The Tor Browser: intl/icu/source/tools/tzcode/asctime.c@fc2d59ddac77

     1 /*

     2 ** This file is in the public domain, so clarified as of

     3 ** 1996-06-05 by Arthur David Olson.

     4 */

     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 */

    12 #ifndef lint

    13 #ifndef NOID

    14 static char	elsieid[] = "@(#)asctime.c	8.2";

    15 #endif /* !defined NOID */

    16 #endif /* !defined lint */

    18 /*LINTLIBRARY*/

    20 #include "private.h"

    21 #include "tzfile.h"

    23 /*

    24 ** Some systems only handle "%.2d"; others only handle "%02d";

    25 ** "%02.2d" makes (most) everybody happy.

    26 ** At least some versions of gcc warn about the %02.2d;

    27 ** we conditionalize below to avoid the warning.

    28 */

    29 /*

    30 ** All years associated with 32-bit time_t values are exactly four digits long;

    31 ** some years associated with 64-bit time_t values are not.

    32 ** Vintage programs are coded for years that are always four digits long

    33 ** and may assume that the newline always lands in the same place.

    34 ** For years that are less than four digits, we pad the output with

    35 ** leading zeroes to get the newline in the traditional place.

    36 ** The -4 ensures that we get four characters of output even if

    37 ** we call a strftime variant that produces fewer characters for some years.

    38 ** The ISO C 1999 and POSIX 1003.1-2004 standards prohibit padding the year,

    39 ** but many implementations pad anyway; most likely the standards are buggy.

    40 */

    41 #ifdef __GNUC__

    42 #define ASCTIME_FMT	"%.3s %.3s%3d %2.2d:%2.2d:%2.2d %-4s\n"

    43 #else /* !defined __GNUC__ */

    44 #define ASCTIME_FMT	"%.3s %.3s%3d %02.2d:%02.2d:%02.2d %-4s\n"

    45 #endif /* !defined __GNUC__ */

    46 /*

    47 ** For years that are more than four digits we put extra spaces before the year

    48 ** so that code trying to overwrite the newline won't end up overwriting

    49 ** a digit within a year and truncating the year (operating on the assumption

    50 ** that no output is better than wrong output).

    51 */

    52 #ifdef __GNUC__

    53 #define ASCTIME_FMT_B	"%.3s %.3s%3d %2.2d:%2.2d:%2.2d     %s\n"

    54 #else /* !defined __GNUC__ */

    55 #define ASCTIME_FMT_B	"%.3s %.3s%3d %02.2d:%02.2d:%02.2d     %s\n"

    56 #endif /* !defined __GNUC__ */

    58 #define STD_ASCTIME_BUF_SIZE	26

    59 /*

    60 ** Big enough for something such as

    61 ** ??? ???-2147483648 -2147483648:-2147483648:-2147483648     -2147483648\n

    62 ** (two three-character abbreviations, five strings denoting integers,

    63 ** seven explicit spaces, two explicit colons, a newline,

    64 ** and a trailing ASCII nul).

    65 ** The values above are for systems where an int is 32 bits and are provided

    66 ** as an example; the define below calculates the maximum for the system at

    67 ** hand.

    68 */

    69 #define MAX_ASCTIME_BUF_SIZE	(2*3+5*INT_STRLEN_MAXIMUM(int)+7+2+1+1)

    71 static char	buf_asctime[MAX_ASCTIME_BUF_SIZE];

    73 /*

    74 ** A la ISO/IEC 9945-1, ANSI/IEEE Std 1003.1, 2004 Edition.

    75 */

    77 char *

    78 asctime_r(timeptr, buf)

    79 register const struct tm *	timeptr;

    80 char *				buf;

    81 {

    82 	static const char	wday_name[][3] = {

    83 		"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"

    84 	};

    85 	static const char	mon_name[][3] = {

    86 		"Jan", "Feb", "Mar", "Apr", "May", "Jun",

    87 		"Jul", "Aug", "Sep", "Oct", "Nov", "Dec"

    88 	};

    89 	register const char *	wn;

    90 	register const char *	mn;

    91 	char			year[INT_STRLEN_MAXIMUM(int) + 2];

    92 	char			result[MAX_ASCTIME_BUF_SIZE];

    94 	if (timeptr->tm_wday < 0 || timeptr->tm_wday >= DAYSPERWEEK)

    95 		wn = "???";

    96 	else	wn = wday_name[timeptr->tm_wday];

    97 	if (timeptr->tm_mon < 0 || timeptr->tm_mon >= MONSPERYEAR)

    98 		mn = "???";

    99 	else	mn = mon_name[timeptr->tm_mon];

   100 	/*

   101 	** Use strftime's %Y to generate the year, to avoid overflow problems

   102 	** when computing timeptr->tm_year + TM_YEAR_BASE.

   103 	** Assume that strftime is unaffected by other out-of-range members

   104 	** (e.g., timeptr->tm_mday) when processing "%Y".

   105 	*/

   106 	(void) strftime(year, sizeof year, "%Y", timeptr);

   107 	/*

   108 	** We avoid using snprintf since it's not available on all systems.

   109 	*/

   110 	(void) sprintf(result,

   111 		((strlen(year) <= 4) ? ASCTIME_FMT : ASCTIME_FMT_B),

   112 		wn, mn,

   113 		timeptr->tm_mday, timeptr->tm_hour,

   114 		timeptr->tm_min, timeptr->tm_sec,

   115 		year);

   116 	if (strlen(result) < STD_ASCTIME_BUF_SIZE || buf == buf_asctime) {

   117 		(void) strcpy(buf, result);

   118 		return buf;

   119 	} else {

   120 #ifdef EOVERFLOW

   121 		errno = EOVERFLOW;

   122 #else /* !defined EOVERFLOW */

   123 		errno = EINVAL;

   124 #endif /* !defined EOVERFLOW */

   125 		return NULL;

   126 	}

   127 }

   129 /*

   130 ** A la ISO/IEC 9945-1, ANSI/IEEE Std 1003.1, 2004 Edition.

   131 */

   133 char *

   134 asctime(timeptr)

   135 register const struct tm *	timeptr;

   136 {

   137 	return asctime_r(timeptr, buf_asctime);

   138 }

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