source: vbox/trunk/src/VBox/ExtPacks/VBoxDTrace/onnv/lib/libdtrace/common/drti.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#include <unistd.h>
#include <fcntl.h>
#include <dlfcn.h>
#include <link.h>
#include <sys/dtrace.h>

#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>

/*
 * In Solaris 10 GA, the only mechanism for communicating helper information
 * is through the DTrace helper pseudo-device node in /devices; there is
 * no /dev link. Because of this, USDT providers and helper actions don't
 * work inside of non-global zones. This issue was addressed by adding
 * the /dev and having this initialization code use that /dev link. If the
 * /dev link doesn't exist it falls back to looking for the /devices node
 * as this code may be embedded in a binary which runs on Solaris 10 GA.
 *
 * Users may set the following environment variable to affect the way
 * helper initialization takes place:
 *
 *      DTRACE_DOF_INIT_DEBUG           enable debugging output
 *      DTRACE_DOF_INIT_DISABLE         disable helper loading
 *      DTRACE_DOF_INIT_DEVNAME         set the path to the helper node
 */

static const char *devname = "/dev/dtrace/helper";
static const char *olddevname = "/devices/pseudo/dtrace@0:helper";

static const char *modname;     /* Name of this load object */
static int gen;                 /* DOF helper generation */
extern dof_hdr_t __SUNW_dof;    /* DOF defined in the .SUNW_dof section */
static boolean_t dof_init_debug = B_FALSE;      /* From DTRACE_DOF_INIT_DEBUG */

static void
dprintf(int debug, const char *fmt, ...)
{
        va_list ap;

        if (debug && !dof_init_debug)
                return;

        va_start(ap, fmt);

        if (modname == NULL)
                (void) fprintf(stderr, "dtrace DOF: ");
        else
                (void) fprintf(stderr, "dtrace DOF %s: ", modname);

        (void) vfprintf(stderr, fmt, ap);

        if (fmt[strlen(fmt) - 1] != '\n')
                (void) fprintf(stderr, ": %s\n", strerror(errno));

        va_end(ap);
}

#pragma init(dtrace_dof_init)
static void
dtrace_dof_init(void)
{
        dof_hdr_t *dof = &__SUNW_dof;
#ifdef _LP64
        Elf64_Ehdr *elf;
#else
        Elf32_Ehdr *elf;
#endif
        dof_helper_t dh;
        Link_map *lmp;
        Lmid_t lmid;
        int fd;
        const char *p;

        if (getenv("DTRACE_DOF_INIT_DISABLE") != NULL)
                return;

        if (getenv("DTRACE_DOF_INIT_DEBUG") != NULL)
                dof_init_debug = B_TRUE;

        if (dlinfo(RTLD_SELF, RTLD_DI_LINKMAP, &lmp) == -1 || lmp == NULL) {
                dprintf(1, "couldn't discover module name or address\n");
                return;
        }

        if (dlinfo(RTLD_SELF, RTLD_DI_LMID, &lmid) == -1) {
                dprintf(1, "couldn't discover link map ID\n");
                return;
        }

        if ((modname = strrchr(lmp->l_name, '/')) == NULL)
                modname = lmp->l_name;
        else
                modname++;

        if (dof->dofh_ident[DOF_ID_MAG0] != DOF_MAG_MAG0 ||
            dof->dofh_ident[DOF_ID_MAG1] != DOF_MAG_MAG1 ||
            dof->dofh_ident[DOF_ID_MAG2] != DOF_MAG_MAG2 ||
            dof->dofh_ident[DOF_ID_MAG3] != DOF_MAG_MAG3) {
                dprintf(0, ".SUNW_dof section corrupt\n");
                return;
        }

        elf = (void *)lmp->l_addr;

        dh.dofhp_dof = (uintptr_t)dof;
        dh.dofhp_addr = elf->e_type == ET_DYN ? lmp->l_addr : 0;

        if (lmid == 0) {
                (void) snprintf(dh.dofhp_mod, sizeof (dh.dofhp_mod),
                    "%s", modname);
        } else {
                (void) snprintf(dh.dofhp_mod, sizeof (dh.dofhp_mod),
                    "LM%lu`%s", lmid, modname);
        }

        if ((p = getenv("DTRACE_DOF_INIT_DEVNAME")) != NULL)
                devname = p;

        if ((fd = open64(devname, O_RDWR)) < 0) {
                dprintf(1, "failed to open helper device %s", devname);

                /*
                 * If the device path wasn't explicitly set, try again with
                 * the old device path.
                 */
                if (p != NULL)
                        return;

                devname = olddevname;

                if ((fd = open64(devname, O_RDWR)) < 0) {
                        dprintf(1, "failed to open helper device %s", devname);
                        return;
                }
        }

        if ((gen = ioctl(fd, DTRACEHIOC_ADDDOF, &dh)) == -1)
                dprintf(1, "DTrace ioctl failed for DOF at %p", dof);
        else
                dprintf(1, "DTrace ioctl succeeded for DOF at %p\n", dof);

        (void) close(fd);
}

#pragma fini(dtrace_dof_fini)
static void
dtrace_dof_fini(void)
{
        int fd;

        if ((fd = open64(devname, O_RDWR)) < 0) {
                dprintf(1, "failed to open helper device %s", devname);
                return;
        }

        if ((gen = ioctl(fd, DTRACEHIOC_REMOVE, gen)) == -1)
                dprintf(1, "DTrace ioctl failed to remove DOF (%d)\n", gen);
        else
                dprintf(1, "DTrace ioctl removed DOF (%d)\n", gen);

        (void) close(fd);
}