cmd/truss/ipc.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 2010 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*  Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
/*    All Rights Reserved   */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <ctype.h>
#include <string.h>
#include <signal.h>
#include <stropts.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/termio.h>
#include <libproc.h>
#include "ramdata.h"
#include "proto.h"

/*
 * Routines related to interprocess communication
 * among the truss processes which are controlling
 * multiple traced processes.
 */

/*
 * Function prototypes for static routines in this module.
 */
void    Ecritical(int);
void    Xcritical(int);

/*
 * Ensure everyone keeps out of each other's way
 * while writing lines of trace output.
 */
void
Flush()
{
    /*
     * Except for regions bounded by Eserialize()/Xserialize(),
     * this is the only place anywhere in the program where a
     * write() to the trace output file takes place, so here
     * is where we detect errors writing to the output.
     */

    errno = 0;

    Ecritical(0);
    (void) fflush(stdout);
    Xcritical(0);

    if (ferror(stdout) && errno)    /* error on write(), probably EPIPE */
        interrupt = SIGTERM;        /* post an interrupt */
}

/*
 * Eserialize() and Xserialize() are used to bracket
 * a region which may produce large amounts of output,
 * such as showargs()/dumpargs().
 */

void
Eserialize()
{
    /* serialize output */
    Ecritical(0);
}

void
Xserialize()
{
    (void) fflush(stdout);
    Xcritical(0);
}

/*
 * Enter critical region --- Wait on mutex, lock out other processes.
 * Lock zero is used to serialize output in situations where multiple processes
 * may be writing to stdout/stderr and order must be preserved.  Most of these
 * are in expound.c
 * Lock one is used to protect the table of processes currently being traced
 * every time a pid is added or removed from the table Ecritical(1)/Xcritical(1)
 * get called.
 */
void
Ecritical(int num)
{
    int rv;

    if (num == 0)
        rv = mutex_lock(&gps->ps_mutex0);
    else if (num == 1)
        rv = mutex_lock(&gps->ps_mutex1);
    else
        abend("Invalid mutex specified", NULL);

    if (rv != 0) {
        char mnum[2];
        mnum[0] = '0' + num;
        mnum[1] = '\0';
        errno = rv;
        perror(command);
        errmsg("cannot grab mutex #", mnum);
    }
}

/*
 * Exit critical region ---
 * Release other processes waiting on mutex.
 */
void
Xcritical(int num)
{
    int rv;

    if (num == 0)
        rv = mutex_unlock(&gps->ps_mutex0);
    else if (num == 1)
        rv = mutex_unlock(&gps->ps_mutex1);
    else
        abend("Invalid mutex specified", NULL);


    if (rv != 0) {
        char mnum[2];
        mnum[0] = '0' + num;
        mnum[1] = '\0';
        errno = rv;
        perror(command);
        errmsg("cannot release mutex #", mnum);
    }
}

/*
 * Add process to set of those being traced.
 */
void
procadd(pid_t spid, const char *lwplist)
{
    int i;
    int j = -1;

    if (gps == NULL)
        return;

    Ecritical(1);
    for (i = 0; i < sizeof (gps->tpid) / sizeof (gps->tpid[0]); i++) {
        if (gps->tpid[i] == 0) {
            if (j == -1)    /* remember first vacant slot */
                j = i;
            if (gps->spid[i] == 0)  /* this slot is better */
                break;
        }
    }
    if (i < sizeof (gps->tpid) / sizeof (gps->tpid[0]))
        j = i;
    if (j >= 0) {
        gps->tpid[j] = getpid();
        gps->spid[j] = spid;
        gps->lwps[j] = lwplist;
    }
    Xcritical(1);
}

/*
 * Delete process from set of those being traced.
 */
void
procdel()
{
    int i;
    pid_t tpid;

    if (gps == NULL)
        return;

    tpid = getpid();

    Ecritical(1);
    for (i = 0; i < sizeof (gps->tpid) / sizeof (gps->tpid[0]); i++) {
        if (gps->tpid[i] == tpid) {
            gps->tpid[i] = 0;
            break;
        }
    }
    Xcritical(1);
}

/*
 * Determine if the lwp for this process should be traced.
 */
int
lwptrace(pid_t spid, lwpid_t lwpid)
{
    int i;
    pid_t tpid;
    const char *lwps;

    if (gps == NULL)
        return (0);

    tpid = getpid();

    Ecritical(1);
    for (i = 0; i < sizeof (gps->tpid) / sizeof (gps->tpid[0]); i++) {
        if (gps->tpid[i] == tpid &&
            gps->spid[i] == spid)
            break;
    }
    lwps = gps->lwps[i];
    Xcritical(1);

    return (proc_lwp_in_set(lwps, lwpid));
}

/*
 * Check for open of a /proc/nnnnn file.
 * Return 0 if this is not an open of a /proc file.
 * Return 1 if the process opened itself.
 * Return 2 if the process failed to open another process
 * in truss's set of controlled processes.
 * Return 3 if the process successfully opened another process
 * in truss's set of controlled processes.
 * We notify and wait for the other controlling truss process
 * to terminate before returning in cases 2 and 3.
 */
/* ARGSUSED */
int
checkproc(private_t *pri)
{
    char *path = pri->sys_path;
    const pstatus_t *Psp = Pstatus(Proc);
    struct ps_lwphandle *Lwp = pri->Lwp;
    const lwpstatus_t *Lsp = pri->lwpstat;
    int what = Lsp->pr_what;    /* one of the SYS_open* syscalls */
    int err = Lsp->pr_errno;
    int pid;
    int i;
    const char *dirname;
    char *next;
    char *sp1;
    char *sp2;
    prgreg_t pc;

