Q: Can the current asctime_r() implementation potentially be threat unsafe?

Christian Baribeau christian.baribeau@amirix.com
Wed Mar 3 19:16:00 GMT 2004


I may have found a potential bug in the reentrant implementation of the
asctime_r(). Here is the implementation taken from newlib CVS.

char *
_DEFUN (asctime_r, (tim_p, result),
_CONST struct tm *tim_p _AND
char *result)
static _CONST char day_name[7][3] = {
"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
static _CONST char mon_name[12][3] = {
"Jan", "Feb", "Mar", "Apr", "May", "Jun",
"Jul", "Aug", "Sep", "Oct", "Nov", "Dec"

sprintf (result, "%.3s %.3s%3d %.2d:%.2d:%.2d %d\n", <- Potential Problem
tim_p->tm_mday, tim_p->tm_hour, tim_p->tm_min,
tim_p->tm_sec, 1900 + tim_p->tm_year);
return result;

Can someone confirm that the call to sprintf() should be replaced with
_sprintf_r() with the appropriate struct _reent in order to make asctime_r()
reentrant or that the current implementation can be considered "thread

Thank you,


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