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/* * strftime.c * Original Author: G. Haley * Additions from: Eric Blake * * Places characters into the array pointed to by s as controlled by the string * pointed to by format. If the total number of resulting characters including * the terminating null character is not more than maxsize, returns the number * of characters placed into the array pointed to by s (not including the * terminating null character); otherwise zero is returned and the contents of * the array indeterminate. */ /* FUNCTION <<strftime>>---flexible calendar time formatter INDEX strftime ANSI_SYNOPSIS #include <time.h> size_t strftime(char *<[s]>, size_t <[maxsize]>, const char *<[format]>, const struct tm *<[timp]>); TRAD_SYNOPSIS #include <time.h> size_t strftime(<[s]>, <[maxsize]>, <[format]>, <[timp]>) char *<[s]>; size_t <[maxsize]>; char *<[format]>; struct tm *<[timp]>; DESCRIPTION <<strftime>> converts a <<struct tm>> representation of the time (at <[timp]>) into a null-terminated string, starting at <[s]> and occupying no more than <[maxsize]> characters. You control the format of the output using the string at <[format]>. <<*<[format]>>> can contain two kinds of specifications: text to be copied literally into the formatted string, and time conversion specifications. Time conversion specifications are two- and three-character sequences beginning with `<<%>>' (use `<<%%>>' to include a percent sign in the output). Each defined conversion specification selects only the specified field(s) of calendar time data from <<*<[timp]>>>, and converts it to a string in one of the following ways: o+ o %a A three-letter abbreviation for the day of the week. [tm_wday] o %A The full name for the day of the week, one of `<<Sunday>>', `<<Monday>>', `<<Tuesday>>', `<<Wednesday>>', `<<Thursday>>', `<<Friday>>', or `<<Saturday>>'. [tm_wday] o %b A three-letter abbreviation for the month name. [tm_mon] o %B The full name of the month, one of `<<January>>', `<<February>>', `<<March>>', `<<April>>', `<<May>>', `<<June>>', `<<July>>', `<<August>>', `<<September>>', `<<October>>', `<<November>>', `<<December>>'. [tm_mon] o %c A string representing the complete date and time, in the form `<<"%a %b %e %H:%M:%S %Y">>' (example "Mon Apr 01 13:13:13 1992"). [tm_sec, tm_min, tm_hour, tm_mday, tm_mon, tm_year, tm_wday] o %C The century, that is, the year divided by 100 then truncated. For 4-digit years, the result is zero-padded and exactly two characters; but for other years, there may a negative sign or more digits. In this way, `<<%C%y>>' is equivalent to `<<%Y>>'. [tm_year] o %d The day of the month, formatted with two digits (from `<<01>>' to `<<31>>'). [tm_mday] o %D A string representing the date, in the form `<<"%m/%d/%y">>'. [tm_mday, tm_mon, tm_year] o %e The day of the month, formatted with leading space if single digit (from `<<1>>' to `<<31>>'). [tm_mday] o %E<<x>> In some locales, the E modifier selects alternative representations of certain modifiers <<x>>. But in the "C" locale supported by newlib, it is ignored, and treated as %<<x>>. o %F A string representing the ISO 8601:2000 date format, in the form `<<"%Y-%m-%d">>'. [tm_mday, tm_mon, tm_year] o %g The last two digits of the week-based year, see specifier %G (from `<<00>>' to `<<99>>'). [tm_year, tm_wday, tm_yday] o %G The week-based year. In the ISO 8601:2000 calendar, week 1 of the year includes January 4th, and begin on Mondays. Therefore, if January 1st, 2nd, or 3rd falls on a Sunday, that day and earlier belong to the last week of the previous year; and if December 29th, 30th, or 31st falls on Monday, that day and later belong to week 1 of the next year. For consistency with %Y, it always has at least four characters. Example: "%G" for Saturday 2nd January 1999 gives "1998", and for Tuesday 