The getvfsent(), getvfsfile(), getvfsspec(), and getvfsany() functions each fill in the structure pointed to by vp with the broken-out fields of a line in the /etc/vfstab file. Each line in the file contains a vfstab structure, declared in the <sys/vfstab.h> header, whose following members are described on the vfstab(4) manual page:
The getvfsent() function returns a pointer to the next vfstab structure in the file; so successive calls can be used to search the entire file.
The getvfsfile() function searches the file referenced by fp until a mount point matching file is found and fills vp
with the fields from the line in the file.
The getvfsspec() function searches the file referenced by fp until a special device matching spec is found and fills vp with the fields from the line in the file. The spec argument will try to match on device type (block or character special) and major and minor device numbers. If it
cannot match in this manner, then it compares the strings.
The getvfsany() function searches the file referenced by fp until a match is found between a line in the file and vref. A match occurrs
if all non-null entries in vref match the corresponding fields in the file.
Note that these functions do not open, close, or rewind the file.