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 #ifndef lint 13 #ifndef NOID 14 static char elsieid[] = "@(#)asctime.c 8.2"; 15 #endif /* !defined NOID */ 16 #endif /* !defined lint */ 17 18 /*LINTLIBRARY*/ 19 20 #include "private.h" 21 #include "tzfile.h" 22 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__ */ 57 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) 70 71 static char buf_asctime[MAX_ASCTIME_BUF_SIZE]; 72 73 /* 74 ** A la ISO/IEC 9945-1, ANSI/IEEE Std 1003.1, 2004 Edition. 75 */ 76 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]; 93 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 } 128 129 /* 130 ** A la ISO/IEC 9945-1, ANSI/IEEE Std 1003.1, 2004 Edition. 131 */ 132 133 char * 134 asctime(timeptr) 135 register const struct tm * timeptr; 136 { 137 return asctime_r(timeptr, buf_asctime); 138 } 139
