libconv/common/demangle.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 (c) 2006, 2010, Oracle and/or its affiliates. All rights reserved.
 */

#include    <stdio.h>
#include    <demangle.h>
#include    "_conv.h"
#include    "demangle_msg.h"

/*
 * Demangle C++ symbols.
 *
 * This routine acts as a generic routine for use by liblddbg (and hence tools
 * like elfdump(1) and pvs(1)), ld(1) and ld.so.1(1).
 *
 * The C++ ABI-2 places no limits on symbol names, thus when demangling a name
 * it's possible the buffer won't be big enough (DEMANGLE_ESPACE) so here we
 * try to allocate bigger buffers.  However, we place a limit on this buffer
 * size for fear of a C++ error sending us into an infinit loop.
 *
 * NOTE. we create and use a common buffer for use by cplus_demangle(), thus
 * each call to this routine will override the contents of any existing call.
 * Normally this is sufficient for typical error diagnostics referencing one
 * symbol.  For those diagnostics using more than one symbol name, all but the
 * last name must be copied to a temporary buffer (regardless of whether
 * demangling occurred, as the process of attempting to demangle may damage the
 * buffer).  One model is:
 *
 *  if ((_name1 = demangle(name1)) != name1) {
 *      char *  __name1 = strdupa(_name1);
 *      name1 = (const char *)__name1;
 *  }
 *  name2 = demangle(name2);
 *  eprintf(format, name1, name2);
 */
#define SYM_MAX 1000

const char *
conv_demangle_name(const char *name)
{
    static char _str[SYM_MAX], *str = _str;
    static size_t   size = SYM_MAX;
    static int  again = 1;
    static int  (*fptr)() = 0;
    int     error;

    if (str == 0)
        return (name);

    /*
     * If we haven't located the demangler yet try now (we do this rather
     * than maintain a static dependency on libdemangle as it's part of an
     * optional package).  Null the str element out to reject any other
     * callers until this operation is complete - under ld.so.1 we can get
     * into serious recursion without this.
     */
    if (fptr == 0) {
        void    *hdl;

        str = 0;
        if (!(hdl = dlopen(MSG_ORIG(MSG_DEM_LIB), RTLD_LAZY)) ||
            !(fptr = (int (*)())dlsym(hdl, MSG_ORIG(MSG_DEM_SYM))))
            return (name);
        str = _str;
    }

    if ((error = (*fptr)(name, str, size)) == 0)
        return ((const char *)str);

    while ((error == DEMANGLE_ESPACE) && again) {
        char    *_str;
        size_t  _size = size;

        /*
         * If we haven't allocated our maximum try incrementing the
         * present buffer size. Use malloc() rather than realloc() so
         * that we at least have the old buffer on failure.
         */
        if (((_size += SYM_MAX) > (SYM_MAX * 4)) ||
            ((_str = malloc(_size)) == 0)) {
            again = 0;
            break;
        }
        if (size != SYM_MAX) {
            free(str);
        }
        str = _str;
        size = _size;

        if ((error = (*fptr)(name, str, size)) == 0)
            return ((const char *)str);
    }
    return (name);
}