From 29c65ad9e18cc7bb25335849d7579f9ca0d077f6 Mon Sep 17 00:00:00 2001
From: Andrew Wood <andrew.wood@ivarch.com>
Date: Wed, 18 Mar 2026 22:28:51 +0000
Subject: [PATCH] Set up stdin/stdout for the monitored command (#67).

---
 src/main/main.c | 37 ++++++++++++++++++++++++++++++++++++-
 1 file changed, 36 insertions(+), 1 deletion(-)

diff --git a/src/main/main.c b/src/main/main.c
index bc051e2..79cee66 100644
--- a/src/main/main.c
+++ b/src/main/main.c
@@ -323,10 +323,45 @@ static int pv__monitor(pvstate_t state, opts_t opts)
 			(void) close(pipefd_out[1]);
 		return PV_ERROREXIT_MONITOR;
 	} else if (0 == command_pid) {
-		/* TODO: set up file descriptors for stdin/out */
+		/* Command process. */
+
+		/* Close the write end of the "in" pipe. */
+		if (-1 != pipefd_in[1])
+			(void) close(pipefd_in[1]);
+		/* Close the read end of the "out" pipe. */
+		if (-1 != pipefd_out[0])
+			(void) close(pipefd_out[0]);
+
+		/* Put the read end of the "in" pipe on stdin. */
+		if (-1 != pipefd_in[0]) {
+			if (dup2(pipefd_in[0], STDIN_FILENO) < 0) {
+				fprintf(stderr, "%s: %s\n", opts->program_name, strerror(errno));
+				exit(1);
+			}
+			(void) close(pipefd_in[0]);
+		}
+
+		/* Put the write end of the "out" pipe on stdout. */
+		if (-1 != pipefd_out[1]) {
+			if (dup2(pipefd_out[1], STDOUT_FILENO) < 0) {
+				fprintf(stderr, "%s: %s\n", opts->program_name, strerror(errno));
+				exit(1);
+			}
+			(void) close(pipefd_out[1]);
+		}
+
 		/* TODO: execute the command */
 	}
 
+	/* Main process, not the command process. */
+
+	/* Close the read end of the "in" pipe. */
+	if (-1 != pipefd_in[0])
+		(void) close(pipefd_in[0]);
+	/* Close the write end of the "out" pipe. */
+	if (-1 != pipefd_out[1])
+		(void) close(pipefd_out[1]);
+
 	/* TODO: fork for out monitor if monitoring both. */
 	/* TODO: monitor the appropriate side; if both, use name1/format1 for the in side. */