Andrew Haynes
318 lines
10 KiB
C
318 lines
10 KiB
C
#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <time.h>
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#include <limits.h>
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typedef struct {
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char* arr;
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size_t size;
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size_t capacity;
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} Vec8_t;
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Vec8_t create(Vec8_t* input) {
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Vec8_t vec = { .arr = nullptr, .size = 0, .capacity = 4 };
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if(input == nullptr) {
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vec.arr = calloc(vec.capacity, sizeof(char));
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return vec;
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}
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if (input->size > 0) {
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vec.size = input->size + 1;
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}
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if (input->capacity >= vec.capacity) {
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vec.capacity = 2 * input->capacity;
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}
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vec.arr = calloc(vec.capacity, sizeof(char));
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return vec;
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}
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void delete(Vec8_t* vec) {
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if (vec->arr != nullptr) free(vec->arr);
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vec->arr = nullptr;
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}
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char at(Vec8_t* vec, int idx) {
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if (vec == nullptr) return -2;
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if (vec->arr == nullptr) return -3;
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if (vec->size <= idx) return -4;
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if (vec != nullptr && vec->arr != nullptr && vec->size > idx) {
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return vec->arr[idx];
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}
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return -1;
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}
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int begin(Vec8_t* vec) {
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if (vec != nullptr && vec->arr != nullptr && vec->size > 0) return 0;
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return -1;
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}
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int end(Vec8_t* vec) {
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if (vec != nullptr && vec->arr != nullptr && vec->size > 0) return (int)(vec->size - 1);
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return -1;
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}
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char front(Vec8_t* vec) {
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return at(vec, 0);
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}
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char back(Vec8_t* vec) {
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if (vec) return at(vec, (int)vec->size - 1);
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return -1;
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}
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Vec8_t add_back(Vec8_t* vec, char val) {
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Vec8_t ret = { .arr = nullptr, .capacity = 0, .size = 0 };
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if (vec->size < vec->capacity) {
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vec->arr[vec->size] = val;
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vec->size++;
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return *vec;
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}
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if (vec->size >= vec->capacity) {
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Vec8_t nvec = create(vec);
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memcpy(&nvec.arr[0], &vec->arr[0], vec->size * sizeof(char));
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if (nvec.arr && (nvec.size > 0 || nvec.size > vec->size)) {
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nvec.arr[vec->size] = val;
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}
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free(vec->arr);
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return nvec;
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}
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return ret;
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}
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int tests_passed = 0;
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int tests_failed = 0;
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int test_num = 0;
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void test(const char* name, int passed) {
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test_num++;
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if (passed) {
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printf("[PASS] #%d: %s\n", test_num, name);
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tests_passed++;
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} else {
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printf("[FAIL] #%d: %s\n", test_num, name);
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tests_failed++;
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}
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}
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int main() {
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printf("=== EDGE CASE BRUTAL TESTS ===\n\n");
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Vec8_t vec;
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char* ptr;
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// === Test 1: Use after reallocation (expected behavior) ===
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printf("--- Reallocation Behavior ---\n");
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vec = create(nullptr);
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for (int i = 0; i < 10; i++) vec = add_back(&vec, (char)('A' + i));
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ptr = vec.arr; // save pointer (will be freed on next realloc)
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for (int i = 0; i < 100; i++) vec = add_back(&vec, (char)('0' + (i % 10)));
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// Pointer changes after reallocation - this is expected
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test("after reallocation, vec.arr is new", ptr != vec.arr);
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test("data preserved in new vec", vec.arr[0] == 'A' && vec.arr[9] == 'J');
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test("vec must be reassigned: vec = add_back()", 1);
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delete(&vec);
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// === Test 2: Stack-allocated struct (not created via create) ===
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printf("\n--- Stack-Allocated Struct ---\n");
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Vec8_t stack_vec;
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stack_vec.arr = nullptr;
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stack_vec.size = 0;
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stack_vec.capacity = 0;
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// This will fail because capacity starts at 0, not 4
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// and there's no way to use add_back properly
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// BUG: User can't easily use functions without calling create()
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test("stack vec: add_back modifies nothing (capacity 0)", 1); // informational
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// === Test 3: Integer overflow potential ===
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printf("\n--- Integer Overflow ---\n");
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// If someone passes SIZE_MAX or near-max to create
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// The doubling could overflow
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vec = create(nullptr);
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vec.capacity = (size_t)-1; // max size_t
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vec.size = 0;
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vec.arr = calloc(1, 1); // tiny allocation
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// BUG: 2 * capacity overflows to 0
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size_t doubled = 2 * vec.capacity;
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test("2 * SIZE_MAX overflows (demonstrates overflow)", 1); // informational
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free(vec.arr);
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// === Test 4: Negative index with signed int ===
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printf("\n--- Signed/Unsigned Mixing ---\n");
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vec = create(nullptr);
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vec = add_back(&vec, 'X');
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int neg_idx = -1;
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// BUG: -1 as unsigned is huge, causing out-of-bounds access
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char result = at(&vec, neg_idx);
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test("at() with negative -1 returns error", result == -4);
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neg_idx = -2147483648;
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result = at(&vec, neg_idx);
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test("at() with INT_MIN returns error", result == -4);
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delete(&vec);
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// === Test 5: Size very large ===
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printf("\n--- Huge Size Values ---\n");
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vec = create(nullptr);
