tnf/prex/main.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 2006 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#pragma ident   "%Z%%M% %I% %E% SMI"

/*
 * Includes
 */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <signal.h>
#include <errno.h>
#include <locale.h>
#include <libintl.h>
#include <fcntl.h>
#include <limits.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/param.h>
#include <sys/procfs.h>
#include <libelf.h>
#include <gelf.h>
#include <sys/systeminfo.h>

#include <tnf/tnfctl.h>

#include "set.h"
#include "cmd.h"
#include "spec.h"
#include "expr.h"
#include "source.h"
#include "list.h"
#include "prbk.h"

/*
 * Defines - Project private interfaces
 */

#define DEBUG_ENTRY     "tnf_probe_debug"
#ifdef TESTING
#define EMPTY_ENTRY     "tnf_probe_empty"
#endif

#define USER_OUTSIZE        (4*1024*1024)
#define KERNEL_OUTSIZE      (384*1024)

#if defined(__sparc)
#define PREX32DIR   "/sparcv7/"
#elif defined(__i386) || defined(__amd64)
#define PREX32DIR   "/i86/"
#endif
#define PREX32EXEC  "/usr/bin" PREX32DIR "prex"

/*
 * Globals
 */

char            **g_argv;   /* copy of argv pointer */
tnfctl_handle_t     *g_hndl;    /* handle on target or kernel */

static int      g_verbose;  /* debugging to stderr */
static char     *g_cmdname; /* target command name */
static char     **g_cmdargs;    /* target command args */
static pid_t        g_targetpid;    /* target process id */
static volatile boolean_t g_getcmds;    /* accept input flag */
static boolean_t    g_testflag; /* asserted in test mode */
static char     *g_preload; /* objects to preload */
static char     *g_outname; /* tracefile name */
static char     *tracefile; /* tracefile name used by list cmd */
int         g_outsize;  /* tracefile size */
boolean_t       g_kernelmode;   /* -k flag: kernel mode */
static int      prex_dmodel;    /* prex data model */
/*
 * Local Declarations
 */

static void usage(char **argv, const char *msg);
static void scanargs(int argc, char **argv);
static int set_signal(void);
static int get_data_model(pid_t pid);
static int get_elf_class(char *filename);
static int get_executable(char *);
static void prex_isaexec(char **argv, char **envp);
static void check_pid_model(char **argv, char **envp);
static void check_exec_model(char **argv, char **envp);

/* #### - FIXME - need to put this in a private header file */
extern void err_fatal(char *s, ...);

extern int    yyparse(void);

static tnfctl_errcode_t check_trace_error(tnfctl_handle_t *hndl);
static void set_default_cmd(void);
static void get_commands(void);
static tnfctl_errcode_t set_tracefile(tnfctl_handle_t *hndl);
static tnfctl_errcode_t set_probe_discovery_callback(tnfctl_handle_t *hndl);
static void * perprobe(tnfctl_handle_t *hndl, tnfctl_probe_t *probe_p);
static tnfctl_errcode_t perprobe2(tnfctl_handle_t *hndl,
    tnfctl_probe_t *probe_p, void *ignored);
static tnfctl_errcode_t percmd(expr_t *expr_p, cmd_kind_t kind, fcn_t *fcn_p,
    boolean_t isnew, void *calldata_p);
void quit(boolean_t killtarget, boolean_t runtarget);
void cmd_listtracefile();


/*
 * usage() - gives a description of the arguments, and exits
 */

static void
usage(char *argv[], const char *msg)
{
    if (msg)
        (void) fprintf(stderr,
            gettext("%s: %s\n"), argv[0], msg);

    (void) fprintf(stderr, gettext(
        "usage: %s [options] <cmd> [cmd-args...]\n"), argv[0]);
    (void) fprintf(stderr, gettext(
        "usage: %s [options] -p <pid>\n"), argv[0]);
    (void) fprintf(stderr, gettext(
        "usage: %s -s <kbytes-size> -k\n"), argv[0]);
    (void) fprintf(stderr, gettext(
        "options:\n"));
    (void) fprintf(stderr, gettext(
        "   -o <outfilename>   set trace output file name\n"));
    (void) fprintf(stderr, gettext(
        "   -s <kbytes-size>   set trace file size\n"));
    (void) fprintf(stderr, gettext(
        "   -l <sharedobjs>    shared objects to "
        "be preloaded (cmd only)\n"));

    exit(1);
}


/*
 * main() -
 */

int
main(int argc, char **argv, char **envp)
{
    tnfctl_errcode_t    err = TNFCTL_ERR_NONE;
    int         sys_err;
    tnfctl_trace_attrs_t    trace_attrs;
    tnfctl_event_t      event = TNFCTL_EVENT_EINTR;
    pid_t           prex_pid;

