stdtime/FreeBSD/asctime.c

   1 /*
   2 ** This file is in the public domain, so clarified as of
   3 ** 1996-06-05 by Arthur David Olson.
   4 */
   5
   6 /*
   7 ** Avoid the temptation to punt entirely to strftime;
   8 ** the output of strftime is supposed to be locale specific
   9 ** whereas the output of asctime is supposed to be constant.
  10 */
  11
  12 #include <sys/cdefs.h>
  13 #ifndef lint
  14 #ifndef NOID
  15 static char     elsieid[] __unused = "@(#)asctime.c     8.2";
  16 #endif /* !defined NOID */
  17 #endif /* !defined lint */
  18 __FBSDID("$FreeBSD: src/lib/libc/stdtime/asctime.c,v 1.13 2009/05/23 06:31:50 edwin Exp $");
  19
  20 /*LINTLIBRARY*/
  21
  22 #include "namespace.h"
  23 #include "private.h"
  24 #include "un-namespace.h"
  25 #include "tzfile.h"
  26
  27 /*
  28 ** Some systems only handle "%.2d"; others only handle "%02d";
  29 ** "%02.2d" makes (most) everybody happy.
  30 ** At least some versions of gcc warn about the %02.2d;
  31 ** we conditionalize below to avoid the warning.
  32 */
  33 /*
  34 ** All years associated with 32-bit time_t values are exactly four digits long;
  35 ** some years associated with 64-bit time_t values are not.
  36 ** Vintage programs are coded for years that are always four digits long
  37 ** and may assume that the newline always lands in the same place.
  38 ** For years that are less than four digits, we pad the output with
  39 ** leading zeroes to get the newline in the traditional place.
  40 ** The -4 ensures that we get four characters of output even if
  41 ** we call a strftime variant that produces fewer characters for some years.
  42 ** The ISO C 1999 and POSIX 1003.1-2004 standards prohibit padding the year,
  43 ** but many implementations pad anyway; most likely the standards are buggy.
  44 */
  45 #ifdef __GNUC__
  46 #define ASCTIME_FMT     "%.3s %.3s%3d %2.2d:%2.2d:%2.2d %-4s\n"
  47 #else /* !defined __GNUC__ */
  48 #define ASCTIME_FMT     "%.3s %.3s%3d %02.2d:%02.2d:%02.2d %-4s\n"
  49 #endif /* !defined __GNUC__ */
  50 /*
  51 ** For years that are more than four digits we put extra spaces before the year
  52 ** so that code trying to overwrite the newline won't end up overwriting
  53 ** a digit within a year and truncating the year (operating on the assumption
  54 ** that no output is better than wrong output).
  55 */
  56 #ifdef __GNUC__
  57 #define ASCTIME_FMT_B   "%.3s %.3s%3d %2.2d:%2.2d:%2.2d     %s\n"
  58 #else /* !defined __GNUC__ */
  59 #define ASCTIME_FMT_B   "%.3s %.3s%3d %02.2d:%02.2d:%02.2d     %s\n"
  60 #endif /* !defined __GNUC__ */
  61
  62 #define STD_ASCTIME_BUF_SIZE    26
  63 /*
  64 ** Big enough for something such as
  65 ** ??? ???-2147483648 -2147483648:-2147483648:-2147483648     -2147483648\n
  66 ** (two three-character abbreviations, five strings denoting integers,
  67 ** seven explicit spaces, two explicit colons, a newline,
  68 ** and a trailing ASCII nul).
  69 ** The values above are for systems where an int is 32 bits and are provided
  70 ** as an example; the define below calculates the maximum for the system at
  71 ** hand.
  72 */
  73 #define MAX_ASCTIME_BUF_SIZE    (2*3+5*INT_STRLEN_MAXIMUM(int)+7+2+1+1)
  74
  75 static char     buf_asctime[MAX_ASCTIME_BUF_SIZE];
  76
  77 /*
  78 ** A la ISO/IEC 9945-1, ANSI/IEEE Std 1003.1, 2004 Edition.
  79 */
  80
  81 char *
  82 asctime_r(const struct tm * __restrict timeptr, char * __restrict buf)
  83 {
  84         static const char       wday_name[][3] = {
  85                 "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
  86         };
  87         static const char       mon_name[][3] = {
  88                 "Jan", "Feb", "Mar", "Apr", "May", "Jun",
  89                 "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
  90         };
  91         const char *    wn;
  92         const char *    mn;
  93         char                    year[INT_STRLEN_MAXIMUM(int) + 2];
  94         char                    result[MAX_ASCTIME_BUF_SIZE];
  95
  96         if (timeptr->tm_wday < 0 || timeptr->tm_wday >= DAYSPERWEEK)
  97                 wn = "???";
  98         else    wn = wday_name[timeptr->tm_wday];
  99         if (timeptr->tm_mon < 0 || timeptr->tm_mon >= MONSPERYEAR)
 100                 mn = "???";
 101         else    mn = mon_name[timeptr->tm_mon];
 102         /*
 103         ** Use strftime's %Y to generate the year, to avoid overflow problems
 104         ** when computing timeptr->tm_year + TM_YEAR_BASE.
 105         ** Assume that strftime is unaffected by other out-of-range members
 106         ** (e.g., timeptr->tm_mday) when processing "%Y".
 107         */
 108         (void) strftime(year, sizeof year, "%Y", timeptr);
 109         /*
 110         ** We avoid using snprintf since it's not available on all systems.
 111         */
 112         (void) sprintf(result,
 113                 ((strlen(year) <= 4) ? ASCTIME_FMT : ASCTIME_FMT_B),
 114                 wn, mn,
 115                 timeptr->tm_mday, timeptr->tm_hour,
 116                 timeptr->tm_min, timeptr->tm_sec,
 117                 year);
 118         if (strlen(result) < STD_ASCTIME_BUF_SIZE || buf == buf_asctime) {
 119                 (void) strcpy(buf, result);
 120                 return buf;
 121         } else {
 122 #ifdef EOVERFLOW
 123                 errno = EOVERFLOW;
 124 #else /* !defined EOVERFLOW */
 125                 errno = EINVAL;
 126 #endif /* !defined EOVERFLOW */
 127                 return NULL;
 128         }
 129 }
 130
 131 /*
 132 ** A la ISO/IEC 9945-1, ANSI/IEEE Std 1003.1, 2004 Edition.
 133 */
 134
 135 char *
 136 asctime(timeptr)
 137 const struct tm *       timeptr;
 138 {
 139         return asctime_r(timeptr, buf_asctime);
 140 }