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 8.2 12 ** $FreeBSD: src/lib/libc/stdtime/asctime.c,v 1.7.6.1 2001/03/05 11:37:20 obrien Exp $ 13 ** $DragonFly: src/lib/libc/stdtime/asctime.c,v 1.6 2008/10/19 20:15:58 swildner Exp $ 14 */ 15 /*LINTLIBRARY*/ 16 17 #include "namespace.h" 18 #include "private.h" 19 #include "un-namespace.h" 20 #include "tzfile.h" 21 22 /* 23 ** Some systems only handle "%.2d"; others only handle "%02d"; 24 ** "%02.2d" makes (most) everybody happy. 25 ** At least some versions of gcc warn about the %02.2d; 26 ** we conditionalize below to avoid the warning. 27 */ 28 /* 29 ** All years associated with 32-bit time_t values are exactly four digits long; 30 ** some years associated with 64-bit time_t values are not. 31 ** Vintage programs are coded for years that are always four digits long 32 ** and may assume that the newline always lands in the same place. 33 ** For years that are less than four digits, we pad the output with 34 ** leading zeroes to get the newline in the traditional place. 35 ** The -4 ensures that we get four characters of output even if 36 ** we call a strftime variant that produces fewer characters for some years. 37 ** The ISO C 1999 and POSIX 1003.1-2004 standards prohibit padding the year, 38 ** but many implementations pad anyway; most likely the standards are buggy. 39 */ 40 #ifdef __GNUC__ 41 #define ASCTIME_FMT "%.3s %.3s%3d %2.2d:%2.2d:%2.2d %-4s\n" 42 #else /* !defined __GNUC__ */ 43 #define ASCTIME_FMT "%.3s %.3s%3d %02.2d:%02.2d:%02.2d %-4s\n" 44 #endif /* !defined __GNUC__ */ 45 /* 46 ** For years that are more than four digits we put extra spaces before the year 47 ** so that code trying to overwrite the newline won't end up overwriting 48 ** a digit within a year and truncating the year (operating on the assumption 49 ** that no output is better than wrong output). 50 */ 51 #ifdef __GNUC__ 52 #define ASCTIME_FMT_B "%.3s %.3s%3d %2.2d:%2.2d:%2.2d %s\n" 53 #else /* !defined __GNUC__ */ 54 #define ASCTIME_FMT_B "%.3s %.3s%3d %02.2d:%02.2d:%02.2d %s\n" 55 #endif /* !defined __GNUC__ */ 56 57 #define STD_ASCTIME_BUF_SIZE 26 58 /* 59 ** Big enough for something such as 60 ** ??? ???-2147483648 -2147483648:-2147483648:-2147483648 -2147483648\n 61 ** (two three-character abbreviations, five strings denoting integers, 62 ** seven explicit spaces, two explicit colons, a newline, 63 ** and a trailing ASCII nul). 64 ** The values above are for systems where an int is 32 bits and are provided 65 ** as an example; the define below calculates the maximum for the system at 66 ** hand. 67 */ 68 #define MAX_ASCTIME_BUF_SIZE (2*3+5*INT_STRLEN_MAXIMUM(int)+7+2+1+1) 69 70 static char buf_asctime[MAX_ASCTIME_BUF_SIZE]; 71 72 /* 73 ** A la ISO/IEC 9945-1, ANSI/IEEE Std 1003.1, 2004 Edition. 74 */ 75 76 77 char * 78 asctime_r(const struct tm *timeptr, char *buf) 79 { 80 static const char wday_name[][3] = { 81 "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat" 82 }; 83 static const char mon_name[][3] = { 84 "Jan", "Feb", "Mar", "Apr", "May", "Jun", 85 "Jul", "Aug", "Sep", "Oct", "Nov", "Dec" 86 }; 87 char year[INT_STRLEN_MAXIMUM(int) + 2]; 88 char result[MAX_ASCTIME_BUF_SIZE]; 89 const char * wn; 90 const char * mn; 91 92 if (timeptr->tm_wday < 0 || timeptr->tm_wday >= DAYSPERWEEK) 93 wn = "???"; 94 else wn = wday_name[timeptr->tm_wday]; 95 if (timeptr->tm_mon < 0 || timeptr->tm_mon >= MONSPERYEAR) 96 mn = "???"; 97 else mn = mon_name[timeptr->tm_mon]; 98 /* 99 ** Use strftime's %Y to generate the year, to avoid overflow problems 100 ** when computing timeptr->tm_year + TM_YEAR_BASE. 101 ** Assume that strftime is unaffected by other out-of-range members 102 ** (e.g., timeptr->tm_mday) when processing "%Y". 103 */ 104 strftime(year, sizeof year, "%Y", timeptr); 105 snprintf(result, sizeof result, 106 ((strlen(year) <= 4) ? ASCTIME_FMT : ASCTIME_FMT_B), 107 wn, mn, 108 timeptr->tm_mday, timeptr->tm_hour, 109 timeptr->tm_min, timeptr->tm_sec, 110 year); 111 if (strlen(result) < STD_ASCTIME_BUF_SIZE || buf == buf_asctime) { 112 (void) strcpy(buf, result); 113 return buf; 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