Magisk/jni/utils/img.c

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/* img.c - All image related functions
*/
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/mount.h>
#include <linux/loop.h>
#include "magisk.h"
#include "utils.h"
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static int e2fsck(const char *img) {
// Check and repair ext4 image
char buffer[128];
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int pid, fd = -1;
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pid = exec_command(1, &fd, NULL, "e2fsck", "-yf", img, NULL);
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if (pid < 0)
return 1;
while (fdgets(buffer, sizeof(buffer), fd))
LOGD("magisk_img: %s", buffer);
waitpid(pid, NULL, 0);
close(fd);
return 0;
}
static char *loopsetup(const char *img) {
char device[20];
struct loop_info64 info;
int i, lfd, ffd;
memset(&info, 0, sizeof(info));
// First get an empty loop device
for (i = 0; i <= 7; ++i) {
sprintf(device, "/dev/block/loop%d", i);
lfd = xopen(device, O_RDWR);
if (ioctl(lfd, LOOP_GET_STATUS64, &info) == -1)
break;
close(lfd);
}
if (i == 8) return NULL;
ffd = xopen(img, O_RDWR);
if (ioctl(lfd, LOOP_SET_FD, ffd) == -1)
return NULL;
strcpy((char *) info.lo_file_name, img);
ioctl(lfd, LOOP_SET_STATUS64, &info);
close(lfd);
close(ffd);
return strdup(device);
}
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int create_img(const char *img, int size) {
unlink(img);
LOGI("Create %s with size %dM\n", img, size);
// Create a temp file with the file contexts
char file_contexts[] = "/magisk(/.*)? u:object_r:system_file:s0\n";
// If not root, attempt to create in current diretory
char *filename = getuid() == UID_ROOT ? "/dev/file_contexts_image" : "file_contexts_image";
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int ret, fd = xopen(filename, O_WRONLY | O_CREAT | O_TRUNC, 0644);
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xwrite(fd, file_contexts, sizeof(file_contexts));
close(fd);
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char buffer[16];
snprintf(buffer, sizeof(buffer), "%dM", size);
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ret = exec_command_sync("make_ext4fs", "-l", buffer, "-a", "/magisk", "-S", filename, img, NULL);
if (ret < 0)
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return 1;
unlink(filename);
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return ret;
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}
int get_img_size(const char *img, int *used, int *total) {
if (access(img, R_OK) == -1)
return 1;
char buffer[PATH_MAX];
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int pid, fd = -1, status = 1;
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pid = exec_command(1, &fd, NULL, "e2fsck", "-n", img, NULL);
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if (pid < 0)
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return 1;
while (fdgets(buffer, sizeof(buffer), fd)) {
if (strstr(buffer, img)) {
char *tok = strtok(buffer, ",");
while(tok != NULL) {
if (strstr(tok, "blocks")) {
status = 0;
break;
}
tok = strtok(NULL, ",");
}
if (status) continue;
sscanf(tok, "%d/%d", used, total);
*used = *used / 256 + 1;
*total /= 256;
break;
}
}
close(fd);
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waitpid(pid, NULL, 0);
return 0;
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}
int resize_img(const char *img, int size) {
LOGI("Resize %s to %dM\n", img, size);
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if (e2fsck(img))
return 1;
char buffer[128];
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int pid, status, fd = -1;
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snprintf(buffer, sizeof(buffer), "%dM", size);
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pid = exec_command(1, &fd, NULL, "resize2fs", img, buffer, NULL);
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if (pid < 0)
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return 1;
while (fdgets(buffer, sizeof(buffer), fd))
LOGD("magisk_img: %s", buffer);
close(fd);
waitpid(pid, &status, 0);
return WEXITSTATUS(status);
}
char *mount_image(const char *img, const char *target) {
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if (access(img, F_OK) == -1)
return NULL;
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if (access(target, F_OK) == -1) {
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if (xmkdir(target, 0755) == -1) {
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xmount(NULL, "/", NULL, MS_REMOUNT, NULL);
xmkdir(target, 0755);
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xmount(NULL, "/", NULL, MS_REMOUNT | MS_RDONLY, NULL);
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}
}
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if (e2fsck(img))
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return NULL;
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char *device = loopsetup(img);
if (device)
xmount(device, target, "ext4", 0, NULL);
return device;
}
void umount_image(const char *target, const char *device) {
xumount(target);
int fd = xopen(device, O_RDWR);
ioctl(fd, LOOP_CLR_FD);
close(fd);
}
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int merge_img(const char *source, const char *target) {
if (access(source, F_OK) == -1)
return 0;
if (access(target, F_OK) == -1) {
rename(source, target);
return 0;
}
char buffer[PATH_MAX];
// resize target to worst case
int s_used, s_total, t_used, t_total, n_total;
get_img_size(source, &s_used, &s_total);
get_img_size(target, &t_used, &t_total);
n_total = round_size(s_used + t_used);
if (n_total != t_total)
resize_img(target, n_total);
xmkdir(SOURCE_TMP, 0755);
xmkdir(TARGET_TMP, 0755);
char *s_loop, *t_loop;
s_loop = mount_image(source, SOURCE_TMP);
if (s_loop == NULL) return 1;
t_loop = mount_image(target, TARGET_TMP);
if (t_loop == NULL) return 1;
DIR *dir;
struct dirent *entry;
if (!(dir = opendir(SOURCE_TMP)))
return 1;
while ((entry = xreaddir(dir))) {
if (entry->d_type == DT_DIR) {
if (strcmp(entry->d_name, ".") == 0 ||
strcmp(entry->d_name, "..") == 0 ||
strcmp(entry->d_name, ".core") == 0 ||
strcmp(entry->d_name, "lost+found") == 0)
continue;
// Cleanup old module if exists
snprintf(buffer, sizeof(buffer), "%s/%s", TARGET_TMP, entry->d_name);
if (access(buffer, F_OK) == 0) {
LOGI("Upgrade module: %s\n", entry->d_name);
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exec_command_sync(BBPATH "/rm", "-rf", buffer, NULL);
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} else {
LOGI("New module: %s\n", entry->d_name);
}
}
}
closedir(dir);
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cp_afc(SOURCE_TMP, TARGET_TMP);
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// Unmount all loop devices
umount_image(SOURCE_TMP, s_loop);
umount_image(TARGET_TMP, t_loop);
rmdir(SOURCE_TMP);
rmdir(TARGET_TMP);
free(s_loop);
free(t_loop);
unlink(source);
return 0;
}
void trim_img(const char *img) {
int used, total, new_size;
get_img_size(img, &used, &total);
new_size = round_size(used);
if (new_size != total)
resize_img(img, new_size);
}