1 /* $OpenBSD: asctime.c,v 1.16 2010/08/23 22:35:34 millert Exp $ */ 2 /* 3 ** This file is in the public domain, so clarified as of 4 ** 1996-06-05 by Arthur David Olson. 5 */ 6 7 /* 8 ** Avoid the temptation to punt entirely to strftime; 9 ** the output of strftime is supposed to be locale specific 10 ** whereas the output of asctime is supposed to be constant. 11 */ 12 13 /*LINTLIBRARY*/ 14 15 #include "private.h" 16 #include "tzfile.h" 17 #include "thread_private.h" 18 19 /* 20 ** Some systems only handle "%.2d"; others only handle "%02d"; 21 ** "%02.2d" makes (most) everybody happy. 22 ** At least some versions of gcc warn about the %02.2d; 23 ** we conditionalize below to avoid the warning. 24 */ 25 /* 26 ** All years associated with 32-bit time_t values are exactly four digits long; 27 ** some years associated with 64-bit time_t values are not. 28 ** Vintage programs are coded for years that are always four digits long 29 ** and may assume that the newline always lands in the same place. 30 ** For years that are less than four digits, we pad the output with 31 ** leading zeroes to get the newline in the traditional place. 32 ** The -4 ensures that we get four characters of output even if 33 ** we call a strftime variant that produces fewer characters for some years. 34 ** The ISO C 1999 and POSIX 1003.1-2004 standards prohibit padding the year, 35 ** but many implementations pad anyway; most likely the standards are buggy. 36 */ 37 #ifdef __GNUC__ 38 #define ASCTIME_FMT "%.3s %.3s%3d %2.2d:%2.2d:%2.2d %-4s\n" 39 #else /* !defined __GNUC__ */ 40 #define ASCTIME_FMT "%.3s %.3s%3d %02.2d:%02.2d:%02.2d %-4s\n" 41 #endif /* !defined __GNUC__ */ 42 /* 43 ** For years that are more than four digits we put extra spaces before the year 44 ** so that code trying to overwrite the newline won't end up overwriting 45 ** a digit within a year and truncating the year (operating on the assumption 46 ** that no output is better than wrong output). 47 */ 48 #ifdef __GNUC__ 49 #define ASCTIME_FMT_B "%.3s %.3s%3d %2.2d:%2.2d:%2.2d %s\n" 50 #else /* !defined __GNUC__ */ 51 #define ASCTIME_FMT_B "%.3s %.3s%3d %02.2d:%02.2d:%02.2d %s\n" 52 #endif /* !defined __GNUC__ */ 53 54 #define STD_ASCTIME_BUF_SIZE 26 55 /* 56 ** Big enough for something such as 57 ** ??? ???-2147483648 -2147483648:-2147483648:-2147483648 -2147483648\n 58 ** (two three-character abbreviations, five strings denoting integers, 59 ** seven explicit spaces, two explicit colons, a newline, 60 ** and a trailing ASCII nul). 61 ** The values above are for systems where an int is 32 bits and are provided 62 ** as an example; the define below calculates the maximum for the system at 63 ** hand. 64 */ 65 #define MAX_ASCTIME_BUF_SIZE (2*3+5*INT_STRLEN_MAXIMUM(int)+7+2+1+1) 66 67 static char * 68 asctime3(timeptr, buf, bufsize) 69 register const struct tm * timeptr; 70 char * buf; 71 int bufsize; 72 { 73 static const char wday_name[][4] = { 74 "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat" 75 }; 76 static const char mon_name[][4] = { 77 "Jan", "Feb", "Mar", "Apr", "May", "Jun", 78 "Jul", "Aug", "Sep", "Oct", "Nov", "Dec" 79 }; 80 register const char * wn; 81 register const char * mn; 82 char year[INT_STRLEN_MAXIMUM(int) + 2]; 83 int len; 84 85 if (timeptr == NULL) { 86 errno = EINVAL; 87 strlcpy(buf, "??? ??? ?? ??:??:?? ????\n", bufsize); 88 return buf; 89 } 90 if (timeptr->tm_wday < 0 || timeptr->tm_wday >= DAYSPERWEEK) 91 wn = "???"; 92 else wn = wday_name[timeptr->tm_wday]; 93 if (timeptr->tm_mon < 0 || timeptr->tm_mon >= MONSPERYEAR) 94 mn = "???"; 95 else mn = mon_name[timeptr->tm_mon]; 96 /* 97 ** Use strftime's %Y to generate the year, to avoid overflow problems 98 ** when computing timeptr->tm_year + TM_YEAR_BASE. 99 ** Assume that strftime is unaffected by other out-of-range members 100 ** (e.g., timeptr->tm_mday) when processing "%Y". 101 */ 102 (void) strftime(year, sizeof year, "%Y", timeptr); 103 len = snprintf(buf, bufsize, 104 ((strlen(year) <= 4) ? ASCTIME_FMT : ASCTIME_FMT_B), 105 wn, mn, 106 timeptr->tm_mday, timeptr->tm_hour, 107 timeptr->tm_min, timeptr->tm_sec, 108 year); 109 if (len != -1 && len < bufsize) { 110 return buf; 111 } else { 112 #ifdef EOVERFLOW 113 errno = EOVERFLOW; 114 #else /* !defined EOVERFLOW */ 115 errno = EINVAL; 116 #endif /* !defined EOVERFLOW */ 117 return NULL; 118 } 119 } 120 121 /* 122 ** A la ISO/IEC 9945-1, ANSI/IEEE Std 1003.1, 2004 Edition. 123 */ 124 125 char * 126 asctime_r(timeptr, buf) 127 register const struct tm * timeptr; 128 char * buf; 129 { 130 /* 131 ** P1003 8.3.5.2 says that asctime_r() can only assume at most 132 ** a 26 byte buffer. 133 */ 134 return asctime3(timeptr, buf, STD_ASCTIME_BUF_SIZE); 135 } 136 137 /* 138 ** A la ISO/IEC 9945-1, ANSI/IEEE Std 1003.1, 2004 Edition. 139 */ 140 141 char * 142 asctime(timeptr) 143 const struct tm * timeptr; 144 { 145 static char result[MAX_ASCTIME_BUF_SIZE]; 146 _THREAD_PRIVATE_KEY(asctime); 147 char *resultp = (char *)_THREAD_PRIVATE(asctime, result, NULL); 148 149 if (resultp == NULL) 150 return NULL; 151 else 152 return asctime3(timeptr, resultp, sizeof(result)); 153 } 154