From e1334ef0226e74d6e6cf5d3e02ad896d1a9a30d5 Mon Sep 17 00:00:00 2001
From: DTB <trinity@trinity.moe>
Date: Sat, 13 Jan 2024 11:16:21 -0700
Subject: [PATCH] make program match ideal

---
 psrelay/psrelay.c | 20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/psrelay/psrelay.c b/psrelay/psrelay.c
index fffb911..f1ef05b 100644
--- a/psrelay/psrelay.c
+++ b/psrelay/psrelay.c
@@ -1,10 +1,11 @@
 #include <errno.h> /* errno */
+#include <fcntl.h> /* open(2), O_RDONLY */
 #include <stdio.h> /* fprintf(3) */
 #include <string.h> /* strerror(3) */
 #if !defined EX_OK || !defined EX_OSERR || !defined EX_USAGE
 #	include <sysexits.h>
 #endif
-#include <unistd.h> /* fork(2) */
+#include <unistd.h> /* dup(2), dup2(2), fork(2), STDIN_FILENO */
 #include <sys/types.h> /* <sys/wait.h> */
 #include <sys/wait.h> /* wait(2), WIFEXITED, WEXITSTATUS */
 #include "libpsargs.h"
@@ -30,18 +31,27 @@ int main(int argc, char *argv[]){
 	int child;
 	char **corr;
 	char **curr;
+	int fd;
 	int i;
 	int r;
 
 	if(argc < 2 || check_arg(curr = &argv[1]) != 2)
 		return usage(argc == 0 ? "<no argv[0]>" : argv[0]);
 
-	do{
+	/* substitute standard input for /dev/null */
+	if((fd = dup(STDIN_FILENO)) < 0
+			|| dup2(open("/dev/null", O_RDONLY), STDIN_FILENO) < 0)
+		return oserr(argv[0], strerror(errno));
+
+	for(i = 0; ; ++i){
 		*(corr = corresponding_arg(curr++)) = NULL;
 
 		if(i == 1 || (r = fork()) == 0)
 			execvp(*curr, curr);
-		if(i == 1 || r == -1 || r == 0)
+
+		if(		r == -1 /* fork(2) failed */
+				|| i == 1 || r == 0 /* exec(3) failed */
+				|| dup2(fd, STDIN_FILENO) != STDIN_FILENO)
 			return oserr(argv[0], strerror(errno));
 
 		wait(&child);
@@ -49,7 +59,7 @@ int main(int argc, char *argv[]){
 			return 1;
 
 		curr = corr + 1;
-	}while(++i < 2);
-	/* UNREACHABLE */
+	}
 
+	/* UNREACHABLE */
 }