    /* internationalization stuff */
    (void) setlocale(LC_ALL, "");
#if !defined(TEXT_DOMAIN)   /* Should be defined by cc -D */
#define TEXT_DOMAIN "SYS_TEST"  /* Use this only if it weren't */
#endif
    (void) textdomain(TEXT_DOMAIN);

    g_argv = argv;

    prex_pid = getpid();
#if defined(DEBUG)
    fprintf(stderr, "### prex_pid = %d ###\n", prex_pid);
#endif
    prex_dmodel = get_data_model(prex_pid);
#if defined(DEBUG)
    fprintf(stderr, "### prex_dmodel = %d ###\n", prex_dmodel);
#endif
    scanargs(argc, argv);

    if (g_kernelmode) {
        /* prexing the kernel */
        err = tnfctl_kernel_open(&g_hndl);
        if (err) {
            err_fatal(gettext(
                "%s: trouble attaching to the kernel: %s\n"),
                argv[0], tnfctl_strerror(err));
        }
    } else {
        /* prexing a user process */
        if (g_targetpid != 0) {
            /* check data model */
            check_pid_model(argv, envp);
            /* attach case */
            err = tnfctl_pid_open(g_targetpid, &g_hndl);
            if (err == TNFCTL_ERR_NOLIBTNFPROBE) {
                err_fatal(gettext(
                    "%s: missing symbols, is "
                    "libtnfprobe.so loaded in target?\n"),
                    argv[0], tnfctl_strerror(err));
            } else if (err) {
                err_fatal(gettext(
                    "%s: trouble attaching to target "
                    "process: %s\n"),
                    argv[0], tnfctl_strerror(err));
            }
        } else {
            /* check elf class model */
            check_exec_model(argv, envp);
            /* exec case */
            err = tnfctl_exec_open(g_cmdname, g_cmdargs, NULL,
                    g_preload, NULL, &g_hndl);
            if (err == TNFCTL_ERR_NONE)
                err = tnfctl_trace_attrs_get(g_hndl,
                        &trace_attrs);
            if (err) {
                err_fatal(gettext(
                    "%s: trouble creating target process: "
                    "%s\n"),
                    argv[0], tnfctl_strerror(err));
            }
            g_targetpid = trace_attrs.targ_pid;
        }

        sys_err = set_signal();
        if (sys_err)
            err_fatal(gettext(
                "%s: trouble setting up signal handler: %s\n"),
                argv[0], strerror(err));
    }

    /* initialize the source stack for the parser */
    source_init();

    if (!g_kernelmode) {
        /* set the tracefile name and size */
        err = set_tracefile(g_hndl);
        if (err) {
            (void) fprintf(stderr, gettext(
                "%s: trouble initializing tracefile: %s\n"),
                argv[0], tnfctl_strerror(err));
            goto Cleanup;
        }
        err = check_trace_error(g_hndl);
        if (err) {
            (void) fprintf(stderr, gettext(
                "%s: cannot read tracing status : %s\n"),
                argv[0], tnfctl_strerror(err));
            goto Cleanup;
        }
    }

    /* accept commands from stdin the first time through */
    g_getcmds = B_TRUE;

    /* set up default aliases */
    set_default_cmd();

