forked from mirrors/linux
9762dc1432
This adds a simple sample program mounting binderfs and adding, then removing a binder device. Hopefully, it will be helpful to users who want to know how binderfs is supposed to be used. Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
83 lines
2 KiB
C
83 lines
2 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#define _GNU_SOURCE
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#include <errno.h>
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#include <fcntl.h>
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#include <sched.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/ioctl.h>
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#include <sys/mount.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <unistd.h>
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#include <linux/android/binder.h>
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#include <linux/android/binderfs.h>
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int main(int argc, char *argv[])
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{
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int fd, ret, saved_errno;
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size_t len;
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struct binderfs_device device = { 0 };
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ret = unshare(CLONE_NEWNS);
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if (ret < 0) {
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fprintf(stderr, "%s - Failed to unshare mount namespace\n",
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strerror(errno));
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exit(EXIT_FAILURE);
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}
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ret = mount(NULL, "/", NULL, MS_REC | MS_PRIVATE, 0);
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if (ret < 0) {
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fprintf(stderr, "%s - Failed to mount / as private\n",
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strerror(errno));
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exit(EXIT_FAILURE);
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}
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ret = mkdir("/dev/binderfs", 0755);
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if (ret < 0 && errno != EEXIST) {
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fprintf(stderr, "%s - Failed to create binderfs mountpoint\n",
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strerror(errno));
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exit(EXIT_FAILURE);
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}
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ret = mount(NULL, "/dev/binderfs", "binder", 0, 0);
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if (ret < 0) {
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fprintf(stderr, "%s - Failed to mount binderfs\n",
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strerror(errno));
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exit(EXIT_FAILURE);
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}
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memcpy(device.name, "my-binder", strlen("my-binder"));
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fd = open("/dev/binderfs/binder-control", O_RDONLY | O_CLOEXEC);
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if (fd < 0) {
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fprintf(stderr, "%s - Failed to open binder-control device\n",
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strerror(errno));
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exit(EXIT_FAILURE);
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}
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ret = ioctl(fd, BINDER_CTL_ADD, &device);
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saved_errno = errno;
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close(fd);
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errno = saved_errno;
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if (ret < 0) {
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fprintf(stderr, "%s - Failed to allocate new binder device\n",
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strerror(errno));
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exit(EXIT_FAILURE);
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}
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printf("Allocated new binder device with major %d, minor %d, and name %s\n",
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device.major, device.minor, device.name);
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ret = unlink("/dev/binderfs/my-binder");
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if (ret < 0) {
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fprintf(stderr, "%s - Failed to delete binder device\n",
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strerror(errno));
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exit(EXIT_FAILURE);
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}
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/* Cleanup happens when the mount namespace dies. */
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exit(EXIT_SUCCESS);
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}
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