Magisk/jni/hexpatch.c

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C
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#include <getopt.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
#include "bootimgtools.h"
int hex2int(char c) {
int first = c / 16 - 3;
int second = c % 16;
int result = first * 10 + second;
if(result > 9) result--;
return result;
}
int hex2ascii(char c, char d) {
int high = hex2int(c) * 16;
int low = hex2int(d);
return high+low;
}
void hexstr2str(char *hex, char *str) {
char buf = 0;
for(int i = 0, length = strlen(hex); i < length; ++i){
if(i % 2){
str[i / 2] = hex2ascii(buf, hex[i]);
} else{
buf = hex[i];
}
}
}
int hexpatch(char * image, char *from, char *to) {
int fd = open(image, O_RDWR), patternsize = strlen(from) / 2, patchsize = strlen(to) / 2;
off_t filesize = lseek(fd, 0, SEEK_END);
char *file, *pattern, *patch, *start;
file = malloc(sizeof (char) * filesize);
pattern = malloc(sizeof (char) * patternsize);
patch = malloc(sizeof (char) * patchsize);
lseek(fd, 0, SEEK_SET);
read(fd, file, filesize);
hexstr2str(from, pattern);
hexstr2str(to, patch);
for (off_t i = 0; i < filesize;) {
int j;
for (j = 0; j < patternsize; ++j) {
if(file[i + j] != pattern[j]) break;
}
if (j == patternsize) {
fprintf(stderr, "Pattern %s found!\nPatching to %s\n", from, to);
lseek(fd, i, SEEK_SET);
write(fd, patch, patchsize);
}
if(j == 0) j = 1;
i += j;
}
free(file);
free(pattern);
free(patch);
close(fd);
return 0;
}