From 5bc1a490fa68187bce15eb9e8305b88ff6fbdbe5 Mon Sep 17 00:00:00 2001
From: Leo Famulari <leo@famulari.name>
Date: Mon, 27 Apr 2020 13:09:54 -0400
Subject: [PATCH] Search for plugins in $GUIX_ALSA_PLUGIN_DIRS.

* src/control/control.c (snd_ctl_open_conf): If ALSA plugins cannot be found in
the default locations, look in the directories in $GUIX_ALSA_PLUGIN_DIRS.
* src/dlmisc.c (snd_dlopen): Likewise.
* src/pcm/pcm.c (snd_pcm_open_conf): Likewise.
---
 src/control/control.c | 35 ++++++++++++++++++++++++++++++++++-
 src/dlmisc.c          | 26 +++++++++++++++++++++-----
 src/pcm/pcm.c         | 35 ++++++++++++++++++++++++++++++++++-
 3 files changed, 89 insertions(+), 7 deletions(-)

diff --git a/src/control/control.c b/src/control/control.c
index 27f42135..108a560b 100644
--- a/src/control/control.c
+++ b/src/control/control.c
@@ -1342,8 +1342,41 @@ static int snd_ctl_open_conf(snd_ctl_t **ctlp, const char *name,
 				err = -ENOMEM;
 				goto _err;
 			}
+			sprintf(buf1, "%s/libasound_module_pcm_%s.so", ALSA_PLUGIN_DIR, str);
+			if (access(buf1, F_OK) != 0) {
+				const char *plugindirs = getenv("GUIX_ALSA_PLUGIN_DIRS");
+
+				if (plugindirs) {
+					char *plugindirs_copy = alloca(strlen(plugindirs) + 1);
+					if (plugindirs_copy == NULL) {
+						err = -ENOMEM;
+						goto _err;
+					}
+					strcpy(plugindirs_copy, plugindirs);
+					char *saveptr;
+					while (1) {
+						char *dir_tok = strtok_r(plugindirs_copy, ":", &saveptr);
+						if (dir_tok == NULL)
+							break;
+						char *so_file = malloc(strlen(dir_tok) + 1 + strlen(str) + 32);
+						if (so_file == NULL) {
+							err = -ENOMEM;
+							goto _err;
+						}
+
+						sprintf(so_file, "%s/libasound_module_ctl_%s.so", dir_tok, str);
+
+						if (access(so_file, F_OK) == 0) {
+							buf1 = so_file;
+							break;
+						} else {
+							free (so_file);
+						}
+						plugindirs_copy = NULL;
+					}
+				}
+			}
 			lib = buf1;
-			sprintf(buf1, "%s/libasound_module_ctl_%s.so", ALSA_PLUGIN_DIR, str);
 		}
 	}
 #ifndef PIC
diff --git a/src/dlmisc.c b/src/dlmisc.c
index 8c8f3ff7..b115447c 100644
--- a/src/dlmisc.c
+++ b/src/dlmisc.c
@@ -82,11 +82,27 @@ void *snd_dlopen(const char *name, int mode, char *errbuf, size_t errbuflen)
 	char *filename = NULL;
 
 	if (name && name[0] != '/') {
-		filename = alloca(sizeof(ALSA_PLUGIN_DIR) + 1 + strlen(name) + 1);
-		if (filename) {
-			strcpy(filename, ALSA_PLUGIN_DIR);
-			strcat(filename, "/");
-			strcat(filename, name);
+		const char *plugindirs = getenv("GUIX_ALSA_PLUGIN_DIRS");
+		if (plugindirs) {
+			char *plugindirs_copy = alloca(strlen(plugindirs) + 1);
+			if (plugindirs_copy == NULL)
+				goto errpath;
+			strcpy(plugindirs_copy, plugindirs);
+			char *saveptr;
+			while (1) {
+				char *dir_tok = strtok_r(plugindirs_copy, ":", &saveptr);
+				if (dir_tok == NULL)
+					break;
+				char *sofilename = malloc(strlen(dir_tok) + 1 + strlen(name) + 1);
+				sprintf(sofilename, "%s/%s" ,dir_tok, name);
+				if (access(sofilename, F_OK) == 0) {
+					filename = sofilename;
+					break;
+				} else {
+					free (sofilename);
+				}
+				plugindirs_copy = NULL;
+			}
 			handle = dlopen(filename, mode);
 			if (!handle) {
 				/* if the filename exists and cannot be opened */
diff --git a/src/pcm/pcm.c b/src/pcm/pcm.c
index 1064044c..90ba00ac 100644
--- a/src/pcm/pcm.c
+++ b/src/pcm/pcm.c
@@ -2578,8 +2578,41 @@ static int snd_pcm_open_conf(snd_pcm_t **pcmp, const char *name,
 				err = -ENOMEM;
 				goto _err;
 			}
-			lib = buf1;
 			sprintf(buf1, "%s/libasound_module_pcm_%s.so", ALSA_PLUGIN_DIR, str);
+			if (access(buf1, F_OK) != 0) {
+				const char *plugindirs = getenv("GUIX_ALSA_PLUGIN_DIRS");
+
+				if (plugindirs) {
+					char *plugindirs_copy = alloca(strlen(plugindirs) + 1);
+					if (plugindirs_copy == NULL) {
+						err = -ENOMEM;
+						goto _err;
+					}
+					strcpy(plugindirs_copy, plugindirs);
+					char *saveptr;
+					while (1) {
+						char *dir_tok = strtok_r(plugindirs_copy, ":", &saveptr);
+						if (dir_tok == NULL)
+							break;
+						char *so_file = malloc(strlen(dir_tok) + 1 + strlen(str) + 32);
+						if (so_file == NULL) {
+							err = -ENOMEM;
+							goto _err;
+						}
+
+						sprintf(so_file, "%s/libasound_module_pcm_%s.so", dir_tok, str);
+
+						if (access(so_file, F_OK) == 0) {
+							buf1 = so_file;
+							break;
+						} else {
+							free (so_file);
+						}
+						plugindirs_copy = NULL;
+					}
+				}
+			}
+			lib = buf1;
 		}
 	}
 #ifndef PIC
-- 
2.26.2