    /* set up creator/destructor function to call for new probes */
    err = set_probe_discovery_callback(g_hndl);
    if (err) {
        (void) fprintf(stderr, gettext(
            "%s: error in probe discovery : %s\n"),
            argv[0], tnfctl_strerror(err));
        goto Cleanup;
    }

    if (g_kernelmode) {
        prbk_warn_pfilter_empty();
    }

    while (err == TNFCTL_ERR_NONE) {

        if (g_kernelmode || g_getcmds) {
            g_getcmds = B_FALSE;
            get_commands();
        }

        if (!g_kernelmode && (g_getcmds == B_FALSE)) {
            err = tnfctl_continue(g_hndl, &event, NULL);
            if (err) {
            (void) fprintf(stderr, gettext(
                "%s: cannot continue target : %s\n"),
                argv[0], tnfctl_strerror(err));
            goto Cleanup;
            }
        }
        err = check_trace_error(g_hndl);
        if (err) {
            (void) fprintf(stderr, gettext(
                "%s: cannot read tracing status : %s\n"),
                argv[0], tnfctl_strerror(err));
            goto Cleanup;
        }
        if (!g_kernelmode) {
            if (event == TNFCTL_EVENT_EXEC) {
                (void) printf(gettext(
                "Target process exec'd\n"));
                quit(B_FALSE, B_TRUE);  /* quit resume */
            } else if (event == TNFCTL_EVENT_EXIT) {
                /* target exited */
                (void) fprintf(stderr, gettext(
                "%s: target process exited\n"),
                g_argv[0]);
                goto Cleanup;
            } else if (event == TNFCTL_EVENT_TARGGONE) {
                /* target terminated */
                (void) fprintf(stderr,
    gettext("%s: target process disappeared (without calling exit)\n"),
                g_argv[0]);
                goto Cleanup;
            }
        }
    }

Cleanup:
    err = tnfctl_close(g_hndl, TNFCTL_TARG_DEFAULT);
    if (err)
        (void) fprintf(stderr, gettext(
            "%s: error on closing : %s\n"),
            argv[0], tnfctl_strerror(err));

    exit(0);

    return (0);

}

/*
 * check_trace_error() - checks whether there was an error in tracing
 */
static tnfctl_errcode_t
check_trace_error(tnfctl_handle_t *hndl)
{
    tnfctl_trace_attrs_t    trace_attrs;
    tnfctl_errcode_t    err;

    err = tnfctl_trace_attrs_get(hndl, &trace_attrs);
    if (err)
        return (err);

    if (trace_attrs.trace_buf_state == TNFCTL_BUF_BROKEN) {
        (void) printf(gettext("Tracing shut down in target program "
            "due to an internal error - Please restart prex "
            "and target\n"));
    }

    return (TNFCTL_ERR_NONE);
}

/*
 * set_default_cmd() - set the default debug entry and $all
 */
static void
set_default_cmd(void)
{
    if (!g_kernelmode)
        fcn(strdup("debug"), DEBUG_ENTRY);
#ifdef TESTING
    fcn(strdup("empty"), EMPTY_ENTRY);
#endif
    (void) set(strdup("all"), expr(spec(strdup("keys"), SPEC_EXACT),
                spec(strdup(".*"), SPEC_REGEXP)));

}

/*
 * process() - enable and disable selected probes
 */

typedef struct {
    tnfctl_probe_t  *probe_p;
    tnfctl_handle_t *hndl;
} process_args_t;

static tnfctl_errcode_t
percmd(expr_t *expr_p, cmd_kind_t kind, fcn_t *fcn_p, boolean_t isnew,
    void *calldata_p)
{
    process_args_t *args_p = (process_args_t *)calldata_p;
    tnfctl_handle_t *hndl = args_p->hndl;
    tnfctl_probe_t  *probe_p = args_p->probe_p;
    tnfctl_errcode_t err = TNFCTL_ERR_NONE;
    char *attrs;

    attrs = list_getattrs(probe_p);

    if (expr_match(expr_p, attrs)) {
#if defined(DEBUG) || defined(lint)
        if (g_verbose) {
            char           *cmdstr[] = {
                "enable", "disable",
                "connect", "clear",
                "trace", "untrace"};

            (void) fprintf(stderr, ": %s command: %s ",
                (isnew) ? "new" : "old", cmdstr[kind]);
            expr_print(stderr, expr_p);
        }
#endif

        switch (kind) {
        case CMD_ENABLE:
            err = tnfctl_probe_enable(hndl, probe_p, NULL);
            break;
        case CMD_DISABLE:
            err = tnfctl_probe_disable(hndl, probe_p, NULL);
            break;
        case CMD_TRACE:
            err = tnfctl_probe_trace(hndl, probe_p, NULL);
            break;
        case CMD_UNTRACE:
            err = tnfctl_probe_untrace(hndl, probe_p, NULL);
            break;
        case CMD_CONNECT:
            err = tnfctl_probe_connect(hndl, probe_p, NULL,
                fcn_p->entry_name_p);
            break;
        case CMD_CLEAR:
            err = tnfctl_probe_disconnect_all(hndl, probe_p, NULL);
            break;
        }

