Initial commit.
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commit
cacea349d3
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#include <stdio.h>
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#include <stdlib.h>
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#include <signal.h>
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#include <math.h>
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#include <unistd.h>
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#include <pthread.h>
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// Function definitions.
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void stack();
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void heap();
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void address();
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void sigHandler(int);
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/*
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* Learned about these from:
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* https://linux.die.net/man/3/etext
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*/
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extern char etext, edata, end;
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// Data variables.
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int UNINITIALIZED1;
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int INITIALIZED1 = 0;
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int INITIALIZED2 = 0;
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int INITIALIZED3 = 0;
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int UNINITIALIZED2;
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int UNINITIALIZED3;
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int UNINITIALIZED4;
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int INITIALIZED4 = 0;
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/**
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* Main function for driving program.
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*/
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int main()
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{
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// Binding signal handler.
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signal(SIGINT, sigHandler);
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/*
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* Getting addresses relating to static program segments
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* (See man page referenced above for sample code)
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*/
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printf("===\n");
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printf("First address past:\n");
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printf("Program text (etext) %10p\n", &etext);
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printf("Initialized data (edata) %10p\n", &edata);
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printf("Uninitialized data (end) %10p\n", &end);
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printf("===\n");
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// Getting some initialized data addresses.
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printf("INITIALIZED\n");
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printf("1: %p\n", &INITIALIZED1);
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printf("2: %p\n", &INITIALIZED2);
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printf("3: %p\n", &INITIALIZED3);
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printf("4: %p\n", &INITIALIZED4);
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printf("===\n");
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// Getting some unitialized data addresses.
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printf("UNINITIALIZED\n");
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printf("1: %p\n", &UNINITIALIZED1);
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printf("2: %p\n", &UNINITIALIZED2);
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printf("3: %p\n", &UNINITIALIZED3);
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printf("4: %p\n", &UNINITIALIZED4);
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printf("===\n");
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// Adding some variables on the stack (will be stored in reverse).
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int stackvar1 = 12313;
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int stackvar2 = 12313;
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int stackvar3 = 12313;
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// Main stack addresses.
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printf("Main Stack\n");
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printf("%p\n", &stackvar1);
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printf("%p\n", &stackvar2);
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printf("%p\n", &stackvar3);
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printf("===\n");
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// Function stack addresses (should be lower than main).
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printf("Function Call Stack\n");
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stack();
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printf("===\n");
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// Printing heap addresses.
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heap();
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// Getting the address of the pow function.
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printf("Address of pow: %p\n", &pow);
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// Getting the address of the pthread_create function.
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address();
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// Pausing so we can examine headers / maps info.
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pause();
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// Probably never will reach here, but bye if we do.
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return 0;
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}
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/**
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* Puts some variables in the function's
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* stack frame and prints out their addresses.
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* Should be lower than main function's addresses,
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* although variables seem to increase in address
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* as we print them out (vars stored in reverse
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* order on the stack)
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*/
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void stack()
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{
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int stackvar1 = 12313;
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int stackvar2 = 12313;
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int stackvar3 = 12313;
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printf("%p\n", &stackvar1);
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printf("%p\n", &stackvar2);
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printf("%p\n", &stackvar3);
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}
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/**
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* Asks for some heap space and prints out the
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* locations of the memory we receive.
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*/
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void heap()
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{
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printf("Heap\n");
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char *heap1 = malloc(16 * sizeof(char));
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char *heap2 = malloc(32 * sizeof(char));
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char *heap3 = malloc(64 * sizeof(char));
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char *heap4 = malloc(128 * sizeof(char));
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char *heap5 = malloc(256 * sizeof(char));
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char *heap6 = malloc(512 * sizeof(char));
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char *heap7 = malloc(1024 * sizeof(char));
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char *heap8 = malloc(2048 * sizeof(char));
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printf("1: %p\n", heap1);
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printf("2: %p\n", heap2);
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printf("3: %p\n", heap3);
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printf("4: %p\n", heap4);
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printf("5: %p\n", heap5);
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printf("6: %p\n", heap6);
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printf("7: %p\n", heap7);
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printf("8: %p\n", heap8);
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printf("===\n");
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free(heap1);
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free(heap2);
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free(heap3);
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free(heap4);
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free(heap5);
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free(heap6);
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free(heap7);
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free(heap8);
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}
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/**
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* Prints a function address from a dynamic library.
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*/
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void address()
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{
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printf("Address of pthread_create: %p\n", &pthread_create);
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}
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/**
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* Handler for signals. Bound for the one signal handled
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* in this application: SIGINT (program interrupt signal ^C).
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*
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* @param sigNum, the identifying number of the signal
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* sent and now being handled. According to the
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* man page for signal, SIGINT = 2.
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*/
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void sigHandler(int sigNum)
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{
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// Just exit if we ^C.
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if (sigNum == SIGINT)
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{
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// Exiting program.
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exit(0);
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}
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}
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@ -0,0 +1,10 @@
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The segments in the diagram below are organized from higher addresses to lower addresses.
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| Location in Test Program Run | Segment | Direction of Growth |
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|:-:|:-:|:-:|
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| 0x7ffc1f885000 to 0x7ffc1f864000 | Stack | Grows ↓ |
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| 0x7fc7431f9000 to 0x7fc742e49000 | Shared C Libraries | Grows ↓ |
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| 0x55772bca6000 to 0x55772bc85000 | Heap / Runtime Data | Grows ↑ |
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| Ends at 0x55772a3aa090 | Uninitialized Data | N/A |
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| Ends at 0x55772a3aa068 | Initialized Data | N/A |
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| Ends at 0x55772a3a76f5 | Program Text | N/A |
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