From 549fa98bdb771079219df2af0ce56bb8f379f992 Mon Sep 17 00:00:00 2001
From: DTB <trinity@trinity.moe>
Date: Mon, 29 Jul 2024 10:53:58 -0600
Subject: [PATCH] npc(1): interpret all retvals

---
 src/npc.c | 35 ++++++++++++++++++++++++-----------
 1 file changed, 24 insertions(+), 11 deletions(-)

diff --git a/src/npc.c b/src/npc.c
index 2e256b0..b35aba4 100644
--- a/src/npc.c
+++ b/src/npc.c
@@ -17,17 +17,23 @@
  * along with this program. If not, see https://www.gnu.org/licenses/.
  */
 
-#include <stdio.h> /* fprintf(3), fputs(3), getc(3), putc(3), stdin, stdout,
-                    * EOF */
-#include <stdlib.h> /* EXIT_FAILURE */
+#include <stdio.h> /* fprintf(3), fputs(3), getc(3), perror(3), putc(3), stdin,
+                    * stdout, EOF */
+#include <sysexits.h> /* EX_IOERR, EX_OK, EX_USAGE */
 #include <unistd.h> /* getopt(3) */
-#include <sysexits.h> /* EX_OK, EX_USAGE */
 
 char *program_name = "npc";
 
+static int
+ioerr(char *argv0, int err) {
+	perror(argv0);
+
+	return EX_IOERR;
+}
+
 static int
 usage(char *argv0) {
-	fprintf(stderr, "Usage: %s [-et]\n", argv0);
+	(void)fprintf(stderr, "Usage: %s [-et]\n", argv0);
 
 	return EX_USAGE;
 }
@@ -52,16 +58,23 @@ int main(int argc, char *argv[]) {
 	if (argc > optind) { return usage(program_name); }
 
 	while ((c = getc(stdin)) != EOF) {
-		if ((c & 0x80) != 0) { fputs("M-", stdout); }
+		if ((c & 0x80) != 0 && fputs("M-", stdout) == EOF) {
+			return ioerr(argv[0]);
+		}
 
 		switch (c ^ 0x80 /* 0b 1000 0000 */) {
-			case 0x7f: fputs("^?", stdout); break; /* delete character */
-			case '\n': if (showend) { putc('$', stdout); }
+			case 0x7f: /* ASCII DEL (127d) */
+				if(fputs("^?", stdout) == EOF) { return ioerr(argv[0]); }
+				break;
+			case '\n':
+				if (showend && fputc('$', stdout) == EOF) {
+					return ioerr(argv[0]); }
+				}
 			default:
 				if (c >= ' ' || c == '\n' || (!showtab && c == '\t')) {
-					putc(c, stdout);
-				} else {
-					fprintf(stdout, "^%c", c + '@');
+					if (fputc(c, stdout) == EOF) { return ioerr(argv[0]); }
+				} else if (fprintf(stdout, "^%c", c + '@') < 0) {
+					return ioerr(argv[0]);
 				}
 		}
 	}