[PATCH v2 4/4] Try to use the canonical version of a sysroot for debug file links.

[John Baldwin <jhb@FreeBSD.org>]

Object file paths passed to find_separate_debug_file are always
canonical paths with symbolic links resolved.  If a sysroot path
traverses a symbolic link, it will not match the object file paths.
Generate a canonical version of the sysroot directory.  If it is
valid, use it instead of gdb_sysroot with child_path to dtermine if an
object file is under a system root.

gdb/ChangeLog:

	* symfile.c (find_separate_debug_file): Use canonical path of
	sysroot while child_path instead of gdb_sysroot if it is valid.
---
 gdb/ChangeLog |  5 +++++
 gdb/symfile.c | 13 ++++++++++---
 2 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index e65182d84d..f581c63198 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,8 @@
+2019-01-28  John Baldwin  <jhb@FreeBSD.org>
+
+	* symfile.c (find_separate_debug_file): Use canonical path of
+	sysroot while child_path instead of gdb_sysroot if it is valid.
+
 2019-01-28  John Baldwin  <jhb@FreeBSD.org>
 
 	* symfile.c (find_separate_debug_file): Use child_path to
diff --git a/gdb/symfile.c b/gdb/symfile.c
index ffcba1a090..61483824f6 100644
--- a/gdb/symfile.c
+++ b/gdb/symfile.c
@@ -1441,6 +1441,7 @@ find_separate_debug_file (const char *dir,
   const char *dir_notarget = target_prefix ? dir + strlen ("target:") : dir;
   std::vector<gdb::unique_xmalloc_ptr<char>> debugdir_vec
     = dirnames_to_char_ptr_vec (debug_file_directory);
+  gdb::unique_xmalloc_ptr<char> canon_sysroot = gdb_realpath (gdb_sysroot);
 
   for (const gdb::unique_xmalloc_ptr<char> &debugdir : debugdir_vec)
     {
@@ -1453,9 +1454,15 @@ find_separate_debug_file (const char *dir,
       if (separate_debug_file_exists (debugfile, crc32, objfile))
 	return debugfile;
 
-      const char *base_path;
-      if (canon_dir != NULL
-	  && (base_path = child_path (gdb_sysroot, canon_dir)) != NULL)
+      const char *base_path = NULL;
+      if (canon_dir != NULL)
+	{
+	  if (canon_sysroot.get () != NULL)
+	    base_path = child_path (canon_sysroot.get (), canon_dir);
+	  else
+	    base_path = child_path (gdb_sysroot, canon_dir);
+	}
+      if (base_path != NULL)
 	{
 	  /* If the file is in the sysroot, try using its base path in
 	     the global debugfile directory.  */
-- 
2.19.2