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Command: knlist | Section: 3 | Source: Digital UNIX | File: knlist.3.gz
knlist(3) Library Functions Manual knlist(3)
NAME
knlist - Look up symbols in the currently running kernel
LIBRARY
Standard C Library (libc.a, libc.so)
SYNOPSIS
#include <nlist.h>
int knlist(
struct nlist namelist);
PARAMETERS
On input, lists the symbol names for which you are requesting ad-
dresses.
On return, contains a list of symbol addresses (or 0 if the at-
tempt to find the addresses was unsuccessful).
DESCRIPTION
The knlist() library routine looks up addresses of kernel symbols in
the currently running kernel.
Communication with the knlist() routine occurs using an array of type
struct nlist. The <nlist.h> header file declares that type as follows:
struct nlist{
char *n_name;
unsigned long n_value;
short n_type; /* 0 if not there, 1 if found */
short reserved; };
When your application calls knlist(), it passes the names of symbols in
the n_name field of the structure.
For each symbol, the knlist() routine attempts to determine its current
address in memory. If the routine can determine the address of the
symbol, it returns that address in the n_value field, and it returns
one (1) in the n_type field. If the routine cannot determine the ad-
dress, it returns zero (0) in both the n_value field and the n_type
field.
For BSD compatibility, the knlist routine allows symbol names to be
preceded by an underscore. If it does not find a symbol that matches
the name as specified, knlist attempts to locate the symbol name with
the leading underscore removed.
EXAMPLES
The following example illustrates the use of the knlist() routine: #in-
clude <stdio.h> #include <string.h> #include <stdlib.h> #include
<nlist.h> main () {
struct nlist nl[2];
int retval, i;
nl[0].n_name = (char *)malloc(10);
nl[1].n_name = (char *)malloc(10);
/*******************************************************/
/* Store names of kernel symbols in the nl array */
strcpy (nl[0].n_name, "ncpus");
strcpy (nl[1].n_name, "lockmode");
/*******************************************************/
/* Call the knlist routine */
retval = knlist(nl);
/******************************************************/
/* Display addresses if returned. Otherwise, display */
/* the appropriate error message. */
if (retval == -1 )
printf ("No kernel symbol addresses returned.0);
else
if (retval >= 0 )
for (i=0; i<2; i++)
if (nl[i].n_type == 0)
printf ("Unable to return address of symbol %s0,
nl[i].n_name);
else
printf ("The address of symbol %s is %lx0,
nl[i].n_name, nl[i].n_value);
free (nl[0].n_name);
free (nl[1].n_name); }
This example tests the return value from the knlist() routine. If the
routine returns an error status, a message is displayed to the applica-
tion user. Otherwise, the application checks the status of each kernel
symbol. If the knlist() routine was unable to return an address, the
application displays a message and the symbol name. If the knlist()
routine returns an address, the application displays the symbol name
and address to the application user.
RETURN VALUES
The knlist() routine returns zero on success. The routine returns -1
if it was unable to connect to the kloadsrv daemon. In this case, the
routine was unable to determine any of the requested addresses. The
routine returns a positive integer if it successfully finds some ad-
dresses and fails to find others. The integer value indicates the num-
ber of addresses knlist() was unable to return.
RELATED INFORMATION
Routines: nlist(3) delim off
knlist(3)