Merge branch 'query-result'

10 files changed, 218 insertions, 23 deletions

diff --git a/src/attacher.c b/src/attacher.c
index 1bba70f..ef3ce8b 100644
--- a/src/attacher.c
+++ b/src/attacher.c
@@ -83,6 +83,21 @@ AttachSigCont SIGDEFARG
   SIGRETURN;
 }
 
+static int QueryResult;
+
+static sigret_t
+QueryResultSuccess SIGDEFARG
+{
+  QueryResult = 1;
+  SIGRETURN;
+}
+
+static sigret_t
+QueryResultFail SIGDEFARG
+{
+  QueryResult = 2;
+  SIGRETURN;
+}
 
 /*
  *  Send message to a screen backend.
@@ -923,10 +938,11 @@ screen_builtin_lck()
 
 
 void
-SendCmdMessage(sty, match, av)
+SendCmdMessage(sty, match, av, query)
 char *sty;
 char *match;
 char **av;
+int query;
 {
   int i, s;
   struct msg m;
@@ -954,7 +970,7 @@ char **av;
 	exit(1);
     }
   bzero((char *)&m, sizeof(m));
-  m.type = MSG_COMMAND;
+  m.type = query ? MSG_QUERY : MSG_COMMAND;
   if (attach_tty)
     {
       strncpy(m.m_tty, attach_tty, sizeof(m.m_tty) - 1);
@@ -979,7 +995,59 @@ char **av;
   m.m.command.preselect[sizeof(m.m.command.preselect) - 1] = 0;
   m.m.command.apid = getpid();
   debug1("SendCommandMsg writing '%s'\n", m.m.command.cmd);
-  if (WriteMessage(s, &m))
-    Msg(errno, "write");
-  close(s);
+  if (query)
+    {
+      /* Create a server socket so we can get back the result */
+      char *sp = SockPath + strlen(SockPath);
+      char query[] = "-queryX";
+      char c;
+      int r = -1;
+      for (c = 'A'; c <= 'Z'; c++)
+	{
+	  query[6] = c;
+	  strcpy(sp, query);	/* XXX: strncpy? */
+	  if ((r = MakeServerSocket()) >= 0)
+	    break;
+	}
+      if (r < 0)
+	{
+	  for (c = '0'; c <= '9'; c++)
+	    {
+	      query[6] = c;
+	      strcpy(sp, query);
+	      if ((r = MakeServerSocket()) >= 0)
+		break;
+	    }
+	}
+
+      if (r < 0)
+	Panic(0, "Could not create a listening socket to read the results.");
+
+      strncpy(m.m.command.writeback, SockPath, sizeof(m.m.command.writeback) - 1);
+      m.m.command.writeback[sizeof(m.m.command.writeback) - 1] = '\0';
+
+      /* Send the message, then wait for a response */
+      signal(SIGCONT, QueryResultSuccess);
+      signal(SIG_BYE, QueryResultFail);
+      if (WriteMessage(s, &m))
+	Msg(errno, "write");
+      close(s);
+      while (!QueryResult)
+	pause();
+      signal(SIGCONT, SIG_DFL);
+      signal(SIG_BYE, SIG_DFL);
+
+      /* Read the result and spit it out to stdout */
+      ReceiveRaw(r);
+      unlink(SockPath);
+      if (QueryResult == 2)	/* An error happened */
+	exit(1);
+    }
+  else
+    {
+      if (WriteMessage(s, &m))
+	Msg(errno, "write");
+      close(s);
+    }
 }
+
diff --git a/src/comm.c b/src/comm.c
index 17fbd56..ba9806b 100644
--- a/src/comm.c
+++ b/src/comm.c
@@ -180,7 +180,7 @@ struct comm comms[RC_LAST + 1] =
   { "dinfo",		NEED_DISPLAY|ARGS_0 },
   { "displays",		NEED_LAYER|ARGS_0 },
   { "dumptermcap",	NEED_FORE|ARGS_0 },
-  { "echo",		ARGS_12 },
+  { "echo",		CAN_QUERY|ARGS_12 },
 #ifdef ENCODINGS
   { "encoding",		ARGS_12 },
 #endif
@@ -207,12 +207,12 @@ struct comm comms[RC_LAST + 1] =
   { "hstatus",		NEED_FORE|ARGS_1 },
   { "idle",		ARGS_0|ARGS_ORMORE },
   { "ignorecase",	ARGS_01 },
-  { "info",		NEED_LAYER|ARGS_0 },
+  { "info",		CAN_QUERY|NEED_LAYER|ARGS_0 },
 #ifdef ENCODINGS
   { "kanji",		NEED_FORE|ARGS_12 },
 #endif
   { "kill",		NEED_FORE|ARGS_0 },
-  { "lastmsg",		NEED_DISPLAY|ARGS_0 },
+  { "lastmsg",		CAN_QUERY|NEED_DISPLAY|ARGS_0 },
   { "layout",           ARGS_1|ARGS_ORMORE},
   { "license",		NEED_LAYER|ARGS_0 },
 #ifdef LOCK
@@ -286,7 +286,7 @@ struct comm comms[RC_LAST + 1] =
 #ifdef COPY_PASTE
   { "scrollback",	NEED_FORE|ARGS_1 },
 #endif
-  { "select",		ARGS_01 },
+  { "select",		CAN_QUERY|ARGS_01 },
   { "sessionname",	ARGS_01 },
   { "setenv",		ARGS_012 },
   { "setsid",		ARGS_1 },
@@ -311,8 +311,8 @@ struct comm comms[RC_LAST + 1] =
   { "termcap",		ARGS_23 },
   { "termcapinfo",	ARGS_23 },
   { "terminfo",		ARGS_23 },
-  { "time",		ARGS_01 },
-  { "title",		NEED_FORE|ARGS_01 },
+  { "time",		CAN_QUERY|ARGS_01 },
+  { "title",		CAN_QUERY|NEED_FORE|ARGS_01 },
   { "umask",		ARGS_1|ARGS_ORMORE },
   { "unbindall",	ARGS_0 },
   { "unsetenv",		ARGS_1 },
@@ -327,7 +327,7 @@ struct comm comms[RC_LAST + 1] =
   { "wall",		NEED_DISPLAY|ARGS_1},
   { "width",		ARGS_0123 },
   { "windowlist",	ARGS_012 },
-  { "windows",		NEED_DISPLAY|ARGS_0 },
+  { "windows",		CAN_QUERY|ARGS_0 },
   { "wrap",		NEED_FORE|ARGS_01 },
 #ifdef COPY_PASTE
   { "writebuf",		ARGS_0123 },
diff --git a/src/comm.sh b/src/comm.sh
index a4b06e7..4fc8cb2 100644
--- a/src/comm.sh
+++ b/src/comm.sh
@@ -43,6 +43,8 @@ struct comm
 #define NEED_FORE	(1<<6)	/* this command needs a fore window */
 #define NEED_DISPLAY	(1<<7)	/* this command needs a display */
 #define NEED_LAYER	(1<<8)	/* this command needs a layer */
+#define CAN_QUERY	(1<<9)  /* this command can be queried, i.e. used with -Q to
+				   get back a result to stdout */
 
