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VC++ 6.0 : system() library call is leaking

Posted on 2006-06-15
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Last Modified: 2012-05-05
Hi,

sytem() library call caused 776 bytes memory leak.

Could u pls explain to delete this memory.

System is spawning a process to execute the given command .
The   CreateProcessW function from  kernel32.dll has allocated some memory from the heap which it has not deallocated. This seems to be causing the memory leak.
How do we get around this problem?
The following is the snapshot of Purify showing the leak.

-------------------------------------------------------------------------------
[W] MLK: Memory leak of 776 bytes from 2 blocks allocated in CreateProcessW [kernel32.dll]

    Allocation location
        RtlAllocateHeap [NTDLL.dll]
        CreateProcessW [kernel32.dll]
        dospawn        [dospawn.c:188]
                                                         NULL,
                                                         &StartupInfo,
                                                         &ProcessInformation
         =>                                            );
           
                    dosretval = GetLastError();
                    _free_crt( StartupInfo.lpReserved2 );
        comexecmd      [spawnve.c:122]
            #ifdef WPRFLAG
                    rc = _wdospawn(mode, name, argblk, envblk);
            #else  /* WPRFLAG */
         =>         rc = _dospawn(mode, name, argblk, envblk);
            #endif  /* WPRFLAG */
            #else  /* EXECVE */
            #ifdef WPRFLAG
        spawnve        [spawnve.c:260]
            #ifdef WPRFLAG
                                    rc = wcomexecmd(mode, pathname, argv, envp);
            #else  /* WPRFLAG */
         =>                         rc = comexecmd(mode, pathname, argv, envp);
            #endif  /* WPRFLAG */
           
            #else  /* EXECVE */
        system         [system.c:69]
           
                    if (argv[0])    /* Do not try to spawn the null string */
                            if ((catch = _tspawnve(_P_WAIT,argv[0],argv,NULL)) != -1
         =>                 || (errno != ENOENT && errno != EACCES))
                                    return(catch);
           
                    /* No COMSPEC so set argv[0] to what COMSPEC should be. */
       
         =>         i=system(pCopyFile);
                    if(0!=i)
-------------------------------------------------------------------------------
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Question by:k_kalyan
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4 Comments
 
LVL 86

Accepted Solution

by:
jkr earned 63 total points
ID: 16913517
>>       =>         i=system(pCopyFile);

If you want to copy a file, use 'CopyFile()', e.g.

CopyFile("c:\\tmp\\file1.txt","c:\\tmp\\file2.txt", FALSE);

BTW, Purify seems to be wrong about the error. Just examine 'dospawn.c'.
0
 
LVL 11

Assisted Solution

by:cup
cup earned 62 total points
ID: 17027241
Is it a one off leak or does it leak every time you call the routine?  Most systems have a one off leak that isn't worth bothering about because when the process is killed, the OS will get rid of it for you.
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