RFR(M): 8038201: Clean up misleading usage of malloc() in init_system_properties_values()
Dmitry Samersoff
dmitry.samersoff at oracle.com
Thu Mar 27 09:49:11 UTC 2014
Goetz,
Thank you for doing it - code is much cleaner now.
os_aix.cpp:
Did you forget FREE_C_HEAP_ARRAY() at ll.548 and ll.576?
os_bsd.cpp:
missed FREE_C_HEAP_ARRAY() at ll. 389, ll. 477
ll.407 sprintf could be moved to ll.420 under else
ll.497 (and below) a trick like one below:
char *l = ::getenv("JAVA_LIBRARY_PATH");
char *v = ::getenv("DYLD_LIBRARY_PATH");
char *v_colon = ":";
if (l != NULL || v != NULL) {
if (v == NULL){ v = "", v_colon = ""; };
if (l == NULL){ l = "", v_colon = ""; };
t = (char *) ... /* allocate memory for all strings */
sprintf(t, "%s%s%s:%s", v,v_colon, l, ld_library_path);
if (ld_library_path != buf){ ... /* free ld_library_path */ }
ld_library_path = t;
}
might be useful to assemble the path in one shot,
without extra copying
ll.520 As you appending constant value ":.", you can just
take it into account at ll. 495
os_linux.cpp:
missed FREE_C_HEAP_ARRAY() at ll. 400
os_solaris.cpp:
missed FREE_C_HEAP_ARRAY() at ll. 714
-Dmitry
On 2014-03-27 12:54, Lindenmaier, Goetz wrote:
> Hi,
>
> please have a look at this new webrev:
> http://cr.openjdk.java.net/~goetz/webrevs/8038201-sec/webrev.02/
>
> Dmitry, sorry I forgot to reply to all in my last mail. I copied the missing parts in here, below.
>
> Avoiding big stack allocations I wanted to remove the buf[MAXPATHLEN]
> at the beginning of the function, too. That's why I said I can't get along
> with a single allocation. strlen(v) is only known later.
>
> I could redesign the whole code, computing sizes first, and then
> doing a single allocation, but I think that doesn't help the
> readability of the code.
>
> So now I compute the max size of all buffers I can estimate at the beginning
> and do a single allocation for them.
> Also, bsd contains an extra section for __APPLE__.
>
> Best regards,
> Goetz.
>
>
>
> Goetz,
>
>> The allocation in 556 must know about the length of the
>> getenv("LIBPATH") result, which may contain several paths.
>
> You can use
>
> MAX(
> strlen(v) + 1 + sizeof(DEFAULT_LIBPATH) + 1,
> MAXPATHLEN + sizeof(EXTENSIONS_DIR) + sizeof(ENDORSED_DIR)
> )
>
> as the size for a buffer at ll. 556 and have one allocation.
>
> But I'm fine with two different allocations.
>
> Thank you for addressing other concerns.
>
> -Dmitry
>
> On 2014-03-25 17:55, Lindenmaier, Goetz wrote:
>> Hi Dmitry,
>>
>> see my comments inline.
>>
>>> -----Original Message-----
>>> From: Dmitry Samersoff [mailto:dmitry.samersoff at oracle.com]
>>> Sent: Dienstag, 25. März 2014 11:12
>>> To: Lindenmaier, Goetz; hotspot-dev at openjdk.java.net; ppc-aix-port-dev at openjdk.java.net
>>> Subject: Re: RFR(M): 8038201: Clean up misleading usage of malloc() in init_system_properties_values()
>>>
>>> Goetz,
>>>
>>> os_aix.cpp: 565
>>>
>>> It might be better to allocate one buffer that satisfy all three
>>> sprintf() calls at ll. 556 and free it at ll. 574
>> I need at least two allocations. The first one has a statically known size. At
>> least more or less, as I know there will be only one path of unknown size in the buffer.
>> The allocation in 556 must know about the length of the getenv("LIBPATH") result,
>> which may contain several paths.
>> Also, in the other files, paths are concatenated, so at least two buffers are needed.
>>
>>> os_bsd.cpp: 350
>>>
>>> I would prefer to have the single #ifdef __APPLE__ block, it makes
>>> code much more readable.
>> I'll fix this.
>>
>>> os_bsd.cpp: 485
>>>
>>> you replace malloc to on-stack allocation of more than 4096 bytes. I
>>> think this allocation should be done through NEW_C_HEAP_ARRAY.
>> > see also comments to os_aix above - you can allocate large enough
>>> buffer once and than reuse it.
>> Is there a boundary at 4k? There was a char buf[MAXPATHLEN] in the
>> code anyways, so I thought a few bytes more would not matter.
>> The space required by the existing buf can be reused by the C compiler.
>>
>> But I'll fix that and only use allocated memory.
>> I'll remove the buf that was already there and replace all spaces
>> I can estimate by MAXPATHLEN + some offset by a single, allocated buffer.
>> I'll do this the same on all four platforms.
>>
>>> os_linux.cpp: 434
>>> the same comments as above.
>>>
>>> os_solaris.cpp: 728
>>>
>>> As soon as you doing cleanup, I would love to have this code changed
>>> a bit. It comes from solaris man page long time ago and doesn't respect
>>> hotspot convention of using underscore to indicate class global variables.
>>>
>>> Could you change it to something like:
>>> Dl_serinfo info_sz, *info;
>> Yes, I'll fix that.
>>
>> Best regards,
>> Goetz.
>>
>>
>>
>
>
> if (dlinfo(RTLD_SELF, RTLD_DI_SERINFOSIZE, (void *)&info_sz) == -1) {
> ...
>
> info = (Dl_serinfo*)NEW_C_HEAP_ARRAY(char, info_sz.dls_size, mtInternal);
> ...
>
> os_solaris.cpp: 829
> The same comment about on-stack allocation as for os_bsd.cpp
>
> -Dmitry
>
> On 2014-03-25 01:50, Lindenmaier, Goetz wrote:
>> Hi,
>>
>> please review and test this change. I please need a sponsor.
>> http://cr.openjdk.java.net/~goetz/webrevs/8038201-sec/webrev.00/
>>
>> This change addresses the implementation of init_system_properties_values
>> on aix, linux, solaris and bsd.
>> In init_system_properties_values a macro was defined mapping malloc to
>> NEW_C_HEAP_ARRAY. NEW_C_HEAP_ARRAY checks for successful allocation
>> or exits the VM. The code of this method handles the allocated pointers as
>> allocated with real malloc, i.e., there were checks for NULL and calls to free().
>>
>> This change replaces the macro malloc with NEW_C_HEAP_ARRAY and removes
>> the unnecessary checks making the code clearer. Also, it uses a local array where
>> possible.
>>
>> The allocated memory is passed to calls that end up at SystemProperty::set_value().
>> set_value copies the strings passed. Thus the memory allocated in
>> init_system_properties_values must be freed after these calls. Most of these
>> frees were missing.
>>
>> This change adds the missing frees.
>>
>> Testing this change I ran into a warning in ppc code which I fixed, too.
>> I did some local test. I'll get broader tests by Wednesday.
>>
>> Best regards,
>> Goetz.
>>
>>
>
>
--
Dmitry Samersoff
Oracle Java development team, Saint Petersburg, Russia
* I would love to change the world, but they won't give me the sources.
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