From f5b4ba6e9236133a6ee18338a1966458b1ea4485 Mon Sep 17 00:00:00 2001
From: XUranus <2257238649wdx@gmail.com>
Date: Sat, 30 Mar 2024 21:01:15 +0800
Subject: [PATCH] add umount hook for udisks

---
 include/native/linux/LinuxMountUtils.h        | 17 +++++++
 .../linux/LinuxDeviceMapperMountProvider.cpp  |  4 ++
 .../linux/LinuxLoopbackMountProvider.cpp      |  4 ++
 src/native/linux/LinuxMountUtils.cpp          | 44 +++++++++++++++++++
 4 files changed, 69 insertions(+)

diff --git a/include/native/linux/LinuxMountUtils.h b/include/native/linux/LinuxMountUtils.h
index 5666260..76e0da4 100644
--- a/include/native/linux/LinuxMountUtils.h
+++ b/include/native/linux/LinuxMountUtils.h
@@ -8,6 +8,15 @@
 namespace volumeprotect {
 namespace linuxmountutil {
 
+// entry of /proc/mounts
+struct MountEntry {
+    std::string devicePath;
+    std::string mountTargetPath;
+    std::string type;
+    std::string options;
+};
+
+// a single implement
 bool Mount(
     const std::string& devicePath,
     const std::string& mountTargetPath,
@@ -15,6 +24,7 @@ bool Mount(
     const std::string& mountOptions,
     bool readOnly);
 
+// a more complicate implement, automatically parse the options into flags
 bool Mount2(
     const std::string& devicePath,
     const std::string& mountTargetPath,
@@ -22,14 +32,21 @@ bool Mount2(
     const std::string& mountOptions,
     bool readOnly);
 
+// umount one mount point
 bool Umount(const std::string& mountTargetPath, bool force);
 
+// umount all mount points releated to the device by force
+bool UmountAll(const std::string& devicePath);
+
 // return if the directory path is a mount point
 bool IsMountPoint(const std::string& dirPath);
 
 // get the block device path of the mount point
 std::string GetMountDevicePath(const std::string& mountTargetPath);
 
+// get all mount points of a device
+std::vector<MountEntry> GetAllMounts(const std::string& devicePath);
+
 }
 }
 
diff --git a/src/native/linux/LinuxDeviceMapperMountProvider.cpp b/src/native/linux/LinuxDeviceMapperMountProvider.cpp
index 300fcda..7948d8f 100644
--- a/src/native/linux/LinuxDeviceMapperMountProvider.cpp
+++ b/src/native/linux/LinuxDeviceMapperMountProvider.cpp
@@ -393,6 +393,10 @@ bool LinuxDeviceMapperUmountProvider::Umount()
         RECORD_INNER_ERROR("failed to umount target %s, errno %u", m_mountTargetPath.c_str(), errno);
         success = false;
     }
+    if (!linuxmountutil::UmountAll(m_dmDeviceName)) {
+        RECORD_INNER_ERROR("failed to umount all mounts of %s", m_dmDeviceName.c_str());
+        success = false;
+    }
     // check if need to remove dm device
     if (!m_dmDeviceName.empty() && !devicemapper::RemoveDeviceIfExists(m_dmDeviceName)) {
         RECORD_INNER_ERROR("failed to remove devicemapper device %s, errno", m_dmDeviceName.c_str(), errno);
diff --git a/src/native/linux/LinuxLoopbackMountProvider.cpp b/src/native/linux/LinuxLoopbackMountProvider.cpp
index 49680e5..5f1ecc5 100644
--- a/src/native/linux/LinuxLoopbackMountProvider.cpp
+++ b/src/native/linux/LinuxLoopbackMountProvider.cpp
@@ -177,6 +177,10 @@ bool LinuxLoopbackUmountProvider::Umount()
         RECORD_INNER_ERROR("failed to umount target %s, errno %u", m_mountTargetPath.c_str(), errno);
         return false;
     }
+    if (!linuxmountutil::UmountAll(m_loopbackDevicePath)) {
+        RECORD_INNER_ERROR("failed to umount all mounts of %s", m_loopbackDevicePath.c_str());
+        return false;
+    }
     // 2. detach loopback device
     if (!m_loopbackDevicePath.empty()
         && loopback::Attached(m_loopbackDevicePath)
diff --git a/src/native/linux/LinuxMountUtils.cpp b/src/native/linux/LinuxMountUtils.cpp
index 4858839..6d46fc1 100644
--- a/src/native/linux/LinuxMountUtils.cpp
+++ b/src/native/linux/LinuxMountUtils.cpp
@@ -23,6 +23,7 @@ namespace {
     const int MNTENT_BUFFER_MAX = 4096;
     const std::string SYS_MOUNTS_ENTRY_PATH = "/proc/mounts";
     const int MAX_MOUNT_RETRY = 3;
+    const int MAX_UMOUNT_RETRY = 3;
 }
 
 using namespace volumeprotect;
@@ -209,6 +210,32 @@ bool linuxmountutil::Umount(const std::string& mountTargetPath, bool force)
     return true;
 }
 
+/**
+ * some linux desktop environment distro may running services like udisks2,
+ * that may mount the created loop device onto path /run/media/$user/uuid.
+ * To prevent residual mounts caused by such service, UmountAll() will try several
+ * times to try to umount all releated mounts of the device.
+*/
+bool linuxmountutil::UmountAll(const std::string& devicePath)
+{
+    std::vector<MountEntry> entries = linuxmountutil::GetAllMounts(devicePath);
+    int retry = 0;
+    while (!entries.empty() && retry < MAX_UMOUNT_RETRY) {
+        for (const auto& entry : entries) {
+            // this umount will not stucked
+            ::umount2(entry.mountTargetPath.c_str(), (MNT_FORCE | MNT_DETACH));
+        }
+        retry++;
+        entries = linuxmountutil::GetAllMounts(devicePath);
+    }
+    if (!entries.empty()) {
+        ERRLOG("%d mount entries remain mounted! failed to clean all mounts for %s",
+            entries.size(), devicePath.c_str());
+        return false;
+    }
+    return true;
+}
+
 bool linuxmountutil::IsMountPoint(const std::string& dirPath)
 {
     bool mounted = false;
@@ -249,4 +276,21 @@ std::string linuxmountutil::GetMountDevicePath(const std::string& mountTargetPat
     return devicePath;
 }
 
+std::vector<MountEntry> linuxmountutil::GetAllMounts(const std::string& devicePath)
+{
+    std::vector<MountEntry> entries {};
+    FILE* mountsFile = ::setmntent(SYS_MOUNTS_ENTRY_PATH.c_str(), "r");
+    if (mountsFile == nullptr) {
+        ERRLOG("failed to open /proc/mounts, errno %u", errno);
+        return {};
+    }
+    struct mntent entry {};
+    char mntentBuffer[MNTENT_BUFFER_MAX] = { 0 };
+    while (::getmntent_r(mountsFile, &entry, mntentBuffer, MNTENT_BUFFER_MAX) != nullptr) {
+        entries.emplace_back(MountEntry {entry.mnt_fsname, entry.mnt_dir, entry.mnt_type, entry.mnt_opts });
+    }
+    ::endmntent(mountsFile);
+    return entries;
+}
+
 #endif
\ No newline at end of file