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Add runtime ramdisk patch support

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topjohnwu 2017-09-13 03:20:29 +08:00
parent 4229ba364f
commit ff7c38f8e9
1 changed files with 45 additions and 0 deletions
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45
jni/magiskinit.c
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@ -6,6 +6,7 @@
#include <sys/stat.h> #include <sys/stat.h>
#include <sys/types.h> #include <sys/types.h>
#include <sys/mount.h> #include <sys/mount.h>
#include <sys/mman.h>
#include <sys/sendfile.h> #include <sys/sendfile.h>
#include <sys/sysmacros.h> #include <sys/sysmacros.h>
@ -22,6 +23,22 @@ struct device {
char path[64]; char path[64];
}; };
static void mmap_ro(const char *filename, void **buf, size_t *size) {
int fd = open(filename, O_RDONLY);
*size = lseek(fd, 0, SEEK_END);
lseek(fd, 0, SEEK_SET);
*buf = mmap(NULL, *size, PROT_READ, MAP_SHARED, fd, 0);
close(fd);
}
static void mmap_rw(const char *filename, void **buf, size_t *size) {
int fd = open(filename, O_RDWR);
*size = lseek(fd, 0, SEEK_END);
lseek(fd, 0, SEEK_SET);
*buf = mmap(NULL, *size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
close(fd);
}
static void clone_dir(int src, int dest) { static void clone_dir(int src, int dest) {
struct dirent *entry; struct dirent *entry;
DIR *dir; DIR *dir;
@ -206,6 +223,32 @@ static int setup_block(struct device *dev, const char *partname) {
return 0; return 0;
} }
static void patch_ramdisk() {
void *addr;
size_t size;
mmap_rw("/init", &addr, &size);
for (int i = 0; i < size; ++i) {
if (memcmp(addr + i, "/system/etc/selinux/plat_sepolicy.cil", 37) == 0) {
memcpy(addr + i, "/system/etc/selinux/plat_sepolicy.xxx", 37);
break;
}
}
munmap(addr, size);
mmap_ro("/init.rc", &addr, &size);
int fd = open("/init.rc.patch", O_WRONLY | O_CREAT | O_CLOEXEC, 0750);
for (int i = 0; i < size; ++i) {
if (memcmp(addr + i, "import", 6) == 0) {
write(fd, addr, i);
write(fd, "import /init.magisk.rc\n", 23);
write(fd, addr + i, size -i);
close(fd);
break;
}
}
munmap(addr, size);
rename("/init.rc.patch", "/init.rc");
}
int main(int argc, char *argv[]) { int main(int argc, char *argv[]) {
umask(0); umask(0);
@ -234,6 +277,8 @@ int main(int argc, char *argv[]) {
if (overlay > 0) if (overlay > 0)
mv_dir(overlay, root); mv_dir(overlay, root);
patch_ramdisk();
close(root); close(root);
close(system_root); close(system_root);
close(overlay); close(overlay);