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* editfns.c (lisp_time_argument): Check for time stamp overflow.

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This commit is contained in:
Paul Eggert 2011-03-12 22:27:18 -08:00
parent 803110b536
commit 313c1e544a
2 changed files with 30 additions and 7 deletions
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4
src/ChangeLog
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@ -1,3 +1,7 @@
2011-03-13 Paul Eggert <eggert@cs.ucla.edu>
* editfns.c (lisp_time_argument): Check for time stamp overflow.
2011-03-12 Paul Eggert <eggert@cs.ucla.edu>
Improve quality of tests for time stamp overflow. For example,

33
src/editfns.c
View file

@ -1439,12 +1439,17 @@ static EMACS_INT
hi_time (time_t t)
{
time_t hi = t >> 16;
if ((TYPE_SIGNED (time_t)
&& TIME_T_MIN >> 16 < MOST_NEGATIVE_FIXNUM
&& hi < MOST_NEGATIVE_FIXNUM)
|| (MOST_POSITIVE_FIXNUM < TIME_T_MAX >> 16
&& MOST_POSITIVE_FIXNUM < hi))
/* Check for overflow, helping the compiler for common cases where
no runtime check is needed, and taking care not to convert
negative numbers to unsigned before comparing them. */
if (! ((! TYPE_SIGNED (time_t)
|| MOST_NEGATIVE_FIXNUM <= TIME_T_MIN >> 16
|| MOST_NEGATIVE_FIXNUM <= hi)
&& (TIME_T_MAX >> 16 <= MOST_POSITIVE_FIXNUM
|| hi <= MOST_POSITIVE_FIXNUM)))
time_overflow ();
return hi;
}
@ -1551,6 +1556,7 @@ lisp_time_argument (Lisp_Object specified_time, time_t *result, int *usec)
else
{
Lisp_Object high, low;
EMACS_INT hi;
high = Fcar (specified_time);
CHECK_NUMBER (high);
low = Fcdr (specified_time);
@ -1574,8 +1580,21 @@ lisp_time_argument (Lisp_Object specified_time, time_t *result, int *usec)
else if (usec)
*usec = 0;
CHECK_NUMBER (low);
*result = (XINT (high) << 16) + (XINT (low) & 0xffff);
return *result >> 16 == XINT (high);
hi = XINT (high);
/* Check for overflow, helping the compiler for common cases
where no runtime check is needed, and taking care not to
convert negative numbers to unsigned before comparing them. */
if (! ((TYPE_SIGNED (time_t)
? (TIME_T_MIN >> 16 <= MOST_NEGATIVE_FIXNUM
|| TIME_T_MIN >> 16 <= hi)
: 0 <= hi)
&& (MOST_POSITIVE_FIXNUM <= TIME_T_MAX >> 16
|| hi <= TIME_T_MAX >> 16)))
return 0;
*result = (hi << 16) + (XINT (low) & 0xffff);
return 1;
}
}