diff options
Diffstat (limited to 'lib-src/b2m.c')
| -rw-r--r-- | lib-src/b2m.c | 21 |
1 files changed, 20 insertions, 1 deletions
diff --git a/lib-src/b2m.c b/lib-src/b2m.c index 5bebe560e2a..adaa736bcd9 100644 --- a/lib-src/b2m.c +++ b/lib-src/b2m.c @@ -26,6 +26,7 @@ #undef static #endif +#include <limits.h> #include <stdio.h> #include <time.h> #include <sys/types.h> @@ -44,6 +45,17 @@ typedef int logical; +/* True if TM_YEAR is a struct tm's tm_year value that is acceptable + to asctime. Glibc asctime returns a useful string unless TM_YEAR + is nearly INT_MAX, but the C Standard lets C libraries overrun a + buffer if TM_YEAR needs more than 4 bytes. */ +#ifdef __GLIBC__ +# define TM_YEAR_IN_ASCTIME_RANGE(tm_year) ((tm_year) <= INT_MAX - 1900) +#else +# define TM_YEAR_IN_ASCTIME_RANGE(tm_year) \ + (-999 - 1900 <= (tm_year) && (tm_year) <= 9999 - 1900) +#endif + /* * A `struct linebuffer' is a structure which holds a line of text. * `readline' reads a line from a stream into a linebuffer and works @@ -87,6 +99,7 @@ main (argc, argv) { logical labels_saved, printing, header; time_t ltoday; + struct tm *tm; char *labels, *p, *today; struct linebuffer data; @@ -131,7 +144,13 @@ main (argc, argv) labels_saved = printing = header = FALSE; ltoday = time (0); - today = ctime (<oday); + /* Convert to a string, checking for out-of-range time stamps. + Don't use 'ctime', as that might dump core if the hardware clock + is set to a bizarre value. */ + tm = localtime (<oday); + if (! (tm && TM_YEAR_IN_ASCTIME_RANGE (tm->tm_year))) + fatal ("current time is out of range"); + today = asctime (tm); data.size = 200; data.buffer = xnew (200, char); |