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authorThiago Macieira <thiago.macieira@intel.com>2020-01-30 12:53:39 -0800
committerThiago Macieira <thiago.macieira@intel.com>2020-02-09 22:19:20 -0800
commit23d42a6a3088904f4d297a98e961fc520d156673 (patch)
treeb36f6e69ddf1e9132832e382c4f1a15ca25a28b8 /src/corelib
parent6b9a1824a4c1e4c773c31db8df6c9bf8c768079f (diff)
QStorageInfo/Linux: resolve non-existent devices via /dev/block
On systems with very simple boot sequences, the kernel will create a device called /dev/root and use that to mount the root filesystem. However, that doesn't actually exist in /dev and could cause confusion. So we try to resolve using /dev/block if the /dev entry does not exist but udev is in use (udevd has the string "/dev/%s/%u:%u"). [ChangeLog][QtCore][QStorageInfo] Improved discovery of device nodes on Linux if the /dev entry was renamed after the filesystem was mounted and udev is in use. Fixes: QTBUG-81464 Change-Id: If79a52e476594446baccfffd15eec573ae3deb0d Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io> Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Diffstat (limited to 'src/corelib')
-rw-r--r--src/corelib/io/qstorageinfo_unix.cpp21
1 files changed, 18 insertions, 3 deletions
diff --git a/src/corelib/io/qstorageinfo_unix.cpp b/src/corelib/io/qstorageinfo_unix.cpp
index 37b8a60c37..698c4ddf41 100644
--- a/src/corelib/io/qstorageinfo_unix.cpp
+++ b/src/corelib/io/qstorageinfo_unix.cpp
@@ -60,6 +60,7 @@
#elif defined(Q_OS_LINUX) || defined(Q_OS_HURD)
# include <mntent.h>
# include <sys/statvfs.h>
+# include <sys/sysmacros.h>
#elif defined(Q_OS_SOLARIS)
# include <sys/mnttab.h>
# include <sys/statvfs.h>
@@ -152,7 +153,7 @@ private:
//(2) parent ID: the ID of the parent mount (or of self for the top of the mount tree).
// int parent_id;
//(3) major:minor: the value of st_dev for files on this filesystem (see stat(2)).
-// dev_t rdev;
+ dev_t rdev;
//(4) root: the pathname of the directory in the filesystem which forms the root of this mount.
char *subvolume;
//(5) mount point: the pathname of the mount point relative to the process's root directory.
@@ -503,8 +504,7 @@ inline bool QStorageIterator::next()
int rdevminor = qstrtoll(ptr + 1, const_cast<const char **>(&ptr), 10, &ok);
if (!ptr || !ok)
return false;
- Q_UNUSED(rdevmajor);
- Q_UNUSED(rdevminor);
+ mnt.rdev = makedev(rdevmajor, rdevminor);
if (*ptr != ' ')
return false;
@@ -566,6 +566,21 @@ inline QByteArray QStorageIterator::fileSystemType() const
inline QByteArray QStorageIterator::device() const
{
+ // check that the device exists
+ if (mnt.mnt_fsname[0] == '/' && access(mnt.mnt_fsname, F_OK) != 0) {
+ // It doesn't, so let's try to resolve the dev_t from /dev/block.
+ // Note how strlen("4294967295") == digits10 + 1, so we need to add 1
+ // for each number, plus the ':'.
+ char buf[sizeof("/dev/block/") + 2 * std::numeric_limits<unsigned>::digits10 + 3];
+ QByteArray dev(PATH_MAX, Qt::Uninitialized);
+ char *devdata = dev.data();
+
+ snprintf(buf, sizeof(buf), "/dev/block/%u:%u", major(mnt.rdev), minor(mnt.rdev));
+ if (realpath(buf, devdata)) {
+ dev.truncate(strlen(devdata));
+ return dev;
+ }
+ }
return QByteArray(mnt.mnt_fsname);
}