Display names of remote threads

This patch adds support for thread names in the remote protocol, and
updates gdb/gdbserver to use it.  The information is added to the XML
description sent in response to the qXfer:threads:read packet.

gdb/ChangeLog:

	* linux-nat.c (linux_nat_thread_name): Replace implementation by call
	to linux_proc_tid_get_name.
	* nat/linux-procfs.c (linux_proc_tid_get_name): New function,
	implementation inspired by linux_nat_thread_name.
	* nat/linux-procfs.h (linux_proc_tid_get_name): New declaration.
	* remote.c (struct private_thread_info) <name>: New field.
	(free_private_thread_info): Free name field.
	(remote_thread_name): New function.
	(thread_item_t) <name>: New field.
	(clear_threads_listing_context): Free name field.
	(start_thread): Get name xml attribute.
	(thread_attributes): Add "name" attribute.
	(remote_update_thread_list): Copy name field.
	(init_remote_ops): Assign remote_thread_name callback.
	* target.h (target_thread_name): Update comment.
	* NEWS: Mention remote thread name support.

gdb/gdbserver/ChangeLog:

	* linux-low.c (linux_target_ops): Use linux_proc_tid_get_name.
	* server.c (handle_qxfer_threads_worker): Refactor to include thread
	name in reply.
	* target.h (struct target_ops) <thread_name>: New field.
	(target_thread_name): New macro.

gdb/doc/ChangeLog:

	* gdb.texinfo (Thread List Format): Mention thread names.

1 files changed, 1 insertions, 32 deletions

diff --git a/gdb/linux-nat.c b/gdb/linux-nat.c
index 2421687..9bc1324 100644
--- a/gdb/linux-nat.c
+++ b/gdb/linux-nat.c
@@ -4100,38 +4100,7 @@ linux_nat_pid_to_str (struct target_ops *ops, ptid_t ptid)
 static const char *
 linux_nat_thread_name (struct target_ops *self, struct thread_info *thr)
 {
-  int pid = ptid_get_pid (thr->ptid);
-  long lwp = ptid_get_lwp (thr->ptid);
-#define FORMAT "/proc/%d/task/%ld/comm"
-  char buf[sizeof (FORMAT) + 30];
-  FILE *comm_file;
-  char *result = NULL;
-
-  snprintf (buf, sizeof (buf), FORMAT, pid, lwp);
-  comm_file = gdb_fopen_cloexec (buf, "r");
-  if (comm_file)
-    {
-      /* Not exported by the kernel, so we define it here.  */
-#define COMM_LEN 16
-      static char line[COMM_LEN + 1];
-
-      if (fgets (line, sizeof (line), comm_file))
-	{
-	  char *nl = strchr (line, '\n');
-
-	  if (nl)
-	    *nl = '\0';
-	  if (*line != '\0')
-	    result = line;
-	}
-
-      fclose (comm_file);
-    }
-
-#undef COMM_LEN
-#undef FORMAT
-
-  return result;
+  return linux_proc_tid_get_name (thr->ptid);
 }
 
 /* Accepts an integer PID; Returns a string representing a file that