VARSYM(2)

NAME
varsym_get, varsym_set, varsym_list - variant symlink variables

LIBRARY
libc

SYNOPSIS
#include <unistd.h>
#include <sys/varsym.h>
int
varsym_get(int mask, const char *wild, char *buf, int bufsize);
int
varsym_set(int level, const char *name, const char *data);
int
varsym_list(int level, char *buf, int maxsize, int *marker);

DESCRIPTION
The varsym_get() system call retrieves the value of the first variable whose left side matches wild and return the value in buf. Bufsize specifies the length of the buffer and mask can be used to further restrict the search to variables of certain type. A value of VARSYM_ALL_MASK will search all variables (see below for other mask definitions).

Varsym_set() sets the variable name of type level to the value pointed to by data.

The varsym_list() system call fills the buffer buf with variable settings for the specified level. A maximum of maxsize bytes of settings are returned and marker is set to the actual number of name/value pairs read, or -1 if no more remain. Varsym_list() must be called repeatedly until marker is -1 if all settings are to be retrieved. The format of the buffer is “\000name\000value\000name\000value...”.

The following varsym levels (and masks) are defined in <sys/varsym.h>:

VARSYM_PROC (VARSYM_PROC_MASK)
    Per-process variables.

VARSYM_SYS (VARSYM_SYS_MASK)
    System wide variables.

VARSYM_PRISON
    Used internally.

RETURN VALUES

The varsym_list() function returns the number of bytes read if successful; otherwise the value -1 is returned and the global variable errno is set to indicate the error.

ERRORS
The varsym system calls will fail when one of the following occurs:

[EINVAL]
    An invalid level was specified.

[ENOENT]
    A variable could not be found.

[EOVERFLOW]
    Insufficient space for storing variable values was specified.

SEE ALSO
varsym(1)

HISTORY
The varsym system calls first appeared in DragonFly 1.0.

AUTHORS
-nosplit The varsym system calls were written by Matthew Dillon and this manual page was written by Sascha Wildner.