582 lines
14 KiB
C
582 lines
14 KiB
C
/*
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* @(#)dlfcn.c 1.11 revision of 96/04/10 20:12:51
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* This is an unpublished work copyright (c) 1992 HELIOS Software GmbH
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* 30159 Hannover, Germany
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*/
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/*
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* Changes marked with `--jwe' were made on April 7 1996 by John W. Eaton
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* <jwe@bevo.che.wisc.edu> to support g++ and/or use with Octave.
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*/
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/*
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* This makes my life easier with Octave. --jwe
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*/
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#ifdef HAVE_CONFIG_H
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#include <config.h>
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#endif
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#include <stdio.h>
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#include <errno.h>
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#include <string.h>
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#include <stdlib.h>
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#include <sys/types.h>
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#include <sys/ldr.h>
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#include <a.out.h>
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#include <ldfcn.h>
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#include "dlfcn.h"
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/*
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* We simulate dlopen() et al. through a call to load. Because AIX has
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* no call to find an exported symbol we read the loader section of the
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* loaded module and build a list of exported symbols and their virtual
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* address.
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*/
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typedef struct {
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char *name; /* the symbols's name */
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void *addr; /* its relocated virtual address */
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} Export, *ExportPtr;
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/*
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* xlC uses the following structure to list its constructors and
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* destructors. This is gleaned from the output of munch.
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*/
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typedef struct {
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void (*init)(void); /* call static constructors */
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void (*term)(void); /* call static destructors */
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} Cdtor, *CdtorPtr;
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typedef void (*GccCDtorPtr)(void);
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/*
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* The void * handle returned from dlopen is actually a ModulePtr.
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*/
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typedef struct Module {
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struct Module *next;
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char *name; /* module name for refcounting */
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int refCnt; /* the number of references */
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void *entry; /* entry point from load */
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struct dl_info *info; /* optional init/terminate functions */
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CdtorPtr cdtors; /* optional C++ constructors */
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GccCDtorPtr gcc_ctor; /* g++ constructors --jwe */
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GccCDtorPtr gcc_dtor; /* g++ destructors --jwe */
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int nExports; /* the number of exports found */
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ExportPtr exports; /* the array of exports */
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} Module, *ModulePtr;
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/*
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* We keep a list of all loaded modules to be able to call the fini
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* handlers and destructors at atexit() time.
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*/
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static ModulePtr modList;
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/*
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* The last error from one of the dl* routines is kept in static
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* variables here. Each error is returned only once to the caller.
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*/
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static char errbuf[BUFSIZ];
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static int errvalid;
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/*
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* The `fixed' gcc header files on AIX 3.2.5 provide a prototype for
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* strdup(). --jwe
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*/
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#ifndef HAVE_STRDUP
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extern char *strdup(const char *);
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#endif
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static void caterr(char *);
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static int readExports(ModulePtr);
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static void terminate(void);
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static void *findMain(void);
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void *dlopen(const char *path, int mode)
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{
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ModulePtr mp;
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static void *mainModule;
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/*
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* Upon the first call register a terminate handler that will
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* close all libraries. Also get a reference to the main module
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* for use with loadbind.
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*/
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if (!mainModule) {
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if ((mainModule = findMain()) == NULL)
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return NULL;
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atexit(terminate);
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}
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/*
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* Scan the list of modules if we have the module already loaded.
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*/
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for (mp = modList; mp; mp = mp->next)
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if (strcmp(mp->name, path) == 0) {
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mp->refCnt++;
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return mp;
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}
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if ((mp = (ModulePtr)calloc(1, sizeof(*mp))) == NULL) {
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errvalid++;
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snprintf (errbuf, sizeof(errbuf), "calloc: %s", strerror(errno));
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return NULL;
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}
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if ((mp->name = strdup(path)) == NULL) {
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errvalid++;
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snprintf (errbuf, sizeof(errbuf), "strdup: %s", strerror(errno));
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free(mp);
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return NULL;
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}
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/*
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* load should be declared load(const char *...). Thus we
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* cast the path to a normal char *. Ugly.
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*/
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if ((mp->entry = (void *)load((char *)path, L_NOAUTODEFER, NULL)) == NULL) {
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free(mp->name);
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free(mp);
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errvalid++;
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snprintf (errbuf, sizeof(errbuf),
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"dlopen: %s: ", path);
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/*
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* If AIX says the file is not executable, the error
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* can be further described by querying the loader about
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* the last error.
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*/
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if (errno == ENOEXEC) {
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char *tmp[BUFSIZ/sizeof(char *)];
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if (loadquery(L_GETMESSAGES, tmp, sizeof(tmp)) == -1)
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strlcpy(errbuf,
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strerror(errno),
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sizeof(errbuf));
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else {
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char **p;
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for (p = tmp; *p; p++)
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caterr(*p);
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}
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} else
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strlcat(errbuf,
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strerror(errno),
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sizeof(errbuf));
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return NULL;
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}
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mp->refCnt = 1;
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mp->next = modList;
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modList = mp;
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if (loadbind(0, mainModule, mp->entry) == -1) {
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dlclose(mp);
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errvalid++;
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snprintf (errbuf, sizeof(errbuf),
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"loadbind: %s", strerror(errno));
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return NULL;
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}
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/*
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* If the user wants global binding, loadbind against all other
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* loaded modules.
