1 files changed, 36 insertions, 22 deletions

diff --git a/vest/line_mediator.pl b/vest/line_mediator.pl
index 2b8fa77c..37dea7d6 100755
--- a/vest/line_mediator.pl
+++ b/vest/line_mediator.pl
@@ -25,7 +25,8 @@ if (scalar @ARGV) {
 pop @c1;
 my @c2=@ARGV;
 @ARGV=();
-(scalar @c1 && scalar @c2) || die "usage: $0 cmd1 args -- cmd2 args; hooks up two processes, 2nd of which has one line of output per line of input, expected by the first, which starts off the communication.  crosses stdin/stderr of cmd1 and cmd2 line by line (both must flush on newline and output.  cmd1 initiates the conversation (sends the first line).  DEBUG=1 env var enables debugging output.  default: attempts to cross stdin/stdout of c1 and c2 directly (via two unidirectional posix pipes created before fork).  env SERIAL=1: (no parallelism possible) but lines exchanged are logged if DEBUG.  if SNAKE then stdin -> c1 -> c2 -> c1 -> stdout";
+(scalar @c1 && scalar @c2) || die qq{usage: $0 cmd1 args -- cmd2 args; all options are environment variables.  CROSS=1 hooks up two processes, 2nd of which has one line of output per line of input, expected by the first, which starts off the communication.  crosses stdin/stderr of cmd1 and cmd2 line by line (both must flush on newline and output.  cmd1 initiates the conversation (sends the first line).  DEBUG=1 env var enables debugging output.  default: attempts to cross stdin/stdout of c1 and c2 directly (via two unidirectional posix pipes created before fork).  env SERIAL=1: (no parallelism possible) but lines exchanged are logged if DEBUG.  if SNAKE then stdin -> c1 -> c2 -> c1 -> stdout.  if PIPE then stdin -> c1 -> c2 -> stdout (same as shell c1|c2, but with SERIAL you can see the intermediate in real time; you could do similar with c1 | tee /dev/fd/2 |c2.  DIRECT=1 (default) will override SERIAL=1.  CROSS=1 (default) will override SNAKE or PIPE.
+};
 
 info("1 cmd:",@c1,"\n");
 info("2 cmd:",@c2,"\n");
@@ -36,14 +37,31 @@ sub lineto {
     shift;
     print @_;
 }
-my $snake=$ENV{SNAKE};
-my $serial=$ENV{SERIAL};
-if ($serial || $snake) {
+my $mode='CROSS';
+my $ser='DIRECT';
+$mode='PIPE' if $ENV{PIPE};
+$mode='SNAKE' if $ENV{SNAKE};
+$mode='CROSS' if $ENV{CROSS};
+$ser='SERIAL' if $ENV{SERIAL};
+$ser='DIRECT' if $ENV{DIRECT};
+$ser='SERIAL' if $mode eq 'SNAKE';
+info("mode: $mode\n");
+info("connection: $ser\n");
+
+if ($ser eq 'SERIAL') {
     my ($R1,$W1,$R2,$W2);
     my $c1p=open2($R1,$W1,@c1); # Open2 R W backward from Open3.
     my $c2p=open2($R2,$W2,@c2);
-    if ($snake) {
-        info("SNAKE mode\n");
+    if ($mode eq 'CROSS') {
+        while(<$R1>) {
+            info("1:",$_);
+            lineto($W2,$_);
+            last unless defined ($_=<$R2>);
+            info("1|2:",$_);
+            lineto($W1,$_);
+        }
+    } else {
+        my $snake=$mode eq 'SNAKE';
         while(<STDIN>) {
             info("IN:",$_);
             lineto($W1,$_);
@@ -52,20 +70,13 @@ if ($serial || $snake) {
             lineto($W2,$_);
             last unless defined ($_=<$R2>);
             info("IN|1|2:",$_);
-            lineto($W1,$_);
-            last unless defined ($_=<$R1>);
-            info("IN|1|2|1:",$_);
+            if ($snake) {
+                lineto($W1,$_);
+                last unless defined ($_=<$R1>);
+                info("IN|1|2|1:",$_);
+            }
             lineto(*STDOUT,$_);
         }
-    } else {
-        info("SERIAL mode\n");
-        while(<$R1>) {
-            info("1:",$_);
-            lineto($W2,$_);
-            last unless defined ($_=<$R2>);
-            info("2:",$_);
-            lineto($W1,$_);
-        }
     }
 } else {
     info("DIRECT mode\n");
@@ -76,14 +87,17 @@ if ($serial || $snake) {
     while (not defined ($pid=fork())) {
         sleep 1;
     }
-    POSIX::close(STDOUT_FILENO);
-    POSIX::close(STDIN_FILENO);
+    my $pipe = $mode eq 'PIPE';
+    unless ($pipe) {
+        POSIX::close(STDOUT_FILENO);
+        POSIX::close(STDIN_FILENO);
+    }
     if ($pid) {
         POSIX::dup2($rw1[1],STDOUT_FILENO);
-        POSIX::dup2($rw2[0],STDIN_FILENO);
+        POSIX::dup2($rw2[0],STDIN_FILENO) unless $pipe;
         exec @c1;
     } else {
-        POSIX::dup2($rw2[1],STDOUT_FILENO);
+        POSIX::dup2($rw2[1],STDOUT_FILENO) unless $pipe;
         POSIX::dup2($rw1[0],STDIN_FILENO);
         exec @c2;
     }