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1// SPDX-License-Identifier: GPL-2.02 3#define _GNU_SOURCE4#include <errno.h>5#include <fcntl.h>6#include <sched.h>7#include <stdio.h>8#include <stdlib.h>9#include <string.h>10#include <sys/ioctl.h>11#include <sys/mount.h>12#include <sys/stat.h>13#include <sys/types.h>14#include <unistd.h>15#include <linux/android/binder.h>16#include <linux/android/binderfs.h>17 18int main(int argc, char *argv[])19{20 int fd, ret, saved_errno;21 struct binderfs_device device = { 0 };22 23 ret = unshare(CLONE_NEWNS);24 if (ret < 0) {25 fprintf(stderr, "%s - Failed to unshare mount namespace\n",26 strerror(errno));27 exit(EXIT_FAILURE);28 }29 30 ret = mount(NULL, "/", NULL, MS_REC | MS_PRIVATE, 0);31 if (ret < 0) {32 fprintf(stderr, "%s - Failed to mount / as private\n",33 strerror(errno));34 exit(EXIT_FAILURE);35 }36 37 ret = mkdir("/dev/binderfs", 0755);38 if (ret < 0 && errno != EEXIST) {39 fprintf(stderr, "%s - Failed to create binderfs mountpoint\n",40 strerror(errno));41 exit(EXIT_FAILURE);42 }43 44 ret = mount(NULL, "/dev/binderfs", "binder", 0, 0);45 if (ret < 0) {46 fprintf(stderr, "%s - Failed to mount binderfs\n",47 strerror(errno));48 exit(EXIT_FAILURE);49 }50 51 memcpy(device.name, "my-binder", strlen("my-binder"));52 53 fd = open("/dev/binderfs/binder-control", O_RDONLY | O_CLOEXEC);54 if (fd < 0) {55 fprintf(stderr, "%s - Failed to open binder-control device\n",56 strerror(errno));57 exit(EXIT_FAILURE);58 }59 60 ret = ioctl(fd, BINDER_CTL_ADD, &device);61 saved_errno = errno;62 close(fd);63 errno = saved_errno;64 if (ret < 0) {65 fprintf(stderr, "%s - Failed to allocate new binder device\n",66 strerror(errno));67 exit(EXIT_FAILURE);68 }69 70 printf("Allocated new binder device with major %d, minor %d, and name %s\n",71 device.major, device.minor, device.name);72 73 ret = unlink("/dev/binderfs/my-binder");74 if (ret < 0) {75 fprintf(stderr, "%s - Failed to delete binder device\n",76 strerror(errno));77 exit(EXIT_FAILURE);78 }79 80 /* Cleanup happens when the mount namespace dies. */81 exit(EXIT_SUCCESS);82}83