[PATCH v2 1/4] Look for separate debug files in debug directories under a sysroot.

[John Baldwin <jhb@FreeBSD.org>]

When an object file is present in a system root, GDB currently looks
for separate debug files under the global debugfile directories.  For
example, if the sysroot is set to "/myroot" and hte global debugfile
directory is set to "/usr/lib/debug", GDB will look for a separate
debug file for "/myroot/lib/libc.so.7" in the following paths:

  /myroot/lib/libc.so.7.debug
  /myroot/lib/.debug/libc.so.7.debug
  /usr/lib/debug//myroot/lib/libc.so.7.debug
  /usr/lib/debug/lib/libc.so.7.debug

However, some system roots include a full system installation
including a nested global debugfile directory under the sysroot.  This
patch adds an additional check to support such systems.  In the
example above the additional path searched is:

  /myroot/usr/lib/debug/lib/libc.so.7.debug

To try to preserve existing behavior as much as possible, this new
path is searched last for each global debugfile directory.

gdb/ChangeLog:

	* symfile.c (find_separate_debug_file): Look for separate debug
	files in debug directories under the sysroot.
---
 gdb/ChangeLog |  5 +++++
 gdb/symfile.c | 17 +++++++++++++++--
 2 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 5d5f72b817..38d740e440 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): Look for separate debug
+	files in debug directories under the sysroot.
+
 2019-01-28  John Baldwin  <jhb@FreeBSD.org>
 
 	* aarch64-fbsd-tdep.c (aarch64_fbsd_gregmap)
diff --git a/gdb/symfile.c b/gdb/symfile.c
index e5ff38462c..b5802e20ad 100644
--- a/gdb/symfile.c
+++ b/gdb/symfile.c
@@ -1452,22 +1452,35 @@ find_separate_debug_file (const char *dir,
       if (separate_debug_file_exists (debugfile, crc32, objfile))
 	return debugfile;
 
-      /* If the file is in the sysroot, try using its base path in the
-	 global debugfile directory.  */
       if (canon_dir != NULL
 	  && filename_ncmp (canon_dir, gdb_sysroot,
 			    strlen (gdb_sysroot)) == 0
 	  && IS_DIR_SEPARATOR (canon_dir[strlen (gdb_sysroot)]))
 	{
+	  /* If the file is in the sysroot, try using its base path in
+	     the global debugfile directory.  */
 	  debugfile = target_prefix ? "target:" : "";
 	  debugfile += debugdir.get ();
 	  debugfile += (canon_dir + strlen (gdb_sysroot));
 	  debugfile += "/";
 	  debugfile += debuglink;
 
+	  if (separate_debug_file_exists (debugfile, crc32, objfile))
+	    return debugfile;
+
+	  /* If the file is in the sysroot, try using its base path in
+	     the sysroot's global debugfile directory.  */
+	  debugfile = target_prefix ? "target:" : "";
+	  debugfile += gdb_sysroot;
+	  debugfile += debugdir.get ();
+	  debugfile += (canon_dir + strlen (gdb_sysroot));
+	  debugfile += "/";
+	  debugfile += debuglink;
+
 	  if (separate_debug_file_exists (debugfile, crc32, objfile))
 	    return debugfile;
 	}
+
     }
 
   return std::string ();
-- 
2.19.2