minecraft-pi-reborn/core/src/core.c
2020-09-25 12:43:53 -04:00

45 lines
1.3 KiB
C

#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <sys/mman.h>
#include <stdint.h>
#include <libcore/libcore.h>
#define PREPARE_PATCH(start) \
size_t page_size = sysconf(_SC_PAGESIZE); \
uintptr_t end = ((uintptr_t) start) + 1; \
uintptr_t page_start = ((uintptr_t) start) & -page_size; \
mprotect((void *) page_start, end - page_start, PROT_READ | PROT_WRITE); \
\
unsigned char *data = (unsigned char *) start; \
int thumb = ((size_t) start) & 1; \
if (thumb) { \
data--; \
} \
fprintf(stderr, "Patching - original: %i %i %i %i %i\n", data[0], data[1], data[2], data[3], data[4]);
#define END_PATCH() \
fprintf(stderr, "Patching - result: %i %i %i %i %i\n", data[0], data[1], data[2], data[3], data[4]); \
\
mprotect((void *) page_start, end - page_start, PROT_READ | PROT_EXEC);
void overwrite(void *start, void *target) {
PREPARE_PATCH(start);
if (thumb) {
unsigned char patch[4] = {0xdf, 0xf8, 0x00, 0xf0};
memcpy(data, patch, 4);
} else {
unsigned char patch[4] = {0x04, 0xf0, 0x1f, 0xe5};
memcpy(data, patch, 4);
}
memcpy(&data[4], &target, sizeof (int));
END_PATCH();
}
void patch(void *start, unsigned char patch[]) {
PREPARE_PATCH(start);
memcpy(data, patch, 4);
END_PATCH();
}