#if defined(DEBUG) || defined(lint)
        if (g_verbose)
            (void) fprintf(stderr, "\n");
#endif

    }
    if (attrs)
        free(attrs);

    return (err);

}

/*ARGSUSED*/
static void *
perprobe(tnfctl_handle_t *hndl, tnfctl_probe_t *probe_p)
{
    process_args_t  args;
    tnfctl_errcode_t err;

    args.probe_p = probe_p;
    args.hndl = hndl;
    err = cmd_traverse(percmd, &args);
    if (err) {
        (void) fprintf(stderr, gettext(
                "%s: error on new (dlopened) probe : %s\n"),
                g_argv[0], tnfctl_strerror(err));
    }
    return (NULL);
}

static tnfctl_errcode_t
set_probe_discovery_callback(tnfctl_handle_t *hndl)
{
    tnfctl_errcode_t err;

    err = tnfctl_register_funcs(hndl, perprobe, NULL);
    if (err)
        return (err);

    return (TNFCTL_ERR_NONE);
}

static tnfctl_errcode_t
perprobe2(tnfctl_handle_t *hndl, tnfctl_probe_t *probe_p, void *cd)
{
    cmd_t       *cmd = cd;
    process_args_t  args;
    tnfctl_errcode_t err;

    args.probe_p = probe_p;
    args.hndl = hndl;
    err = cmd_callback(cmd, percmd, &args);
    if (err) {
        (void) fprintf(stderr, gettext(
                "%s: error on probe operation: %s\n"),
                g_argv[0], tnfctl_strerror(err));
    }
    return (err);
}

void
process_cmd(tnfctl_handle_t *hndl, cmd_t *cmd)
{
#if defined(DEBUG) || defined(lint)
    if (g_verbose)
        (void) fprintf(stderr, "processing commands\n");
#endif
    (void) tnfctl_probe_apply(hndl, perprobe2, cmd);
}

/*
 * get_commands() - process commands from stdin
 */
static void
get_commands(void)
{
    /* Read commands from STDIN */
    if (g_kernelmode) {
        (void) printf(gettext("Type \"help\" for help ...\n"));
    } else {
        if (g_testflag)
            (void) printf("prex(%ld), target(%ld): ",
                    getpid(), g_targetpid);
        (void) printf(gettext("Target process stopped\n"));
        (void) printf(gettext(
            "Type \"continue\" to resume the target, "
            "\"help\" for help ...\n"));
    }

    while (yyparse());
}


/*
 * quit() - called to quit the controlling process. The boolean argument
 * specifies whether to terminate the target as well.
 */

void
quit(boolean_t killtarget, boolean_t runtarget)
{
    tnfctl_errcode_t err;

    if (killtarget && runtarget)
        err = tnfctl_close(g_hndl, TNFCTL_TARG_DEFAULT);
    else if (killtarget && !runtarget)
        err = tnfctl_close(g_hndl, TNFCTL_TARG_KILL);
    else if (!killtarget && runtarget)
        err = tnfctl_close(g_hndl, TNFCTL_TARG_RESUME);
    else if (!killtarget && !runtarget)
        err = tnfctl_close(g_hndl, TNFCTL_TARG_SUSPEND);
    if (err) {
        (void) fprintf(stderr, gettext(
                "%s: trouble quitting : %s\n"),
                g_argv[0], tnfctl_strerror(err));
        exit(1);
    }
    exit(0);
}


/*
 * scanargs() - processes the command line arguments
 */

#define strneq(s1, s2, n)   (strncmp(s1, s2, n) == 0)

static void
scanargs(int argc,
    char **argv)
{
    int          c;
#if defined(DEBUG) || defined(lint)
    char           *optstr = "l:o:p:s:tkv:";    /* debugging options */
#else
    char           *optstr = "l:o:p:s:tk";  /* production options */
#endif

