Apply upstream commit 943a6621866e9d6e654f5cfe1494378c1fb8957a.

Author: Paul Eggert <eggert@cs.ucla.edu>
Date:   Thu Aug 22 12:47:51 2013 -0700

    * localtime.c: Fix another integer overflow bug in mktime.

    (time2sub): Avoid undefined behavior on time_t overflow.
    Reported by Elliott Hughes in
    <http://mm.icann.org/pipermail/tz/2013-August/019580.html>.

Bug: 10310929

(cherry picked from commit 713fe6463e)

Change-Id: I9ec79fd8d825e6b9e8bb5af549dbfc2182346c05

libc/Android.mk

@@ -718,8 +718,6 @@ LOCAL_CFLAGS := \
     -DTZDIR=\"/system/usr/share/zoneinfo\" \
     -DTM_GMTOFF=tm_gmtoff \
     -DUSG_COMPAT=1
-# tzcode currently relies on signed overflow in numerous places (http://b/10310929).
-LOCAL_CFLAGS += -fno-strict-overflow
 LOCAL_C_INCLUDES := $(libc_common_c_includes)
 LOCAL_MODULE := libc_tzcode
 LOCAL_ADDITIONAL_DEPENDENCIES := $(LOCAL_PATH)/Android.mk

libc/tzcode/localtime.c

@@ -1812,14 +1812,14 @@ time2sub(struct tm * const tmp,
         } 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)

libc/tzcode/private.h

@@ -304,6 +304,16 @@ const char *	scheck(const char * string, const char * format);
 #define TYPE_SIGNED(type) (((type) -1) < 0)
 #endif /* !defined TYPE_SIGNED */
 
+/* The minimum and maximum finite time values.  */
+static time_t const time_t_min =
+  (TYPE_SIGNED(time_t)
+   ? (time_t) -1 << (CHAR_BIT * sizeof (time_t) - 1)
+   : 0);
+static time_t const time_t_max =
+  (TYPE_SIGNED(time_t)
+   ? - (~ 0 < 0) - ((time_t) -1 << (CHAR_BIT * sizeof (time_t) - 1))
+   : -1);
+
 /*
 ** Since the definition of TYPE_INTEGRAL contains floating point numbers,
 ** it cannot be used in preprocessor directives.