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 ** @(#)asctime.c 8.5 12 ** $FreeBSD: src/lib/libc/stdtime/asctime.c,v 1.7.6.1 2001/03/05 11:37:20 obrien Exp $ 13 */ 14 /*LINTLIBRARY*/ 15 16 #include "namespace.h" 17 #include "private.h" 18 #include "un-namespace.h" 19 #include "tzfile.h" 20 21 /* 22 ** Some systems only handle "%.2d"; others only handle "%02d"; 23 ** "%02.2d" makes (most) everybody happy. 24 ** At least some versions of gcc warn about the %02.2d; 25 ** we conditionalize below to avoid the warning. 26 */ 27 /* 28 ** All years associated with 32-bit time_t values are exactly four digits long; 29 ** some years associated with 64-bit time_t values are not. 30 ** Vintage programs are coded for years that are always four digits long 31 ** and may assume that the newline always lands in the same place. 32 ** For years that are less than four digits, we pad the output with 33 ** leading zeroes to get the newline in the traditional place. 34 ** The -4 ensures that we get four characters of output even if 35 ** we call a strftime variant that produces fewer characters for some years. 36 ** The ISO C 1999 and POSIX 1003.1-2004 standards prohibit padding the year, 37 ** but many implementations pad anyway; most likely the standards are buggy. 38 */ 39 #ifdef __GNUC__ 40 #define ASCTIME_FMT "%.3s %.3s%3d %2.2d:%2.2d:%2.2d %-4s\n" 41 #else /* !defined __GNUC__ */ 42 #define ASCTIME_FMT "%.3s %.3s%3d %02.2d:%02.2d:%02.2d %-4s\n" 43 #endif /* !defined __GNUC__ */ 44 /* 45 ** For years that are more than four digits we put extra spaces before the year 46 ** so that code trying to overwrite the newline won't end up overwriting 47 ** a digit within a year and truncating the year (operating on the assumption 48 ** that no output is better than wrong output). 49 */ 50 #ifdef __GNUC__ 51 #define ASCTIME_FMT_B "%.3s %.3s%3d %2.2d:%2.2d:%2.2d %s\n" 52 #else /* !defined __GNUC__ */ 53 #define ASCTIME_FMT_B "%.3s %.3s%3d %02.2d:%02.2d:%02.2d %s\n" 54 #endif /* !defined __GNUC__ */ 55 56 #define STD_ASCTIME_BUF_SIZE 26 57 /* 58 ** Big enough for something such as 59 ** ??? ???-2147483648 -2147483648:-2147483648:-2147483648 -2147483648\n 60 ** (two three-character abbreviations, five strings denoting integers, 61 ** seven explicit spaces, two explicit colons, a newline, 62 ** and a trailing ASCII nul). 63 ** The values above are for systems where an int is 32 bits and are provided 64 ** as an example; the define below calculates the maximum for the system at 65 ** hand. 66 */ 67 #define MAX_ASCTIME_BUF_SIZE (2*3+5*INT_STRLEN_MAXIMUM(int)+7+2+1+1) 68 69 static char buf_asctime[MAX_ASCTIME_BUF_SIZE]; 70 71 /* 72 ** A la ISO/IEC 9945-1, ANSI/IEEE Std 1003.1, 2004 Edition. 73 */ 74 75 76 char * 77 asctime_r(const struct tm *timeptr, char *buf) 78 { 79 static const char wday_name[][3] = { 80 "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat" 81 }; 82 static const char mon_name[][3] = { 83 "Jan", "Feb", "Mar", "Apr", "May", "Jun", 84 "Jul", "Aug", "Sep", "Oct", "Nov", "Dec" 85 }; 86 char year[INT_STRLEN_MAXIMUM(int) + 2]; 87 char result[MAX_ASCTIME_BUF_SIZE]; 88 const char * wn; 89 const char * mn; 90 91 if (timeptr == NULL) { 92 errno = EINVAL; 93 return strcpy(buf, "??? ??? ?? ??:??:?? ????\n"); 94 } 95 if (timeptr->tm_wday < 0 || timeptr->tm_wday >= DAYSPERWEEK) 96 wn = "???"; 97 else wn = wday_name[timeptr->tm_wday]; 98 if (timeptr->tm_mon < 0 || timeptr->tm_mon >= MONSPERYEAR) 99 mn = "???"; 100 else mn = mon_name[timeptr->tm_mon]; 101 /* 102 ** Use strftime's %Y to generate the year, to avoid overflow problems 103 ** when computing timeptr->tm_year + TM_YEAR_BASE. 104 ** Assume that strftime is unaffected by other out-of-range members 105 ** (e.g., timeptr->tm_mday) when processing "%Y". 106 */ 107 strftime(year, sizeof year, "%Y", timeptr); 108 snprintf(result, sizeof result, 109 ((strlen(year) <= 4) ? ASCTIME_FMT : ASCTIME_FMT_B), 110 wn, mn, 111 timeptr->tm_mday, timeptr->tm_hour, 112 timeptr->tm_min, timeptr->tm_sec, 113 year); 114 if (strlen(result) < STD_ASCTIME_BUF_SIZE || buf == buf_asctime) { 115 return strcpy(buf, result); 116 } else { 117 errno = EOVERFLOW; 118 return NULL; 119 } 120 } 121 122 /* 123 ** A la ISO/IEC 9945-1, ANSI/IEEE Std 1003.1, 2004 Edition. 124 */ 125 126 char * 127 asctime(const struct tm *timeptr) 128 { 129 return asctime_r(timeptr, buf_asctime); 130 } 131