 #define ARGS_01		(ARGS_0 | ARGS_PLUS1)
 #define ARGS_02		(ARGS_0 | ARGS_PLUS2)
diff --git a/src/doc/screen.1 b/src/doc/screen.1
index 3ac5571..c26bbc8 100644
--- a/src/doc/screen.1
+++ b/src/doc/screen.1
@@ -305,6 +305,22 @@ there is no session to resume. 12 (or more) indicates that there are 2 (or
 more) sessions to resume and you should specify which one to choose. 
 In all other cases \*Q-q\*U has no effect.
 .TP 5
+.B \-Q
+Some commands now can be queried from a remote session using this
+flag, e.g. 'screen -Q windows'. The commands will send the
+response to the stdout of the querying process. If there was an
+error in the command, then the querying process will exit with
+a non-zero status.
+
+The commands that can be queried now are:
+ \fBecho\fP
+ \fBinfo\fP
+ \fBlastmsg\fP
+ \fBselect\fP
+ \fBtime\fP
+ \fBtitle\fP
+ \fBwindows\fP
+.TP 5
 .BR \-r " [" \fIpid.tty.host ]
 .PD 0
 .TP 5
@@ -376,7 +392,6 @@ the \fB-d\fP or \fB-r\fP option to tell screen to look only for
 attached or detached screen sessions. Note that this command doesn't
 work if the session is password protected.
 
