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kvm_openfiles(3)

NAME

     kvm_open, kvm_openfiles, kvm_close -- initialize kernel virtual memory
     access

LIBRARY

     Kernel Data Access Library (libkvm, -lkvm)

SYNOPSIS

     #include <fcntl.h>
     #include <kvm.h>

     kvm_t *
     kvm_open(const char *execfile, const char *corefile,
	 const char *swapfile, int flags, const char *errstr);

     kvm_t *
     kvm_openfiles(const char *execfile, const char *corefile,
	 const char *swapfile, int flags, char *errbuf);

     int
     kvm_close(kvm_t *kd);

DESCRIPTION

     The functions kvm_open() and kvm_openfiles() return a descriptor used to
     access kernel virtual memory via the kvm(3) library routines.  Both
     active kernels and crash dumps are accessible through this interface.

     The execfile argument is the executable image of the kernel being exam-
     ined.  This file must contain a symbol table.  If this argument is NULL,
     the currently running system is assumed, as determined from
     getbootfile(3).

     The corefile argument is the kernel memory device file.  It can be either
     /dev/mem or a crash dump core generated by savecore(8).  If corefile is
     NULL, the default indicated by _PATH_MEM from <paths.h> is used.  It can
     also be set to a special value /dev/null by utilities like ps(1) that do
     not directly access kernel memory.

     The swapfile argument is currently unused.

     The flags argument indicates read/write access as in open(2) and applies
     only to the core file.  Only O_RDONLY, O_WRONLY, and O_RDWR are permit-
     ted.

     There are two open routines which differ only with respect to the error
     mechanism.  One provides backward compatibility with the SunOS kvm
     library, while the other provides an improved error reporting framework.

     The kvm_open() function is the Sun kvm compatible open call.  Here, the
     errstr argument indicates how errors should be handled.  If it is NULL,
     no errors are reported and the application cannot know the specific
     nature of the failed kvm call.  If it is not NULL, errors are printed to
     stderr with errstr prepended to the message, as in perror(3).  Normally,
     the name of the program is used here.  The string is assumed to persist
     at least until the corresponding kvm_close() call.

     The kvm_openfiles() function provides BSD style error reporting.  Here,
     <limits.h>).

RETURN VALUES

     The kvm_open() and kvm_openfiles() functions both return a descriptor to
     be used in all subsequent kvm library calls.  The library is fully re-
     entrant.  On failure, NULL is returned, in which case kvm_openfiles()
     writes the error message into errbuf.

     The kvm_close() function returns 0 on success and -1 on failure.

BUGS

     There should not be two open calls.  The ill-defined error semantics of
     the Sun library and the desire to have a backward-compatible library for
     BSD left little choice.

SEE ALSO

     open(2), kvm(3), kvm_getargv(3), kvm_getenvv(3), kvm_geterr(3),
     kvm_getprocs(3), kvm_nlist(3), kvm_read(3), kvm_write(3), kmem(4), mem(4)

FreeBSD 5.4		       January 29, 2004 		   FreeBSD 5.4

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