external/alsa-lib 1.0.16

1 files changed, 234 insertions, 0 deletions

diff --git a/src/dlmisc.c b/src/dlmisc.c
new file mode 100644
index 0000000..c882cdc
--- /dev/null
+++ b/src/dlmisc.c
@@ -0,0 +1,234 @@
+/**
+ * \file dlmisc.c
+ * \brief dynamic loader helpers
+ * \author Jaroslav Kysela <perex@perex.cz>
+ * \date 2001
+ *
+ * Dynamic loader helpers
+ */
+/*
+ *  Dynamic loader helpers
+ *  Copyright (c) 2000 by Jaroslav Kysela <perex@perex.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