copy a file in safe and efficient way in thread - c++

Question

I'm trying to copy the contents of tempFile to CacheFile in a thread in safe and
efficient way.
what is myscript takes 1-2 min times to write to a file (ie. tempFile) and after sucessfull .I need to copy to cacheFile so who ever call the function (getStudentDetails) will get serve from cachefile rather than tempFile to avoid the delay(though first call always will be delay for 1-2 min since cacheFIle will empty).
Note: I NEED TO USE FILE NOT PRIMARY STORAGE
Below is my approach it working fine but can it be more efficient and safe?
bool unlock=true;
pthread_mutex_t count_mutex = PTHREAD_MUTEX_INITIALIZER;
pthread_cond_t condition_var = PTHREAD_COND_INITIALIZER;
void * runScriptAndUpdateCacheFile ( void * arg )
{
std::cout<<"Inside thread lock"<<endl;
unlock=false; // to avoid multiple call to this thread till it get complete
char tempFile[32]={0};
strncpy(tempFile,"/tmp/smbXXXXXX",14); // tempFile is the main file where my script will dump the output
if( mkstemp(tempFile) < 1)
{
cout<<"fail to create temp file"<<endl;
return (NULL);
}
if (tempFile != NULL)
{
char command[256] = {0};
sprintf(command, " myscript > %s", tempFile);
int status=system(command); // write ouput of script to tempFile
if (status < 0)
{
std::cout << "Error: " << strerror(errno) << '\n';
return(NULL);
}
else
{
if (WIFEXITED(status)) // fetch exit code
{
std::cout << "Program returned normally, exit code " << WEXITSTATUS(status) << '\n';
std::ifstream src(tempFile, std::ios::binary);
std::ofstream CacheFile((char*)arg, std::ios::binary);
Cache << src.rdbuf(); // Copy to cacheFile
}
else
{
std::cout << "Program exited abnormaly\n";
return(NULL);
}
}
}
cout<<" thread is unlock"<<endl;
unlock=true;
}
getStudentDetails can be called multiple times
void getStudentDetails()
{
pthread_t threads;
char CacheFile[32]={0};
strncpy(CacheFile,"/tmp/CacheFile",19);
//Serve from CacheFile rather than orignal file coz this file
//will take 1-2 min to dump in it
std::ifstream fin(CacheFile);
if(unlock) // to avoid multiple call to thread when multile call made to getStudentDetails
// this unlock is made false when it enter to thread and made true when exit
{
pthread_mutex_lock( &count_mutex );
int rc = pthread_create(&threads, NULL, runSmbtree, CacheFile); // pass cache file to thread this file will get updated with
// orignal file create by script.
pthread_mutex_unlock( &count_mutex );
}
std::string line;
while (getline(fin, line))
{
// reading Cachefile and serveing when getStudentDetails called by client
}
}
Valgrind complains with below error
=3535== HEAP SUMMARY:
==3535== in use at exit: 864 bytes in 3 blocks
==3535== total heap usage: 169 allocs, 166 frees, 78,323 bytes allocated
==3535==
==3535== Searching for pointers to 3 not-freed blocks
==3535== Checked 25,373,616 byte
==3535==
==3535== Thread 1:
==3535== 864 bytes in 3 blocks are possibly lost in loss record 1 of 1
==3535== at 0x4C2CC70: calloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==3535== by 0x4012E54: allocate_dtv (dl-tls.c:296)
==3535== by 0x4012E54: _dl_allocate_tls (dl-tls.c:460)
==3535== by 0x5359DA0: allocate_stack (allocatestack.c:589)
==3535== by 0x5359DA0: pthread_create##GLIBC_2.2.5 (pthread_create.c:500)
==3535==
==3535== LEAK SUMMARY:
==3535== definitely lost: 0 bytes in 0 blocks
==3535== indirectly lost: 0 bytes in 0 blocks
==3535== possibly lost: 864 bytes in 3 blocks
==3535== still reachable: 0 bytes in 0 blocks
==3535== suppressed: 0 bytes in 0 blocks
==3535==
==3535== ERROR SUMMARY: 3 errors from 2 contexts (suppressed: 0 from 0)
==3535==
==3535== 2 errors in context 1 of 2:
==3535== Thread 2:
==3535== Syscall param open(filename) points to unaddressable byte(s)
==3535== at 0x565B4CD: ??? (syscall-template.S:81)
==3535== by 0x55E9E07: _IO_file_open (fileops.c:228)
==3535== by 0x55E9E07: _IO_file_fopen##GLIBC_2.2.5 (fileops.c:333)
==3535== by 0x55DE2E3: __fopen_internal (iofopen.c:90)
==3535== by 0x4EB29BF: std::__basic_file::open(char const*, std::_Ios_Openmode, int) (in
/usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.19)
==3535== by 0x4EEAEA9: std::basic_filebuf >::open(char const*, std::_Ios_Openmode) (in
/usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.19)
==3535== by 0x4EEC747: std::basic_ofstream >::basic_ofstream(char const*,
std::_Ios_Openmode) (in
/usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.19)
==3535== by 0x40200B: runScriptAndUpdateCacheFile(void*) (in ***)
==3535== by 0x5359181: start_thread (pthread_create.c:312)
==3535== by 0x566A30C: clone (clone.S:111)
==3535== Address 0xffefffba0 is on thread 1's stack
==3535== 384 bytes below stack pointer
==3535==
==3535== ERROR SUMMARY: 3 errors from 2 contexts (suppressed: 0 from 0)