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*/
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if (mode & RTLD_GLOBAL) {
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ModulePtr mp1;
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for (mp1 = mp->next; mp1; mp1 = mp1->next)
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if (loadbind(0, mp1->entry, mp->entry) == -1) {
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dlclose(mp);
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errvalid++;
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snprintf (errbuf, sizeof(errbuf),
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"loadbind: %s",
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strerror(errno));
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return NULL;
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}
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}
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if (readExports(mp) == -1) {
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dlclose(mp);
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return NULL;
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}
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/*
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* If there is a dl_info structure, call the init function.
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*/
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if (mp->info = (struct dl_info *)dlsym(mp, "dl_info")) {
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if (mp->info->init)
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(*mp->info->init)();
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} else
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errvalid = 0;
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/*
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* If the shared object was compiled using xlC we will need
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* to call static constructors (and later on dlclose destructors).
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*/
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if (mp->cdtors = (CdtorPtr)dlsym(mp, "__cdtors")) {
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CdtorPtr cp = mp->cdtors;
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while (cp->init || cp->term) {
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if (cp->init && cp->init != (void (*)(void))0xffffffff)
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(*cp->init)();
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cp++;
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}
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/*
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* If the shared object was compiled using g++, we will need
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* to call global constructors using the _GLOBAL__DI function,
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* and later, global destructors using the _GLOBAL_DD
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* funciton. --jwe
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*/
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} else if (mp->gcc_ctor = (GccCDtorPtr)dlsym(mp, "_GLOBAL__DI")) {
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(*mp->gcc_ctor)();
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mp->gcc_dtor = (GccCDtorPtr)dlsym(mp, "_GLOBAL__DD");
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} else
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errvalid = 0;
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return mp;
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}
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/*
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* Attempt to decipher an AIX loader error message and append it
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* to our static error message buffer.
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*/
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static void caterr(char *s)
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{
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char *p = s;
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while (*p >= '0' && *p <= '9')
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p++;
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switch(atoi(s)) {
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case L_ERROR_TOOMANY:
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strlcat(errbuf, "to many errors", sizeof(errbuf));
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break;
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case L_ERROR_NOLIB:
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strlcat(errbuf, "can't load library", sizeof(errbuf));
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strlcat(errbuf, p, sizeof(errbuf));
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break;
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case L_ERROR_UNDEF:
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strlcat(errbuf, "can't find symbol", sizeof(errbuf));
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strlcat(errbuf, p, sizeof(errbuf));
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break;
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case L_ERROR_RLDBAD:
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strlcat(errbuf, "bad RLD", sizeof(errbuf));
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strlcat(errbuf, p, sizeof(errbuf));
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break;
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case L_ERROR_FORMAT:
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strlcat(errbuf, "bad exec format in", sizeof(errbuf));
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strlcat(errbuf, p, sizeof(errbuf));
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break;
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case L_ERROR_ERRNO:
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strlcat(errbuf, strerror(atoi(++p)), sizeof(errbuf));
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break;
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default:
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strlcat(errbuf, s, sizeof(errbuf));
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break;
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}
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}
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void *dlsym(void *handle, const char *symbol)
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{
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ModulePtr mp = (ModulePtr)handle;
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ExportPtr ep;
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int i;
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/*
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* Could speed up the search, but I assume that one assigns
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* the result to function pointers anyways.
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*/
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for (ep = mp->exports, i = mp->nExports; i; i--, ep++)
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if (strcmp(ep->name, symbol) == 0)
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return ep->addr;
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errvalid++;
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snprintf (errbuf, sizeof(errbuf),
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"dlsym: undefined symbol %s", symbol);
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return NULL;
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}
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char *dlerror(void)
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{
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if (errvalid) {
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errvalid = 0;
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return errbuf;
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}
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return NULL;
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}
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int dlclose(void *handle)
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{
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ModulePtr mp = (ModulePtr)handle;
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int result;
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ModulePtr mp1;
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if (--mp->refCnt > 0)
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return 0;
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if (mp->info && mp->info->fini)
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(*mp->info->fini)();
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if (mp->cdtors) {
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CdtorPtr cp = mp->cdtors;
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while (cp->init || cp->term) {
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if (cp->term && cp->init != (void (*)(void))0xffffffff)
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(*cp->term)();
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cp++;
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}
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/*
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* If the function to handle global destructors for g++
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* exists, call it. --jwe
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*/
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} else if (mp->gcc_dtor) {
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(*mp->gcc_dtor)();
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}
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result = unload(mp->entry);
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if (result == -1) {
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errvalid++;
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snprintf (errbuf, sizeof(errbuf),
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"%s", strerror(errno));
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}
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if (mp->exports) {
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ExportPtr ep;
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int i;
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for (ep = mp->exports, i = mp->nExports; i; i--, ep++)
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if (ep->name)
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free(ep->name);
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free(mp->exports);
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}
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if (mp == modList)
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modList = mp->next;
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else {
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for (mp1 = modList; mp1; mp1 = mp1->next)
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if (mp1->next == mp) {
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mp1->next = mp->next;
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break;
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}
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}
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free(mp->name);
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free(mp);
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return result;
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}
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static void terminate(void)
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{
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while (modList)
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dlclose(modList);
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}
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/*
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* Build the export table from the XCOFF .loader section.
