Magisk/jni/magiskboot/boot_utils.c

#include <unistd.h>
#include <stdio.h>

#include "utils.h"

void write_zero(int fd, size_t size) {
	size_t pos = lseek(fd, 0, SEEK_CUR);
	ftruncate(fd, pos + size);
	lseek(fd, pos + size, SEEK_SET);
}

void mem_align(size_t *pos, size_t align) {
	size_t mask = align - 1;
	if (*pos & mask) {
		*pos += align - (*pos & mask);
	}
}

void file_align(int fd, size_t align, int out) {
	size_t pos = lseek(fd, 0, SEEK_CUR);
	size_t mask = align - 1;
	size_t off;
	if (pos & mask) {
		off = align - (pos & mask);
		if (out) {
			write_zero(fd, off);
		} else {
			lseek(fd, pos + off, SEEK_SET);
		}
	}
}

int open_new(const char *filename) {
	return xopen(filename, O_WRONLY | O_CREAT | O_TRUNC, 0644);
}

int check_verity_pattern(const char *s) {
	int pos = 0;
	if (s[0] == ',') ++pos;
	if (strncmp(s + pos, "verify", 6) != 0) return -1;
	pos += 6;
	if (s[pos] == '=') {
		while (s[pos] != '\0' && s[pos] != ' ' && s[pos] != '\n' && s[pos] != ',') ++pos;
	}
	return pos;
}

int check_encryption_pattern(const char *s) {
	const char *encrypt_list[] = { "forceencrypt", "forcefdeorfbe", NULL };
	for (int i = 0 ; encrypt_list[i]; ++i) {
		int len = strlen(encrypt_list[i]);
		if (strncmp(s, encrypt_list[i], len) == 0)
			return len;
	}
	return -1;
}