, struct tm *result, char **err_out)
 177 {
 178   struct tm *r;
 179   static tor_mutex_t *m=NULL;
 180   if (!m) { m=tor_mutex_new(); }
 181   raw_assert(result);
 182   tor_mutex_acquire(m);
 183   r = gmtime(timep);
 184   if (r)
 185     memcpy(result, r, sizeof(struct tm));
 186   tor_mutex_release(m);
 187   return correct_tm(0, timep, result, r, err_out);
 188 }
 189 #else
 190 struct tm *
 191 tor_gmtime_r_msg(const time_t *timep, struct tm *result, char **err_out)
 192 {
 193   struct tm *r;
 194   raw_assert(result);
 195   r = gmtime(timep);
 196   if (r)
 197     memcpy(result, r, sizeof(struct tm));
 198   return correct_tm(0, timep, result, r, err_out);
 199 }
 200 #endif /* defined(HAVE_GMTIME_R) || ... */
 201 /**@}*/