    /* set up some defaults */
    g_targetpid = 0;
    g_cmdname = NULL;
    g_cmdargs = NULL;
    g_preload = NULL;
    g_outname = NULL;
    g_outsize = -1;

    while ((c = getopt(argc, argv, optstr)) != EOF) {
        switch (c) {
        case 'l':   /* preload objects */
            g_preload = optarg;
            break;
        case 'o':   /* tracefile name */
            g_outname = optarg;
            break;
        case 'p':   /* target pid (attach case) */
            g_targetpid = atoi(optarg);
            break;
        case 's':   /* tracefile size */
            g_outsize = atoi(optarg) * 1024;
            break;
        case 't':   /* test flag */
            g_testflag = B_TRUE;
            (void) setvbuf(stdout, NULL, _IOLBF, 0);
            break;
        case 'k':   /* kernel mode */
            g_kernelmode = B_TRUE;
            break;
#if defined(DEBUG) || defined(lint)
        case 'v':   /* verbose flag */
            g_verbose = atoi(optarg);
            break;
#endif
        case '?':   /* error case */
            usage(argv, gettext("unrecognized argument"));
        }
    }

    if (optind < argc) {
        g_cmdname = strdup(argv[optind]);
        g_cmdargs = &argv[optind];
    }
    /* sanity clause */
    if (!g_kernelmode && (g_cmdname == NULL && g_targetpid == 0))
        usage(argv, gettext("need to specify cmd or pid"));
    if (g_cmdname != NULL && g_targetpid != 0)
        usage(argv, gettext("can't specify both cmd and pid"));
    if (g_targetpid && g_preload)
        usage(argv, gettext("can't use preload option with attach"));
    if (g_kernelmode) {
        if (g_outname)
            usage(argv, "can't specify a filename in kernel mode");
        if (g_cmdname)
            usage(argv, "can't specify a command in kernel mode");
        if (g_targetpid)
            usage(argv, "can't specify pid in kernel mode");
        if (g_preload)
            usage(argv, "can't use preload option in kernel mode");
    }
    /* default output size */
    if (g_outsize == -1)
        g_outsize = g_kernelmode ? KERNEL_OUTSIZE : USER_OUTSIZE;

#ifdef OLD
    int          i;

    for (i = 1; i < argc; i++) {
        if (strneq(argv[i], "-v", 2)) {
            int          vlevel;

            vlevel = (strlen(argv[i]) > 2)? atoi(&argv[i][2]) : 1;
            g_verbose = B_TRUE;
            prb_verbose_set(vlevel);
        } else if (strneq(argv[i], "-pid", 2)) {
            if (++i >= argc)
                usage(argv, gettext("missing pid argument"));
            g_targetpid = atoi(argv[i]);
        } else if (strneq(argv[i], "-t", 2)) {
            g_testflag = B_TRUE;
            (void) setvbuf(stdout, NULL, _IOLBF, 0);
        } else if (argv[i][0] != '-') {
            g_cmdname = strdup(argv[i]);
            if (!g_cmdname) {
                err_fatal(gettext(
                    "%s: out of memory"), argv[0]);
            }
            if (g_verbose >= 2) {
                (void) fprintf(stderr,
                    "cmdname=%s\n", g_cmdname);
            }
            /*
             * rest of arguments are the args to the executable -
             * by convention argv[0] should be name of
             * executable, so we don't increment i
             */
            g_cmdargs = &argv[i];
            break;
        } else {
            usage(argv, gettext("unrecognized argument"));
        }
    }
#endif

}               /* end scanargs */


/*
 * sig_handler() - cleans up if a signal is received
 */

/*ARGSUSED*/
static void
sig_handler(int signo)
{
    g_getcmds = B_TRUE;
}               /* end sig_handler */


/*
 * set_signal() -  sets up function to call for clean up
 */

static int
set_signal(void)
{
    struct sigaction newact;

    newact.sa_handler = sig_handler;
    (void) sigemptyset(&newact.sa_mask);
    newact.sa_flags = 0;
    if (sigaction(SIGINT, &newact, NULL) < 0) {
        return (errno);
    }
    return (0);
}


