/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2000 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Apache" and "Apache Software Foundation" must
 *    not be used to endorse or promote products derived from this
 *    software without prior written permission. For written
 *    permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache",
 *    nor may "Apache" appear in their name, without prior written
 *    permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 * Portions of this software are based upon public domain software
 * originally written at the National Center for Supercomputing Applications,
 * University of Illinois, Urbana-Champaign.
 */
/*
**  os-aix-dso.c -- DSO system function emulation for AIX
 */
/*
**  Based on libdl (dlfcn.c/dlfcn.h) which is
**  Copyright (c) 1992,1993,1995,1996,1997,1988
**  Jens-Uwe Mager, Helios Software GmbH, Hannover, Germany.
**
**  Not derived from licensed software.
**
**  Permission is granted to freely use, copy, modify, and redistribute
**  this software, provided that the author is not construed to be liable
**  for any results of using the software, alterations are clearly marked
**  as such, and this notice is not modified.
**
**  Changes marked with `--jwe' were made on April 7 1996 by
**  John W. Eaton <jwe@bevo.che.wisc.edu> to support g++ 
**
**  Bundled, stripped and adjusted on April 1998 as one single source file 
**  for inclusion into the Apache HTTP server by 
**  Ralf S. Engelschall <rse@apache.org>
*/
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/ldr.h>
#include <a.out.h>
#undef FREAD
#undef FWRITE
#include <ldfcn.h>
/*
 * AIX 4.3 does remove some useful definitions from ldfcn.h. Define
 * these here to compensate for that lossage.
 */
#ifndef BEGINNING
#define BEGINNING SEEK_SET
#endif
#ifndef FSEEK
#define FSEEK(ldptr,o,p)   fseek(IOPTR(ldptr),(p==BEGINNING)?(OFFSET(ldptr) +o):o,p)
#endif
#ifndef FREAD
#define FREAD(p,s,n,ldptr) fread(p,s,n,IOPTR(ldptr))
#endif
/*
 * Mode flags for the dlopen routine.
 */
#undef  RTLD_LAZY
#define RTLD_LAZY       1       /* lazy function call binding */
#undef  RTLD_NOW
#define RTLD_NOW        2       /* immediate function call binding */
#undef  RTLD_GLOBAL
#define RTLD_GLOBAL     0x100   /* allow symbols to be global */
/*
 * To be able to intialize, a library may provide a dl_info structure
 * that contains functions to be called to initialize and terminate.
 */
struct dl_info {
    void (*init) (void);
    void (*fini) (void);
};
/*
 *  Forward declarations
 */
void *dlopen(const char *path, int mode);
void *dlsym(void *handle, const char *symbol);
const char *dlerror(void);
int dlclose(void *handle);
/*
 * We simulate dlopen() et al. through a call to load. Because AIX has
 * no call to find an exported symbol we read the loader section of the
 * loaded module and build a list of exported symbols and their virtual
 * address.
 */
typedef struct {
    char *name;                 /* the symbols's name */
    void *addr;                 /* its relocated virtual address */
} Export, *ExportPtr;
/*
 * xlC uses the following structure to list its constructors and
 * destructors. This is gleaned from the output of munch.
 */
typedef struct {
    void (*init) (void);        /* call static constructors */
    void (*term) (void);        /* call static destructors */
} Cdtor, *CdtorPtr;
typedef void (*GccCDtorPtr) (void);
/*
 * The void * handle returned from dlopen is actually a ModulePtr.
 */
typedef struct Module {
    struct Module *next;
    char *name;                 /* module name for refcounting */
    int refCnt;                 /* the number of references */
    void *entry;                /* entry point from load */
    struct dl_info *info;       /* optional init/terminate functions */
    CdtorPtr cdtors;            /* optional C++ constructors */
    GccCDtorPtr gcc_ctor;       /* g++ constructors  --jwe */
    GccCDtorPtr gcc_dtor;       /* g++ destructors  --jwe */
    int nExports;               /* the number of exports found */
    ExportPtr exports;          /* the array of exports */
} Module, *ModulePtr;
/*
 * We keep a list of all loaded modules to be able to call the fini
 * handlers and destructors at atexit() time.
 */
static ModulePtr modList;
/*
 * The last error from one of the dl* routines is kept in static
 * variables here. Each error is returned only once to the caller.
 */
static char errbuf[BUFSIZ];
static int errvalid;
/*
 * The `fixed' gcc header files on AIX 3.2.5 provide a prototype for
 * strdup().  --jwe
 */
extern char *strdup(const char *);
static void caterr(char *);
static int readExports(ModulePtr);
static void terminate(void);
static void *findMain(void);
void *dlopen(const char *path, int mode)
{
    register ModulePtr mp;
    static void *mainModule;
    /*
     * Upon the first call register a terminate handler that will
     * close all libraries. Also get a reference to the main module
     * for use with loadbind.
