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132 lines
3.4 KiB
C
132 lines
3.4 KiB
C
/**
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* \file dlmisc.c
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* \brief dynamic loader helpers
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* \author Jaroslav Kysela <perex@suse.cz>
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* \date 2001
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*
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* Dynamic loader helpers
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*/
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/*
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* Dynamic loader helpers
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* Copyright (c) 2000 by Jaroslav Kysela <perex@suse.cz>
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*
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*
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* This library is free software; you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as
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* published by the Free Software Foundation; either version 2.1 of
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* the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*
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*/
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#include <dlfcn.h>
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#include "local.h"
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#ifndef DOC_HIDDEN
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#ifndef PIC
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struct snd_dlsym_link *snd_dlsym_start = NULL;
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#endif
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#endif
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/**
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* \brief Open the dynamic library, with ALSA extension
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* \param name name, similar to dlopen
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* \param mode mode, similar to dlopen
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* \return pointer to handle
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*
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* The extension is a special code for the static build of
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* the alsa-lib library.
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*/
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void *snd_dlopen(const char *name, int mode)
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{
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#ifndef PIC
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if (name == NULL)
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return &snd_dlsym_start;
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#endif
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return dlopen(name, mode);
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}
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/**
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* \brief Close the dynamic library, with ALSA extension
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* \param handle handle, similar to dlclose
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* \return zero if success, otherwise an error code
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*
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* The extension is a special code for the static build of
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* the alsa-lib library.
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*/
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int snd_dlclose(void *handle)
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{
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#ifndef PIC
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if (handle == &snd_dlsym_start)
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return 0;
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#endif
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return dlclose(handle);
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}
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/**
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* \brief Verify dynamically loaded symbol
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* \param handle dlopen handle
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* \param name name of symbol
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* \param version version of symbol
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* \return zero is success, otherwise a negative error code
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*/
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static int snd_dlsym_verify(void *handle, const char *name, const char *version)
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{
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int res;
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char *vname;
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if (handle == NULL)
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return -EINVAL;
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vname = alloca(1 + strlen(name) + strlen(version) + 1);
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if (vname == NULL)
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return -ENOMEM;
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vname[0] = '_';
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strcpy(vname + 1, name);
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strcat(vname, version);
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res = dlsym(handle, vname) == NULL ? -ENOENT : 0;
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// printf("dlsym verify: %i, vname = '%s'\n", res, vname);
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if (res < 0)
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SNDERR("unable to verify version for symbol %s", name);
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return res;
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}
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/**
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* \brief Resolve the symbol, with ALSA extension
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* \param handle handle, similar to dlsym
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* \param name symbol name
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* \param version symbol version
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*
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* This special version of dlsym function checks also
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* the version of symbol. The version of a symbol should
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* be defined using #SND_DLSYM_BUILD_VERSION macro.
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*/
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void *snd_dlsym(void *handle, const char *name, const char *version)
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{
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int err;
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#ifndef PIC
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if (handle == &snd_dlsym_start) {
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/* it's the funny part: */
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/* we are looking for a symbol in a static library */
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struct snd_dlsym_link *link = snd_dlsym_start;
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while (link) {
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if (!strcmp(name, link->dlsym_name))
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return (void *)link->dlsym_ptr;
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link = link->next;
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}
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return NULL;
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}
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#endif
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err = snd_dlsym_verify(handle, name, version);
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if (err < 0)
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return NULL;
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return dlsym(handle, name);
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}
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