NAME

       pmem2_source_device_usc() - returns the unsafe shutdown counter value of a device

SYNOPSIS

              #include <libpmem2.h>

              struct pmem2_source;
              int pmem2_source_device_usc(const struct pmem2_source *source, uint64_t *usc);

DESCRIPTION

       The pmem2_source_device_usc() function retrieves the sum of the unsafe shutdown count(USC)
       values of all hardware devices backing the data source and stores it in *usc.

       Please refer to libpmem2_unsafe_shutdown(7) for detailed description on  how  to  properly
       consume this information.

RETURN VALUE

       The  pmem2_source_device_usc()  function returns 0 on success.  If the function fails, the
       *usc variable content is left unmodified and a negative error code is returned.

ERRORS

       The pmem2_source_device_usc() can fail with the following errors:

       On all systems:

       • PMEM2_E_NOSUPP  -  the  underlying  platform  does  not  expose  unsafe  shutdown  count
         information.

       On Windows:

       • -errno  equivalent  of  return  code  set  by failing GetFinalPathNameByHandleW(), while
         trying to resolve volume path from the file handle.

       • -errno set by failing malloc(3), while trying to allocate a buffer  for  storing  volume
         path.

       • -errno  equivalent of return code set by failing CreateFileW(), while trying to obtain a
         handle to the volume.

       • -errno equivalent of return code set  by  failing  DeviceIoControl(),  while  trying  to
         obtain volume USC value.

       On Linux:

       • -errno set by failing fstat(2), while trying to validate the file descriptor.

       • -errno set by failing ndctl_new(), while trying to initiate a new NDCTL library context.

       • -errno  set  by failing ndctl_dimm_get_dirty_shutdown(), while trying to obtain DIMM USC
         value.

SEE ALSO

       fstat(2), errno(3), malloc(3), libpmem2_unsafe_shutdown(7), and <https://pmem.io>