30th December 1997 gives "1998". [tm_year, tm_wday, tm_yday] o %h A three-letter abbreviation for the month name (synonym for "%b"). [tm_mon] o %H The hour (on a 24-hour clock), formatted with two digits (from `<<00>>' to `<<23>>'). [tm_hour] o %I The hour (on a 12-hour clock), formatted with two digits (from `<<01>>' to `<<12>>'). [tm_hour] o %j The count of days in the year, formatted with three digits (from `<<001>>' to `<<366>>'). [tm_yday] o %k The hour (on a 24-hour clock), formatted with leading space if single digit (from `<<0>>' to `<<23>>'). Non-POSIX extension. [tm_hour] o %l The hour (on a 12-hour clock), formatted with leading space if single digit (from `<<1>>' to `<<12>>'). Non-POSIX extension. [tm_hour] o %m The month number, formatted with two digits (from `<<01>>' to `<<12>>'). [tm_mon] o %M The minute, formatted with two digits (from `<<00>>' to `<<59>>'). [tm_min] o %n A newline character (`<<\n>>'). o %O<<x>> In some locales, the O modifier selects alternative digit characters for certain modifiers <<x>>. But in the "C" locale supported by newlib, it is ignored, and treated as %<<x>>. o %p Either `<<AM>>' or `<<PM>>' as appropriate. [tm_hour] o %r The 12-hour time, to the second. Equivalent to "%I:%M:%S %p". [tm_sec, tm_min, tm_hour] o %R The 24-hour time, to the minute. Equivalent to "%H:%M". [tm_min, tm_hour] o %S The second, formatted with two digits (from `<<00>>' to `<<60>>'). The value 60 accounts for the occasional leap second. [tm_sec] o %t A tab character (`<<\t>>'). o %T The 24-hour time, to the second. Equivalent to "%H:%M:%S". [tm_sec, tm_min, tm_hour] o %u The weekday as a number, 1-based from Monday (from `<<1>>' to `<<7>>'). [tm_wday] o %U The week number, where weeks start on Sunday, week 1 contains the first Sunday in a year, and earlier days are in week 0. Formatted with two digits (from `<<00>>' to `<<53>>'). See also <<%W>>. [tm_wday, tm_yday] o %V The week number, where weeks start on Monday, week 1 contains January 4th, and earlier days are in the previous year. Formatted with two digits (from `<<01>>' to `<<53>>'). See also <<%G>>. [tm_year, tm_wday, tm_yday] o %w The weekday as a number, 0-based from Sunday (from `<<0>>' to `<<6>>'). [tm_wday] o %W The week number, where weeks start on Monday, week 1 contains the first Monday in a year, and earlier days are in week 0. Formatted with two digits (from `<<00>>' to `<<53>>'). [tm_wday, tm_yday] o %x A string representing the complete date, equivalent to "%m/%d/%y". [tm_mon, tm_mday, tm_year] o %X A string representing the full time of day (hours, minutes, and seconds), equivalent to "%H:%M:%S". [tm_sec, tm_min, tm_hour] o %y The last two digits of the year (from `<<00>>' to `<<99>>'). [tm_year] o %Y The full year, equivalent to <<%C%y>>. It will always have at least four characters, but may have more. The year is accurate even when tm_year added to the offset of 1900 overflows an int. [tm_year] o %z The offset from UTC. The format consists of a sign (negative is west of Greewich), two characters for hour, then two characters for minutes (-hhmm or +hhmm). If tm_isdst is negative, the offset is unknown and no output is generated; if it is zero, the offset is the standard offset for the current time zone; and if it is positive, the offset is the daylight savings offset for the current timezone. The offset is determined from the TZ environment variable, as if by calling tzset(). [tm_isdst] o %Z The time zone name. If tm_isdst is negative, no output is generated. Otherwise, the time zone name is based on the TZ environment variable, as if by calling tzset(). [tm_isdst] o %% A single character, `<<%>>'. o- RETURNS When the formatted time takes up no more than <[maxsize]> characters, the result is the length of the formatted string. Otherwise, if the formatting operation was