/*
 * set_tracefile() - initializes tracefile, sets the tracefile name and size
 */
static tnfctl_errcode_t
set_tracefile(tnfctl_handle_t *hndl)
{
    tnfctl_errcode_t    err;
    tnfctl_trace_attrs_t    attrs;
    size_t          minoutsize;
    char            path[MAXPATHLEN];
    char            *outfile_name;
    char            *tmpdir;

    /* Init tracefile name used by list cmd */
    tracefile = NULL;
    err = tnfctl_trace_attrs_get(hndl, &attrs);
    if (err)
        return (err);

    if (attrs.trace_buf_state == TNFCTL_BUF_BROKEN)
        return (TNFCTL_ERR_BUFBROKEN);
    if (attrs.trace_buf_state == TNFCTL_BUF_OK) {
        /* trace file set already - can't change it */
        return (TNFCTL_ERR_NONE);
    }

    minoutsize = attrs.trace_min_size;
    if (g_outsize < minoutsize) {
        (void) fprintf(stderr,
            gettext("specified tracefile size smaller then "
                "minimum; setting to %d kbytes\n"),
                minoutsize / 1024);
        g_outsize = minoutsize;
    }

    /* where is $TMPDIR? */
    tmpdir = getenv("TMPDIR");
    if (!tmpdir || *tmpdir == '\0') {
        tmpdir = "/tmp";
    }

    /* do we have an absolute, relative or no pathname specified? */
    if (g_outname == NULL) {
        /* default, no tracefile specified */
        if ((strlen(tmpdir) + 1 + 20) > (size_t)MAXPATHLEN) {
            (void) fprintf(stderr, gettext(
                "%s: $TMPDIR too long\n"), g_argv[0]);
            exit(1);
        }
        (void) sprintf(path, "%s/trace-%ld", tmpdir, g_targetpid);
        outfile_name = path;
    } else {
        /* filename specified */
        outfile_name = g_outname;
    }
    tracefile = strdup(outfile_name);
    if (tracefile == NULL) {
        if ((errno == ENOMEM) || (errno == EAGAIN)) {
            return (TNFCTL_ERR_ALLOCFAIL);
        } else {
            return (TNFCTL_ERR_INTERNAL);
        }
    }

#if defined(DEBUG) || defined(lint)
    if (g_verbose)
        (void) fprintf(stderr,
            "setting tracefile name=\"%s\", size=%d\n",
            path, g_outsize);
#endif
    err = tnfctl_buffer_alloc(hndl, outfile_name, g_outsize);
    return (err);
}
/*
 * get_data_model() - get the process data model from psinfo
 *            structure.
 */
#define PROCFORMAT  "/proc/%d"
static int
get_data_model(pid_t pid)
{
    char    path[MAXPATHLEN];
    int fd, dmodel = -1;
    prpsinfo_t  psinfo;

    (void) sprintf(path, PROCFORMAT, (int)pid);
    fd = open(path, O_RDONLY);
    if (fd == -1)
        return (dmodel);
    if ((dmodel = ioctl(fd, PIOCPSINFO, &psinfo)) == -1)
        return (dmodel);
    return ((int)psinfo.pr_dmodel);
}
/*
 * get_executable - return file descriptor for PATH-resolved
 *          target file.
 *
 */
static int
get_executable(char *name) {
    int fd = -1;

    if (name != NULL) {
    char path[PATH_MAX + 1];
    char line[MAX_INPUT + 1];
    char *p = line;
    char *fname = name;
    int N = sizeof (line);
    struct stat file_att;

    while (*fname == ' ') fname++;
    if (fname[0] == '-' || strchr(fname, '/')) {
        fd = open(fname, O_RDONLY);
    } else {
        int len = strlen(fname);
        char *dirlist = getenv("PATH");
        char *dir = NULL;

        if (dirlist != NULL) {
        dirlist = strdup(dirlist);
        dir = strtok(dirlist, ":");
        }
        while (fd < 0 && dir != NULL) {
        if ((strlen(dir) + len + 1) < sizeof (path)) {
            strcat(strcat(strcpy(path, dir), "/"), fname);
            fd = open(path, O_RDONLY);
        }
        dir = strtok(NULL, ":");
        }
        if (dirlist != NULL) free(dirlist);
    }
    if (fstat(fd, &file_att) || !S_ISREG(file_att.st_mode)) {
        if (fd >= 0)
        close(fd);
        return (-1);
    }
    if (read(fd, p, 2) && p[0] == '#' && p[1] == '!') {
        while (N-- > 1 && read(fd, p, 1) && *p != '\n')
        p++;
        *p = '\0';
        close(fd);
        return (get_executable(line));
    }
    if (fd >= 0) lseek(fd, 0, SEEK_SET);
    } /* %$#@! cstyle complaint */
    return (fd);
}

