1 /* $NetBSD: asctime.c,v 1.18 2012/10/28 17:11:33 christos Exp $ */ 2 3 /* 4 ** This file is in the public domain, so clarified as of 5 ** 1996-06-05 by Arthur David Olson. 6 */ 7 8 /* 9 ** Avoid the temptation to punt entirely to strftime; 10 ** the output of strftime is supposed to be locale specific 11 ** whereas the output of asctime is supposed to be constant. 12 */ 13 14 #include <sys/cdefs.h> 15 #if defined(LIBC_SCCS) && !defined(lint) 16 #if 0 17 static char elsieid[] = "@(#)asctime.c 8.5"; 18 #else 19 __RCSID("$NetBSD: asctime.c,v 1.18 2012/10/28 17:11:33 christos Exp $"); 20 #endif 21 #endif /* LIBC_SCCS and not lint */ 22 23 /*LINTLIBRARY*/ 24 25 #include "namespace.h" 26 #include "private.h" 27 #include "tzfile.h" 28 29 #ifdef __weak_alias 30 __weak_alias(asctime_r,_asctime_r) 31 #endif 32 33 /* 34 ** Some systems only handle "%.2d"; others only handle "%02d"; 35 ** "%02.2d" makes (most) everybody happy. 36 ** At least some versions of gcc warn about the %02.2d; 37 ** we conditionalize below to avoid the warning. 38 */ 39 /* 40 ** All years associated with 32-bit time_t values are exactly four digits long; 41 ** some years associated with 64-bit time_t values are not. 42 ** Vintage programs are coded for years that are always four digits long 43 ** and may assume that the newline always lands in the same place. 44 ** For years that are less than four digits, we pad the output with 45 ** leading zeroes to get the newline in the traditional place. 46 ** The -4 ensures that we get four characters of output even if 47 ** we call a strftime variant that produces fewer characters for some years. 48 ** The ISO C 1999 and POSIX 1003.1-2004 standards prohibit padding the year, 49 ** but many implementations pad anyway; most likely the standards are buggy. 50 */ 51 #ifdef __GNUC__ 52 #define ASCTIME_FMT "%.3s %.3s%3d %2.2d:%2.2d:%2.2d %-4s\n" 53 #else /* !defined __GNUC__ */ 54 #define ASCTIME_FMT "%.3s %.3s%3d %02.2d:%02.2d:%02.2d %-4s\n" 55 #endif /* !defined __GNUC__ */ 56 /* 57 ** For years that are more than four digits we put extra spaces before the year 58 ** so that code trying to overwrite the newline won't end up overwriting 59 ** a digit within a year and truncating the year (operating on the assumption 60 ** that no output is better than wrong output). 61 */ 62 #ifdef __GNUC__ 63 #define ASCTIME_FMT_B "%.3s %.3s%3d %2.2d:%2.2d:%2.2d %s\n" 64 #else /* !defined __GNUC__ */ 65 #define ASCTIME_FMT_B "%.3s %.3s%3d %02.2d:%02.2d:%02.2d %s\n" 66 #endif /* !defined __GNUC__ */ 67 68 #define STD_ASCTIME_BUF_SIZE 26 69 /* 70 ** Big enough for something such as 71 ** ??? ???-2147483648 -2147483648:-2147483648:-2147483648 -2147483648\n 72 ** (two three-character abbreviations, five strings denoting integers, 73 ** seven explicit spaces, two explicit colons, a newline, 74 ** and a trailing ASCII nul). 75 ** The values above are for systems where an int is 32 bits and are provided 76 ** as an example; the define below calculates the maximum for the system at 77 ** hand. 78 */ 79 #define MAX_ASCTIME_BUF_SIZE (2*3+5*INT_STRLEN_MAXIMUM(int)+7+2+1+1) 80 81 static char buf_asctime[MAX_ASCTIME_BUF_SIZE]; 82 83 /* 84 ** A la ISO/IEC 9945-1, ANSI/IEEE Std 1003.1, 2004 Edition. 85 */ 86 87 char * 88 asctime_r(const struct tm *timeptr, char *buf) 89 { 90 static const char wday_name[][3] = { 91 "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat" 92 }; 93 static const char mon_name[][3] = { 94 "Jan", "Feb", "Mar", "Apr", "May", "Jun", 95 "Jul", "Aug", "Sep", "Oct", "Nov", "Dec" 96 }; 97 const char * wn; 98 const char * mn; 99 char year[INT_STRLEN_MAXIMUM(int) + 2]; 100 char result[MAX_ASCTIME_BUF_SIZE]; 101 102 if (timeptr == NULL) { 103 errno = EINVAL; 104 return strcpy(buf, "??? ??? ?? ??:??:?? ????\n"); 105 } 106 if (timeptr->tm_wday < 0 || timeptr->tm_wday >= DAYSPERWEEK) 107 wn = "???"; 108 else wn = wday_name[timeptr->tm_wday]; 109 if (timeptr->tm_mon < 0 || timeptr->tm_mon >= MONSPERYEAR) 110 mn = "???"; 111 else mn = mon_name[timeptr->tm_mon]; 112 /* 113 ** Use strftime's %Y to generate the year, to avoid overflow problems 114 ** when computing timeptr->tm_year + TM_YEAR_BASE. 115 ** Assume that strftime is unaffected by other out-of-range members 116 ** (e.g., timeptr->tm_mday) when processing "%Y". 117 */ 118 (void) strftime(year, sizeof year, "%Y", timeptr); 119 (void) snprintf(result, 120 sizeof(result), 121 ((strlen(year) <= 4) ? ASCTIME_FMT : ASCTIME_FMT_B), 122 wn, mn, 123 timeptr->tm_mday, timeptr->tm_hour, 124 timeptr->tm_min, timeptr->tm_sec, 125 year); 126 if (strlen(result) < STD_ASCTIME_BUF_SIZE || buf == buf_asctime) 127 return strcpy(buf, result); 128 else { 129 #ifdef EOVERFLOW 130 errno = EOVERFLOW; 131 #else /* !defined EOVERFLOW */ 132 errno = EINVAL; 133 #endif /* !defined EOVERFLOW */ 134 return NULL; 135 } 136 } 137 138 /* 139 ** A la ISO/IEC 9945-1, ANSI/IEEE Std 1003.1, 2004 Edition. 140 */ 141 142 char * 143 asctime(const struct tm *timeptr) 144 { 145 return asctime_r(timeptr, buf_asctime); 146 } 147