dlopen utility

bin/Makefile

@@ -9,6 +9,7 @@ SUBDIR= cat \
 	date \
 	dd \
 	df \
+	dlopen \
 	domainname \
 	echo \
 	ed \

bin/dlopen/Makefile

@@ -0,0 +1,6 @@
+PACKAGE=runtime
+PROG=	dlopen
+
+LIBADD=	util
+
+.include <bsd.prog.mk>

bin/dlopen/dlopen.1

@@ -0,0 +1,66 @@
+.\"-
+.\" SPDX-License-Identifier: BSD-2-Clause
+.\"
+.\" Copyright (c) 2025 (holder)
+.\"
+.\" This software was developed by SRI International, the University of
+.\" Cambridge Computer Laboratory (Department of Computer Science and
+.\" Technology), and Capabilities Limited under Defense Advanced Research
+.\" Projects Agency (DARPA) Contract No. FA8750-24-C-B047 ("DEC").
+.\"
+.Dd April 23, 2025
+.Dt DLOPEN 1
+.Os
+.Sh Name
+.Nm dlopen
+.Nd load libraries with dlopen(3) and sleep for analysis
+.Sh SYNOPSIS
+.Nm
+.Op Brq Fl L | Fl N
+.Op Brq Fl g | Fl l
+.Op Fl v
+.Op Fl s Ar seconds
+.Ar library ...
+.Sh DESCRIPTION
+The
+.Nm
+utility supports analysis of the linkage and loading behavior of dynamiclly
+loaded libraries without the need for custom software.
+It loads each library listed on the command line and then waits for
+input on stdin unless the
+.Fl s
+flag use used to pass a positive number of seconds to sleep.
+.Pp
+The
+.Fl L
+and
+.Fl N
+flags control the use of
+.Dv RTLD_LAZY
+versus
+.Dv RTLD_NOW
+flags.
+.Dv RTLD_NOW is
+the
+.Nm
+utility's default.
+Likewise
+.Fl g
+and
+.Fl l
+control the use of
+.Dv RTLD_GLOBAL
+or
+.Dv RTLD_LOCAL .
+The
+.Fl v
+flag enables verbose mode.
+.Sh EXIT STATUS
+.Ex -std
+.Sh AUTHORS
+This software and this manual page were
+developed by SRI International, the University of Cambridge Computer
+Laboratory (Department of Computer Science and Technology), and
+Capabilities Limited under contract
+.Pq FA8750-24-C-B047
+.Pq Do DEC Dc .

bin/dlopen/dlopen.c

@@ -0,0 +1,91 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2025 SRI International
+ *
+ * This software was developed by SRI International, the University of
+ * Cambridge Computer Laboratory (Department of Computer Science and
+ * Technology), and Capabilities Limited under Defense Advanced Research
+ * Projects Agency (DARPA) Contract No. FA8750-24-C-B047 ("DEC").
+ */
+
+#include <sys/cdefs.h>
+
+#include <dlfcn.h>
+#include <err.h>
+#include <libutil.h>
+#include <limits.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <unistd.h>
+
+static bool verbose = false;
+static int seconds = -1;
+static int dlopen_mode = RTLD_NOW;
+static int dlopen_local_global = 0; /* dlopen(3)'s default is RTLD_LOCAL */
+
+static void _Noreturn
+usage(void)
+{
+	printf("usage: dlopen [-L|N] [-g|l] [-s <seconds>] [-v] <lib> [...]\n");
+	exit(1);
+}
+
+int
+main(int argc, char **argv)
+{
+	int ch;
+	uint64_t num;
+
+	while ((ch = getopt(argc, argv, "gLlNs:v")) != -1) {
+		switch (ch) {
+		case 'g':
+			dlopen_local_global = RTLD_GLOBAL;
+			break;
+		case 'l':
+			dlopen_local_global = RTLD_LOCAL;
+			break;
+		case 'L':
+			dlopen_mode = RTLD_LAZY;
+			break;
+		case 'N':
+			dlopen_mode = RTLD_NOW;
+			break;
+		case 's':
+			if (expand_number(optarg, &num) != 0)
+				err(1, "bad number '%s'", optarg);
+			if (num > INT_MAX)
+				seconds = INT_MAX;
+			else
+				seconds = num;
+			break;
+		case 'v':
+			verbose = true;
+			break;
+		case '?':
+		default:
+			usage();
+		}
+	}
+	argc -= optind;
+	argv += optind;
+
+	for (int i = 0; i < argc; i++) {
+		if (dlopen(argv[i], dlopen_mode | dlopen_local_global) == NULL)
+			errx(1, "dlopen(%s)", argv[i]);
+		if (verbose)
+			printf("loaded %s\n", argv[i]);
+	}
+
+	if (seconds < 0) {
+		if (verbose)
+			printf("waiting for input\n");
+		(void)getchar();
+	} else {
+		if (seconds != 0 && verbose)
+			printf("sleeping for %d seconds\n", seconds);
+		sleep(seconds);
+	}
+	return (0);
+}