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/*

 * tclLoadAix.c --

 *

 *      This file implements the dlopen and dlsym APIs under the

 *      AIX operating system, to enable the Tcl "load" command to

 *      work.  This code was provided by Jens-Uwe Mager.

 *

 *      This file is subject to the following copyright notice, which is

 *      different from the notice used elsewhere in Tcl.  The file has

 *      been modified to incorporate the file dlfcn.h in-line.

 *

 *      Copyright (c) 1992,1993,1995,1996, Jens-Uwe Mager, Helios Software GmbH

 *      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.

 *

 * RCS: @(#) $Id: tclLoadAix.c,v 1.1.1.1 2002-01-16 10:25:37 markom Exp $

 *

 * Note:  this file has been altered from the original in a few

 * ways in order to work properly with Tcl.

 */

/*

 * @(#)dlfcn.c  1.7 revision of 95/08/14  19:08:38

 * This is an unpublished work copyright (c) 1992 HELIOS Software GmbH

 * 30159 Hannover, Germany

 */

#include <stdio.h>

#include <errno.h>

#include <string.h>

#include <stdlib.h>

#include <sys/types.h>

#include <sys/ldr.h>

#include <a.out.h>

#include <ldfcn.h>

#include "../compat/dlfcn.h"

/*

 * 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;

/*

 * 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 */

        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;

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 (VOID *) mp;

                }

        if ((mp = (ModulePtr)calloc(1, sizeof(*mp))) == NULL) {

                errvalid++;

                strcpy(errbuf, "calloc: ");

                strcat(errbuf, strerror(errno));

                return (VOID *) NULL;

        }

        mp->name = malloc((unsigned) (strlen(path) + 1));

        strcpy(mp->name, path);

        /*

         * 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 (VOID *) 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 (VOID *) 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 (VOID *) NULL;

                        }

        }

        if (readExports(mp) == -1) {

                dlclose(mp);

                return (VOID *) 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")) {

                while (mp->cdtors->init) {

                        (*mp->cdtors->init)();

                        mp->cdtors++;

                }

        } else

                errvalid = 0;

        return (VOID *) 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;

}

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)

                while (mp->cdtors->term) {

                        (*mp->cdtors->term)();

                        mp->cdtors++;

                }

        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;

        if ((ldp = ldopen(mp->name, ldp)) == NULL) {

                struct ld_info *lp;

                char *buf;

                int size = 4*1024;

                if (errno != ENOENT) {

                        errvalid++;

                        strcpy(errbuf, "readExports: ");

                        strcat(errbuf, strerror(errno));

                        return -1;

                }

                /*

                 * 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 data

                 * segment origin.

                 */

                lp = (struct ld_info *)buf;

                while (lp) {

                        if (lp->ldinfo_dataorg == mp->entry) {

                                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 entry point we got from load.

         */

        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 = malloc((unsigned) (strlen(symname) + 1));

                strcpy(ep->name, symname);

                ep->addr = (void *)((unsigned long)mp->entry +

                                        ls->l_value - shdata.s_vaddr);

                ep++;

        }

        free(ldbuf);

        while(ldclose(ldp) == FAILURE)

                ;

        return 0;

}

/*

 * Find the main modules entry point. 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 entry point

         * returned by load() does actually point to the data

         * segment origin.

         */

        lp = (struct ld_info *)buf;

        ret = lp->ldinfo_dataorg;

        free(buf);

        return ret;

}