From 89041ad29d55afc396aff3e403eec3b8c6055113 Mon Sep 17 00:00:00 2001
From: Antonio Larrosa <alarrosa@suse.com>
Date: Mon, 11 Mar 2024 15:10:25 +0100
Subject: [PATCH] registry, ptp: Canonicalize the library path returned by
 dladdr

On systems using UsrMerge (like openSUSE or Fedora), /lib64 is
a symlink to /usr/lib64. So dladdr is returning the path to
the gstreamer library in /lib64 in priv_gst_get_relocated_libgstreamer.
Later gst_plugin_loader_spawn tries to build the path to the
gst-plugin-scanner helper from /lib64 and ends up trying to use
/lib64/../libexec/gstreamer-1.0/gst-plugin-scanner which doesn't exist.

By canonicalizing the path with a call to realpath, gst-plugin-scanner
is found correctly under
/usr/lib64/../libexec/gstreamer-1.0/gst-plugin-scanner

Similar change applied to gstreamer/libs/gst/net/gstptpclock.c

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/6343>
---
 subprojects/gstreamer/gst/gstregistry.c       | 21 ++++++++++++++++++-
 .../gstreamer/libs/gst/net/gstptpclock.c      | 21 ++++++++++++++++++-
 2 files changed, 40 insertions(+), 2 deletions(-)

diff --git a/subprojects/gstreamer/gst/gstregistry.c b/subprojects/gstreamer/gst/gstregistry.c
index c84de1d7f6..2226d1853f 100644
--- a/subprojects/gstreamer/gst/gstregistry.c
+++ b/subprojects/gstreamer/gst/gstregistry.c
@@ -1599,6 +1599,8 @@ priv_gst_get_relocated_libgstreamer (void)
 #elif defined(HAVE_DLADDR)
   {
     Dl_info info;
+    char *real_fname = NULL;
+    long path_max = 0;
 
     GST_DEBUG ("attempting to retrieve libgstreamer-1.0 location using "
         "dladdr()");
@@ -1609,8 +1611,25 @@ priv_gst_get_relocated_libgstreamer (void)
       if (!info.dli_fname) {
         return NULL;
       }
+#ifdef PATH_MAX
+      path_max = PATH_MAX;
+#else
+      path_max = pathconf (info.dli_fname, _PC_PATH_MAX);
+      if (path_max <= 0)
+        path_max = 4096;
+#endif
+
+      real_fname = g_malloc (path_max);
+      if (realpath (info.dli_fname, real_fname)) {
+        dir = g_path_get_dirname (real_fname);
+        GST_DEBUG ("real directory location: %s", dir);
+      } else {
+        GST_ERROR ("could not canonicalize path %s: %s", info.dli_fname,
+            g_strerror (errno));
+        dir = g_path_get_dirname (info.dli_fname);
+      }
+      g_free (real_fname);
 
-      dir = g_path_get_dirname (info.dli_fname);
     } else {
       GST_LOG ("dladdr() failed");
       return NULL;
diff --git a/subprojects/gstreamer/libs/gst/net/gstptpclock.c b/subprojects/gstreamer/libs/gst/net/gstptpclock.c
index 09f482ecd1..fc3268fae4 100644
--- a/subprojects/gstreamer/libs/gst/net/gstptpclock.c
+++ b/subprojects/gstreamer/libs/gst/net/gstptpclock.c
@@ -2569,6 +2569,8 @@ get_relocated_libgstnet (void)
 #elif defined(HAVE_DLADDR)
   {
     Dl_info info;
+    char *real_fname = NULL;
+    long path_max = 0;
 
     GST_DEBUG ("attempting to retrieve libgstnet-1.0 location using "
         "dladdr()");
@@ -2579,8 +2581,25 @@ get_relocated_libgstnet (void)
       if (!info.dli_fname) {
         return NULL;
       }
+#ifdef PATH_MAX
+      path_max = PATH_MAX;
+#else
+      path_max = pathconf (info.dli_fname, _PC_PATH_MAX);
+      if (path_max <= 0)
+        path_max = 4096;
+#endif
+
+      real_fname = g_malloc (path_max);
+      if (realpath (info.dli_fname, real_fname)) {
+        dir = g_path_get_dirname (real_fname);
+        GST_DEBUG ("real directory location: %s", dir);
+      } else {
+        GST_ERROR ("could not canonicalize path %s: %s", info.dli_fname,
+            g_strerror (errno));
+        dir = g_path_get_dirname (info.dli_fname);
+      }
+      g_free (real_fname);
 
-      dir = g_path_get_dirname (info.dli_fname);
     } else {
       GST_LOG ("dladdr() failed");
       return NULL;