OPENDISK(3)

NAME
opendisk, opendisk1 - open a disk partition

LIBRARY
libutil

SYNOPSIS
#include <util.h>
int
opendisk(const char *path, int flags, char *buf, size_t buflen, int iscooked);
int
opendisk1(const char *path, int flags, char *buf, size_t buflen, int iscooked, int (*ofn)(const char *, int, ...)));

DESCRIPTION
opendisk() opens path, for reading and/or writing as specified by the argument flags using open(2), and the file descriptor is returned to the caller. buf is used to store the resultant filename. buflen is the size, in bytes, of the array referenced by buf (usually MAXPATHLEN bytes). iscooked controls which paths in /dev are tried.

opendisk() attempts to open the following variations of path, in order:

If path does not contain a slash (“/”), the following variations are attempted:

-   If iscooked is zero:
    /dev/rpath
        path with a prefix of “/dev/r”.
    /dev/rpathX
        path with a prefix of “/dev/r” and a suffix of ‘X’ (q.v.).
-   If iscooked is non-zero:
    /dev/path
        path with a prefix of “/dev/”.
    /dev/pathX
        path with a prefix of “/dev/” and a suffix of ‘X’ (q.v.).

If the above fails, then the original path is tried using the following two variations:

-   The iscooked value is ignored:
    path
        The pathname as given.
    pathX
        path with a suffix of ‘X’, where ‘X’ represents the raw partition of the device, as determined by getrawpartition(3), usually “c” or “d”.

opendisk1() is identical to opendisk() except uses the supplied ofn function instead of open(2). This function must be compatible with open(2) in the parameters it takes, the value it returns, and way that errors are indicated.

RETURN VALUES
An open file descriptor, or -1 if the open(2) failed.

ERRORS
opendisk() and opendisk1() may set errno to one of the following values:

[EFAULT]
    buf was the NULL pointer.

[EINVAL]
    O_CREAT was set in flags, or getrawpartition(3) didn't return a valid partition.

The opendisk() function may also set errno to any value specified by the open(2) function.

The opendisk1() function may also set errno to any value set by the ofn function.

SEE ALSO
open(2), getrawpartition(3)

HISTORY
The opendisk() function first appeared in NetBSD 1.3.

The opendisk1() function first appeared in NetBSD 6.0, and was documented in NetBSD 8.0.

The lookup order of opendisk() was changed in NetBSD 7.1 to first look in /dev in order to avoid opening random files in the current working directory.