alsapid: initial code

alsapid/alsapid.h

@@ -0,0 +1,33 @@
+/* -*- Mode: C ; c-basic-offset: 2 -*- */
+/*
+ * LADI Session Handler (ladish)
+ *
+ * Copyright (C) 2010 Nedko Arnaudov <nedko@arnaudov.name>
+ *
+ **************************************************************************
+ * This file contains interface to alsapid functionality
+ **************************************************************************
+ *
+ * LADI Session Handler 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 of the License, or
+ * (at your option) any later version.
+ *
+ * LADI Session Handler 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 LADI Session Handler. If not, see <http://www.gnu.org/licenses/>
+ * or write to the Free Software Foundation, Inc.,
+ * 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef ALSAPID_H__0A27F284_7538_4791_8023_0FBED929EAF3__INCLUDED
+#define ALSAPID_H__0A27F284_7538_4791_8023_0FBED929EAF3__INCLUDED
+
+void alsapid_compose_src_link(int alsa_client_id, char * buffer);
+void alsapid_compose_dst_link(char * buffer);
+
+#endif /* #ifndef ALSAPID_H__0A27F284_7538_4791_8023_0FBED929EAF3__INCLUDED */

alsapid/asound.versions

@@ -0,0 +1,16 @@
+ALSA_0.9 {
+  global:
+    snd_*;
+
+    _snd_*_open;
+    _snd_*_dlsym_*;
+    _snd_*_poll_descriptor;
+    _snd_pcm_hook_*;
+
+    __snd_pcm_hw_params_*;
+    __snd_pcm_sw_params_*;
+    __snd_*_dlsym_*;
+
+  local:
+    *;
+};

alsapid/helper.c

@@ -0,0 +1,42 @@
+/* -*- Mode: C ; c-basic-offset: 2 -*- */
+/*
+ * LADI Session Handler (ladish)
+ *
+ * Copyright (C) 2010 Nedko Arnaudov <nedko@arnaudov.name>
+ *
+ **************************************************************************
+ * This file contains alsapid helper functionality
+ **************************************************************************
+ *
+ * LADI Session Handler 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 of the License, or
+ * (at your option) any later version.
+ *
+ * LADI Session Handler 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 LADI Session Handler. If not, see <http://www.gnu.org/licenses/>
+ * or write to the Free Software Foundation, Inc.,
+ * 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/types.h>
+
+#include "alsapid.h"
+
+void alsapid_compose_src_link(int alsa_client_id, char * buffer)
+{
+  sprintf(buffer, "/tmp/alsapid-%lld-%d", (long long)getuid(), alsa_client_id);
+}
+
+void alsapid_compose_dst_link(char * buffer)
+{
+  sprintf(buffer, "/proc/%lld", (long long)getpid());
+}
+

