cdcf28f54f
For applying update from SD card, we used to use a thread to serve the file with fuse. Since accessing through fuse involves going from kernel to userspace to kernel, it may run into deadlock (e.g. for mmap_sem) when a page fault occurs. Switch to using a process instead. Bug: 23783099 Bug: 26313124 Change-Id: Iac0f55b1bdb078cadb520cfe1133e70fbb26eadd
88 lines
2.5 KiB
C++
88 lines
2.5 KiB
C++
/*
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* Copyright (C) 2014 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <stdlib.h>
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#include <stdio.h>
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#include <string.h>
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#include <errno.h>
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#include <sys/mount.h>
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#include <sys/stat.h>
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#include <unistd.h>
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#include <fcntl.h>
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#include "fuse_sideload.h"
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struct file_data {
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int fd; // the underlying sdcard file
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uint64_t file_size;
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uint32_t block_size;
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};
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static int read_block_file(void* cookie, uint32_t block, uint8_t* buffer, uint32_t fetch_size) {
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file_data* fd = reinterpret_cast<file_data*>(cookie);
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off64_t offset = ((off64_t) block) * fd->block_size;
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if (TEMP_FAILURE_RETRY(lseek64(fd->fd, offset, SEEK_SET)) == -1) {
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fprintf(stderr, "seek on sdcard failed: %s\n", strerror(errno));
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return -EIO;
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}
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while (fetch_size > 0) {
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ssize_t r = TEMP_FAILURE_RETRY(read(fd->fd, buffer, fetch_size));
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if (r == -1) {
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fprintf(stderr, "read on sdcard failed: %s\n", strerror(errno));
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return -EIO;
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}
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fetch_size -= r;
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buffer += r;
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}
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return 0;
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}
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static void close_file(void* cookie) {
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file_data* fd = reinterpret_cast<file_data*>(cookie);
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close(fd->fd);
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}
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bool start_sdcard_fuse(const char* path) {
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struct stat sb;
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if (stat(path, &sb) == -1) {
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fprintf(stderr, "failed to stat %s: %s\n", path, strerror(errno));
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return false;
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}
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file_data fd;
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fd.fd = open(path, O_RDONLY);
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if (fd.fd == -1) {
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fprintf(stderr, "failed to open %s: %s\n", path, strerror(errno));
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return false;
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}
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fd.file_size = sb.st_size;
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fd.block_size = 65536;
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provider_vtab vtab;
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vtab.read_block = read_block_file;
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vtab.close = close_file;
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// The installation process expects to find the sdcard unmounted.
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// Unmount it with MNT_DETACH so that our open file continues to
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// work but new references see it as unmounted.
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umount2("/sdcard", MNT_DETACH);
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return run_fuse_sideload(&vtab, &fd, fd.file_size, fd.block_size) == 0;
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}
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