On 3/5/10, Garrett Cooper <[email protected]> wrote:
> On Thu, Mar 4, 2010 at 9:54 PM, Silesh C V <[email protected]> wrote:
>> On 3/4/10, Rishikesh K Rajak <[email protected]> wrote:
>>>>Rishi,
>>>
>>>>Can you test this patch on the machine on which the tests got stuck
>>>>earlier?
>>>
>>> Yes i tested and found that, it is failing.
>>
>> It is supposed to fail :) . What we  wanted was a way to come out of
>> the tests if the
>> alarm fails to ring.
>>
>>
>>>
>>> [r...@x335a rtc]# ./rtc-test /dev/rtc
>>> rtc01       0  TINFO  :  RTC READ TEST:
>>> rtc01       1  TPASS  :  RTC READ TEST Passed
>>> rtc01       0  TINFO  :  Current Date/time is  03/03/10 12:38:26 PM
>>> rtc01       0  TINFO  :  RTC ALARM TEST :
>>> rtc01       0  TINFO  :  Alarm time set to 12:38:31.
>>> rtc01       0  TINFO  :  Waiting 5 seconds for the alarm...
>>> rtc01       2  TFAIL  :  Timed out waiting for the alarm
>>> rtc01       0  TINFO  :  RTC UPDATE INTERRUPTS TEST :
>>> rtc01       0  TINFO  :  Waiting for  5 update interrupts...
>>> rtc01       0  TINFO  :  Update interrupt 1
>>> rtc01       0  TINFO  :  Update interrupt 2
>>> rtc01       0  TINFO  :  Update interrupt 3
>>> rtc01       0  TINFO  :  Update interrupt 4
>>> rtc01       0  TINFO  :  Update interrupt 5
>>> rtc01       3  TPASS  :  RTC UPDATE INTERRUPTS TEST Passed
>>> rtc01       0  TINFO  :  RTC Tests Done!
>>> [r...@x335a rtc]# ls -l /dev/rtc*
>>> crw-r--r-- 1 root root 10, 135 Feb 20 13:51 /dev/rtc
>>> [r...@x335a rtc]#
>>>
>>>
>>>
>>> In fact while compiling there is some warning also.
>>> [r...@x335a rtc]# make
>>> cc rtc-test.c -O2 -Wall -I ../../../../include/ -L ../../../../lib/
>>> -lltp  -o rtc-test
>>> rtc-test.c: In function ‘read_alarm_test’:
>>> rtc-test.c:64: warning: dereferencing type-punned pointer will break
>>> strict-aliasing rules
>>
>> I did not get this warning on gcc-4.3.0 . Anyways I think we can get rid
>> of this
>> warning by using -fno-strict-aliasing option at the cost of some
>> optimizations.
>> I will send you another patch.
>>
>
> Or maybe just fix the code to not type-pun by converting everything to
> struct tm on the fly?
>
> Let's look at the difference between the two structures:
>
> struct rtc_time {
>         int tm_sec;
>         int tm_min;
>         int tm_hour;
>         int tm_mday;
>         int tm_mon;
>         int tm_year;
>         int tm_wday;
>         int tm_yday;
>         int tm_isdst;
> };
>
> struct tm
> {
>   int tm_sec;                   /* Seconds.     [0-60] (1 leap second) */
>   int tm_min;                   /* Minutes.     [0-59] */
>   int tm_hour;                  /* Hours.       [0-23] */
>   int tm_mday;                  /* Day.         [1-31] */
>   int tm_mon;                   /* Month.       [0-11] */
>   int tm_year;                  /* Year - 1900.  */
>   int tm_wday;                  /* Day of week. [0-6] */
>   int tm_yday;                  /* Days in year.[0-365] */
>   int tm_isdst;                 /* DST.         [-1/0/1]*/
>
> #ifdef  __USE_BSD
>   long int tm_gmtoff;           /* Seconds east of UTC.  */
>   __const char *tm_zone;        /* Timezone abbreviation.  */
> #else
>   long int __tm_gmtoff;         /* Seconds east of UTC.  */
>   __const char *__tm_zone;      /* Timezone abbreviation.  */
> #endif
> };
>
> Note the extra fields down below -- they increase the structure size
> by a non-trivial amount (12 bytes on 32-bit, 16 bytes on 64-bit),
> which means that if one of the following two cases are made in
> strftime tomorrow:
>
> 1. They use one of the timezone fields and it isn't properly cleared
> (not the case today, but it could be on some older versions of Linux).
> 2. They make assumptions about the size of the memory allocated and
> thus go out of bounds.
>
> BOOM! Segfault... could worse happen in this case after the ioctl is
> written out to /dev/rtc ?

OK. Can we drop strftime then ?


>
>>> Please solve these problems and please send me a revised patch.
>
> Thanks,
> -Garrett
>


-- 
Silesh

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