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POGetting Segmentation Fault in C program
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copied!<p>I am getting segmentation fault on line 8 in the code below.</p> <pre><code>typedef struct _my_struct { int pArr[21]; int arr1[8191]; int arr2[8191]; int m; int cLen; int gArr[53]; int dArr[8191]; int data[4096]; int rArr[53]; int eArr[1024]; }; void *populate_data(void *arg) { 1 register int mask =1, iG; 2 struct _my_struct *var ; 3 var = arg; // arg is passed as initialized struct variable while creating thread 4 var->m = 13; 5 var->arr2[var->m] = 0; 6 for (iG = 0; iG < var->m; iG++) { 7 var->arr2[iG] = mask; 8 var->arr1[var->arr2[iG]] = iG; 9 if (var->pArr[iG] != 0) // pArr[]= 1011000000001 10 var->arr2[var->m] ^= mask; 11 mask <<= 1; 12 } 13 var->arr1[var->arr2[var->m]] = var->m; 14 mask >>= 1; 15 for (iG = var->m+ 1; iG < var->cLen; iG++) { 16 if (var->arr2[iG - 1] >= mask) 17 var->arr2[iG] = var->arr2[var->m] ^ ((var->arr2[iG- 1] ^ mask) << 1); 18 else 19 var->arr2[iG] = var->arr2[iG- 1] << 1; 20 var->arr1[var->arr2[iG]] = iG; 21 } 22 var->arr1[0] = -1; } </code></pre> <p>Here is the thread function:</p> <pre><code>void main() { unsigned int tid; struct _my_struct *instance = NULL; instance = (struct _my_struct *)malloc(sizeof(_my_struct )); start_thread(&tid , 119312, populate_data, instance ); } int start_thread(unsigned int *tid, int stack_size, void * (*my_function)(void *), void *arg) { pthread_t ptid = -1; pthread_attr_t pattrib; pthread_attr_init(&pattrib); if(stack_size > 0) { pthread_attr_setstacksize(&pattrib, stack_size); } else { pthread_attr_destroy(&pattrib); return -1; } pthread_create(&ptid, &pattrib, my_function, arg); pthread_attr_destroy(&pattrib); return 0; } </code></pre> <p>Once I debug it through gdb, got this error, </p> <pre><code>Program received signal SIGSEGV, Segmentation fault. [Switching to Thread 0x7ffdfec80700 (LWP 22985)] 0x0000000000401034 in populate_data (arg=0x7fffffffe5d8) at Queue.c:19 19 var->arr1[var->arr2[iG]] = iG; </code></pre> <p>and its backtrace is:</p> <pre><code>#0 0x0000000000401034 in populate_data (arg=0x7fffffffe5d8) at Queue.c:159 #1 0x00007ffff7bc6971 in start_thread () from /lib/libpthread.so.0 #2 0x00007ffff792292d in clone () from /lib/libc.so.6 #3 0x0000000000000000 in ?? () </code></pre> <p>However, I'm unable to correct the error.</p> <p>Anyhelp is really appreciated.</p>

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