-
 .SH "DEFAULT KEY BINDINGS"
 .ta 12n 26n
 As mentioned, each
diff --git a/src/doc/screen.texinfo b/src/doc/screen.texinfo
index 44d233e..f7371e1 100644
--- a/src/doc/screen.texinfo
+++ b/src/doc/screen.texinfo
@@ -374,6 +374,22 @@ there is no session to resume. 12 (or more) indicates that there are 2 (or
 more) sessions to resume and you should specify which one to choose. 
 In all other cases @samp{-q} has no effect.
 
+@item -Q
+Some commands now can be queried from a remote session using this
+flag, e.g. 'screen -Q windows'. The commands will send the
+response to the stdout of the querying process. If there was an
+error in the command, then the querying process will exit with
+a non-zero status.
+
+The commands that can be queried now are:
+ @code{echo}
+ @code{info}
+ @code{lastmsg}
+ @code{select}
+ @code{time}
+ @code{title}
+ @code{windows}
+
 @item -r [@var{pid.sessionname}]
 @itemx -r @var{sessionowner}/[@var{pid.sessionname}]
 Resume a detached @code{screen} session.  No other options (except
diff --git a/src/extern.h b/src/extern.h
index 38a8d6e..dc5857e 100644
--- a/src/extern.h
+++ b/src/extern.h
@@ -241,7 +241,7 @@ extern void  FreeTransTable __P((void));
 extern int   Attach __P((int));
 extern void  Attacher __P((void));
 extern sigret_t AttacherFinit __P(SIGPROTOARG);
-extern void  SendCmdMessage __P((char *, char *, char **));
+extern void  SendCmdMessage __P((char *, char *, char **, int));
 
