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/**
* \file dlmisc.c
* \brief dynamic loader helpers
* \author Jaroslav Kysela <perex@suse.cz>
* \date 2001
*
* Dynamic loader helpers
*/
/*
* Dynamic loader helpers
* Copyright (c) 2000 by Jaroslav Kysela <perex@suse.cz>
*
*
* This library is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* This program 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 Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*/
#define _GNU_SOURCE
#include "list.h"
#include "local.h"
#ifndef DOC_HIDDEN
#ifndef PIC
struct snd_dlsym_link *snd_dlsym_start = NULL;
#endif
#endif
/**
* \brief Opens a dynamic library - ALSA wrapper for \c dlopen.
* \param name name of the library, similar to \c dlopen.
* \param mode mode flags, similar to \c dlopen.
* \return Library handle if successful, otherwise \c NULL.
*
* This function can emulate dynamic linking for the static build of
* the alsa-lib library. In that case, \p name is set to \c NULL.
*/
void *snd_dlopen(const char *name, int mode)
{
#ifndef PIC
if (name == NULL)
return &snd_dlsym_start;
#else
#ifdef HAVE_LIBDL
if (name == NULL) {
Dl_info dlinfo;
if (dladdr(snd_dlopen, &dlinfo) > 0)
name = dlinfo.dli_fname;
}
#endif
#endif
#ifdef HAVE_LIBDL
return dlopen(name, mode);
#else
return NULL;
#endif
}
/**
* \brief Closes a dynamic library - ALSA wrapper for \c dlclose.
* \param handle Library handle, similar to \c dlclose.
* \return Zero if successful, otherwise an error code.
*
* This function can emulate dynamic linking for the static build of
* the alsa-lib library.
*/
int snd_dlclose(void *handle)
{
#ifndef PIC
if (handle == &snd_dlsym_start)
return 0;
#endif
#ifdef HAVE_LIBDL
return dlclose(handle);
#else
return 0;
#endif
}
/**
* \brief Verifies a dynamically loaded symbol.
* \param handle Library handle, similar to \c dlsym.
* \param name Symbol name.
* \param version Version of the symbol.
* \return Zero is successful, otherwise a negative error code.
*
* This function checks that the symbol with the version appended to its name
* does exist in the library.
*/
static int snd_dlsym_verify(void *handle, const char *name, const char *version)
{
#ifdef HAVE_LIBDL
int res;
char *vname;
if (handle == NULL)
return -EINVAL;
vname = alloca(1 + strlen(name) + strlen(version) + 1);
if (vname == NULL)
return -ENOMEM;
vname[0] = '_';
strcpy(vname + 1, name);
strcat(vname, version);
res = dlsym(handle, vname) == NULL ? -ENOENT : 0;
// printf("dlsym verify: %i, vname = '%s'\n", res, vname);
if (res < 0)
SNDERR("unable to verify version for symbol %s", name);
return res;
#else
return 0;
#endif
}
/**
* \brief Resolves a symbol from a dynamic library - ALSA wrapper for \c dlsym.
* \param handle Library handle, similar to \c dlsym.
* \param name Symbol name.
* \param version Version of the symbol.
*
* This function can emulate dynamic linking for the static build of
* the alsa-lib library.
*
* This special version of the \c dlsym function checks also the version
* of the symbol. A versioned symbol should be defined using the
* #SND_DLSYM_BUILD_VERSION macro.
*/
void *snd_dlsym(void *handle, const char *name, const char *version)
{
int err;
#ifndef PIC
if (handle == &snd_dlsym_start) {
/* it's the funny part: */
/* we are looking for a symbol in a static library */
struct snd_dlsym_link *link = snd_dlsym_start;
while (link) {
if (!strcmp(name, link->dlsym_name))
return (void *)link->dlsym_ptr;
link = link->next;
}
return NULL;
}
#endif
#ifdef HAVE_LIBDL
if (version) {
err = snd_dlsym_verify(handle, name, version);
if (err < 0)
return NULL;
}
return dlsym(handle, name);
#else
return NULL;
#endif
}
/*
* dlobj cache
*
* FIXME: add reference counter and proper locking
*/
#ifndef DOC_HIDDEN
struct dlobj_cache {
const char *name;
void *obj;
void *func;
struct list_head list;
};
static LIST_HEAD(pcm_dlobj_list);
void *snd_dlobj_cache_lookup(const char *name)
{
struct list_head *p;
struct dlobj_cache *c;
list_for_each(p, &pcm_dlobj_list) {
c = list_entry(p, struct dlobj_cache, list);
if (strcmp(c->name, name) == 0)
return c->func;
}
return NULL;
}
int snd_dlobj_cache_add(const char *name, void *dlobj, void *open_func)
{
struct list_head *p;
struct dlobj_cache *c;
list_for_each(p, &pcm_dlobj_list) {
c = list_entry(p, struct dlobj_cache, list);
if (strcmp(c->name, name) == 0)
return 0; /* already exists */
}
c = malloc(sizeof(*c));
if (! c)
return -ENOMEM;
c->name = strdup(name);
if (! c->name) {
free(c);
return -ENOMEM;
}
c->obj = dlobj;
c->func = open_func;
list_add_tail(&c->list, &pcm_dlobj_list);
return 0;
}
void snd_dlobj_cache_cleanup(void)
{
struct list_head *p;
struct dlobj_cache *c;
while (! list_empty(&pcm_dlobj_list)) {
p = pcm_dlobj_list.next;
c = list_entry(p, struct dlobj_cache, list);
list_del(p);
snd_dlclose(c->obj);
free((void *)c->name); /* shut up gcc warning */
free(c);
}
}
#endif
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