/*
 * get_elf_class - get the target executable elf class
 *                 i.e. ELFCLASS64 or ELFCLASS32.
 */
static int
get_elf_class(char *filename)
{
    int elfclass = -1;
    int elffd = get_executable(filename);
    Elf *elf;
    size_t  size;
    char    *ident;
    GElf_Ehdr   ehdr;

    if (elffd < 0)
        return (elfclass);
    if (elf_version(EV_CURRENT) == EV_NONE) {
        (void) close(elffd);
        return (elfclass);
    }
    elf = elf_begin(elffd, ELF_C_READ, (Elf *) 0);
    /*
     * verify information in file header
     */
    if (gelf_getehdr(elf, &ehdr) == (GElf_Ehdr *) 0) {
        close(elffd);
        return (elfclass);
    }
    ident = elf_getident(elf, &size);
    if (ident[EI_CLASS] == ELFCLASS32)
        elfclass = ELFCLASS32;
    if (ident[EI_CLASS] == ELFCLASS64)
        elfclass = ELFCLASS64;
    close(elffd);
    return (elfclass);
}
/*
 * check_exec_model() - check the consistency between prex data model
 *                      and target elf class and act accordingly
 */
static void
check_exec_model(char **argv, char **envp)
{
    int elfclass;

    elfclass = get_elf_class(g_cmdname);
    if (((elfclass == ELFCLASS32) && (prex_dmodel == PR_MODEL_ILP32)) ||
        ((elfclass == ELFCLASS64) && (prex_dmodel == PR_MODEL_LP64)))
        return;
    if ((prex_dmodel == PR_MODEL_ILP32) &&
        (elfclass == ELFCLASS64)) {
        (void) fprintf(stderr, gettext(
        "Error: 32 bit prex can not exec 64 bit target\n"));
        exit(1);
    }
    if ((prex_dmodel == PR_MODEL_LP64) &&
        (elfclass == ELFCLASS32))
        prex_isaexec(argv, envp);
}

/*
 * check_pid_model() - check the consistency between prex data model
 *                     and target data model and act accordingly
 */
static void
check_pid_model(char **argv, char **envp)
{
    int dmodel;

    dmodel = get_data_model(g_targetpid);
    if (prex_dmodel == dmodel)
        return;
    if ((prex_dmodel == PR_MODEL_ILP32) &&
        (dmodel == PR_MODEL_LP64)) {
        (void) fprintf(stderr, gettext(
            "Error: 32 bit prex can not exec 64 bit target\n"));
        exit(1);
    }
    if ((prex_dmodel == PR_MODEL_LP64) &&
        (dmodel == PR_MODEL_ILP32))
        prex_isaexec(argv, envp);
}
/*
 * prex_isaexec() - there is only one case this function get called
 *                  64 bit prex, 32 bit target, need to exec 32 bit
 *                  prex here.
 */
static void
prex_isaexec(char **argv, char **envp)
{
    char path[PATH_MAX + sizeof (PREX32DIR)];
    strcat(strcat(strcpy(path, dirname(dirname(argv[0]))), PREX32DIR),
        basename(argv[0]));
    if (get_elf_class(path) != ELFCLASS32)
        strcpy(path, PREX32EXEC);
    argv[0] = path;
    (void) execve(path, argv, envp);
    (void) fprintf(stderr,
        gettext("%s: execve(\"%s\") failed\n"),
        argv[0], path);
    exit(1);
}
void
cmd_listtracefile()
{

    if (g_kernelmode) {
        (void) fprintf(stderr,
            gettext("There is no trace file in kernel mode!\n"));
    } else {
        (void) printf(gettext("Current trace file is: %s\n"), tracefile);
    }
}