abandoned due to lack of room, the result is <<0>>, and the string starting at <[s]> corresponds to just those parts of <<*<[format]>>> that could be completely filled in within the <[maxsize]> limit. PORTABILITY ANSI C requires <<strftime>>, but does not specify the contents of <<*<[s]>>> when the formatted string would require more than <[maxsize]> characters. Unrecognized specifiers and fields of <<timp>> that are out of range cause undefined results. Since some formats expand to 0 bytes, it is wise to set <<*<[s]>>> to a nonzero value beforehand to distinguish between failure and an empty string. This implementation does not support <<s>> being NULL, nor overlapping <<s>> and <<format>>. <<strftime>> requires no supporting OS subroutines. */ #include <stddef.h> #include <stdio.h> #include <time.h> #include <string.h> #include <stdlib.h> #include "local.h" static _CONST int dname_len[7] = {6, 6, 7, 9, 8, 6, 8}; static _CONST char *_CONST dname[7] = {"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"}; static _CONST int mname_len[12] = {7, 8, 5, 5, 3, 4, 4, 6, 9, 7, 8, 8}; static _CONST char *_CONST mname[12] = {"January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"}; /* Using the tm_year, tm_wday, and tm_yday components of TIM_P, return -1, 0, or 1 as the adjustment to add to the year for the ISO week numbering used in "%g%G%V", avoiding overflow. */ static int _DEFUN (iso_year_adjust, (tim_p), _CONST struct tm *tim_p) { /* Account for fact that tm_year==0 is year 1900. */ int leap = isleap (tim_p->tm_year + (YEAR_BASE - (tim_p->tm_year < 0 ? 0 : 2000))); /* Pack the yday, wday, and leap year into a single int since there are so many disparate cases. */ #define PACK(yd, wd, lp) (((yd) << 4) + (wd << 1) + (lp)) switch (PACK (tim_p->tm_yday, tim_p->tm_wday, leap)) { case PACK (0, 5, 0): /* Jan 1 is Fri, not leap. */ case PACK (0, 6, 0): /* Jan 1 is Sat, not leap. */ case PACK (0, 0, 0): /* Jan 1 is Sun, not leap. */ case PACK (0, 5, 1): /* Jan 1 is Fri, leap year. */ case PACK (0, 6, 1): /* Jan 1 is Sat, leap year. */ case PACK (0, 0, 1): /* Jan 1 is Sun, leap year. */ case PACK (1, 6, 0): /* Jan 2 is Sat, not leap. */ case PACK (1, 0, 0): /* Jan 2 is Sun, not leap. */ case PACK (1, 6, 1): /* Jan 2 is Sat, leap year. */ case PACK (1, 0, 1): /* Jan 2 is Sun, leap year. */ case PACK (2, 0, 0): /* Jan 3 is Sun, not leap. */ case PACK (2, 0, 1): /* Jan 3 is Sun, leap year. */ return -1; /* Belongs to last week of previous year. */ case PACK (362, 1, 0): /* Dec 29 is Mon, not leap. */ case PACK (363, 1, 1): /* Dec 29 is Mon, leap year. */ case PACK (363, 1, 0): /* Dec 30 is Mon, not leap. */ case PACK (363, 2, 0): /* Dec 30 is Tue, not leap. */ case PACK (364, 1, 1): /* Dec 30 is Mon, leap year. */ case PACK (364, 2, 1): /* Dec 30 is Tue, leap year. */ case PACK (364, 1, 0): /* Dec 31 is Mon, not leap. */ case PACK (364, 2, 0): /* Dec 31 is Tue, not leap. */ case PACK (364, 3, 0): /* Dec 31 is Wed, not leap. */ case PACK (365, 1, 1): /* Dec 31 is Mon, leap year. */ case PACK (365, 2, 1): /* Dec 31 is Tue, leap year. */ case PACK (365, 3, 1): /* Dec 31 is Wed, leap year. */ return 1; /* Belongs to first week of next year. */ } return 0; /* Belongs to specified year. */ #undef PACK } size_t _DEFUN (strftime, (s, maxsize, format, tim_p), char *s _AND size_t maxsize _AND _CONST char *format _AND _CONST struct tm *tim_p) { size_t count = 0; int i; for (;;) { while (*format && *format != '%') { if (count < maxsize - 1) s[count++] = *format++; else return 0; } if (*format == '\0') break; format++; if (*format == 'E' || *format == 'O') format++; switch (*format) { case 'a': for (i = 0; i < 3; i++) { if (count < maxsize - 1) s[count++] = dname[tim_p->tm_wday][i]; else return 0; } break; case 'A': for (i = 0; i < dname_len[tim_p->tm_wday]; i++) { if (count < maxsize - 1) s[count++] = dname[tim_p->tm_wday][i]; else return 0; } break; case 'b': case 'h': for (i = 0; i < 3; i++) { if (count < maxsize - 1) s[count++] = mname[tim_p->tm_mon][i]; else return 0; } break; case 'B': for (i = 0; i < mname_len[tim_p->tm_mon]; i++) { if (count < maxsize - 1) s[count++] = mname[tim_p->tm_mon][i]; else return 0; } break; case 'c': { /* Length is not known because of %C%y, so recurse. */ size_t adjust = strftime (&s[count], maxsize - count, "%a %b %e %H:%M:%S %C%y", tim_p); if (adjust > 0) count += adjust; else return 0; } break; case 'C': { /* Examples of (tm_year + YEAR_BASE) that show how %Y == %C%y with 32-bit int. %Y %C %y 2147485547 21474855 47 10000 100 00 9999 99 99 0999 09 99 0099 00 99 0001 00 01 0000 00 00 -001 -0 01 -099 -0 99 -999 -9 99 -1000 -10 00 -10000 -100 00 -2147481748 -21474817 48 Be careful of both overflow and sign adjustment due to the asymmetric range of years. */ int neg = tim_p->tm_year < -YEAR_BASE; int century = tim_p->tm_year >= 0 ? tim_p->tm_year / 100 + YEAR_BASE / 100 : abs (tim_p->tm_year + YEAR_BASE) / 100; count += snprintf (&s[count], maxsize - count, "%s%.*d", neg ? "-" : "", 2 - neg, century); if (count >= maxsize) return 0; } break; case 'd': case 'e': if (count < maxsize - 2) { sprintf (&s[count], *format == 'd' ? "%.2d" : "%2d", tim_p->tm_mday); count += 2; } else return 0; break; case 'D': case 'x': /* %m/%d/%y */ if (count < maxsize - 8) { sprintf (&s[count], "%.2d/%.2d/%.2d", tim_p->tm_mon + 1, tim_p->tm_mday, tim_p->tm_year >= 0 ? tim_p->tm_year % 100 : abs (tim_p->tm_year + YEAR_BASE) % 100); count += 8; } else return 0; break; case 'F': { /* Length is not known because of %C%y, so recurse. */ size_t adjust = strftime (&s[count], maxsize - count, "%C%y-%m-%d", tim_p); if (adjust > 0) count += adjust; else return 0; } break; case 'g': if (count < maxsize - 2) { /* Be careful of both overflow and negative years, thanks to the asymmetric range of years. */ int adjust = iso_year_adjust (tim_p); int year = tim_p->tm_year >= 0 ? tim_p->tm_year % 100 : abs (tim_p->tm_year + YEAR_BASE) % 100; if (adjust < 0 && tim_p->tm_year <= -YEAR_BASE) adjust = 1; else if (adjust > 0 && tim_p->tm_year < -YEAR_BASE) adjust = -1; sprintf (&s[count], "%.2d", ((year + adjust) % 100 + 100) % 100); count += 2; } else return 0; break; case 'G': { /* See the comments for 'C' and 'Y'; this is a variable length field. Although there is no requirement for a minimum number of digits, we use 4 for consistency with 'Y'. */ int neg = tim_p->tm_year < -YEAR_BASE; int adjust = iso_year_adjust (tim_p); int century = tim_p->tm_year >= 0 ? tim_p->tm_year / 100 + YEAR_BASE / 100 : abs (tim_p->tm_year + YEAR_BASE) / 100; int year = tim_p->tm_year >= 0 ? tim_p->tm_year % 100 : abs (tim_p->tm_year + YEAR_BASE) % 100; if (adjust < 0 && tim_p->tm_year <= -YEAR_BASE) neg = adjust = 1; else if (adjust > 0 && neg) adjust = -1; year += adjust; if (year == -1) { year = 99; --century; } else if (year == 100) { year = 0; ++century; } count += snprintf (&s[count], maxsize - count, "%s%.*d%.2d", neg ? "-" : "", 2 - neg, century, year); if (count >= maxsize) return 0; } break; case 'H': case 'k': if (count < maxsize - 2) { sprintf (&s[count], *format == 'k' ? "%2d" : "%.2d", tim_p->tm_hour); count += 2; } else return 0; break; case 'I': case 'l': if (count < maxsize - 2) { if (tim_p->tm_hour == 0 || tim_p->tm_hour == 12) { s[count++] = '1'; s[count++] = '2'; } else { sprintf (&s[count], *format == 'I' ? "%.2d" : "%2d", tim_p->tm_hour % 12); count += 2; } } else return 0; break; case 'j': if (count < maxsize - 3) { sprintf (&s[count], "%.3d", tim_p->tm_yday + 1); count += 3; } else return 0; break; case 'm': if (count < maxsize - 2) { sprintf (&s[count], "%.2d", tim_p->tm_mon + 1); count += 2; } else return 0; break; case 'M': if (count < maxsize - 