/* $OpenBSD: asctime.c,v 1.24 2019/07/03 03:24:04 deraadt Exp $ */ /* ** This file is in the public domain, so clarified as of ** 1996-06-05 by Arthur David Olson. */ /* ** Avoid the temptation to punt entirely to strftime; ** the output of strftime is supposed to be locale specific ** whereas the output of asctime is supposed to be constant. */ #include #include #include #include "private.h" #include "tzfile.h" #include "thread_private.h" /* ** Some systems only handle "%.2d"; others only handle "%02d"; ** "%02.2d" makes (most) everybody happy. ** At least some versions of gcc warn about the %02.2d; ** we conditionalize below to avoid the warning. */ /* ** All years associated with 32-bit time_t values are exactly four digits long; ** some years associated with 64-bit time_t values are not. ** Vintage programs are coded for years that are always four digits long ** and may assume that the newline always lands in the same place. ** For years that are less than four digits, we pad the output with ** leading zeroes to get the newline in the traditional place. ** The -4 ensures that we get four characters of output even if ** we call a strftime variant that produces fewer characters for some years. ** The ISO C 1999 and POSIX 1003.1-2004 standards prohibit padding the year, ** but many implementations pad anyway; most likely the standards are buggy. */ #define ASCTIME_FMT "%.3s %.3s%3d %2.2d:%2.2d:%2.2d %-4s\n" /* ** For years that are more than four digits we put extra spaces before the year ** so that code trying to overwrite the newline won't end up overwriting ** a digit within a year and truncating the year (operating on the assumption ** that no output is better than wrong output). */ #define ASCTIME_FMT_B "%.3s %.3s%3d %2.2d:%2.2d:%2.2d %s\n" #define STD_ASCTIME_BUF_SIZE 26 /* ** Big enough for something such as ** ??? ???-2147483648 -2147483648:-2147483648:-2147483648 -2147483648\n ** (two three-character abbreviations, five strings denoting integers, ** seven explicit spaces, two explicit colons, a newline, ** and a trailing ASCII nul). ** The values above are for systems where an int is 32 bits and are provided ** as an example; the define below calculates the maximum for the system at ** hand. */ #define MAX_ASCTIME_BUF_SIZE (2*3+5*INT_STRLEN_MAXIMUM(int)+7+2+1+1) static char * asctime3(const struct tm *timeptr, char *buf, int bufsize) { static const char wday_name[][4] = { "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat" }; static const char mon_name[][4] = { "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec" }; const char * wn; const char * mn; char year[INT_STRLEN_MAXIMUM(int) + 2]; int len; if (timeptr == NULL) { errno = EINVAL; strlcpy(buf, "??? ??? ?? ??:??:?? ????\n", bufsize); return buf; } if (timeptr->tm_wday < 0 || timeptr->tm_wday >= DAYSPERWEEK) wn = "???"; else wn = wday_name[timeptr->tm_wday]; if (timeptr->tm_mon < 0 || timeptr->tm_mon >= MONSPERYEAR) mn = "???"; else mn = mon_name[timeptr->tm_mon]; /* ** Use strftime's %Y to generate the year, to avoid overflow problems ** when computing timeptr->tm_year + TM_YEAR_BASE. ** Assume that strftime is unaffected by other out-of-range members ** (e.g., timeptr->tm_mday) when processing "%Y". */ (void) strftime(year, sizeof year, "%Y", timeptr); len = snprintf(buf, bufsize, ((strlen(year) <= 4) ? ASCTIME_FMT : ASCTIME_FMT_B), wn, mn, timeptr->tm_mday, timeptr->tm_hour, timeptr->tm_min, timeptr->tm_sec, year); if (len >= 0 && len < bufsize) { return buf; } else { errno = EOVERFLOW; return NULL; } } /* ** A la ISO/IEC 9945-1, ANSI/IEEE Std 1003.1, 2004 Edition. */ char * asctime_r(const struct tm *timeptr, char *buf) { /* ** P1003 8.3.5.2 says that asctime_r() can only assume at most ** a 26 byte buffer. */ return asctime3(timeptr, buf, STD_ASCTIME_BUF_SIZE); } DEF_WEAK(asctime_r); /* ** A la ISO/IEC 9945-1, ANSI/IEEE Std 1003.1, 2004 Edition. */ char * asctime(const struct tm *timeptr) { static char result[MAX_ASCTIME_BUF_SIZE]; _THREAD_PRIVATE_KEY(asctime); char *resultp = (char *)_THREAD_PRIVATE(asctime, result, NULL); if (resultp == NULL) return NULL; else return asctime3(timeptr, resultp, sizeof(result)); } DEF_STRONG(asctime);