     */
    if (!mainModule) {
        if ((mainModule = findMain()) == NULL)
            return NULL;
        atexit(terminate);
    }
    /*
     * Scan the list of modules if we have the module already loaded.
     */
    for (mp = modList; mp; mp = mp->next)
        if (strcmp(mp->name, path) == 0) {
            mp->refCnt++;
            return mp;
        }
    if ((mp = (ModulePtr) calloc(1, sizeof(*mp))) == NULL) {
        errvalid++;
        strcpy(errbuf, "calloc: ");
        strcat(errbuf, strerror(errno));
        return NULL;
    }
    if ((mp->name = strdup(path)) == NULL) {
        errvalid++;
        strcpy(errbuf, "strdup: ");
        strcat(errbuf, strerror(errno));
        free(mp);
        return NULL;
    }
    /*
     * load should be declared load(const char *...). Thus we
     * cast the path to a normal char *. Ugly.
     */
    if ((mp->entry = (void *) load((char *) path, L_NOAUTODEFER, NULL)) == NULL) {
        free(mp->name);
        free(mp);
        errvalid++;
        strcpy(errbuf, "dlopen: ");
        strcat(errbuf, path);
        strcat(errbuf, ": ");
        /*
         * If AIX says the file is not executable, the error
         * can be further described by querying the loader about
         * the last error.
         */
        if (errno == ENOEXEC) {
            char *tmp[BUFSIZ / sizeof(char *)];
            if (loadquery(L_GETMESSAGES, tmp, sizeof(tmp)) == -1)
                strcpy(errbuf, strerror(errno));
            else {
                char **p;
                for (p = tmp; *p; p++)
                    caterr(*p);
            }
        }
        else
            strcat(errbuf, strerror(errno));
        return NULL;
    }
    mp->refCnt = 1;
    mp->next = modList;
    modList = mp;
    if (loadbind(0, mainModule, mp->entry) == -1) {
        dlclose(mp);
        errvalid++;
        strcpy(errbuf, "loadbind: ");
        strcat(errbuf, strerror(errno));
        return NULL;
    }
    /*
     * If the user wants global binding, loadbind against all other
     * loaded modules.
     */
    if (mode & RTLD_GLOBAL) {
        register ModulePtr mp1;
        for (mp1 = mp->next; mp1; mp1 = mp1->next)
            if (loadbind(0, mp1->entry, mp->entry) == -1) {
                dlclose(mp);
                errvalid++;
                strcpy(errbuf, "loadbind: ");
                strcat(errbuf, strerror(errno));
                return NULL;
            }
    }
    if (readExports(mp) == -1) {
        dlclose(mp);
        return NULL;
    }
    /*
     * If there is a dl_info structure, call the init function.
     */
    if (mp->info = (struct dl_info *) dlsym(mp, "dl_info")) {
        if (mp->info->init)
            (*mp->info->init) ();
    }
    else
        errvalid = 0;
    /*
     * If the shared object was compiled using xlC we will need
     * to call static constructors (and later on dlclose destructors).
     */
    if (mp->cdtors = (CdtorPtr) dlsym(mp, "__cdtors")) {
        CdtorPtr cp = mp->cdtors;
        while (cp->init || cp->term) {
            if (cp->init && cp->init != (void (*)(void)) 0xffffffff)
                (*cp->init) ();
            cp++;
        }
        /*
         * If the shared object was compiled using g++, we will need
         * to call global constructors using the _GLOBAL__DI function,
         * and later, global destructors using the _GLOBAL_DD
         * funciton.  --jwe
         */
    }
    else if (mp->gcc_ctor = (GccCDtorPtr) dlsym(mp, "_GLOBAL__DI")) {
        (*mp->gcc_ctor) ();
        mp->gcc_dtor = (GccCDtorPtr) dlsym(mp, "_GLOBAL__DD");
    }
    else
        errvalid = 0;
    return mp;
}
/*
 * Attempt to decipher an AIX loader error message and append it
 * to our static error message buffer.
 */
static void caterr(char *s)
{
    register char *p = s;
    while (*p >= '0' && *p <= '9')
        p++;
    switch (atoi(s)) {
    case L_ERROR_TOOMANY:
        strcat(errbuf, "to many errors");
        break;
    case L_ERROR_NOLIB:
        strcat(errbuf, "can't load library");
        strcat(errbuf, p);
        break;
    case L_ERROR_UNDEF:
        strcat(errbuf, "can't find symbol");
        strcat(errbuf, p);
        break;
    case L_ERROR_RLDBAD:
        strcat(errbuf, "bad RLD");
        strcat(errbuf, p);
        break;
    case L_ERROR_FORMAT:
        strcat(errbuf, "bad exec format in");
        strcat(errbuf, p);
        break;
    case L_ERROR_ERRNO:
        strcat(errbuf, strerror(atoi(++p)));
        break;
    default:
        strcat(errbuf, s);
        break;
    }
}
void *dlsym(void *handle, const char *symbol)
{
    register ModulePtr mp = (ModulePtr) handle;
    register ExportPtr ep;
    register int i;
    /*
     * Could speed up the search, but I assume that one assigns
     * the result to function pointers anyways.
