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icu46/source/tools/tzcode/asctime.c

+/*
+** This file is in the public domain, so clarified as of
+** 1996-06-05 by Arthur David Olson.
+*/
+
+/*
+** Avoid the temptation to punt entirely to strftime;
+** the output of strftime is supposed to be locale specific
+** whereas the output of asctime is supposed to be constant.
+*/
+
+#ifndef lint
+#ifndef NOID
+static char     elsieid[] = "@(#)asctime.c      8.2";
+#endif /* !defined NOID */
+#endif /* !defined lint */
+
+/*LINTLIBRARY*/
+
+#include "private.h"
+#include "tzfile.h"
+
+/*
+** Some systems only handle "%.2d"; others only handle "%02d";
+** "%02.2d" makes (most) everybody happy.
+** At least some versions of gcc warn about the %02.2d;
+** we conditionalize below to avoid the warning.
+*/
+/*
+** All years associated with 32-bit time_t values are exactly four digits long;
+** some years associated with 64-bit time_t values are not.
+** Vintage programs are coded for years that are always four digits long
+** and may assume that the newline always lands in the same place.
+** For years that are less than four digits, we pad the output with
+** leading zeroes to get the newline in the traditional place.
+** The -4 ensures that we get four characters of output even if
+** we call a strftime variant that produces fewer characters for some years.
+** The ISO C 1999 and POSIX 1003.1-2004 standards prohibit padding the year,
+** but many implementations pad anyway; most likely the standards are buggy.
+*/
+#ifdef __GNUC__
+#define ASCTIME_FMT     "%.3s %.3s%3d %2.2d:%2.2d:%2.2d %-4s\n"
+#else /* !defined __GNUC__ */
+#define ASCTIME_FMT     "%.3s %.3s%3d %02.2d:%02.2d:%02.2d %-4s\n"
+#endif /* !defined __GNUC__ */
+/*
+** For years that are more than four digits we put extra spaces before the year
+** so that code trying to overwrite the newline won't end up overwriting
+** a digit within a year and truncating the year (operating on the assumption
+** that no output is better than wrong output).
+*/
+#ifdef __GNUC__
+#define ASCTIME_FMT_B   "%.3s %.3s%3d %2.2d:%2.2d:%2.2d     %s\n"
+#else /* !defined __GNUC__ */
+#define ASCTIME_FMT_B   "%.3s %.3s%3d %02.2d:%02.2d:%02.2d     %s\n"
+#endif /* !defined __GNUC__ */
+
+#define STD_ASCTIME_BUF_SIZE    26
+/*
+** Big enough for something such as
+** ??? ???-2147483648 -2147483648:-2147483648:-2147483648     -2147483648\n
+** (two three-character abbreviations, five strings denoting integers,
+** seven explicit spaces, two explicit colons, a newline,
+** and a trailing ASCII nul).
+** The values above are for systems where an int is 32 bits and are provided
+** as an example; the define below calculates the maximum for the system at
+** hand.
+*/
+#define MAX_ASCTIME_BUF_SIZE    (2*3+5*INT_STRLEN_MAXIMUM(int)+7+2+1+1)
+
+static char     buf_asctime[MAX_ASCTIME_BUF_SIZE];
+
+/*
+** A la ISO/IEC 9945-1, ANSI/IEEE Std 1003.1, 2004 Edition.
+*/
+
+char *
+asctime_r(timeptr, buf)
+register const struct tm *      timeptr;
+char *                          buf;
+{
+        static const char       wday_name[][3] = {
+                "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
+        };
+        static const char       mon_name[][3] = {
+                "Jan", "Feb", "Mar", "Apr", "May", "Jun",
+                "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
+        };
+        register const char *   wn;
+        register const char *   mn;
+        char                    year[INT_STRLEN_MAXIMUM(int) + 2];
+        char                    result[MAX_ASCTIME_BUF_SIZE];
+
+        if (timeptr->tm_wday < 0 || timeptr->tm_wday >= DAYSPERWEEK)
+                wn = "???";
+        else    wn = wday_name[timeptr->tm_wday];
+        if (timeptr->tm_mon < 0 || timeptr->tm_mon >= MONSPERYEAR)
+                mn = "???";
+        else    mn = mon_name[timeptr->tm_mon];
+        /*
+        ** Use strftime's %Y to generate the year, to avoid overflow problems
+        ** when computing timeptr->tm_year + TM_YEAR_BASE.
+        ** Assume that strftime is unaffected by other out-of-range members
+        ** (e.g., timeptr->tm_mday) when processing "%Y".
+        */
+        (void) strftime(year, sizeof year, "%Y", timeptr);
+        /*
+        ** We avoid using snprintf since it's not available on all systems.
+        */
+        (void) sprintf(result,
+                ((strlen(year) <= 4) ? ASCTIME_FMT : ASCTIME_FMT_B),
+                wn, mn,
+                timeptr->tm_mday, timeptr->tm_hour,
+                timeptr->tm_min, timeptr->tm_sec,
+                year);
+        if (strlen(result) < STD_ASCTIME_BUF_SIZE || buf == buf_asctime) {
+                (void) strcpy(buf, result);
+                return buf;
+        } else {
+#ifdef EOVERFLOW
+                errno = EOVERFLOW;
+#else /* !defined EOVERFLOW */
+                errno = EINVAL;
+#endif /* !defined EOVERFLOW */
+                return NULL;
+        }
+}
+
+/*
+** A la ISO/IEC 9945-1, ANSI/IEEE Std 1003.1, 2004 Edition.
+*/
+
+char *
+asctime(timeptr)
+register const struct tm *      timeptr;
+{
+        return asctime_r(timeptr, buf_asctime);
+}