/*
* 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 1.6 2007/04/16 13:36:36 dkf 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* This is an unpublished work copyright (c) 1992 HELIOS Software GmbH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) {
mainModule = findMain();
if (mainModule == 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;
}
}
mp = (ModulePtr) calloc(1, sizeof(*mp));
if (mp == NULL) {
errvalid++;
strcpy(errbuf, "calloc: ");
strcat(errbuf, strerror(errno));
return 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.
*/
mp->entry = (void *) load((char *)path, L_NOAUTODEFER, NULL);
if (mp->entry == 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 *)], **p;
if (loadquery(L_GETMESSAGES, tmp, sizeof(tmp)) == -1) {
strcpy(errbuf, strerror(errno));
} else {
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) {
loadbindFailure:
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) {
goto loadbindFailure;
}
}
}
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")) {
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;
const char *errMsg;
#define Error(msg) do{errMsg=(msg);goto error;}while(0)
#define SysErr() Error(strerror(errno))
ldp = ldopen(mp->name, ldp);
if (ldp == NULL) {
struct ld_info *lp;
char *buf;
int size = 0;
if (errno != ENOENT) {
SysErr();
}
/*
* The module might be loaded due to the LIBPATH environment variable.
* Search for the loaded module using L_GETINFO.
*/
while (1) {
size += 4 * 1024;
buf = malloc(size);
if (buf == NULL) {
SysErr();
}
i = loadquery(L_GETINFO, buf, size);
if (i != -1) {
break;
}
free(buf);
if (errno != ENOMEM) {
SysErr();
}
}
/*
* 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) {
SysErr();
}
}
if (TYPE(ldp) != U802TOCMAGIC) {
Error("bad magic");
}
/*
* 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) {
Error("cannot read data section header");
}
if (ldnshread(ldp, _LOADER, &sh) != SUCCESS) {
Error("cannot read loader section header");
}
/*
* We read the complete loader section in one chunk, this makes finding
* long symbol names residing in the string table easier.
*/
ldbuf = (char *) malloc(sh.s_size);
if (ldbuf == NULL) {
SysErr();
}
if (FSEEK(ldp, sh.s_scnptr, BEGINNING) != OKFSEEK) {
free(ldbuf);
Error("cannot seek to loader section");
}
if (FREAD(ldbuf, sh.s_size, 1, ldp) != 1) {
free(ldbuf);
Error("cannot read loader section");
}
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++;
}
mp->exports = (ExportPtr) calloc(mp->nExports, sizeof(*mp->exports));
if (mp->exports == NULL) {
free(ldbuf);
SysErr();
}
/*
* 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!=0 ; 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) {
/* Empty body */
}
return 0;
/*
* This is a factoring out of the error-handling code to make the rest of
* the function much simpler to read.
*/
error:
errvalid++;
strcpy(errbuf, "readExports: ");
strcat(errbuf, errMsg);
if (ldp != NULL) {
while (ldclose(ldp) == FAILURE) {
/* Empty body */
}
}
return -1;
}
/*
* 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;
buf = malloc(size);
if (buf == NULL) {
goto error;
}
while ((i = loadquery(L_GETINFO, buf, size)) == -1 && errno == ENOMEM) {
free(buf);
size += 4*1024;
buf = malloc(size);
if (buf == NULL) {
goto error;
}
}
if (i == -1) {
free(buf);
goto error;
}
/*
* 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;
error:
errvalid++;
strcpy(errbuf, "findMain: ");
strcat(errbuf, strerror(errno));
return NULL;
}
/*
* Local Variables:
* mode: c
* c-basic-offset: 4
* fill-column: 78
* End:
*/
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