NAME
varsym_get,
varsym_set, varsym_list
— variant symlink
variables
LIBRARY
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
Thevarsym_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_get() and
varsym_set() functions return the value 0 if
successful; otherwise the value -1 is returned and the global
variable errno is set to indicate the error.
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
HISTORY
The varsym system calls first appeared in
DragonFly 1.0.
AUTHORS
The varsym system calls were written by
Matthew Dillon and this manual page was written by
Sascha Wildner.