1 /* $OpenBSD: asctime.c,v 1.15 2007/02/06 19:35:16 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->tm_wday < 0 || timeptr->tm_wday >= DAYSPERWEEK) 86 wn = "???"; 87 else wn = wday_name[timeptr->tm_wday]; 88 if (timeptr->tm_mon < 0 || timeptr->tm_mon >= MONSPERYEAR) 89 mn = "???"; 90 else mn = mon_name[timeptr->tm_mon]; 91 /* 92 ** Use strftime's %Y to generate the year, to avoid overflow problems 93 ** when computing timeptr->tm_year + TM_YEAR_BASE. 94 ** Assume that strftime is unaffected by other out-of-range members 95 ** (e.g., timeptr->tm_mday) when processing "%Y". 96 */ 97 (void) strftime(year, sizeof year, "%Y", timeptr); 98 len = snprintf(buf, bufsize, 99 ((strlen(year) <= 4) ? ASCTIME_FMT : ASCTIME_FMT_B), 100 wn, mn, 101 timeptr->tm_mday, timeptr->tm_hour, 102 timeptr->tm_min, timeptr->tm_sec, 103 year); 104 if (len != -1 && len < bufsize) { 105 return buf; 106 } else { 107 #ifdef EOVERFLOW 108 errno = EOVERFLOW; 109 #else /* !defined EOVERFLOW */ 110 errno = EINVAL; 111 #endif /* !defined EOVERFLOW */ 112 return NULL; 113 } 114 } 115 116 /* 117 ** A la ISO/IEC 9945-1, ANSI/IEEE Std 1003.1, 2004 Edition. 118 */ 119 120 char * 121 asctime_r(timeptr, buf) 122 register const struct tm * timeptr; 123 char * buf; 124 { 125 /* 126 ** P1003 8.3.5.2 says that asctime_r() can only assume at most 127 ** a 26 byte buffer. 128 */ 129 return asctime3(timeptr, buf, STD_ASCTIME_BUF_SIZE); 130 } 131 132 /* 133 ** A la ISO/IEC 9945-1, ANSI/IEEE Std 1003.1, 2004 Edition. 134 */ 135 136 char * 137 asctime(timeptr) 138 const struct tm * timeptr; 139 { 140 static char result[MAX_ASCTIME_BUF_SIZE]; 141 _THREAD_PRIVATE_KEY(asctime); 142 char *resultp = (char *)_THREAD_PRIVATE(asctime, result, NULL); 143 144 if (resultp == NULL) 145 return NULL; 146 else 147 return asctime3(timeptr, resultp, sizeof(result)); 148 } 149