 /* display.c */
 extern struct display *MakeDisplay __P((char *, char *, char *, int, int, struct mode *));
diff --git a/src/process.c b/src/process.c
index 128b0e2..34ed63d 100644
--- a/src/process.c
+++ b/src/process.c
@@ -59,6 +59,7 @@ extern char *BellString, *ActivityString, *ShellProg, *ShellArgs[];
 extern char *hstatusstring, *captionstring, *timestring;
 extern char *wliststr, *wlisttit;
 extern int captionalways;
+extern int queryflag;
 extern char *hardcopydir, *screenlogfile, *logtstamp_string;
 extern int log_flush, logtstamp_on, logtstamp_after;
 extern char *VisualBellString;
@@ -1147,19 +1148,35 @@ int key;
       return;
     }
   n = comms[nr].flags;
+  /* Commands will have a CAN_QUERY flag, depending on whether they have
+   * something to return on a query. For example, 'windows' can return a result,
+   * but 'other' cannot.
+   * If some command causes an error, then it should reset queryflag to -1, so that
+   * the process requesting the query can be notified that an error happened.
+   */
+  if (!(n & CAN_QUERY) && queryflag >= 0)
+    {
+      /* Query flag is set, but this command cannot be queried. */
+      Msg(0, "%s command cannot be queried.", comms[nr].name);
+      queryflag = -1;
+      return;
+    }
   if ((n & NEED_DISPLAY) && display == 0)
     {
       Msg(0, "%s: %s: display required", rc_name, comms[nr].name);
+      queryflag = -1;
       return;
     }
   if ((n & NEED_FORE) && fore == 0)
     {
       Msg(0, "%s: %s: window required", rc_name, comms[nr].name);
+      queryflag = -1;
       return;
     }
   if ((n & NEED_LAYER) && flayer == 0)
     {
       Msg(0, "%s: %s: display or window required", rc_name, comms[nr].name);
+      queryflag = -1;
       return;
     }
   if ((argc = CheckArgNum(nr, args)) < 0)
@@ -1171,6 +1188,7 @@ int key;
         {
 	  Msg(0, "%s: %s: permission denied (user %s)", 
 	      rc_name, comms[nr].name, (EffectiveAclUser ? EffectiveAclUser : D_user)->u_name);
+	  queryflag = -1;
 	  return;
 	}
     }
@@ -1190,7 +1208,10 @@ int key;
       else if (args[0][0] == '.' && !args[0][1])
 	{
 	  if (!fore)
-	    Msg(0, "select . needs a window");
+	    {
+	      Msg(0, "select . needs a window");
+	      queryflag = -1;
+	    }
 	  else
 	    {
 	      SetForeWindow(fore);
@@ -1199,6 +1220,8 @@ int key;
 	}
       else if (ParseWinNum(act, &n) == 0)
         SwitchWindow(n);
+      else if (queryflag >= 0)
+	queryflag = -1;	/* ParseWinNum already prints out an appropriate error message. */
       break;
 #ifdef AUTO_NUKE
     case RC_DEFAUTONUKE:
@@ -2026,6 +2049,13 @@ int key;
       }
       break;
     case RC_TITLE:
+      if (queryflag >= 0)
+	{
+	  if (fore)
+	    Msg(0, "%s", fore->w_title);
+	  else
+	    queryflag = -1;
+	}
       if (*args == 0)
 	InputAKA();
       else
@@ -2635,7 +2665,10 @@ int key;
       if (s)
 	Msg(0, "%s", s);
       else
-	Msg(0, "%s: 'echo [-n] [-p] \"string\"' expected.", rc_name);
+	{
+	  Msg(0, "%s: 'echo [-n] [-p] \"string\"' expected.", rc_name);
+	  queryflag = -1;
+	}
       break;
     case RC_BELL:
     case RC_BELL_MSG:
@@ -5318,7 +5351,7 @@ int where;
 	continue;
       if ((flags & 1) && display && p == D_fore)
 	continue;
-      if (D_fore && D_fore->w_group != p->w_group)
+      if (display && D_fore && D_fore->w_group != p->w_group)
 	continue;
 
       cmd = p->w_title;
@@ -5460,13 +5493,11 @@ int where;
   char buf[1024];
   char *s, *ss;
 
-  if (!display)
-    return;
-  if (where == -1 && D_fore)
+  if (display && where == -1 && D_fore)
     where = D_fore->w_number;
   ss = AddWindows(buf, sizeof(buf), 0, where);
   s = buf + strlen(buf);
-  if (ss - buf > D_width / 2)
+  if (display && ss - buf > D_width / 2)
     {
       ss -= D_width / 2;
       if (s - ss < D_width)
diff --git a/src/screen.c b/src/screen.c
index 92b2001..67cddbc 100644
--- a/src/screen.c
+++ b/src/screen.c
@@ -207,6 +207,7 @@ char *wlisttit;
 int auto_detach = 1;
 int iflag, rflag, dflag, lsflag, quietflag, wipeflag, xflag;
 int cmdflag;
+int queryflag = -1;
 int adaptflag;
 
 #ifdef MULTIUSER
@@ -680,6 +681,10 @@ char **av;
 		case 'q':
 		  quietflag = 1;
 		  break;
+		case 'Q':
+		  queryflag = 1;
+		  cmdflag = 1;
+		  break;
 		case 'r':
 		case 'R':
 #ifdef MULTI
@@ -1176,7 +1181,7 @@ char **av;
       if (!*av)
 	Panic(0, "Please specify a command.");
       SET_GUID();
-      SendCmdMessage(sty, SockMatch, av);
+      SendCmdMessage(sty, SockMatch, av, queryflag >= 0);
       exit(0);
     }
   else if (rflag || xflag)
@@ -2105,6 +2110,9 @@ VA_DECL
     }
   else
     printf("%s\r\n", buf);
+
+  if (queryflag >= 0)
+    write(queryflag, buf, strlen(buf));
 }
 
