Don't print too much if remote_debug is on

If we turn "remote debug" on and GDB does some vFile operations,
a lot of things will be printed in the screen, which makes
"remote debug" useless.

This patch changes the code that we only print 512 chars in max in
debugging messages, like this,

Sending packet: $qXfer:features:read:target.xml:0,fff#7d...Packet received: l<?xml version="1.0"?>\n<!-- Copyright (C) 2010-2016 Free Software Foundation, Inc.\n\n     Copying and distribution of this file, with or without modification,\n     are permitted in any medium without royalty provided the copyright\n     notice and this notice are preserved.  -->\n\n<!-- AMD64 with AVX - Includes Linux-only special "register".  -->\n\n<!DOCTYPE target SYSTEM "gdb-target.dtd">\n<target>\n  <architecture>i386:x86-64</architecture>\n  <osabi>GNU/Linux</osabi>\n  <xi:include href="64bit-core.xml"/>\n  <xi:[14 bytes omitted]

Sending packet: $qXfer:auxv:read::0,1000#6b...Packet received: l!\000\000\000\000\000\000\000\000d\000\000\000\000\000\000\000\003\000\000\000\000\000\000\000@\000@\000\000\000\000\000\004\000\000\000\000\000\000\0008\000\000\000\000\000\000\000\005\000\000\000\000\000\000\000\t\000\000\000\000\000\000\000\a\000\000\000\000\000\000\000\177\000\000\b\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\t\000\000\000\000\000\000\000\000\004@\000\000\000\000\000\013\000\000\000\000\000\000\003\000\000\000\000\000\000\f\000\000\000\000\000\000\003\000\000\000\000\000\000\r\000\000\000\000\000\000\003\000\000\000\000\000\000\016\000\000\000\000\000\000\003\000\000\000\000\000\000\027\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\031\000\000\000\000\000\000\177\000\000\037\000\000\000\000\000\000\000\000\017\000\000\000\000\000\000\00\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000[582 bytes omitted]

gdb:

2017-01-13  Yao Qi  <yao.qi@linaro.org>

	* remote.c (REMOTE_DEBUG_MAX_CHAR): New macro.
	(putpkt_binary): Print only REMOTE_DEBUG_MAX_CHAR chars in debug
	output.
	(getpkt_or_notif_sane_1): Likewise.

2 files changed, 39 insertions, 4 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index dde53bd..39d66b8 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,12 @@
 2017-01-13  Yao Qi  <yao.qi@linaro.org>
 
+	* remote.c (REMOTE_DEBUG_MAX_CHAR): New macro.
+	(putpkt_binary): Print only REMOTE_DEBUG_MAX_CHAR chars in debug
+	output.
+	(getpkt_or_notif_sane_1): Likewise.
+
+2017-01-13  Yao Qi  <yao.qi@linaro.org>
+
 	* Makefile.in (checker-headers): Use CXX and CXX_DIALET instead
 	of CC.  Pass "-x c++-header" instead of "-x c".
 
diff --git a/gdb/remote.c b/gdb/remote.c
index c73c30a..2f7954a 100644
--- a/gdb/remote.c
+++ b/gdb/remote.c
@@ -283,6 +283,11 @@ typedef unsigned char threadref[OPAQUETHREADBYTES];
 
 #define MAXTHREADLISTRESULTS 32
 
+/* The max number of chars in debug output.  The rest of chars are
+   omitted.  */
+
+#define REMOTE_DEBUG_MAX_CHAR 512
+
 /* Data for the vFile:pread readahead cache.  */
 
 struct readahead_cache
@@ -8749,9 +8754,21 @@ putpkt_binary (const char *buf, int cnt)
 	{
 	  *p = '\0';
 
-	  std::string str = escape_buffer (buf2, p - buf2);
+	  int len = (int) (p - buf2);
+
+	  std::string str
+	    = escape_buffer (buf2, std::min (len, REMOTE_DEBUG_MAX_CHAR));
+
+	  fprintf_unfiltered (gdb_stdlog, "Sending packet: %s", str.c_str ());
+
+	  if (str.length () > REMOTE_DEBUG_MAX_CHAR)
+	    {
+	      fprintf_unfiltered (gdb_stdlog, "[%zu bytes omitted]",
+				  str.length () - REMOTE_DEBUG_MAX_CHAR);
+	    }
+
+	  fprintf_unfiltered (gdb_stdlog, "...");
 
-	  fprintf_unfiltered (gdb_stdlog, "Sending packet: %s...", str.c_str ());
 	  gdb_flush (gdb_stdlog);
 	}
       remote_serial_write (buf2, p - buf2);
@@ -9179,9 +9196,20 @@ getpkt_or_notif_sane_1 (char **buf, long *sizeof_buf, int forever,
 	{
 	  if (remote_debug)
 	    {
-	      std::string str = escape_buffer (*buf, val);
+	      std::string str
+		= escape_buffer (*buf,
+				 std::min (val, REMOTE_DEBUG_MAX_CHAR));
+
+	      fprintf_unfiltered (gdb_stdlog, "Packet received: %s",
+				  str.c_str ());
+
+	      if (str.length () >  REMOTE_DEBUG_MAX_CHAR)
+		{
+		  fprintf_unfiltered (gdb_stdlog, "[%zu bytes omitted]",
+				      str.length () - REMOTE_DEBUG_MAX_CHAR);
+		}
 
-	      fprintf_unfiltered (gdb_stdlog, "Packet received: %s\n", str.c_str ());
+	      fprintf_unfiltered (gdb_stdlog, "\n");
 	    }
 
 	  /* Skip the ack char if we're in no-ack mode.  */