2) { sprintf (&s[count], "%.2d", tim_p->tm_min); count += 2; } else return 0; break; case 'n': if (count < maxsize - 1) s[count++] = '\n'; else return 0; break; case 'p': if (count < maxsize - 2) { if (tim_p->tm_hour < 12) s[count++] = 'A'; else s[count++] = 'P'; s[count++] = 'M'; } else return 0; break; case 'r': if (count < maxsize - 11) { if (tim_p->tm_hour == 0 || tim_p->tm_hour == 12) { s[count++] = '1'; s[count++] = '2'; } else { sprintf (&s[count], "%.2d", tim_p->tm_hour % 12); count += 2; } s[count++] = ':'; sprintf (&s[count], "%.2d", tim_p->tm_min); count += 2; s[count++] = ':'; sprintf (&s[count], "%.2d", tim_p->tm_sec); count += 2; s[count++] = ' '; if (tim_p->tm_hour < 12) s[count++] = 'A'; else s[count++] = 'P'; s[count++] = 'M'; } else return 0; break; case 'R': if (count < maxsize - 5) { sprintf (&s[count], "%.2d:%.2d", tim_p->tm_hour, tim_p->tm_min); count += 5; } else return 0; break; case 'S': if (count < maxsize - 2) { sprintf (&s[count], "%.2d", tim_p->tm_sec); count += 2; } else return 0; break; case 't': if (count < maxsize - 1) s[count++] = '\t'; else return 0; break; case 'T': case 'X': if (count < maxsize - 8) { sprintf (&s[count], "%.2d:%.2d:%.2d", tim_p->tm_hour, tim_p->tm_min, tim_p->tm_sec); count += 8; } else return 0; break; case 'u': if (count < maxsize - 1) { if (tim_p->tm_wday == 0) s[count++] = '7'; else s[count++] = '0' + tim_p->tm_wday; } else return 0; break; case 'U': if (count < maxsize - 2) { sprintf (&s[count], "%.2d", (tim_p->tm_yday + 7 - tim_p->tm_wday) / 7); count += 2; } else return 0; break; case 'V': if (count < maxsize - 2) { int adjust = iso_year_adjust (tim_p); int wday = (tim_p->tm_wday) ? tim_p->tm_wday - 1 : 6; int week = (tim_p->tm_yday + 10 - wday) / 7; if (adjust > 0) week = 1; else if (adjust < 0) /* Previous year has 53 weeks if current year starts on Fri, and also if current year starts on Sat and previous year was leap year. */ week = 52 + (4 >= (wday - tim_p->tm_yday - isleap (tim_p->tm_year + (YEAR_BASE - 1 - (tim_p->tm_year < 0 ? 0 : 2000))))); sprintf (&s[count], "%.2d", week); count += 2; } else return 0; break; case 'w': if (count < maxsize - 1) s[count++] = '0' + tim_p->tm_wday; else return 0; break; case 'W': if (count < maxsize - 2) { int wday = (tim_p->tm_wday) ? tim_p->tm_wday - 1 : 6; sprintf (&s[count], "%.2d", (tim_p->tm_yday + 7 - wday) / 7); count += 2; } else return 0; break; case 'y': if (count < maxsize - 2) { /* Be careful of both overflow and negative years, thanks to the asymmetric range of years. */ int year = tim_p->tm_year >= 0 ? tim_p->tm_year % 100 : abs (tim_p->tm_year + YEAR_BASE) % 100; sprintf (&s[count], "%.2d", year); count += 2; } else return 0; break; case 'Y': { /* Length is not known because of %C%y, so recurse. */ size_t adjust = strftime (&s[count], maxsize - count, "%C%y", tim_p); if (adjust > 0) count += adjust; else return 0; } break; case 'z': if (tim_p->tm_isdst >= 0) { if (count < maxsize - 5) { long offset; __tzinfo_type *tz = __gettzinfo (); TZ_LOCK; /* The sign of this is exactly opposite the envvar TZ. We could directly use the global _timezone for tm_isdst==0, but have to use __tzrule for daylight savings. */ offset = -tz->__tzrule[tim_p->tm_isdst > 0].offset; TZ_UNLOCK; sprintf (&s[count], "%+03ld%.2ld", offset / SECSPERHOUR, labs (offset / SECSPERMIN) % 60L); count += 5; } else return 0; } break; case 'Z': if (tim_p->tm_isdst >= 0) { int size; TZ_LOCK; size = strlen(_tzname[tim_p->tm_isdst > 0]); for (i = 0; i < size; i++) { if (count < maxsize - 1) s[count++] = _tzname[tim_p->tm_isdst > 0][i]; else { TZ_UNLOCK; return 0; } } TZ_UNLOCK; } break; case '%': if (count < maxsize - 1) s[count++] = '%'; else return 0; break; } if (*format) format++; else break; } if (maxsize) s[count] = '\0'; return count; }
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