 /*
diff --git a/src/screen.h b/src/screen.h
index a151e38..fa4cc82 100644
--- a/src/screen.h
+++ b/src/screen.h
@@ -173,6 +173,7 @@ struct mode
 #define MSG_WINCH	6
 #define MSG_HANGUP	7
 #define MSG_COMMAND	8
+#define MSG_QUERY       9
 
 /*
  * versions of struct msg:
@@ -227,6 +228,8 @@ struct msg
 	  char cmd[MAXPATHLEN];	/* command */
 	  int apid;		/* pid of frontend */
 	  char preselect[20];
+	  char writeback[MAXPATHLEN];  /* The socket to write the result.
+					  Only used for MSG_QUERY */
 	}
       command;
       char message[MAXPATHLEN * 2];
diff --git a/src/socket.c b/src/socket.c
index a174b72..70b57db 100644
--- a/src/socket.c
+++ b/src/socket.c
@@ -65,6 +65,7 @@ static void  AskPassword __P((struct msg *));
 extern char *RcFileName, *extra_incap, *extra_outcap;
 extern int ServerSocket, real_uid, real_gid, eff_uid, eff_gid;
 extern int dflag, iflag, rflag, lsflag, quietflag, wipeflag, xflag;
+extern int queryflag;
 extern char *attach_tty, *LoginName, HostName[];
 extern struct display *display, *displays;
 extern struct win *fore, **wtab, *console_window, *windows;
@@ -1170,6 +1171,26 @@ ReceiveMsg()
 	FinishDetach(&m);
       break;
 #endif
+    case MSG_QUERY:
+	{
+	  char *oldSockPath = SaveStr(SockPath);
+	  strcpy(SockPath, m.m.command.writeback);
+	  int s = MakeClientSocket(0);
+	  strcpy(SockPath, oldSockPath);
+	  Free(oldSockPath);
+	  if (s >= 0)
+	    {
+	      queryflag = s;
+	      DoCommandMsg(&m);
+	      close(s);
+	    }
+	  else
+	    queryflag = -1;
+
+	  Kill(m.m.command.apid, (queryflag >= 0) ? SIGCONT : SIG_BYE);	/* Send SIG_BYE if an error happened */
+	  queryflag = -1;
+	}
+      break;
     case MSG_COMMAND:
       DoCommandMsg(&m);
       break;
@@ -1178,6 +1199,32 @@ ReceiveMsg()
     }
 }
 
+void
+ReceiveRaw(s)
+int s;
+{
+  char rd[256];
+  int len = 0;
+#ifdef NAMEDPIPE
+  if (fcntl(s, F_SETFL, 0) == -1)
+    Panic(errno, "BLOCK fcntl");
+#else
+  struct sockaddr_un a;
+  len = sizeof(a);
+  if ((s = accept(s, (struct sockaddr *) &a, (void *)&len)) < 0)
+    {
+      Msg(errno, "accept");
+      return;
+    }
+#endif
+  while ((len = read(s, rd, 255)) > 0)
+    {
+      rd[len] = 0;
+      printf("%s", rd);
+    }
+  close(s);
+}
+
 #if defined(_SEQUENT_) && !defined(NAMEDPIPE)
 #undef connect
 /*
@@ -1605,12 +1652,16 @@ struct msg *mp;
   if (fc != fullcmd)
     *--fc = 0;
   if (Parse(fullcmd, fc - fullcmd, args, argl) <= 0)
-    return;
+    {
+      /* XXX: Return some useful message back if MSG_QUERY */
+      return;
+    }
 #ifdef MULTIUSER
   user = *FindUserPtr(mp->m.attach.auser);
   if (user == 0)
     {
       Msg(0, "Unknown user %s tried to send a command!", mp->m.attach.auser);
+      /* XXX: Return some useful message back if MSG_QUERY */
       return;
     }
 #else
@@ -1620,6 +1671,7 @@ struct msg *mp;
   if (user->u_password && *user->u_password)
     {
       Msg(0, "User %s has a password, cannot use -X option.", mp->m.attach.auser);
+      /* XXX: Return some useful message back if MSG_QUERY */
       return;
     }
 #endif