     */
    for (ep = mp->exports, i = mp->nExports; i; i--, ep++)
        if (strcmp(ep->name, symbol) == 0)
            return ep->addr;
    errvalid++;
    strcpy(errbuf, "dlsym: undefined symbol ");
    strcat(errbuf, symbol);
    return NULL;
}
const char *dlerror(void)
{
    if (errvalid) {
        errvalid = 0;
        return errbuf;
    }
    return NULL;
}
int dlclose(void *handle)
{
    register ModulePtr mp = (ModulePtr) handle;
    int result;
    register ModulePtr mp1;
    if (--mp->refCnt > 0)
        return 0;
    if (mp->info && mp->info->fini)
        (*mp->info->fini) ();
    if (mp->cdtors) {
        CdtorPtr cp = mp->cdtors;
        while (cp->init || cp->term) {
            if (cp->term && cp->init != (void (*)(void)) 0xffffffff)
                (*cp->term) ();
            cp++;
        }
        /*
         * If the function to handle global destructors for g++
         * exists, call it.  --jwe
         */
    }
    else if (mp->gcc_dtor) {
        (*mp->gcc_dtor) ();
    }
    result = unload(mp->entry);
    if (result == -1) {
        errvalid++;
        strcpy(errbuf, strerror(errno));
    }
    if (mp->exports) {
        register ExportPtr ep;
        register int i;
        for (ep = mp->exports, i = mp->nExports; i; i--, ep++)
            if (ep->name)
                free(ep->name);
        free(mp->exports);
    }
    if (mp == modList)
        modList = mp->next;
    else {
        for (mp1 = modList; mp1; mp1 = mp1->next)
            if (mp1->next == mp) {
                mp1->next = mp->next;
                break;
            }
    }
    free(mp->name);
    free(mp);
    return result;
}
static void terminate(void)
{
    while (modList)
        dlclose(modList);
}
/*
 * Build the export table from the XCOFF .loader section.
 */
static int readExports(ModulePtr mp)
{
    LDFILE *ldp = NULL;
    SCNHDR sh, shdata;
    LDHDR *lhp;
    char *ldbuf;
    LDSYM *ls;
    int i;
    ExportPtr ep;
    struct ld_info *lp;
    char *buf;
    int size = 4 * 1024;
    void *dataorg;
    /*
     * The module might be loaded due to the LIBPATH
     * environment variable. Search for the loaded
     * module using L_GETINFO.
     */
    if ((buf = malloc(size)) == NULL) {
        errvalid++;
        strcpy(errbuf, "readExports: ");
        strcat(errbuf, strerror(errno));
        return -1;
    }
    while ((i = loadquery(L_GETINFO, buf, size)) == -1 && errno == ENOMEM) {
        free(buf);
        size += 4 * 1024;
        if ((buf = malloc(size)) == NULL) {
            errvalid++;
            strcpy(errbuf, "readExports: ");
            strcat(errbuf, strerror(errno));
            return -1;
        }
    }
    if (i == -1) {
        errvalid++;
        strcpy(errbuf, "readExports: ");
        strcat(errbuf, strerror(errno));
        free(buf);
        return -1;
    }
    /*
     * Traverse the list of loaded modules. The entry point
     * returned by load() does actually point to the TOC
     * entry contained in the data segment.
     */
    lp = (struct ld_info *) buf;
    while (lp) {
        if ((unsigned long) mp->entry >= (unsigned long) lp->ldinfo_dataorg &&
            (unsigned long) mp->entry < (unsigned long) lp->ldinfo_dataorg +
            lp->ldinfo_datasize) {
            dataorg = lp->ldinfo_dataorg;
            ldp = ldopen(lp->ldinfo_filename, ldp);
            break;
        }
        if (lp->ldinfo_next == 0)
            lp = NULL;
        else
            lp = (struct ld_info *) ((char *) lp + lp->ldinfo_next);
    }
    free(buf);
    if (!ldp) {
        errvalid++;
        strcpy(errbuf, "readExports: ");
        strcat(errbuf, strerror(errno));
        return -1;
    }
    if (TYPE(ldp) != U802TOCMAGIC) {
        errvalid++;
        strcpy(errbuf, "readExports: bad magic");
        while (ldclose(ldp) == FAILURE);
        return -1;
    }
    /*
     * Get the padding for the data section. This is needed for
     * AIX 4.1 compilers. This is used when building the final
     * function pointer to the exported symbol.
