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Using util_path_sysfs always leaves 5 bytes of memory unfreed as the value for the sysfs mount point is stored in a static variable to avoid multiple queries of /proc/mount. $ valgrind ./util_path_example sysfs ==3629315== Memcheck, a memory error detector ==3629315== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al. ==3629315== Using Valgrind-3.15.0 and LibVEX; rerun with -h for copyright info ==3629315== Command: ./util_path_example sysfs ==3629315== Path for cpu: "/sys/devices/system/cpu" Path for memory: "/sys/devices/system/memory" ==3629315== ==3629315== HEAP SUMMARY: ==3629315== in use at exit: 5 bytes in 1 blocks ==3629315== total heap usage: 22 allocs, 21 frees, 18,435 bytes allocated ==3629315== ==3629315== LEAK SUMMARY: ==3629315== definitely lost: 0 bytes in 0 blocks ==3629315== indirectly lost: 0 bytes in 0 blocks ==3629315== possibly lost: 0 bytes in 0 blocks ==3629315== still reachable: 5 bytes in 1 blocks ==3629315== suppressed: 0 bytes in 0 blocks ==3629315== Rerun with --leak-check=full to see details of leaked memory ==3629315== ==3629315== For lists of detected and suppressed errors, rerun with: -s ==3629315== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0) As per the Kernel rules for accessing sysfs information [1], searching for the sysfs mount point is a waste of time and systems that don't have sysfs mounted at /sys are considered broken. With those things in mind, util_path_sysfs() and especially sys_mount_point() can be simplified. sys_mount_point() will always return '/sys' unless the environment variable SYSFS_ROOT is set. With SYSFS_ROOT still being present, special container setups or test case scenarios are still possible but might need to be modified if they previously relied on util_path_sysfs() automatically finding the correct sysfs mount point. To make things more secure against malicious strings in SYSFS_ROOT, secure_getenv() is being used and the ordering of creating the formatted path string in util_path_sysfs() is changed slightly. Furthermore, the static variable is removed as no complicated query of the /proc fs is required anymore. Memory for the sysfs mount point value is properly freed now at the end of util_path_sysfs(). [1] https://www.kernel.org/doc/html/latest/admin-guide/sysfs-rules.html Reviewed-by: Ingo Franzki <ifranzki@linux.ibm.com> Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
5.4 KiB
5.4 KiB