[PATCH 2/2] Use exec_file_find to locate executable on attach (sometimes)

[Gary Benson <gbenson@redhat.com>]

This commit updates attach_command_post_wait to use exec_file_find
to compute the full pathname of the main executable if the pathname
returned by target_pid_to_exec_file is absolute and if gdb_sysroot
is non-empty and not remote.  The net effect of this is to prefix
the main executable's path with gdb_sysroot if gdb_sysroot is set;
this is useful for attaching to processes running in chroot jails
or containerized environments.  This logic is skipped for remote
gdb_sysroots because the subsequent code does not support opening
the main executable remotely.

gdb/ChangeLog:

	* infcmd.c (filenames.h): New include.
	(remote.h): Likewise.
	(solist.h): Likewise.
	(attach_command_post_wait): Prefix absolute executable
	paths with gdb_sysroot if set and not remote.
---
 gdb/ChangeLog |    8 ++++++++
 gdb/infcmd.c  |   37 +++++++++++++++++++++++++++++--------
 2 files changed, 37 insertions(+), 8 deletions(-)

diff --git a/gdb/infcmd.c b/gdb/infcmd.c
index 3737b8f..23c7a6c 100644
--- a/gdb/infcmd.c
+++ b/gdb/infcmd.c
@@ -54,6 +54,9 @@
 #include "continuations.h"
 #include "linespec.h"
 #include "cli/cli-utils.h"
+#include "filenames.h"
+#include "remote.h"
+#include "solist.h"
 
 /* Local functions: */
 
@@ -2493,16 +2496,34 @@ attach_command_post_wait (char *args, int from_tty, int async_exec)
       exec_file = target_pid_to_exec_file (ptid_get_pid (inferior_ptid));
       if (exec_file)
 	{
-	  /* It's possible we don't have a full path, but rather just a
-	     filename.  Some targets, such as HP-UX, don't provide the
-	     full path, sigh.
+	  /* If there is a gdb_sysroot and exec_file is absolute we
+	     prepend gdb_sysroot to exec_file.  This is currently
+	     disabled for remote sysroot as the subsequent code cannot
+	     yet cope with these.  */
+	  if (IS_ABSOLUTE_PATH (exec_file)
+	      && gdb_sysroot != NULL && *gdb_sysroot != '\0'
+	      && !remote_filename_p (gdb_sysroot))
+	    {
+	      int fd = -1;
+
+	      full_exec_path = exec_file_find (exec_file, &fd);
+	      if (fd >= 0)
+		close (fd);
+	    }
 
-	     Attempt to qualify the filename against the source path.
-	     (If that fails, we'll just fall back on the original
-	     filename.  Not much more we can do...)  */
+	  if (full_exec_path == NULL)
+	    {
+	      /* It's possible we don't have a full path, but rather
+		 just a filename.  Some targets, such as HP-UX, don't
+		 provide the full path, sigh.
+
+		 Attempt to qualify the filename against the source
+		 path.  (If that fails, we'll just fall back on the
+		 original filename.  Not much more we can do...)  */
 
-	  if (!source_full_path_of (exec_file, &full_exec_path))
-	    full_exec_path = xstrdup (exec_file);
+	      if (!source_full_path_of (exec_file, &full_exec_path))
+		full_exec_path = xstrdup (exec_file);
+	    }
 
 	  exec_file_attach (full_exec_path, from_tty);
 	  symbol_file_add_main (full_exec_path, from_tty);
-- 
1.7.1