     */
    if (ldnshread(ldp, _DATA, &shdata) != SUCCESS) {
        errvalid++;
        strcpy(errbuf, "readExports: cannot read data section header");
        while (ldclose(ldp) == FAILURE);
        return -1;
    }
    if (ldnshread(ldp, _LOADER, &sh) != SUCCESS) {
        errvalid++;
        strcpy(errbuf, "readExports: cannot read loader section header");
        while (ldclose(ldp) == FAILURE);
        return -1;
    }
    /*
     * We read the complete loader section in one chunk, this makes
     * finding long symbol names residing in the string table easier.
     */
    if ((ldbuf = (char *) malloc(sh.s_size)) == NULL) {
        errvalid++;
        strcpy(errbuf, "readExports: ");
        strcat(errbuf, strerror(errno));
        while (ldclose(ldp) == FAILURE);
        return -1;
    }
    if (FSEEK(ldp, sh.s_scnptr, BEGINNING) != OKFSEEK) {
        errvalid++;
        strcpy(errbuf, "readExports: cannot seek to loader section");
        free(ldbuf);
        while (ldclose(ldp) == FAILURE);
        return -1;
    }
    if (FREAD(ldbuf, sh.s_size, 1, ldp) != 1) {
        errvalid++;
        strcpy(errbuf, "readExports: cannot read loader section");
        free(ldbuf);
        while (ldclose(ldp) == FAILURE);
        return -1;
    }
    lhp = (LDHDR *) ldbuf;
    ls = (LDSYM *) (ldbuf + LDHDRSZ);
    /*
     * Count the number of exports to include in our export table.
     */
    for (i = lhp->l_nsyms; i; i--, ls++) {
        if (!LDR_EXPORT(*ls))
            continue;
        mp->nExports++;
    }
    if ((mp->exports = (ExportPtr) calloc(mp->nExports, sizeof(*mp->exports))) == NULL) {
        errvalid++;
        strcpy(errbuf, "readExports: ");
        strcat(errbuf, strerror(errno));
        free(ldbuf);
        while (ldclose(ldp) == FAILURE);
        return -1;
    }
    /*
     * Fill in the export table. All entries are relative to
     * the beginning of the data origin.
     */
    ep = mp->exports;
    ls = (LDSYM *) (ldbuf + LDHDRSZ);
    for (i = lhp->l_nsyms; i; i--, ls++) {
        char *symname;
        char tmpsym[SYMNMLEN + 1];
        if (!LDR_EXPORT(*ls))
            continue;
        if (ls->l_zeroes == 0)
            symname = ls->l_offset + lhp->l_stoff + ldbuf;
        else {
            /*
             * The l_name member is not zero terminated, we
             * must copy the first SYMNMLEN chars and make
             * sure we have a zero byte at the end.
             */
            strncpy(tmpsym, ls->l_name, SYMNMLEN);
            tmpsym[SYMNMLEN] = '\0';
            symname = tmpsym;
        }
        ep->name = strdup(symname);
        ep->addr = (void *) ((unsigned long) dataorg +
                             ls->l_value - shdata.s_vaddr);
        ep++;
    }
    free(ldbuf);
    while (ldclose(ldp) == FAILURE);
    return 0;
}
/*
 * Find the main modules data origin. This is used as export pointer
 * for loadbind() to be able to resolve references to the main part.
 */
static void *findMain(void)
{
    struct ld_info *lp;
    char *buf;
    int size = 4 * 1024;
    int i;
    void *ret;
    if ((buf = malloc(size)) == NULL) {
        errvalid++;
        strcpy(errbuf, "findMain: ");
        strcat(errbuf, strerror(errno));
        return NULL;
    }
    while ((i = loadquery(L_GETINFO, buf, size)) == -1 && errno == ENOMEM) {
        free(buf);
        size += 4 * 1024;
        if ((buf = malloc(size)) == NULL) {
            errvalid++;
            strcpy(errbuf, "findMain: ");
            strcat(errbuf, strerror(errno));
            return NULL;
        }
    }
    if (i == -1) {
        errvalid++;
        strcpy(errbuf, "findMain: ");
        strcat(errbuf, strerror(errno));
        free(buf);
        return NULL;
    }
    /*
     * The first entry is the main module. The data segment
     * starts with the TOC entries for all exports, so the
     * data segment origin works as argument for loadbind.
     */
    lp = (struct ld_info *) buf;
    ret = lp->ldinfo_dataorg;
    free(buf);
    return ret;
}