[PATCH v2 3/4] Use child_path to determine if an object file is under a sysroot.

[John Baldwin <jhb@FreeBSD.org>]

This fixes the case where the sysroot happens to end in a trailing
'/'.  Note that the path returned from child_path always skips over
the directory separator at the start of the base path, so a separator
must always be explicitly added before the base path.

gdb/ChangeLog:

	* symfile.c (find_separate_debug_file): Use child_path to
	determine if an object file is under a sysroot.
---
 gdb/ChangeLog |  5 +++++
 gdb/symfile.c | 12 +++++++-----
 2 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 93a2cebe1c..e65182d84d 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 child_path to
+	determine if an object file is under a sysroot.
+
 2019-01-28  John Baldwin  <jhb@FreeBSD.org>
 
 	* Makefile.in (SUBDIR_UNITTESTS_SRCS): Add
diff --git a/gdb/symfile.c b/gdb/symfile.c
index b5802e20ad..ffcba1a090 100644
--- a/gdb/symfile.c
+++ b/gdb/symfile.c
@@ -57,6 +57,7 @@
 #include "gdb_bfd.h"
 #include "cli/cli-utils.h"
 #include "common/byte-vector.h"
+#include "common/pathstuff.h"
 #include "common/selftest.h"
 #include "cli/cli-style.h"
 #include "common/forward-scope-exit.h"
@@ -1452,16 +1453,16 @@ 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
-	  && filename_ncmp (canon_dir, gdb_sysroot,
-			    strlen (gdb_sysroot)) == 0
-	  && IS_DIR_SEPARATOR (canon_dir[strlen (gdb_sysroot)]))
+	  && (base_path = child_path (gdb_sysroot, canon_dir)) != NULL)
 	{
 	  /* 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 += base_path;
 	  debugfile += "/";
 	  debugfile += debuglink;
 
@@ -1473,7 +1474,8 @@ find_separate_debug_file (const char *dir,
 	  debugfile = target_prefix ? "target:" : "";
 	  debugfile += gdb_sysroot;
 	  debugfile += debugdir.get ();
-	  debugfile += (canon_dir + strlen (gdb_sysroot));
+	  debugfile += "/";
+	  debugfile += base_path;
 	  debugfile += "/";
 	  debugfile += debuglink;
 
-- 
2.19.2