Magisk/native/jni/utils/cpio.cpp
topjohnwu e72c6685ed Support A only System-as-root Devices
Most Chinese devices (and supposedly Galaxy S10) running Android Pie
is using system-as-root without A/B partition.

https://source.android.com/devices/bootloader/system-as-root#about-system-as-root

According to the docs above, these devices will have a ramdisk block
with size 0 in their boot images. Since magiskinit can run independently
on system-as-root devices, we simply just create an empty ramdisk with
magiskinit added as init.

Huge thanks to @vvb2060 for the heads up and original PR.
Close #980, close #1102
2019-02-28 05:46:36 -05:00

275 lines
6.7 KiB
C++

#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <stdlib.h>
#include <algorithm>
#include <utils.h>
#include <logging.h>
#include <cpio.h>
using namespace std;
struct cpio_newc_header {
char magic[6];
char ino[8];
char mode[8];
char uid[8];
char gid[8];
char nlink[8];
char mtime[8];
char filesize[8];
char devmajor[8];
char devminor[8];
char rdevmajor[8];
char rdevminor[8];
char namesize[8];
char check[8];
} __attribute__((packed));
static uint32_t x8u(const char *hex) {
uint32_t val, inpos = 8, outpos;
char pattern[6];
while (*hex == '0') {
hex++;
if (!--inpos) return 0;
}
// Because scanf gratuitously treats %*X differently than printf does.
sprintf(pattern, "%%%dx%%n", inpos);
sscanf(hex, pattern, &val, &outpos);
if (inpos != outpos)
LOGE("bad cpio header\n");
return val;
}
cpio_entry_base::cpio_entry_base(const cpio_newc_header *h)
: mode(x8u(h->mode)), uid(x8u(h->uid)), gid(x8u(h->gid)), filesize(x8u(h->filesize)) {};
void cpio::dump(const char *file) {
fprintf(stderr, "Dump cpio: [%s]\n", file);
FDOutStream fd_out(xopen(file, O_WRONLY | O_CREAT | O_TRUNC, 0644), true);
output(fd_out);
}
void cpio::rm(entry_map::iterator &it) {
fprintf(stderr, "Remove [%s]\n", it->first.data());
entries.erase(it);
}
void cpio::rm(const char *name, bool r) {
size_t len = strlen(name);
for (auto it = entries.begin(); it != entries.end();) {
if (it->first.compare(0, len, name) == 0 &&
((r && it->first[len] == '/') || it->first[len] == '\0')) {
auto tmp = it;
++it;
rm(tmp);
if (!r) return;
} else {
++it;
}
}
}
static void extract_entry(const entry_map::value_type &e, const char *file) {
fprintf(stderr, "Extract [%s] to [%s]\n", e.first.data(), file);
unlink(file);
rmdir(file);
if (S_ISDIR(e.second->mode)) {
mkdir(file, e.second->mode & 0777);
} else if (S_ISREG(e.second->mode)) {
int fd = creat(file, e.second->mode & 0777);
xwrite(fd, e.second->data, e.second->filesize);
fchown(fd, e.second->uid, e.second->gid);
close(fd);
} else if (S_ISLNK(e.second->mode)) {
auto target = strndup((char *) e.second->data, e.second->filesize);
symlink(target, file);
free(target);
}
}
void cpio::extract() {
for (auto &e : entries)
extract_entry(e, e.first.data());
}
bool cpio::extract(const char *name, const char *file) {
auto it = entries.find(name);
if (it != entries.end()) {
extract_entry(*it, file);
return true;
}
fprintf(stderr, "Cannot find the file entry [%s]\n", name);
return false;
}
bool cpio::exists(const char *name) {
return entries.count(name) != 0;
}
#define do_out(b, l) out.write(b, l); pos += (l)
#define out_align() out.write(zeros, align_off(pos, 4)); pos = do_align(pos, 4)
void cpio::output(OutStream &out) {
size_t pos = 0;
unsigned inode = 300000;
char header[111];
char zeros[4] = {0};
for (auto &e : entries) {
sprintf(header, "070701%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x",
inode++, // e->ino
e.second->mode,
e.second->uid,
