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Add support to mount rootfs image via squashfuse

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This commit is contained in:
Simon Fels 2017-07-12 09:28:01 +02:00
commit f6e421a089
1 changed files with 58 additions and 20 deletions
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78
src/anbox/cmds/container_manager.cpp
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@ -23,6 +23,7 @@
#include "anbox/config.h"
#include "core/posix/signal.h"
#include "core/posix/exec.h"
#include <sys/mount.h>
#include <linux/loop.h>
@ -121,30 +122,67 @@ bool anbox::cmds::ContainerManager::setup_mounts() {
if (!fs::exists(android_rootfs_dir))
fs::create_directory(android_rootfs_dir);
std::shared_ptr<common::LoopDevice> loop_device;
// We prefer using the kernel for mounting the squashfs image but
// for some cases (unprivileged containers) where no loop support
// is available we do the mount instead via squashfuse which will
// work entirely in userspace.
if (fs::exists("/dev/loop-control")) {
std::shared_ptr<common::LoopDevice> loop_device;
try {
loop_device = common::LoopDeviceAllocator::new_device();
} catch (const std::exception& e) {
ERROR("Could not create loopback device: %s", e.what());
return false;
} catch (...) {
ERROR("Could not create loopback device");
try {
loop_device = common::LoopDeviceAllocator::new_device();
} catch (const std::exception& e) {
ERROR("Could not create loopback device: %s", e.what());
return false;
} catch (...) {
ERROR("Could not create loopback device");
return false;
}
if (!loop_device->attach_file(android_img_path)) {
ERROR("Failed to attach Android rootfs image to loopback device");
return false;
}
auto m = common::MountEntry::create(loop_device, android_rootfs_dir, "squashfs", MS_MGC_VAL | MS_RDONLY | MS_PRIVATE);
if (!m) {
ERROR("Failed to mount Android rootfs");
return false;
}
mounts_.push_back(m);
} else if (fs::exists("/dev/fuse") && !utils::find_program_on_path("squashfuse").empty()) {
std::vector<std::string> args = {
"-t", "fuse.squashfuse",
// Allow other users than root to access the rootfs
"-o", "allow_other",
android_img_path.string(),
android_rootfs_dir,
};
// Easiest is here to go with the standard mount program as that
// will handle everything for us which is relevant to get the
// squashfs via squashfuse properly mount without having to
// reimplement all the details. Once the mount call comes back
// without an error we can expect the image to be mounted.
auto child = core::posix::exec("/bin/mount", args, {}, core::posix::StandardStream::empty, []() {});
const auto result = child.wait_for(core::posix::wait::Flags::untraced);
if (result.status != core::posix::wait::Result::Status::exited ||
result.detail.if_exited.status != core::posix::exit::Status::success) {
ERROR("Failed to mount squashfs Android image");
return false;
}
auto m = common::MountEntry::create(android_rootfs_dir);
if (!m) {
ERROR("Failed to create mount entry for Android rootfs");
return false;
}
mounts_.push_back(m);
} else {
ERROR("No loop device or FUSE support found. Can't setup Android rootfs!");
return false;
}
if (!loop_device->attach_file(android_img_path)) {
ERROR("Failed to attach Android rootfs image to loopback device");
return false;
}
auto m = common::MountEntry::create(loop_device, android_rootfs_dir, "squashfs", MS_MGC_VAL | MS_RDONLY | MS_PRIVATE);
if (!m) {
ERROR("Failed to mount Android rootfs");
return false;
}
mounts_.push_back(m);
for (const auto &dir_name : std::vector<std::string>{"cache", "data"}) {
auto target_dir_path = fs::path(android_rootfs_dir) / dir_name;
auto src_dir_path = SystemConfiguration::instance().data_dir() / dir_name;