rtld/common/debug.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.
 */

#include    <sys/types.h>
#include    <sys/stat.h>
#include    <sys/param.h>
#include    <stdio.h>
#include    <fcntl.h>
#include    <stdarg.h>
#include    <dlfcn.h>
#include    <unistd.h>
#include    <string.h>
#include    <thread.h>
#include    <debug.h>
#include    <conv.h>
#include    "_rtld.h"
#include    "_elf.h"
#include    "msg.h"


static int      dbg_fd;     /* debugging output file descriptor */
static dev_t        dbg_dev;
static rtld_ino_t   dbg_ino;
static int      dbg_add_pid;    /* True to add pid to debug file name */
static pid_t        pid;

/*
 * Enable diagnostic output.  All debugging functions reside in the linker
 * debugging library liblddbg.so which is lazy loaded when required.
 */
int
dbg_setup(const char *options, Dbg_desc *dbp)
{
    rtld_stat_t status;
    const char  *ofile;

    /*
     * If we're running secure, only allow debugging if ld.so.1 itself is
     * owned by root and has its mode setuid.  Fail silently.
     */
    if ((rtld_flags & RT_FL_SECURE) && (is_rtld_setuid() == 0))
        return (1);

    /*
     * As Dbg_setup() will effectively lazy load the necessary support
     * libraries, make sure ld.so.1 is initialized for plt relocations.
     */
    if (elf_rtld_load() == 0)
        return (1);

    /*
     * Call the debugging setup routine.  This function verifies the
     * debugging tokens provided and returns a mask indicating the debugging
     * categories selected.  The mask effectively enables calls to the
     * debugging library.
     */
    if (Dbg_setup(DBG_CALLER_RTLD, options, dbp, &ofile) == 0)
        return (0);

    /*
     * Obtain the process id.
     */
    pid = getpid();

    /*
     * If an LD_DEBUG_OUTPUT file was specified then we need to direct all
     * diagnostics to the specified file.  Add the process id as a file
     * suffix so that multiple processes that inherit the same debugging
     * environment variable don't fight over the same file.
     *
     * If LD_DEBUG_OUTPUT is not specified, and the output=file token
     * was, then we direct all diagnostics to that file. Unlike
     * LD_DEBUG_OUTPUT, we do not add the process id suffix. This
     * is more convenient for interactive use.
     *
     * If neither redirection option is present, we send debugging
     * output to stderr. Note that the caller will not be able
     * to pipe or redirect this output at the shell level. libc
     * has not yet initialized things to make that possible.
     */
    if (dbg_file == NULL) {
        if (ofile && (*ofile != '\0'))
            dbg_file = ofile;
    } else {
        dbg_add_pid = 1;
    }

    if (dbg_file) {
        char        _file[MAXPATHLEN];
        const char  *file;

        if (dbg_add_pid) {
            file = _file;
            (void) snprintf(_file, MAXPATHLEN,
                MSG_ORIG(MSG_DBG_FILE), dbg_file, pid);
        } else {
            file = dbg_file;
        }
        dbg_fd = open(file, O_RDWR | O_CREAT | O_TRUNC, 0666);
        if (dbg_fd == -1) {
            int err = errno;

            eprintf(&lml_rtld, ERR_FATAL, MSG_INTL(MSG_SYS_OPEN),
                file, strerror(err));
            dbp->d_class = 0;
            return (0);
        }
    } else {
        /*
         * The default is to direct debugging to the stderr.
         */
        dbg_fd = 2;
    }

    /*
     * Initialize the dev/inode pair to enable us to determine if
     * the debugging file descriptor is still available once the
     * application has been entered.
     */
    (void) rtld_fstat(dbg_fd, &status);
    dbg_dev = status.st_dev;
    dbg_ino = status.st_ino;

    /*
     * Now that the output file is established, identify the linker
     * package, and generate help output if the user specified the
     * debug help token.
     */
    Dbg_version();
    if (dbp->d_extra & DBG_E_HELP)
        Dbg_help();

    return (1);
}

/*
 * Return True (1) if dbg_print() should produce output for the
 * specified link-map list, and False (0) otherwise.
 */
static int
dbg_lmid_validate(Lm_list *lml)
{
    const char  *str;
    Aliste      idx;

    /*
     * The LDSO link-map list is a special case, requiring
     * an explicit user request.
     */
    if (lml->lm_flags & LML_FLG_RTLDLM)
        return ((dbg_desc->d_extra & DBG_E_LMID_LDSO) != 0);

    /*
     * Approve special cases:
     * -    The link-map list has no name
     * -    lmid=all was set
     * -    lmid=alt was set, and this is not the BASE linkmap
     */
    if ((lml->lm_lmidstr == NULL) ||
        ((dbg_desc->d_extra & DBG_E_LMID_ALL) != 0) ||
        (((dbg_desc->d_extra & DBG_E_LMID_ALT) != 0) &&
        ((lml->lm_flags & LML_FLG_BASELM) == 0)))
        return (1);