e.second->gid,
1, // e->nlink
0, // e->mtime
e.second->filesize,
0, // e->devmajor
0, // e->devminor
0, // e->rdevmajor
0, // e->rdevminor
(uint32_t) e.first.size() + 1,
0 // e->check
);
do_out(header, 110);
do_out(e.first.data(), e.first.size() + 1);
out_align();
if (e.second->filesize) {
do_out(e.second->data, e.second->filesize);
out_align();
}
}
// Write trailer
sprintf(header, "070701%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x",
inode++, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 11, 0);
do_out(header, 110);
do_out("TRAILER!!!\0", 11);
out_align();
}
cpio_rw::cpio_rw(const char *file) {
load_cpio(file);
}
void cpio_rw::load_cpio(const char *file) {
char *buf;
size_t sz;
mmap_ro(file, buf, sz);
fprintf(stderr, "Loading cpio: [%s]\n", file);
load_cpio(buf, sz);
munmap(buf, sz);
}
void cpio_rw::insert(cpio_entry *e) {
auto ex = entries.extract(e->filename);
if (!ex) {
entries[e->filename].reset(e);
} else {
ex.key() = e->filename;
ex.mapped().reset(e);
entries.insert(std::move(ex));
}
}
void cpio_rw::add(mode_t mode, const char *name, const char *file) {
void *buf;
size_t sz;
mmap_ro(file, buf, sz);
auto e = new cpio_entry(name, S_IFREG | mode);
e->filesize = sz;
e->data = xmalloc(sz);
memcpy(e->data, buf, sz);
munmap(buf, sz);
insert(e);
fprintf(stderr, "Add entry [%s] (%04o)\n", name, mode);
}
void cpio_rw::mkdir(mode_t mode, const char *name) {
insert(new cpio_entry(name, S_IFDIR | mode));
fprintf(stderr, "Create directory [%s] (%04o)\n", name, mode);
}
void cpio_rw::ln(const char *target, const char *name) {
auto e = new cpio_entry(name, S_IFLNK);
e->filesize = strlen(target);
e->data = strdup(target);
insert(e);
fprintf(stderr, "Create symlink [%s] -> [%s]\n", name, target);
}
void cpio_rw::mv(entry_map::iterator &it, const char *to) {
fprintf(stderr, "Move [%s] -> [%s]\n", it->first.data(), to);
auto ex = entries.extract(it);
auto &name = static_cast<cpio_entry*>(ex.mapped().get())->filename;
name = to;
ex.key() = name;
entries.erase(name);
entries.insert(std::move(ex));
}
bool cpio_rw::mv(const char *from, const char *to) {
auto it = entries.find(from);
if (it != entries.end()) {
mv(it, to);
return true;
}
fprintf(stderr, "Cannot find entry %s\n", from);
return false;
}
#define pos_align(p) p = do_align(p, 4)
void cpio_rw::load_cpio(char *buf, size_t sz) {
size_t pos = 0;
cpio_newc_header *header;
unique_ptr<cpio_entry> entry;
while (pos < sz) {
header = (cpio_newc_header *)(buf + pos);
entry = make_unique<cpio_entry>(header);
pos += sizeof(*header);
string_view name_view(buf + pos);
pos += x8u(header->namesize);
pos_align(pos);
if (name_view == "." || name_view == "..")
continue;
if (name_view == "TRAILER!!!")
break;
entry->filename = name_view;
entry->data = xmalloc(entry->filesize);
memcpy(entry->data, buf + pos, entry->filesize);
pos += entry->filesize;
entries[entry->filename] = std::move(entry);
pos_align(pos);
}
}
cpio_mmap::cpio_mmap(const char *file) {
mmap_ro(file, buf, sz);
fprintf(stderr, "Loading cpio: [%s]\n", file);
size_t pos = 0;
cpio_newc_header *header;
unique_ptr<cpio_entry_base> entry;
while (pos < sz) {
header = (cpio_newc_header *)(buf + pos);
entry = make_unique<cpio_entry_base>(header);
pos += sizeof(*header);
string_view name_view(buf + pos);
pos += x8u(header->namesize);
pos_align(pos);
if (name_view == "." || name_view == "..")
continue;
if (name_view == "TRAILER!!!")
break;
entry->data = buf + pos;
pos += entry->filesize;
entries[name_view] = std::move(entry);
pos_align(pos);
}
}
cpio_mmap::~cpio_mmap() {
munmap(buf, sz);
}