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/* Dynamic loading of store class modules
Copyright (C) 2002 Free Software Foundation, Inc.
This file is part of the GNU Hurd.
The GNU Hurd is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License as
published by the Free Software Foundation; either version 2, or (at
your option) any later version.
The GNU Hurd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111, USA. */
#include "store.h"
#include <dlfcn.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <error.h> /* XXX */
static error_t
open_class (int need_open,
const char *name, const char *clname_end,
const struct store_class **classp)
{
char *modname, *clsym;
void *mod;
/* Construct the name of the shared object for this module. */
if (asprintf (&modname,
"libstore_%.*s%s", clname_end - name, name,
STORE_SONAME_SUFFIX) < 0)
return ENOMEM;
/* Now try to load the module.
Note we never dlclose the module, and add a ref every time we open it
anew. We can't dlclose it until no stores of this class exist, so
we'd need a creation/deletion hook for that. */
errno = 0;
mod = dlopen (modname, RTLD_LAZY);
if (mod == NULL)
{
const char *errstring = dlerror (); /* Must always call or it leaks! */
if (errno != ENOENT)
/* XXX not good, but how else to report the error? */
error (0, 0, "cannot load %s: %s", modname, errstring);
}
free (modname);
if (mod == NULL)
return errno ?: ENOENT;
if (asprintf (&clsym, "store_%.*s_class", clname_end - name, name) < 0)
{
dlclose (mod);
return ENOMEM;
}
*classp = dlsym (mod, clsym);
free (clsym);
if (*classp == NULL)
{
error (0, 0, "invalid store module %.*s: %s",
clname_end - name, name, dlerror ());
dlclose (mod);
return EGRATUITOUS;
}
if (need_open && ! (*classp)->open)
{
/* This class cannot be opened as needed. */
dlclose (mod);
return EOPNOTSUPP;
}
return 0;
}
error_t
store_module_find_class (const char *name, const char *clname_end,
const struct store_class **classp)
{
return open_class (0, name, clname_end, classp);
}
error_t
store_module_open (const char *name, int flags,
const struct store_class *const *classes,
struct store **store)
{
const struct store_class *cl;
const char *clname_end = strchr (name, ':');
error_t err;
if (! clname_end)
return EINVAL;
err = open_class (1, name, clname_end, &cl);
if (err)
return err;
if (*clname_end)
/* Skip the ':' separating the class-name from the device name. */
clname_end++;
if (! *clname_end)
/* The class-specific portion of the name is empty, so make it *really*
empty. */
clname_end = 0;
return (*cl->open) (clname_end, flags, classes, store);
}
const struct store_class store_module_open_class =
{ -1, "module", open: store_module_open };
STORE_STD_CLASS (module_open);
error_t
store_module_decode (struct store_enc *enc,
const struct store_class *const *classes,
struct store **store)
{
char *modname;
void *mod;
const struct store_class *const *cl, *const *clend;
enum file_storage_class id;
if (enc->cur_int >= enc->num_ints)
/* The first int should always be the type. */
return EINVAL;
id = enc->ints[enc->cur_int];
/* Construct the name of the shared object for this module. */
if (asprintf (&modname, "libstore_type-%d%s", id, STORE_SONAME_SUFFIX) < 0)
return ENOMEM;
/* Try to open the module. */
mod = dlopen (modname, RTLD_LAZY);
free (modname);
if (mod == NULL)
{
(void) dlerror (); /* otherwise it leaks */
return ENOENT;
}
/* Now find its "store_std_classes" section, which points to each
`struct store_class' defined in this module. */
cl = dlsym (mod, "__start_store_std_classes");
if (cl == NULL)
{
error (0, 0, "invalid store module type-%d: %s", id, dlerror ());
dlclose (mod);
return EGRATUITOUS;
}
clend = dlsym (mod, "__stop_store_std_classes");
if (clend == NULL)
{
error (0, 0, "invalid store module type-%d: %s", id, dlerror ());
dlclose (mod);
return EGRATUITOUS;
}
while (cl < clend)
if ((*cl)->decode && (*cl)->id == id)
return (*(*cl)->decode) (enc, classes, store);
else
++cl;
/* This class cannot be opened via store_decode. */
dlclose (mod);
return EOPNOTSUPP;
}
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