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Make alsapid work when libasound is loaded with dlopen(). Fix for #180 

when alsapid is preloaded libasound is not loaded yet
for some unknown reason, late call to dlvsym() fails as well,
at least for mididings (python loads _mididings.so that
implicitly loads libasound.so)

this changeset implements the late symbol lookup,
because it makes the code smaller

the actual fix is to LD_PRELOAD libasound.so as well
This commit is contained in:
Nedko Arnaudov 2011-06-03 00:44:00 +03:00
parent cd3c2e4af4
commit 60aaa492db
2 changed files with 11 additions and 17 deletions
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22
alsapid/lib.c
View File

@ -2,7 +2,7 @@
/*
* LADI Session Handler (ladish)
*
* Copyright (C) 2010 Nedko Arnaudov <nedko@arnaudov.name>
* Copyright (C) 2010, 2011 Nedko Arnaudov <nedko@arnaudov.name>
*
**************************************************************************
* This file contains implementation of the libasound LD_PRELOAD-ed alsapid library
@ -76,23 +76,15 @@ 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);
static 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; \
real_ ## func = dlvsym(RTLD_NEXT, #func, API_VERSION); \
if (real_ ## func == NULL) \
{ \
fprintf(stderr, "dlvsym(\""#func"\", \""API_VERSION"\") failed. %s\n", dlerror()); \
return -1; \
} \
}
#if 0

6
daemon/loader.c
View File

@ -484,6 +484,8 @@ loader_run(void)
loader_childs_bury();
}
#define LD_PRELOAD_ADD "libalsapid.so libasound.so"
static void set_ldpreload(void)
{
const char * old;
@ -492,7 +494,7 @@ static void set_ldpreload(void)
old = getenv("LD_PRELOAD");
if (old != NULL)
{
new = catdup3("libalsapid.so", " ", old);
new = catdup3(LD_PRELOAD_ADD, " ", old);
if (new == NULL)
{
fprintf(stderr, "Memory allocation failure. Cannot hook libalsapid.so through LD_PRELOAD.\n");
@ -501,7 +503,7 @@ static void set_ldpreload(void)
}
else
{
new = "libalsapid.so";
new = LD_PRELOAD_ADD;
}
printf("LD_PRELOAD set to \"%s\"\n", new);