82 lines
1.7 KiB
C
Executable File
82 lines
1.7 KiB
C
Executable File
#include <errno.h>
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#include <stdbool.h>
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#include <stdint.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#define NUM_ELEMENTS 8
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typedef struct creds creds_t;
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typedef struct creds {
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void (*welcome)(void);
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uint64_t buffer[NUM_ELEMENTS];
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} creds_t;
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static creds_t *creds;
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/* internal prototypes */
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static void insert(uint64_t value, int64_t index);
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static void print(void);
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static void s3cr3t(void);
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/* entry point */
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int main(int argc, char **argv) {
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if (argc < 3) {
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printf("usage: %s <hex value> <index>\n", argv[0]);
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return -1;
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}
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char *endptr;
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errno = 0;
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uint64_t value = (uint64_t)strtoull(argv[1], &endptr, 16);
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if (errno || *endptr) {
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fprintf(stderr, "Conversion error, non-convertible part: %s\n", endptr);
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exit(EXIT_FAILURE);
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}
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errno = 0;
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uint64_t index = (uint64_t)strtoull(argv[2], &endptr, 10);
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if (errno || *endptr) {
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fprintf(stderr, "Conversion error, non-convertible part: %s\n", endptr);
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exit(EXIT_FAILURE);
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}
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if (index < 0) {
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fprintf(stderr, "Negative index\n");
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exit(EXIT_FAILURE);
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}
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creds = (creds_t *)calloc(1, sizeof(creds_t));
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if (!creds) {
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perror("calloc");
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return -1;
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}
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creds->welcome = print;
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insert(value, index);
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creds->welcome();
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free(creds);
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return 0;
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}
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/* internal function definitions */
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static void insert(uint64_t value, int64_t index) {
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if (index >= NUM_ELEMENTS) {
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fprintf(stderr, "Invalid index!\n");
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exit(EXIT_FAILURE);
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}
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creds->buffer[index] = value;
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}
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static void print(void) {
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for (int i = 0; i < NUM_ELEMENTS; ++i) {
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printf("Index %d: %#lx\n", i, creds->buffer[i]);
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}
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}
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static void s3cr3t(void) { printf("You've gathered secret material!\n"); }
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