Fix an infinite loop in time2sub.
The problem is that time_t is signed, and the original code relied on the
fact that (X + c < X) in case of overflow for c >= 0. Unfortunately, this
condition is only guaranteed by the standard for unsigned arithmetic, and
the gcc 4.4.0 optimizer did completely remove the corresponding test from
the code. This resulted in a missing boundary check, and an infinite loop.
The problem is solved by testing explicitely for TIME_T_MIN and TIME_T_MAX
in the loop that uses this.
Also fix increment_overflow and long_increment_overflow which were buggy
for exactly the same reasons.
Note: a similar fix is needed for system/core/libcutils
diff --git a/libc/tzcode/localtime.c b/libc/tzcode/localtime.c
index 9c5f218..83c1011 100644
--- a/libc/tzcode/localtime.c
+++ b/libc/tzcode/localtime.c
@@ -75,6 +75,31 @@
pthread_mutex_unlock(&_tzMutex);
}
+/* Complex computations to determine the min/max of time_t depending
+ * on TYPE_BIT / TYPE_SIGNED / TYPE_INTEGRAL.
+ * These macros cannot be used in pre-processor directives, so we
+ * let the C compiler do the work, which makes things a bit funky.
+ */
+static const time_t TIME_T_MAX =
+ TYPE_INTEGRAL(time_t) ?
+ ( TYPE_SIGNED(time_t) ?
+ ~((time_t)1 << (TYPE_BIT(time_t)-1))
+ :
+ ~(time_t)0
+ )
+ : /* if time_t is a floating point number */
+ ( sizeof(time_t) > sizeof(float) ? (time_t)DBL_MAX : (time_t)FLT_MAX );
+
+static const time_t TIME_T_MIN =
+ TYPE_INTEGRAL(time_t) ?
+ ( TYPE_SIGNED(time_t) ?
+ ((time_t)1 << (TYPE_BIT(time_t)-1))
+ :
+ 0
+ )
+ :
+ ( sizeof(time_t) > sizeof(float) ? (time_t)DBL_MIN : (time_t)FLT_MIN );
+
#ifndef WILDABBR
/*
** Someone might make incorrect use of a time zone abbreviation:
@@ -1683,11 +1708,16 @@
int * number;
int delta;
{
- int number0;
+ unsigned number0 = (unsigned)*number;
+ unsigned number1 = (unsigned)(number0 + delta);
- number0 = *number;
- *number += delta;
- return (*number < number0) != (delta < 0);
+ *number = (int)number1;
+
+ if (delta >= 0) {
+ return ((int)number1 < (int)number0);
+ } else {
+ return ((int)number1 > (int)number0);
+ }
}
static int
@@ -1695,11 +1725,16 @@
long * number;
int delta;
{
- long number0;
+ unsigned long number0 = (unsigned long)*number;
+ unsigned long number1 = (unsigned long)(number0 + delta);
- number0 = *number;
- *number += delta;
- return (*number < number0) != (delta < 0);
+ *number = (long)number1;
+
+ if (delta >= 0) {
+ return ((long)number1 < (long)number0);
+ } else {
+ return ((long)number1 > (long)number0);
+ }
}
static int
@@ -1868,14 +1903,14 @@
} else dir = tmcomp(&mytm, &yourtm);
if (dir != 0) {
if (t == lo) {
- ++t;
- if (t <= lo)
+ if (t == TIME_T_MAX)
return WRONG;
+ ++t;
++lo;
} else if (t == hi) {
- --t;
- if (t >= hi)
+ if (t == TIME_T_MIN)
return WRONG;
+ --t;
--hi;
}
if (lo > hi)