alsapid/lib.c

@@ -0,0 +1,170 @@
+/* -*- Mode: C ; c-basic-offset: 2 -*- */
+/*
+ * LADI Session Handler (ladish)
+ *
+ * Copyright (C) 2010 Nedko Arnaudov <nedko@arnaudov.name>
+ *
+ **************************************************************************
+ * This file contains implementation of the libasound LD_PRELOAD-ed alsapid library
+ **************************************************************************
+ *
+ * LADI Session Handler 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 of the License, or
+ * (at your option) any later version.
+ *
+ * LADI Session Handler 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 LADI Session Handler. If not, see <http://www.gnu.org/licenses/>
+ * or write to the Free Software Foundation, Inc.,
+ * 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#define _GNU_SOURCE
+
+#include <alsa/asoundlib.h>
+#include <dlfcn.h>
+#include <linux/limits.h>
+#include <stdio.h>
+
+#include "alsapid.h"
+
+#define API_VERSION "ALSA_0.9"
+
+// gcc -g -shared -Wl,--version-script=asound.versions -o libasound.so -fPIC -ldl -Wall -Werror lib.c helper.c
+// LD_LIBRARY_PATH=alsapid LD_PRELOAD=libasound.so seq24
+
+static void create_symlink(int alsa_client_id)
+{
+  char src[PATH_MAX];
+  char dst[PATH_MAX];
+
+  alsapid_compose_src_link(alsa_client_id, src);
+  alsapid_compose_dst_link(dst);
+
+  //printf("'%s' -> '%s'\n", src, dst);
+  if (symlink(dst, src) != 0)
+  {
+    fprintf(stderr, "symlink(\"%s\", \"%s\") failed with %d (%s)", dst, src, errno, strerror(errno));
+  }
+}
+
+static void destroy_symlink(int alsa_client_id)
+{
+  char src[PATH_MAX];
+
+  alsapid_compose_src_link(alsa_client_id, src);
+
+  //printf("'%s'\n", src);
+  if (unlink(src) != 0)
+  {
+    fprintf(stderr, "unlink(\"%s\") failed with %d (%s)", src, errno, strerror(errno));
+  }
+}
+
+//static int (* real_snd_seq_open)(snd_seq_t ** handle, const char * name, int streams, int mode);
+static int (* real_snd_seq_set_client_name)(snd_seq_t * seq, const char * name);
+static int (* real_snd_seq_close)(snd_seq_t * handle);
+//static int (* real_snd_seq_create_port)(snd_seq_t * handle, snd_seq_port_info_t * info);
+//static int (* real_snd_seq_create_simple_port)(snd_seq_t * seq, const char * name, unsigned int caps, unsigned int type);
+
+void __attribute__ ((constructor)) init(void);
+
+/* Library constructor */
+void init(void)
+{
+//  real_snd_seq_open               = dlvsym(RTLD_NEXT, "snd_seq_open",               API_VERSION);
+  real_snd_seq_set_client_name    = dlvsym(RTLD_NEXT, "snd_seq_set_client_name",    API_VERSION);
+  real_snd_seq_close              = dlvsym(RTLD_NEXT, "snd_seq_close",              API_VERSION);
+//  real_snd_seq_create_port        = dlvsym(RTLD_NEXT, "snd_seq_create_port",        API_VERSION);
+//  real_snd_seq_create_simple_port = dlvsym(RTLD_NEXT, "snd_seq_create_simple_port", API_VERSION);
+}
+
+#define CHECK_FUNC(func)                                                \
+  if (real_ ## func == NULL)                                            \
+  {                                                                     \
+    fprintf(stderr, "dlvsym(\"" #func "\", \""API_VERSION"\") failed.\n"); \
+    return -1;                                                          \
+  }
+
+#if 0
+int snd_seq_open(snd_seq_t ** handle, const char * name, int streams, int mode)
+{
+  int ret;
+
+  //printf("Attempt to create alsa client '%s', %d streams and mode %d\n", name, streams, mode);
+
+  CHECK_FUNC(snd_seq_open);
+
+  //printf("real_snd_seq_open = %p\n", real_snd_seq_open);
+  ret = real_snd_seq_open(handle, name, streams, mode);
+  if (ret == 0)
+  {
+    //printf("alsa client %p (%d) created\n", *handle, snd_seq_client_id(*handle));
+  }
+  return ret;
+}
+#endif
+
+int snd_seq_set_client_name(snd_seq_t * seq, const char * name)
+{
+  int ret;
+
+  //printf("Attempt to set alsa client name to '%s' of %p\n", name, seq); getchar();
+
+  CHECK_FUNC(snd_seq_set_client_name);
+
+  ret = real_snd_seq_set_client_name(seq, name);
+
+  //printf("name set?\n"); getchar();
+
+  if (ret == 0)
+  {
+    //printf("ALSAPID: pid = %lld SETNAME %d '%s'\n", (long long)getpid(), snd_seq_client_id(seq), name);
+    create_symlink(snd_seq_client_id(seq));
+  }
+
+  return ret;
+}
+
+int snd_seq_close(snd_seq_t * handle)
+{
+  CHECK_FUNC(snd_seq_close);
+
+  //printf("ALSAPID: pid = %lld CLOSE %d\n", (long long)getpid(), snd_seq_client_id(handle));
+  destroy_symlink(snd_seq_client_id(handle));
+
+  return real_snd_seq_close(handle);
+}
+
+#if 0
+int snd_seq_create_port(snd_seq_t * handle, snd_seq_port_info_t * info)
+{
+  int ret;
+
+  CHECK_FUNC(snd_seq_create_port);
+
+  ret = real_snd_seq_create_port(handle, info);
+
+  //printf("port created?\n"); getchar();
+
+  return ret;
+}
+
+int snd_seq_create_simple_port(snd_seq_t * seq, const char * name, unsigned int caps, unsigned int type)
+{
+  int ret;
+
+  CHECK_FUNC(snd_seq_create_simple_port);
+
+  ret = real_snd_seq_create_simple_port(seq, name, caps, type);
+
+  //printf("simple port created?\n"); getchar();
+
+  return ret;
+}
+#endif