[LTP] [ ltp-Bugs-1537172 ] Improper condition decision of mmap()

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Bugs item #1537172, was opened at 2006-08-09 06:18
Message generated for change (Comment added) made by subrata_modak
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Category: Testcases
Group: Inter-Process Comm. (IPC)
>Status: Closed
>Resolution: Fixed
Priority: 5
Private: No
Submitted By: Kongh (bstqc-kh)
Assigned to: mreed (mreed10)
Summary: Improper condition decision of mmap()

Initial Comment:
ltp-full-
20060717\testcases\kernel\ipc\ipc_stress\shmem_test_02.
c
After type "./shmem_test_02", I got the error message:
ERROR [line: 183] mmap failed: Success
------------------------------------------

Checking code:
179:        shmem_size = sizeof (unsigned long);
180:        if ((long)(checksum = (unsigned long *)
181:                    mmap (0, shmem_size, PROT_READ 
| PROT_WRITE,
182:                          MAP_ANON | MAP_SHARED, -
1, 0)) < 0)
183:                    sys_error ("mmap failed", 
__LINE__);

mmap() here is supposed to do a anonymous mapping, if 
mmap() exit unsuccessful, it returns '-1', but I don't 
think "< 0" can work correctly everywhere and 
everywhen. 

consider the range of "unsigned long" and "long":
long:　-2147483648~2147483647
unsigned long:　0~4294967295
if a "unsigned long" number is large than 2147483647 
and be transformed to "long" violently, something 
unsupposed would happen.

in my test, I got value 3086903536 from (unsigned long 
*)mmap(...) , after transforming to "long", it turned 
to -1208053760 and triggered the sys_error("mmap 
failed", __LINE__).

Maybe it's more wise of changing the determinant 
condition "< 0" to " == -1" .

----------------------------------------------------------------------

>Comment By: Subrata (subrata_modak)
Date: 2007-05-09 10:13

Message:
Logged In: YES 
user_id=1737361
Originator: NO

Fix included into Code.
Regards--
Subrata

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