minecraft-pi-reborn/mods/src/core.c

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#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <sys/mman.h>
#include <stdint.h>
#include <libcore/libcore.h>
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#define PATCH_PRINTF(file, line, start, str) if (file != NULL) fprintf(stderr, "[%s:%i] Patching (0x%04x) - "str": 0x%02x 0x%02x 0x%02x 0x%02x\n", file, line, (uint32_t) start, data[0], data[1], data[2], data[3]);
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#define ORIGINAL_SIZE 8
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void *_overwrite(const char *file, int line, void *start, void *target) {
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void *original = malloc(ORIGINAL_SIZE);
memcpy(original, start, ORIGINAL_SIZE);
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int thumb = ((uint32_t) start) & 1;
unsigned char *patch_data;
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if (thumb) {
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unsigned char patch_data_temp[4] = {0xdf, 0xf8, 0x00, 0xf0};
patch_data = patch_data_temp;
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} else {
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unsigned char patch_data_temp[4] = {0x04, 0xf0, 0x1f, 0xe5};
patch_data = patch_data_temp;
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}
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_patch(file, line, start, patch_data);
_patch(file, line, start + 4, (unsigned char *) &target);
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return original;
}
void revert_overwrite(void *start, void *original) {
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unsigned char *data = (unsigned char *) start;
int thumb = ((uint32_t) start) & 1;
if (thumb) {
data--;
}
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// Store Current Value In Temp
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void *temp = malloc(ORIGINAL_SIZE);
memcpy(temp, data, ORIGINAL_SIZE);
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// Insert Original Value
_patch(NULL, -1, start, original);
_patch(NULL, -1, start + 4, original + 4);
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// Complete Memory Swap
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memcpy(original, temp, ORIGINAL_SIZE);
free(temp);
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}
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void _patch(const char *file, int line, void *start, unsigned char patch[]) {
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size_t page_size = sysconf(_SC_PAGESIZE);
uintptr_t end = ((uintptr_t) start) + 4;
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 = ((uint32_t) start) & 1;
if (thumb) {
data--;
}
PATCH_PRINTF(file, line, start, "original");
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memcpy(data, patch, 4);
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PATCH_PRINTF(file, line, start, "result");
mprotect((void *) page_start, end - page_start, PROT_READ | PROT_EXEC);
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__builtin___clear_cache(start, (void *) end);
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}
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void _patch_address(const char *file, int line, void *start, void *target) {
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uint32_t addr = (uint32_t) target;
unsigned char patch_data[4] = {addr & 0xff, (addr >> 8) & 0xff, (addr >> 16) & 0xff, (addr >> 24) & 0xff};
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_patch(file, line, start, patch_data);
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}