File 0001-Make-plugin-directory-relative-to-ORIGIN.patch of Package v4l-utils

From 09acccbb24c551c4b05b8fd1be0d6c2ba22c68ef Mon Sep 17 00:00:00 2001
From: Matt Madison <matt@madison.systems>
Date: Mon, 16 Mar 2020 12:21:55 -0700
Subject: [PATCH] Make plugin directory relative to $ORIGIN

---
 lib/libv4l2/v4l2-plugin.c | 39 ++++++++++++++++++++++++++++++++++++++-
 1 file changed, 38 insertions(+), 1 deletion(-)

diff --git a/lib/libv4l2/v4l2-plugin.c b/lib/libv4l2/v4l2-plugin.c
index fbf92d8..6bca645 100644
--- a/lib/libv4l2/v4l2-plugin.c
+++ b/lib/libv4l2/v4l2-plugin.c
@@ -21,6 +21,8 @@
 #include <dlfcn.h>
 #include <fcntl.h>
 #include <glob.h>
+#include <limits.h>
+#include <string.h>
 #include <sys/stat.h>
 #include <sys/mman.h>
 #include "libv4l2.h"
@@ -47,6 +49,39 @@
 */
 
 #define PLUGINS_PATTERN LIBV4L2_PLUGIN_DIR "/*.so"
+static char *plugins_pattern;
+
+static void init_plugins_pattern(void)
+{
+	void *handle;
+	char buf[PATH_MAX];
+
+	if (plugins_pattern)
+		return;
+	handle = dlopen("libv4l2.so.0", RTLD_NOLOAD|RTLD_NOW);
+	if (handle) {
+		if (dlinfo(handle, RTLD_DI_ORIGIN, buf) < 0)
+			V4L2_LOG_ERR("cannot identify $ORIGIN for plugins: %s\n", dlerror());
+		else {
+			char *cp;
+			char patbuf[PATH_MAX];
+			ssize_t n;
+			n = snprintf(patbuf, sizeof(patbuf)-1, "%s/libv4l/plugins/*.so", buf);
+			if (n < 0)
+				V4L2_LOG_ERR("error formatting pattern buf for plugins\n");
+			else {
+				patbuf[n] = '\0';
+				plugins_pattern = strdup(patbuf);
+				dlclose(handle);
+				return;
+			}
+		}
+		dlclose(handle);
+	} else
+		V4L2_LOG_ERR("dlopen failed for $ORIGIN lookup: %s\n", dlerror());
+
+	plugins_pattern = strdup(PLUGINS_PATTERN);
+}
 
 void v4l2_plugin_init(int fd, void **plugin_lib_ret, void **plugin_priv_ret,
 		      const struct libv4l_dev_ops **dev_ops_ret)
@@ -61,7 +96,9 @@ void v4l2_plugin_init(int fd, void **plugin_lib_ret, void **plugin_priv_ret,
 	*plugin_lib_ret = NULL;
 	*plugin_priv_ret = NULL;
 
-	glob_ret = glob(PLUGINS_PATTERN, 0, NULL, &globbuf);
+	init_plugins_pattern();
+
+	glob_ret = glob(plugins_pattern, 0, NULL, &globbuf);
 
 	if (glob_ret == GLOB_NOSPACE)
 		return;