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 ** $FreeBSD: head/contrib/tzcode/stdtime/asctime.c 214411 2010-10-27 07:14:46Z edwin $ 12 */ 13 /*LINTLIBRARY*/ 14 15 #include "namespace.h" 16 #include "private.h" 17 #include "un-namespace.h" 18 #include "tzfile.h" 19 20 /* 21 ** Some systems only handle "%.2d"; others only handle "%02d"; 22 ** "%02.2d" makes (most) everybody happy. 23 ** At least some versions of gcc warn about the %02.2d; 24 ** we conditionalize below to avoid the warning. 25 */ 26 /* 27 ** All years associated with 32-bit time_t values are exactly four digits long; 28 ** some years associated with 64-bit time_t values are not. 29 ** Vintage programs are coded for years that are always four digits long 30 ** and may assume that the newline always lands in the same place. 31 ** For years that are less than four digits, we pad the output with 32 ** leading zeroes to get the newline in the traditional place. 33 ** The -4 ensures that we get four characters of output even if 34 ** we call a strftime variant that produces fewer characters for some years. 35 ** The ISO C 1999 and POSIX 1003.1-2004 standards prohibit padding the year, 36 ** but many implementations pad anyway; most likely the standards are buggy. 37 */ 38 #ifdef __GNUC__ 39 #define ASCTIME_FMT "%.3s %.3s%3d %2.2d:%2.2d:%2.2d %-4s\n" 40 #else /* !defined __GNUC__ */ 41 #define ASCTIME_FMT "%.3s %.3s%3d %02.2d:%02.2d:%02.2d %-4s\n" 42 #endif /* !defined __GNUC__ */ 43 /* 44 ** For years that are more than four digits we put extra spaces before the year 45 ** so that code trying to overwrite the newline won't end up overwriting 46 ** a digit within a year and truncating the year (operating on the assumption 47 ** that no output is better than wrong output). 48 */ 49 #ifdef __GNUC__ 50 #define ASCTIME_FMT_B "%.3s %.3s%3d %2.2d:%2.2d:%2.2d %s\n" 51 #else /* !defined __GNUC__ */ 52 #define ASCTIME_FMT_B "%.3s %.3s%3d %02.2d:%02.2d:%02.2d %s\n" 53 #endif /* !defined __GNUC__ */ 54 55 #define STD_ASCTIME_BUF_SIZE 26 56 /* 57 ** Big enough for something such as 58 ** ??? ???-2147483648 -2147483648:-2147483648:-2147483648 -2147483648\n 59 ** (two three-character abbreviations, five strings denoting integers, 60 ** seven explicit spaces, two explicit colons, a newline, 61 ** and a trailing ASCII nul). 62 ** The values above are for systems where an int is 32 bits and are provided 63 ** as an example; the define below calculates the maximum for the system at 64 ** hand. 65 */ 66 #define MAX_ASCTIME_BUF_SIZE (2*3+5*INT_STRLEN_MAXIMUM(int)+7+2+1+1) 67 68 static char buf_asctime[MAX_ASCTIME_BUF_SIZE]; 69 70 /* 71 ** A la ISO/IEC 9945-1, ANSI/IEEE Std 1003.1, 2004 Edition. 72 */ 73 74 char * 75 asctime_r(const struct tm *timeptr, char *buf) 76 { 77 static const char wday_name[][3] = { 78 "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat" 79 }; 80 static const char mon_name[][3] = { 81 "Jan", "Feb", "Mar", "Apr", "May", "Jun", 82 "Jul", "Aug", "Sep", "Oct", "Nov", "Dec" 83 }; 84 char year[INT_STRLEN_MAXIMUM(int) + 2]; 85 char result[MAX_ASCTIME_BUF_SIZE]; 86 const char * wn; 87 const char * mn; 88 89 if (timeptr == NULL) { 90 errno = EINVAL; 91 return strcpy(buf, "??? ??? ?? ??:??:?? ????\n"); 92 } 93 if (timeptr->tm_wday < 0 || timeptr->tm_wday >= DAYSPERWEEK) 94 wn = "???"; 95 else wn = wday_name[timeptr->tm_wday]; 96 if (timeptr->tm_mon < 0 || timeptr->tm_mon >= MONSPERYEAR) 97 mn = "???"; 98 else mn = mon_name[timeptr->tm_mon]; 99 /* 100 ** Use strftime's %Y to generate the year, to avoid overflow problems 101 ** when computing timeptr->tm_year + TM_YEAR_BASE. 102 ** Assume that strftime is unaffected by other out-of-range members 103 ** (e.g., timeptr->tm_mday) when processing "%Y". 104 */ 105 strftime(year, sizeof year, "%Y", timeptr); 106 snprintf(result, sizeof result, 107 ((strlen(year) <= 4) ? ASCTIME_FMT : ASCTIME_FMT_B), 108 wn, mn, 109 timeptr->tm_mday, timeptr->tm_hour, 110 timeptr->tm_min, timeptr->tm_sec, 111 year); 112 if (strlen(result) < STD_ASCTIME_BUF_SIZE || buf == buf_asctime) { 113 return strcpy(buf, result); 114 } else { 115 errno = EOVERFLOW; 116 return NULL; 117 } 118 } 119 120 /* 121 ** A la ISO/IEC 9945-1, ANSI/IEEE Std 1003.1, 2004 Edition. 122 */ 123 124 char * 125 asctime(const struct tm *timeptr) 126 { 127 return asctime_r(timeptr, buf_asctime); 128 } 129