From 52b4d08cf24c987c97a2210e69251f826f34c531 Mon Sep 17 00:00:00 2001
From: Jakob Kaivo <jkk@ung.org>
Date: Thu, 14 Mar 2019 13:41:50 -0400
Subject: first cut

---
 nohup.c | 69 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 69 insertions(+)
 create mode 100644 nohup.c

diff --git a/nohup.c b/nohup.c
new file mode 100644
index 0000000..7132340
--- /dev/null
+++ b/nohup.c
@@ -0,0 +1,69 @@
+#define _XOPEN_SOURCE 700
+#include <errno.h>
+#include <fcntl.h>
+#include <locale.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#define NOHUP_UTILITY_NOT_FOUND		127
+#define NOHUP_UTILITY_NOT_INVOKED	126
+
+int main(int argc, char *argv[])
+{
+	int c;
+
+	setlocale(LC_ALL, "");
+
+	while ((c = getopt(argc, argv, "")) != -1) {
+		switch (c) {
+		default:
+			return 1;
+		}
+	}
+
+	argv += optind;
+
+	if (argv[0] == NULL) {
+		fprintf(stderr, "nohup: utility required\n");
+		return NOHUP_UTILITY_NOT_INVOKED;
+	}
+
+	signal(SIGHUP, SIG_IGN);
+
+	if (isatty(STDOUT_FILENO)) {
+		char out[FILENAME_MAX] = "nohup.out";
+		int fd = open(out, O_WRONLY | O_CREAT | O_APPEND, S_IRUSR | S_IWUSR);
+		if (fd == -1) {
+			char *home = getenv("HOME");
+			if (home == NULL) {
+				fprintf(stderr, "nohup: $HOME unset\n");
+				return NOHUP_UTILITY_NOT_INVOKED;
+			}
+			snprintf(out, sizeof(out), "%s/nohup.out", home);
+			fd = open(out, O_WRONLY | O_CREAT | O_APPEND, S_IRUSR | S_IWUSR);
+			if (fd == -1) {
+				perror("nohup: couldn't open nohup.out or $HOME/nohup.out");
+				return NOHUP_UTILITY_NOT_INVOKED;
+			}
+		}
+
+		fprintf(stderr, "nohup: appending to %s\n", out);
+		dup2(fd, STDOUT_FILENO);
+	}
+
+	if (isatty(STDERR_FILENO)) {
+		dup2(STDOUT_FILENO, STDERR_FILENO);
+	}
+
+	execvp(argv[0], argv);
+
+	perror("nohup");
+
+	if (errno == ENOENT) {
+		return NOHUP_UTILITY_NOT_FOUND;
+	}
+
+	return NOHUP_UTILITY_NOT_INVOKED;
+}
-- 
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