diff options
Diffstat (limited to 'lib/libc/stdtime/asctime.c')
| -rw-r--r-- | lib/libc/stdtime/asctime.c | 106 |
1 files changed, 85 insertions, 21 deletions
diff --git a/lib/libc/stdtime/asctime.c b/lib/libc/stdtime/asctime.c index 0f4212f..30606f1 100644 --- a/lib/libc/stdtime/asctime.c +++ b/lib/libc/stdtime/asctime.c @@ -1,12 +1,18 @@ /* ** This file is in the public domain, so clarified as of -** 1996-06-05 by Arthur David Olson (arthur_david_olson@nih.gov). +** 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 <sys/cdefs.h> #ifndef lint #ifndef NOID -static char elsieid[] __unused = "@(#)asctime.c 7.9"; +static char elsieid[] __unused = "@(#)asctime.c 8.2"; #endif /* !defined NOID */ #endif /* !defined lint */ __FBSDID("$FreeBSD$"); @@ -19,7 +25,57 @@ __FBSDID("$FreeBSD$"); #include "tzfile.h" /* -** A la ISO/IEC 9945-1, ANSI/IEEE Std 1003.1, Second Edition, 1996-07-12. +** 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. +*/ +#ifdef __GNUC__ +#define ASCTIME_FMT "%.3s %.3s%3d %2.2d:%2.2d:%2.2d %-4s\n" +#else /* !defined __GNUC__ */ +#define ASCTIME_FMT "%.3s %.3s%3d %02.2d:%02.2d:%02.2d %-4s\n" +#endif /* !defined __GNUC__ */ +/* +** 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). +*/ +#ifdef __GNUC__ +#define ASCTIME_FMT_B "%.3s %.3s%3d %2.2d:%2.2d:%2.2d %s\n" +#else /* !defined __GNUC__ */ +#define ASCTIME_FMT_B "%.3s %.3s%3d %02.2d:%02.2d:%02.2d %s\n" +#endif /* !defined __GNUC__ */ + +#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 buf_asctime[MAX_ASCTIME_BUF_SIZE]; + +/* +** A la ISO/IEC 9945-1, ANSI/IEEE Std 1003.1, 2004 Edition. */ char * @@ -36,6 +92,8 @@ char * buf; }; const char * wn; const char * mn; + char year[INT_STRLEN_MAXIMUM(int) + 2]; + char result[MAX_ASCTIME_BUF_SIZE]; if (timeptr->tm_wday < 0 || timeptr->tm_wday >= DAYSPERWEEK) wn = "???"; @@ -44,35 +102,41 @@ char * buf; mn = "???"; else mn = mon_name[timeptr->tm_mon]; /* - ** The X3J11-suggested format is - ** "%.3s %.3s%3d %02.2d:%02.2d:%02.2d %d\n" - ** Since the .2 in 02.2d is ignored, we drop it. + ** 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) sprintf(buf, "%.3s %.3s%3d %02d:%02d:%02d %d\n", + (void) strftime(year, sizeof year, "%Y", timeptr); + /* + ** We avoid using snprintf since it's not available on all systems. + */ + (void) sprintf(result, + ((strlen(year) <= 4) ? ASCTIME_FMT : ASCTIME_FMT_B), wn, mn, timeptr->tm_mday, timeptr->tm_hour, timeptr->tm_min, timeptr->tm_sec, - TM_YEAR_BASE + timeptr->tm_year); - return buf; + year); + if (strlen(result) < STD_ASCTIME_BUF_SIZE || buf == buf_asctime) { + (void) strcpy(buf, result); + return buf; + } else { +#ifdef EOVERFLOW + errno = EOVERFLOW; +#else /* !defined EOVERFLOW */ + errno = EINVAL; +#endif /* !defined EOVERFLOW */ + return NULL; + } } /* -** A la X3J11, with core dump avoidance. +** A la ISO/IEC 9945-1, ANSI/IEEE Std 1003.1, 2004 Edition. */ char * asctime(timeptr) const struct tm * timeptr; { - /* - ** Big enough for something such as - ** ??? ???-2147483648 -2147483648:-2147483648:-2147483648 -2147483648\n - ** (two three-character abbreviations, five strings denoting integers, - ** three explicit spaces, two explicit colons, a newline, - ** and a trailing ASCII nul). - */ - static char result[3 * 2 + 5 * INT_STRLEN_MAXIMUM(int) + - 3 + 2 + 1 + 1]; - - return asctime_r(timeptr, result); + return asctime_r(timeptr, buf_asctime); } |