    /*
     * If there is no list of specific link-map list names to check,
     * then approval depends on lmid={ldso|alt} not being specified.
     */
    if (aplist_nitems(dbg_desc->d_list) == 0)
        return ((dbg_desc->d_extra &
            (DBG_E_LMID_LDSO | DBG_E_LMID_ALT)) == 0);

    /*
     * Compare the link-map list name against the list of approved names
     */
    for (APLIST_TRAVERSE(dbg_desc->d_list, idx, str))
        if (strcmp(lml->lm_lmidstr, str) == 0)
            return (1);

    /* Output for this linkmap is denied */
    return (0);
}

/*
 * All diagnostic requests are funneled to this routine.
 */
/* PRINTFLIKE2 */
void
dbg_print(Lm_list *lml, const char *format, ...)
{
    va_list     args;
    char        buffer[ERRSIZE + 1];
    pid_t       _pid;
    rtld_stat_t status;
    Prfbuf      prf;

    /*
     * Knock off any newline indicator to signify that a diagnostic has
     * been processed.
     */
    dbg_desc->d_extra &= ~DBG_E_STDNL;

    /*
     * If debugging has been isolated to individual link-map lists,
     * determine whether this request originates from a link-map list that
     * is being monitored.
     */
    if (lml && (dbg_lmid_validate(lml) == 0))
        return;

    /*
     * If we're in the application make sure the debugging file descriptor
     * is still available (ie, the user hasn't closed and/or reused the
     * same descriptor).
     */
    if (rtld_flags & RT_FL_APPLIC) {
        if ((rtld_fstat(dbg_fd, &status) == -1) ||
            (status.st_dev != dbg_dev) ||
            (status.st_ino != dbg_ino)) {
            if (dbg_file) {
                /*
                 * If the user specified output file has been
                 * disconnected try and reconnect to it.
                 */
                char        _file[MAXPATHLEN];
                const char  *file;

                if (dbg_add_pid) {
                    file = _file;
                    (void) snprintf(_file, MAXPATHLEN,
                        MSG_ORIG(MSG_DBG_FILE), dbg_file,
                        pid);
                } else {
                    file = dbg_file;
                }
                if ((dbg_fd = open(file, (O_RDWR | O_APPEND),
                    0)) == -1) {
                    dbg_desc->d_class = 0;
                    return;
                }
                (void) rtld_fstat(dbg_fd, &status);
                dbg_dev = status.st_dev;
                dbg_ino = status.st_ino;
            } else {
                /*
                 * If stderr has been stolen from us simply
                 * turn debugging off.
                 */
                dbg_desc->d_class = 0;
                return;
            }
        }
    }

    prf.pr_fd = dbg_fd;

    /*
     * Obtain the process id.
     */
    _pid = getpid();

    /*
     * Each time ld.so.1 is entered, the diagnostic times are reset.  It is
     * useful to convey this reset as part of our diagnostics, but only if
     * other diagnostics will follow.  If a reset has preceded this
     * diagnostic, print a division line.
     */
    if (DBG_ISRESET()) {
        DBG_OFFRESET();

        prf.pr_buf = prf.pr_cur = buffer;
        prf.pr_len = ERRSIZE;

        if (lml)
            (void) bufprint(&prf, MSG_ORIG(MSG_DBG_PID), _pid);
        else
            (void) bufprint(&prf, MSG_ORIG(MSG_DBG_UNDEF));
        prf.pr_cur--;

        (void) bufprint(&prf, MSG_ORIG(MSG_DBG_RESET));
        (void) dowrite(&prf);
    }

    /*
     * Reestablish the buffer for standard printing.
     */
    prf.pr_buf = prf.pr_cur = buffer;
    prf.pr_len = ERRSIZE;

    /*
     * Establish any diagnostic prefix strings.
     */
    if (lml)
        (void) bufprint(&prf, MSG_ORIG(MSG_DBG_PID), _pid);
    else
        (void) bufprint(&prf, MSG_ORIG(MSG_DBG_UNDEF));
    prf.pr_cur--;

    if (DBG_ISLMID() && lml && lml->lm_lmidstr) {
        (void) bufprint(&prf, MSG_ORIG(MSG_DBG_LMID), lml->lm_lmidstr);
        prf.pr_cur--;
    }
    if (DBG_ISTIME()) {
        struct timeval  new;

        if (gettimeofday(&new, NULL) == 0) {
            Conv_time_buf_t buf;

            if (DBG_ISTTIME()) {
                (void) bufprint(&prf,
                    conv_time(&DBG_TOTALTIME, &new, &buf));
                prf.pr_cur--;
            }
            if (DBG_ISDTIME()) {
                (void) bufprint(&prf,
                    conv_time(&DBG_DELTATIME, &new, &buf));
                prf.pr_cur--;
            }
            DBG_DELTATIME = new;
        }
    }
    if (rtld_flags & RT_FL_THREADS) {
        (void) bufprint(&prf, MSG_ORIG(MSG_DBG_THREAD), rt_thr_self());
        prf.pr_cur--;
    }

    /*
     * Format the message and print it.
     */
    va_start(args, format);
    (void) doprf(format, args, &prf);
    *(prf.pr_cur - 1) = '\n';
    (void) dowrite(&prf);
    va_end(args);
}