/* 

 * 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 1.3 1999/04/16 00:48:04 stanton 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 * This is an unpublished work copyright (c) 1992 HELIOS Software GmbH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)) {		/* INTL: "C", UTF safe. */

	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)));	/* INTL: "C", UTF safe. */

		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;

}