    /*
     * A bit heuristic ...
     * Test for the cases:
     *  1234
     *  1234/as
     *  1234/ctl
     *  1234/lwp/24/lwpctl
     *  .../1234
     *  .../1234/as
     *  .../1234/ctl
     *  .../1234/lwp/24/lwpctl
     * Insert a '\0', if necessary, so the path becomes ".../1234".
     *
     * Along the way, watch out for /proc/self and /proc/1234/lwp/agent
     */
    if ((sp1 = strrchr(path, '/')) == NULL)     /* last component */
        /* EMPTY */;
    else if (isdigit(*(sp1+1))) {
        sp1 += strlen(sp1);
        while (--sp1 > path && isdigit(*sp1))
            ;
        if (*sp1 != '/')
            return (0);
    } else if (strcmp(sp1+1, "as") == 0 ||
        strcmp(sp1+1, "ctl") == 0) {
        *sp1 = '\0';
    } else if (strcmp(sp1+1, "lwpctl") == 0) {
        /*
         * .../1234/lwp/24/lwpctl
         * ............   ^-- sp1
         */
        if (sp1-6 >= path && strncmp(sp1-6, "/agent", 6) == 0)
            sp1 -= 6;
        else {
            while (--sp1 > path && isdigit(*sp1))
                ;
        }
        if (*sp1 != '/' ||
            (sp1 -= 4) <= path ||
            strncmp(sp1, "/lwp", 4) != 0)
            return (0);
        *sp1 = '\0';
    } else if (strcmp(sp1+1, "self") != 0) {
        return (0);
    }

    if ((sp2 = strrchr(path, '/')) == NULL)
        dirname = path;
    else
        dirname = sp2 + 1;

    if (strcmp(dirname, "self") == 0) {
        pid = Psp->pr_pid;
    } else if ((pid = strtol(dirname, &next, 10)) < 0 ||
        *next != '\0') {    /* dirname not a number */
        if (sp1 != NULL)
            *sp1 = '/';
        return (0);
    }
    if (sp2 == NULL)
        dirname = ".";
    else {
        *sp2 = '\0';
        dirname = path;
    }

    if (!Pisprocdir(Proc, dirname) || /* file not in a /proc directory */
        pid == getpid() ||      /* process opened truss's /proc file */
        pid == 0) {         /* process opened process 0 */
        if (sp1 != NULL)
            *sp1 = '/';
        if (sp2 != NULL)
            *sp2 = '/';
        return (0);
    }
    if (sp1 != NULL)
        *sp1 = '/';
    if (sp2 != NULL)
        *sp2 = '/';

    /*
     * Process did open a /proc file ---
     */
    if (pid == Psp->pr_pid) {   /* process opened its own /proc file */
        /*
         * In SunOS 5.6 and beyond, self-opens always succeed.
         */
        return (1);
    }

    /*
     * Search for a matching pid in our set of controlled processes.
     */
    for (i = 0; i < sizeof (gps->tpid)/sizeof (gps->tpid[0]); i++) {
        if (gps->spid[i] == pid) {
            pid = gps->tpid[i];
            break;
        }
    }
    if (i >= sizeof (gps->tpid) / sizeof (gps->tpid[0])) {
        /*
         * The process opened a /proc file, but not one we care about.
         */
        return (0);
    }

    /*
     * Notify and wait for the controlling process to terminate.
     */
    while (pid && gps->tpid[i] == pid) {
        if (kill(pid, SIGUSR1) == -1)
            break;
        (void) usleep(1000000);
    }
    Ecritical(1);
    if (gps->tpid[i] == 0)
        gps->spid[i] = 0;
    Xcritical(1);

    if (err) {  /* prepare to reissue the failed open() system call */
#if defined(__sparc)
        (void) Lgetareg(Lwp, R_PC, &pc);
        if (pri->sys_indirect) {
            (void) Lputareg(Lwp, R_G1, (prgreg_t)SYS_syscall);
            (void) Lputareg(Lwp, R_O0, (prgreg_t)what);
            for (i = 0; i < 5; i++)
                (void) Lputareg(Lwp, R_O1+i, pri->sys_args[i]);
        } else {
            (void) Lputareg(Lwp, R_G1, (prgreg_t)what);
            for (i = 0; i < 6; i++)
                (void) Lputareg(Lwp, R_O0+i, pri->sys_args[i]);
        }
        (void) Lputareg(Lwp, R_nPC, pc);
#elif defined(__amd64)
        (void) Lgetareg(Lwp, R_PC, &pc);
        (void) Lputareg(Lwp, REG_RAX, (prgreg_t)what);
#elif defined(__i386)
        (void) Lgetareg(Lwp, R_PC, &pc);
        (void) Lputareg(Lwp, EAX, (prgreg_t)what);
#else
#error "unrecognized architecture"
#endif
        (void) Pissyscall_prev(Proc, pc, (uintptr_t *)&pc);
        (void) Lputareg(Lwp, R_PC, pc);
        return (2);
    }

    return (3);
}