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vec.size = 1000000; // manually corrupt size (bad user code)
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vec.capacity = 4;
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vec.arr = calloc(4, 1);
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// BUG: size > capacity, add_back will try to create with size+1 = 1000001
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// which allocates based on old logic
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result = at(&vec, 0);
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// Should still work for valid indices within actual capacity
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test("at() works for valid idx despite bad size", result == 0);
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delete(&vec);
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// === Test 6: Uninitialized struct ===
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printf("\n--- Uninitialized Struct ---\n");
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Vec8_t uninit;
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// BUG: arr, size, capacity contain garbage
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// Any function call is undefined behavior
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printf(" Calling at() on uninitialized struct...\n");
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printf(" This is undefined behavior - results unpredictable!\n");
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test("uninitialized: expect garbage or crash (UB)", 1); // informational
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// === Test 7: Capacity not matching allocation ===
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printf("\n--- Capacity Mismatch ---\n");
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vec = create(nullptr);
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vec.arr = realloc(vec.arr, 1000); // manually grow
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vec.capacity = 1000; // but don't tell anyone
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for (int i = 0; i < 50; i++) vec = add_back(&vec, (char)i);
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test("manual realloc: capacity grows (add_back doesn't know)", 1); // informational
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delete(&vec);
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// === Test 8: memcpy with null ===
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printf("\n--- Memcpy Edge Cases ---\n");
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vec = create(nullptr);
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vec.size = 0;
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// BUG: memcpy(&vec.arr[0], &vec.arr[0], 0) - this is actually fine (no-op)
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for (int i = 0; i < 5; i++) vec = add_back(&vec, (char)('A' + i));
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test("empty memcpy edge case: works fine", vec.size == 5);
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delete(&vec);
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// === Test 9: Return value ignored ===
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printf("\n--- Ignored Return Values ---\n");
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vec = create(nullptr);
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add_back(&vec, 'X'); // Modifies in-place when capacity available
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test("add_back modifies in-place when capacity available", vec.size == 1);
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test("data stored correctly", vec.arr[0] == 'X');
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// Fill to capacity (4): size goes 1->4
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for (int i = 0; i < 3; i++) vec = add_back(&vec, (char)('A' + i));
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// Now size=4, cap=4
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// Add more: this triggers reallocation (size >= capacity)
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char* old_ptr = vec.arr;
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vec = add_back(&vec, 'Z'); // reallocates! size becomes 5, cap becomes 8
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test("reallocation triggered", old_ptr != vec.arr);
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test("realloc: data preserved in new vec", vec.arr[4] == 'Z');
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delete(&vec);
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// === Test 10: Multiple vectors, aliasing ===
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printf("\n--- Aliasing Issues ---\n");
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Vec8_t v1 = create(nullptr);
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Vec8_t v2 = create(nullptr);
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for (int i = 0; i < 5; i++) v1 = add_back(&v1, (char)('A' + i));
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for (int i = 0; i < 5; i++) v2 = add_back(&v2, (char)('1' + i));
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test("v1 and v2 are separate", v1.arr != v2.arr);
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test("v1 data correct", v1.arr[0] == 'A');
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test("v2 data correct", v2.arr[0] == '1');
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delete(&v1);
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delete(&v2);
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// === Test 11: Freeing already-freed memory ===
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printf("\n--- Double Free ---\n");
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vec = create(nullptr);
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vec = add_back(&vec, 'X');
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char* data = vec.arr;
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delete(&vec);
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free(data); // BUG: double free!
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printf(" Double free detected (would crash with sanitizers)\n");
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test("double free: undefined behavior", 1); // informational
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// === Test 12: Realloc failure ===
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printf("\n--- Realloc Failure ---\n");
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// Hard to test without mocking, but conceptually:
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// If malloc/calloc fails, the library doesn't check
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// BUG: nvec.arr could be NULL, then memcpy with NULL crashes
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printf(" If realloc fails: nvec.arr is NULL, memcpy crashes\n");
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test("no malloc failure check in create()", 1); // informational
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// === Test 13: Reading freed memory ===
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printf("\n--- Use After Delete ---\n");
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vec = create(nullptr);
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for (int i = 0; i < 10; i++) vec = add_back(&vec, (char)i);
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delete(&vec);
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// BUG: vec.arr is nullptr, vec.size is still 10
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// User might expect size to be 0 after delete
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test("after delete: arr is null", vec.arr == nullptr);
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test("after delete: size is still 10 (not cleared)", vec.size == 10);
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test("after delete: accessing returns error", at(&vec, 0) == -3);
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// === Test 14: Size 0 with capacity 0 ===
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printf("\n--- Size/Capacity Edge ---\n");
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vec.arr = malloc(100);
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vec.size = 0;
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vec.capacity = 100;
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// BUG: begin() checks size > 0, so returns -1 even though we have capacity
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test("begin() returns -1 when size=0", begin(&vec) == -1);
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test("end() returns -1 when size=0", end(&vec) == -1);
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test("front() returns -4 when size=0", front(&vec) == -4);
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test("back() returns -4 when size=0", back(&vec) == -4);
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free(vec.arr);
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// === Test 15: Concurrent modification (conceptual) ===
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printf("\n--- Iterator Invalidation Concept ---\n");
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vec = create(nullptr);
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for (int i = 0; i < 10; i++) vec = add_back(&vec, (char)('A' + i));
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// If user iterates while adding:
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// for (int i = 0; i < 1000; i++) {
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// if (i == 10) vec = add_back(&vec, 'Z'); // reallocation!
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// use vec.arr[i]; // BUG: pointer invalid after realloc
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// }
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printf(" Iteration + reallocation invalidates pointers\n");
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test("conceptual: iteration during add_back is unsafe", 1);
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delete(&vec);
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// === Summary ===
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printf("\n=== Summary ===\n");
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printf("Passed: %d\n", tests_passed);
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printf("Failed: %d\n", tests_failed);
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printf("Note: 'informational' tests always pass, real bugs above\n");
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return 0;
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}
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