Add stdio support to gdbreplay

I've been using gdbreplay to help debug an intermittent failure, and I
wanted it to be a little simpler to use.  This patch adds support for
"-" as the "address" argument.  With this patch you can do:

    (gdb) target remote | gdbreplay logfile -

... and not have to start gdbreplay in a separate shell.

2021-02-12  Tom Tromey  <tromey@adacore.com>

	* gdbreplay.cc (remote_desc): Remove.
	(remote_desc_in, remote_desc_out): New globals.
	(remote_close): Update.
	(remote_open): Handle "-".
	(remote_open): Update.
	(logchar): Log to stderr.
	(expect, play): Update.

2 files changed, 45 insertions, 21 deletions

diff --git a/gdbserver/ChangeLog b/gdbserver/ChangeLog
index e98c43913fd..0c93ae0c086 100644
--- a/gdbserver/ChangeLog
+++ b/gdbserver/ChangeLog
@@ -1,5 +1,15 @@
 2021-02-12  Tom Tromey  <tromey@adacore.com>
 
+	* gdbreplay.cc (remote_desc): Remove.
+	(remote_desc_in, remote_desc_out): New globals.
+	(remote_close): Update.
+	(remote_open): Handle "-".
+	(remote_open): Update.
+	(logchar): Log to stderr.
+	(expect, play): Update.
+
+2021-02-12  Tom Tromey  <tromey@adacore.com>
+
 	* gdbreplay.cc (remote_open): Constify.
 
 2021-02-05  Paul E. Murphy  <murphyp@linux.ibm.com>
diff --git a/gdbserver/gdbreplay.cc b/gdbserver/gdbreplay.cc
index 1a53b9880c0..864a31e58f7 100644
--- a/gdbserver/gdbreplay.cc
+++ b/gdbserver/gdbreplay.cc
@@ -66,7 +66,8 @@ typedef int socklen_t;
 /* Sort of a hack... */
 #define EOL (EOF - 1)
 
-static int remote_desc;
+static int remote_desc_in;
+static int remote_desc_out;
 
 #ifdef __MINGW32CE__
 
@@ -141,9 +142,12 @@ static void
 remote_close (void)
 {
 #ifdef USE_WIN32API
-  closesocket (remote_desc);
+  gdb_assert (remote_desc_in == remote_desc_out);
+  closesocket (remote_desc_in);
 #else
-  close (remote_desc);
+  close (remote_desc_in);
+  if (remote_desc_in != remote_desc_out)
+    close (remote_desc_out);
 #endif
 }
 
@@ -153,6 +157,15 @@ remote_close (void)
 static void
 remote_open (const char *name)
 {
+#ifndef USE_WIN32API
+  if (strcmp (name, "-") == 0)
+    {
+      remote_desc_in = 0;
+      remote_desc_out = 1;
+      return;
+    }
+#endif
+
   const char *last_colon = strrchr (name, ':');
 
   if (last_colon == NULL)
@@ -241,7 +254,7 @@ remote_open (const char *name)
     perror_with_name ("Can't bind address");
 
   if (p->ai_socktype == SOCK_DGRAM)
-    remote_desc = tmp_desc;
+    remote_desc_in = tmp_desc;
   else
     {
       struct sockaddr_storage sockaddr;
@@ -251,10 +264,10 @@ remote_open (const char *name)
       if (listen (tmp_desc, 1) != 0)
 	perror_with_name ("Can't listen on socket");
 
-      remote_desc = accept (tmp_desc, (struct sockaddr *) &sockaddr,
-			    &sockaddrsize);
+      remote_desc_in = accept (tmp_desc, (struct sockaddr *) &sockaddr,
+			       &sockaddrsize);
 
-      if (remote_desc == -1)
+      if (remote_desc_in == -1)
 	perror_with_name ("Accept failed");
 
       /* Enable TCP keep alive process. */
@@ -265,7 +278,7 @@ remote_open (const char *name)
       /* Tell TCP not to delay small packets.  This greatly speeds up
 	 interactive response. */
       tmp = 1;
-      setsockopt (remote_desc, IPPROTO_TCP, TCP_NODELAY,
+      setsockopt (remote_desc_in, IPPROTO_TCP, TCP_NODELAY,
 		  (char *) &tmp, sizeof (tmp));
 
       if (getnameinfo ((struct sockaddr *) &sockaddr, sockaddrsize,
@@ -290,8 +303,9 @@ remote_open (const char *name)
     }
 
 #if defined(F_SETFL) && defined (FASYNC)
-  fcntl (remote_desc, F_SETFL, FASYNC);
+  fcntl (remote_desc_in, F_SETFL, FASYNC);
 #endif
+  remote_desc_out = remote_desc_in;
 
   fprintf (stderr, "Replay logfile using %s\n", name);
   fflush (stderr);
@@ -306,8 +320,8 @@ logchar (FILE *fp)
   ch = fgetc (fp);
   if (ch != '\r')
     {
-      fputc (ch, stdout);
-      fflush (stdout);
+      fputc (ch, stderr);
+      fflush (stderr);
     }
   switch (ch)
     {
@@ -321,16 +335,16 @@ logchar (FILE *fp)
 	  ungetc (ch, fp);
 	  ch = '\r';
 	}
-      fputc (ch == EOL ? '\n' : '\r', stdout);
-      fflush (stdout);
+      fputc (ch == EOL ? '\n' : '\r', stderr);
+      fflush (stderr);
       break;
     case '\n':
       ch = EOL;
       break;
     case '\\':
       ch = fgetc (fp);
-      fputc (ch, stdout);
-      fflush (stdout);
+      fputc (ch, stderr);
+      fflush (stderr);
       switch (ch)
 	{
 	case '\\':
@@ -355,12 +369,12 @@ logchar (FILE *fp)
 	  break;
 	case 'x':
 	  ch2 = fgetc (fp);
-	  fputc (ch2, stdout);
-	  fflush (stdout);
+	  fputc (ch2, stderr);
+	  fflush (stderr);
 	  ch = fromhex (ch2) << 4;
 	  ch2 = fgetc (fp);
-	  fputc (ch2, stdout);
-	  fflush (stdout);
+	  fputc (ch2, stderr);
+	  fflush (stderr);
 	  ch |= fromhex (ch2);
 	  break;
 	default:
@@ -403,7 +417,7 @@ expect (FILE *fp)
       fromlog = logchar (fp);
       if (fromlog == EOL)
 	break;
-      fromgdb = gdbchar (remote_desc);
+      fromgdb = gdbchar (remote_desc_in);
       if (fromgdb < 0)
 	remote_error ("Error during read from gdb");
     }
@@ -433,7 +447,7 @@ play (FILE *fp)
   while ((fromlog = logchar (fp)) != EOL)
     {
       ch = fromlog;
-      if (write (remote_desc, &ch, 1) != 1)
+      if (write (remote_desc_out, &ch, 1) != 1)
 	remote_error ("Error during write to gdb");
     }
 }