Logo Search packages:      
Sourcecode: postgresql-8.4 version File versions

aix.c

/*
 * $PostgreSQL:$ 
 *
 *
 * @(#)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 * This is an unpublished work copyright (c) 1992 HELIOS Software GmbH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 "postgres.h"

#include "sys/ldr.h"
#include <a.out.h>
#include "ldfcn.h"

#include "dynloader.h"

#ifndef HAVE_DLOPEN

/*
 * AIX 4.3 and up has dlopen() and friends in -ldl.
 * A la long, the homebrewn dl*() functions below should be obsolete.
 */

/*
 * 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;

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)
{
      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)
      {
            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"))
      {
            while (mp->cdtors->init)
            {
                  (*mp->cdtors->init) ();
                  mp->cdtors++;
            }
      }
      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)
{
      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, "cannot load library");
                  strcat(errbuf, p);
                  break;
            case L_ERROR_UNDEF:
                  strcat(errbuf, "cannot 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)
{
      ModulePtr   mp = (ModulePtr) handle;
      ExportPtr   ep;
      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)
{
      ModulePtr   mp = (ModulePtr) handle;
      int               result;
      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)
      {
            ExportPtr   ep;
            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 = 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++;
            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;
}

#endif   /* HAVE_DLOPEN */

Generated by  Doxygen 1.6.0   Back to index