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knlist(3)
NAME
  knlist - look up symbols in the currently running kernel

SYNOPSIS
  #include <nlist.h>

  int knlist(
	  struct nlist namelist );

LIBRARY
  Standard C Library (libc.a, libc.so)

PARAMETERS
  namelist
      On input, lists the symbol names for which you are requesting
      addresses. The namelist must be terminated with a null name at end.
      Without a terminating null name at end, knlist() cannot determine how
      many symbols are in the namelist and therefore may dump core.

      On return, contains a list of symbol addresses (or 0 if the attempt to
      find the addresses was unsuccessful).

DESCRIPTION
  The knlist() library routine looks up addresses of kernel symbols in the
  currently running kernel. In addition to finding symbols associated with
  the kernel image, knlist() will also find symbols defined in dynamically
  loaded subsystems.

  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 address, 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.

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 addresses and fails to find
  others. The integer value indicates the number of addresses knlist() was
  unable to return.

  The routine returns the negative value of EINVAL if the argument is bad.

EXAMPLES
  The following example illustrates the use of the knlist() routine:

       #include <stdio.h>
       #include <string.h>
       #include <stdlib.h>
       #include <nlist.h>
       main ()
       {
	  struct nlist	 nl[3];
	  int		 retval, i;
	  nl[0].n_name = (char *)malloc(10);
	  nl[1].n_name = (char *)malloc(10);
	  nl[2].n_name = ;

	  /*******************************************************/
	  /* 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 < 0)
	     printf ("No kernel symbol addresses returned.\n");
	  else
	     if (retval >= 0 )
		for (i=0; i<2; i++)
		    if (nl[i].n_type == 0)
			printf ("Unable to return address of symbol %s\n",
				nl[i].n_name);
		    else
			printf ("The address of symbol %s is %lx\n",
				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 application
  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.

SEE ALSO
  Routines: nlist(3)

Index for Section 3

Alphabetical listing for K

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