recovery: Fork a process for fuse when sideloading from SD card.
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
diff --git a/fuse_sdcard_provider.cpp b/fuse_sdcard_provider.cpp
index eb6454f..df96312 100644
--- a/fuse_sdcard_provider.cpp
+++ b/fuse_sdcard_provider.cpp
@@ -18,7 +18,6 @@
#include <stdio.h>
#include <string.h>
#include <errno.h>
-#include <pthread.h>
#include <sys/mount.h>
#include <sys/stat.h>
#include <unistd.h>
@@ -60,81 +59,30 @@
close(fd->fd);
}
-struct token {
- pthread_t th;
- const char* path;
- int result;
-};
-
-static void* run_sdcard_fuse(void* cookie) {
- token* t = reinterpret_cast<token*>(cookie);
-
+bool start_sdcard_fuse(const char* path) {
struct stat sb;
- if (stat(t->path, &sb) < 0) {
- fprintf(stderr, "failed to stat %s: %s\n", t->path, strerror(errno));
- t->result = -1;
- return NULL;
+ if (stat(path, &sb) == -1) {
+ fprintf(stderr, "failed to stat %s: %s\n", path, strerror(errno));
+ return false;
}
- struct file_data fd;
- struct provider_vtab vtab;
-
- fd.fd = open(t->path, O_RDONLY);
- if (fd.fd < 0) {
- fprintf(stderr, "failed to open %s: %s\n", t->path, strerror(errno));
- t->result = -1;
- return NULL;
+ file_data fd;
+ fd.fd = open(path, O_RDONLY);
+ if (fd.fd == -1) {
+ fprintf(stderr, "failed to open %s: %s\n", path, strerror(errno));
+ return false;
}
fd.file_size = sb.st_size;
fd.block_size = 65536;
+ provider_vtab vtab;
vtab.read_block = read_block_file;
vtab.close = close_file;
- t->result = run_fuse_sideload(&vtab, &fd, fd.file_size, fd.block_size);
- return NULL;
-}
-
-// How long (in seconds) we wait for the fuse-provided package file to
-// appear, before timing out.
-#define SDCARD_INSTALL_TIMEOUT 10
-
-void* start_sdcard_fuse(const char* path) {
- token* t = new token;
-
- t->path = path;
- pthread_create(&(t->th), NULL, run_sdcard_fuse, t);
-
- struct stat st;
- int i;
- for (i = 0; i < SDCARD_INSTALL_TIMEOUT; ++i) {
- if (stat(FUSE_SIDELOAD_HOST_PATHNAME, &st) != 0) {
- if (errno == ENOENT && i < SDCARD_INSTALL_TIMEOUT-1) {
- sleep(1);
- continue;
- } else {
- return NULL;
- }
- }
- }
-
// The installation process expects to find the sdcard unmounted.
// Unmount it with MNT_DETACH so that our open file continues to
// work but new references see it as unmounted.
umount2("/sdcard", MNT_DETACH);
- return t;
-}
-
-void finish_sdcard_fuse(void* cookie) {
- if (cookie == NULL) return;
- token* t = reinterpret_cast<token*>(cookie);
-
- // Calling stat() on this magic filename signals the fuse
- // filesystem to shut down.
- struct stat st;
- stat(FUSE_SIDELOAD_HOST_EXIT_PATHNAME, &st);
-
- pthread_join(t->th, NULL);
- delete t;
+ return run_fuse_sideload(&vtab, &fd, fd.file_size, fd.block_size) == 0;
}