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*/
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static int readExports(ModulePtr mp)
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{
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LDFILE *ldp = NULL;
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SCNHDR sh, shdata;
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LDHDR *lhp;
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char *ldbuf;
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LDSYM *ls;
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int i;
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ExportPtr ep;
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if ((ldp = ldopen(mp->name, ldp)) == NULL) {
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struct ld_info *lp;
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char *buf;
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int size = 4*1024;
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if (errno != ENOENT) {
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errvalid++;
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snprintf(errbuf, sizeof(errbuf),
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"readExports: %s",
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strerror(errno));
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return -1;
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}
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/*
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* The module might be loaded due to the LIBPATH
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* environment variable. Search for the loaded
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* module using L_GETINFO.
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*/
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if ((buf = malloc(size)) == NULL) {
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errvalid++;
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snprintf(errbuf, sizeof(errbuf),
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"readExports: %s",
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strerror(errno));
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return -1;
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}
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while ((i = loadquery(L_GETINFO, buf, size)) == -1 && errno == ENOMEM) {
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free(buf);
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size += 4*1024;
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if ((buf = malloc(size)) == NULL) {
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errvalid++;
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snprintf(errbuf, sizeof(errbuf),
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"readExports: %s",
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strerror(errno));
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return -1;
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}
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}
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if (i == -1) {
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errvalid++;
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snprintf(errbuf, sizeof(errbuf),
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"readExports: %s",
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strerror(errno));
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free(buf);
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return -1;
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}
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/*
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* Traverse the list of loaded modules. The entry point
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* returned by load() does actually point to the data
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* segment origin.
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*/
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lp = (struct ld_info *)buf;
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while (lp) {
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if (lp->ldinfo_dataorg == mp->entry) {
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ldp = ldopen(lp->ldinfo_filename, ldp);
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break;
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}
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if (lp->ldinfo_next == 0)
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lp = NULL;
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else
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lp = (struct ld_info *)((char *)lp + lp->ldinfo_next);
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}
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free(buf);
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if (!ldp) {
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errvalid++;
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snprintf (errbuf, sizeof(errbuf),
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"readExports: %s", strerror(errno));
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return -1;
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}
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}
|
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if (TYPE(ldp) != U802TOCMAGIC) {
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errvalid++;
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snprintf(errbuf, sizeof(errbuf), "readExports: bad magic");
|
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while(ldclose(ldp) == FAILURE)
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;
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return -1;
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}
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/*
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* Get the padding for the data section. This is needed for
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* AIX 4.1 compilers. This is used when building the final
|
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* function pointer to the exported symbol.
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*/
|
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if (ldnshread(ldp, _DATA, &shdata) != SUCCESS) {
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errvalid++;
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snprintf(errbuf, sizeof(errbuf),
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"readExports: cannot read data section header");
|
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while(ldclose(ldp) == FAILURE)
|
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;
|
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return -1;
|
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}
|
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if (ldnshread(ldp, _LOADER, &sh) != SUCCESS) {
|
|
errvalid++;
|
|
snprintf(errbuf, sizeof(errbuf),
|
|
"readExports: cannot read loader section header");
|
|
while(ldclose(ldp) == FAILURE)
|
|
;
|
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return -1;
|
|
}
|
|
/*
|
|
* We read the complete loader section in one chunk, this makes
|
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* finding long symbol names residing in the string table easier.
|
|
*/
|
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if ((ldbuf = (char *)malloc(sh.s_size)) == NULL) {
|
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errvalid++;
|
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snprintf (errbuf, sizeof(errbuf),
|
|
"readExports: %s", strerror(errno));
|
|
while(ldclose(ldp) == FAILURE)
|
|
;
|
|
return -1;
|
|
}
|
|
if (FSEEK(ldp, sh.s_scnptr, BEGINNING) != OKFSEEK) {
|
|
errvalid++;
|
|
snprintf(errbuf, sizeof(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++;
|
|
snprintf(errbuf, sizeof(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++;
|
|
snprintf (errbuf, sizeof(errbuf),
|
|
"readExports: %s", 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.
|
|
*/
|
|
strlcpy (tmpsym, ls->l_name,
|
|
SYMNMLEN + 1);
|
|
symname = tmpsym;
|
|
}
|
|
ep->name = strdup(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++;
|
|
snprintf (errbuf, sizeof(errbuf),
|
|
"findMail: %s", 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++;
|
|
snprintf (errbuf, sizeof(errbuf),
|
|
"findMail: %s", strerror(errno));
|
|
return NULL;
|
|
}
|
|
}
|
|
if (i == -1) {
|
|
errvalid++;
|
|
snprintf (errbuf, sizeof(errbuf),
|
|
"findMail: %s", 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;
|
|
}
|