1 files changed, 82 insertions, 0 deletions
diff --git a/setpgrp.c b/setpgrp.c
new file mode 100644
index 0000000..1cb75fc
--- /dev/null
+++ b/setpgrp.c
@@ -0,0 +1,82 @@
+/* See LICENSE file for copyright and license details. */
+#include <errno.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "arg.h"
+
+#define EXIT_ERROR  125
+#define EXIT_EXEC   126
+#define EXIT_NOENT  127
+
+
+char *argv0;
+
+static void
+usage(void)
+{
+	fprintf(stderr, "usage: %s [-e variable] [-pv] command [argument] ...\n", argv0);
+	exit(EXIT_ERROR);
+}
+
+int
+main(int argc, char *argv[])
+{
+	char group_str[3 * sizeof(pid_t) + 1];
+	int print_to_stdout = 0;
+	int print_to_stderr = 0;
+	char *export = NULL;
+	pid_t group;
+
+	ARGBEGIN {
+	case 'e':
+		export = EARGF(usage());
+		if (!*export)
+			usage();
+		break;
+	case 'p':
+		print_to_stdout = 1;
+		break;
+	case 'v':
+		print_to_stderr = 1;
+		break;
+	default:
+		usage();
+	} ARGEND;
+
+	if (!argc)
+		usage();
+
+	if (setpgid(0, 0)) {
+		fprintf(stderr, "%s: setpgid 0 0: %s\n", argv0, strerror(errno));
+		return EXIT_ERROR;
+	}
+	group = getpgrp();
+
+	if (print_to_stdout) {
+		printf("%ji\n", (intmax_t)group);
+		if (fflush(stdout) || ferror(stdout)) {
+			fprintf(stderr, "%s: printf: %s\n", argv0, strerror(errno));
+			return EXIT_ERROR;
+		}
+	}
+
+	if (export) {
+		sprintf(group_str, "%ji", (intmax_t)group);
+		if (setenv(export, group_str, 1)) {
+			fprintf(stderr, "%s: setenv %s %s 1: %s\n", argv0, export, group_str, strerror(errno));
+			return EXIT_ERROR;
+		}
+	}
+
+	if (print_to_stderr)
+		fprintf(stderr, "%s: running %s in process group %ji\n", argv0, argv[0], (intmax_t)group);
+
+	execvp(argv[0], argv);
+	fprintf(stderr, "%s: execvp %s: %s\n", argv0, argv[0], strerror(errno));
+	return errno == ENOENT ? EXIT_NOENT : EXIT_EXEC;
+}