It's very unlikely that people have more than one fingerprint reader
on their computers and being actively used.
The current design of fprint library loads all the drivers as built-ins.
On systems with smaller memory (such as embedded systems), a few KBs are
also important.
This commit adds basic API for loading/unloading modules.
Right now, only the drivers are treated as loadable modules.
The implementation is just a wrapper around dlopen()/dlsym() API.
The design derives from the linux kernel's implementation of loadable
modules.
Signed-off-by: Kunal Gangakhedkar <kunal.gangakhed...@gmail.com>
---
libfprint/module.c | 148 ++++++++++++++++++++++++++++++++++++++++++++++++++++
libfprint/module.h | 57 ++++++++++++++++++++
2 files changed, 205 insertions(+)
create mode 100644 libfprint/module.c
create mode 100644 libfprint/module.h
diff --git a/libfprint/module.c b/libfprint/module.c
new file mode 100644
index 0000000..05368af
--- /dev/null
+++ b/libfprint/module.c
@@ -0,0 +1,148 @@
+/*
+ * Support for dynamically loading drivers
+ * Copyright (C) 2012 Kunal Gangakhedkar <kunal.gangakhed...@gmail.com>
+ *
+ * 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 library 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include <errno.h>
+#include <string.h>
+#include <dlfcn.h>
+
+#include <glib.h>
+#include <config.h>
+#include <fp_internal.h>
+
+#include "module.h"
+
+static GSList *modules = NULL;
+
+static int module_exists(const char *mod_path, GSList **entry);
+
+API_EXPORTED int load_module(const char *mod_path)
+{
+ int rc = 0;
+ initcall_t init_call = NULL;
+ exitcall_t exit_call = NULL;
+ struct fp_mod *mod = NULL;
+ void *handle = NULL;
+
+ if (module_exists(mod_path, NULL)) {
+ fp_info("Module '%s' already loaded - skipping..\n", mod_path);
+ return rc;
+ }
+
+ handle = dlopen(mod_path, RTLD_LAZY);
+ if (!handle) {
+ fp_err("failed to load module %s\n", dlerror());
+ return errno;
+ }
+
+ init_call = (initcall_t)dlsym(handle, "init_mod");
+ if (!init_call) {
+ fp_err("failed to get init call pointer: %s\n", dlerror());
+ rc = errno;
+ goto close_lib;
+ }
+
+ exit_call = (exitcall_t)dlsym(handle, "cleanup_mod");
+
+ mod = g_malloc0(sizeof(*mod));
+ mod->init = init_call;
+ mod->exit = exit_call;
+ mod->handle = handle;
+ strncpy(mod->path, mod_path, MODULE_PATH_LEN);
+
+ /*
+ * TODO:
+ * For now, copy the file path into name.
+ * When we add support for MODULE_NAME(), we need to change this
+ * to copy the actual module name.
+ */
+ strncpy(mod->name, mod_path, MODULE_NAME_LEN);
+
+ rc = init_call();
+ if (rc < 0) {
+ /* Init routine failed. Abort loading of module.. */
+ fp_warn("module '%s' returned %d - aborting loading",
mod->name, rc);
+ g_free(mod);
+ } else {
+ modules = g_slist_prepend(modules, (gpointer) mod);
+ }
+ goto out;
+
+close_lib:
+ dlclose(handle);
+out:
+ return rc;
+}
+
+API_EXPORTED int unload_module(const char *mod_path)
+{
+ GSList *entry = NULL;
+ struct fp_mod *mod = NULL;
+ int rc = 0;
+
+ if (!module_exists(mod_path, &entry)) {
+ fp_err("Module '%s' not found. Perhaps not loaded?\n",
mod_path);
+ return -ENOENT;
+ }
+
+ mod = (struct fp_mod*)entry->data;
+
+ modules = g_slist_delete_link(modules, entry);
+
+ if (mod->exit) {
+ mod->exit();
+ }
+
+ rc = dlclose(mod->handle);
+ if (rc < 0) {
+ /*
+ * This is a potential memory leak.
+ * The loaded library is dangling here.
+ * Hopefully, sensible OS will clean it out when the main
process
+ * terminates.
+ */
+ fp_dbg("Failed to unload module '%s': %s\n", mod->name,
dlerror());
+ }
+
+ if (entry)
+ entry = NULL;
+
+ g_free(mod);
+ mod = NULL;
+
+ return rc;
+}
+
+static int module_exists(const char *mod_path, GSList **entry)
+{
+ GSList *elem = modules;
+
+ if (g_slist_length(elem) == 0)
+ return 0;
+
+ do {
+ struct fp_mod *mod = (struct fp_mod*)elem->data;
+ if (strncmp(mod->path, mod_path, MODULE_PATH_LEN) == 0) {
+ if (entry)
+ *entry = elem;
+ return 1;
+ }
+ } while ((elem = g_slist_next(elem)));
+
+ return 0;
+}
diff --git a/libfprint/module.h b/libfprint/module.h
new file mode 100644
index 0000000..f9cd74e
--- /dev/null
+++ b/libfprint/module.h
@@ -0,0 +1,57 @@
+/*
+ * Support for dynamically loading drivers
+ * Copyright (C) 2012 Kunal Gangakhedkar <kunal.gangakhed...@gmail.com>
+ *
+ * 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 library 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#ifndef __FPRINT_MODULE_H__
+#define __FPRINT_MODULE_H__
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <sys/param.h>
+#include <config.h>
+
+#define MODULE_PATH_LEN MAXPATHLEN
+#define MODULE_NAME_LEN MODULE_PATH_LEN
+
+typedef int (*initcall_t)(void);
+typedef void (*exitcall_t)(void);
+
+struct fp_mod {
+ char name[MODULE_NAME_LEN];
+ char path[MODULE_PATH_LEN];
+ initcall_t init;
+ exitcall_t exit;
+ void *handle;
+};
+
+#define module_init(initfn) \
+ API_EXPORTED int init_mod(void) __attribute__((alias(#initfn)));
+
+#define module_exit(exitfn) \
+ API_EXPORTED int cleanup_mod(void) __attribute__((alias(#exitfn)));
+
+int load_module(const char *modpath);
+int unload_module(const char *modpath);
+
+#ifdef __cplusplus
+}
+#endif /* __cplusplus */
+
+#endif /* __FPRINT_MODULE_H__ */
--
1.7.9.5
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