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- // SPDX-License-Identifier: GPL-2.0
- #define _GNU_SOURCE
- #include <errno.h>
- #include <fcntl.h>
- #include <sched.h>
- #include <stdio.h>
- #include <stdlib.h>
- #include <string.h>
- #include <sys/ioctl.h>
- #include <sys/mount.h>
- #include <sys/stat.h>
- #include <sys/types.h>
- #include <unistd.h>
- #include <linux/android/binder.h>
- #include <linux/android/binderfs.h>
- int main(int argc, char *argv[])
- {
- int fd, ret, saved_errno;
- struct binderfs_device device = { 0 };
- ret = unshare(CLONE_NEWNS);
- if (ret < 0) {
- fprintf(stderr, "%s - Failed to unshare mount namespace\n",
- strerror(errno));
- exit(EXIT_FAILURE);
- }
- ret = mount(NULL, "/", NULL, MS_REC | MS_PRIVATE, 0);
- if (ret < 0) {
- fprintf(stderr, "%s - Failed to mount / as private\n",
- strerror(errno));
- exit(EXIT_FAILURE);
- }
- ret = mkdir("/dev/binderfs", 0755);
- if (ret < 0 && errno != EEXIST) {
- fprintf(stderr, "%s - Failed to create binderfs mountpoint\n",
- strerror(errno));
- exit(EXIT_FAILURE);
- }
- ret = mount(NULL, "/dev/binderfs", "binder", 0, 0);
- if (ret < 0) {
- fprintf(stderr, "%s - Failed to mount binderfs\n",
- strerror(errno));
- exit(EXIT_FAILURE);
- }
- memcpy(device.name, "my-binder", strlen("my-binder"));
- fd = open("/dev/binderfs/binder-control", O_RDONLY | O_CLOEXEC);
- if (fd < 0) {
- fprintf(stderr, "%s - Failed to open binder-control device\n",
- strerror(errno));
- exit(EXIT_FAILURE);
- }
- ret = ioctl(fd, BINDER_CTL_ADD, &device);
- saved_errno = errno;
- close(fd);
- errno = saved_errno;
- if (ret < 0) {
- fprintf(stderr, "%s - Failed to allocate new binder device\n",
- strerror(errno));
- exit(EXIT_FAILURE);
- }
- printf("Allocated new binder device with major %d, minor %d, and name %s\n",
- device.major, device.minor, device.name);
- ret = unlink("/dev/binderfs/my-binder");
- if (ret < 0) {
- fprintf(stderr, "%s - Failed to delete binder device\n",
- strerror(errno));
- exit(EXIT_FAILURE);
- }
- /* Cleanup happens when the mount namespace dies. */
- exit(EXIT_SUCCESS);
- }
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