tests: New utility for making and testing socket files

1 files changed, 131 insertions, 0 deletions

diff --git a/tests/mksock.c b/tests/mksock.c
new file mode 100644
index 0000000..a996d58
--- /dev/null
+++ b/tests/mksock.c
@@ -0,0 +1,131 @@
+/****************************************************************************
+ * bfs                                                                      *
+ * Copyright (C) 2019 Tavian Barnes <tavianator@tavianator.com>             *
+ *                                                                          *
+ * Permission to use, copy, modify, and/or distribute this software for any *
+ * purpose with or without fee is hereby granted.                           *
+ *                                                                          *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES *
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF         *
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR  *
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES   *
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN    *
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF  *
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.           *
+ ****************************************************************************/
+
+/**
+ * There's no standard Unix utility that creates a socket file, so this small
+ * program does the job.
+ */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <libgen.h>
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <sys/un.h>
+#include <unistd.h>
+
+/**
+ * Print an error message.
+ */
+static void errmsg(const char *cmd, const char *path) {
+	fprintf(stderr, "%s: '%s': %s.\n", cmd, path, strerror(errno));
+}
+
+/**
+ * struct sockaddr_un::sun_path is very short, so we chdir() into the target
+ * directory before creating sockets in case the full path is too long but the
+ * file name is not.
+ */
+static int chdir_parent(const char *path) {
+	char *copy = strdup(path);
+	if (!copy) {
+		return -1;
+	}
+	const char *dir = dirname(copy);
+
+	int ret = chdir(dir);
+
+	int error = errno;
+	free(copy);
+	errno = error;
+
+	return ret;
+}
+
+/**
+ * Initialize a struct sockaddr_un with the right filename.
+ */
+static int init_sun(struct sockaddr_un *sock, const char *path) {
+	size_t len = strlen(path);
+	if (len == 0 || path[len - 1] == '/') {
+		errno = ENOENT;
+		return -1;
+	}
+
+	char *copy = strdup(path);
+	if (!copy) {
+		return -1;
+	}
+	const char *base = basename(copy);
+
+	len = strlen(base);
+	if (len >= sizeof(sock->sun_path)) {
+		free(copy);
+		errno = ENAMETOOLONG;
+		return -1;
+	}
+
+	sock->sun_family = AF_UNIX;
+	memcpy(sock->sun_path, base, len + 1);
+	free(copy);
+	return 0;
+}
+
+int main(int argc, char *argv[]) {
+	const char *cmd = argc > 0 ? argv[0] : "mksock";
+
+	if (argc != 2) {
+		fprintf(stderr, "Usage: %s NAME\n", cmd);
+		return EXIT_FAILURE;
+	}
+
+	const char *path = argv[1];
+
+	if (chdir_parent(path) != 0) {
+		errmsg(cmd, path);
+		return EXIT_FAILURE;
+	}
+
+	struct sockaddr_un sock;
+	if (init_sun(&sock, path) != 0) {
+		errmsg(cmd, path);
+		return EXIT_FAILURE;
+	}
+
+	int fd = socket(AF_UNIX, SOCK_STREAM, 0);
+	if (fd < 0) {
+		errmsg(cmd, path);
+		return EXIT_FAILURE;
+	}
+
+	int ret = EXIT_SUCCESS;
+
+	if (bind(fd, (struct sockaddr *)&sock, sizeof(sock)) != 0) {
+		errmsg(cmd, path);
+		ret = EXIT_FAILURE;
+	}
+
+	if (close(fd) != 0) {
+		errmsg(cmd, path);
+		ret = EXIT_FAILURE;
+	}
+
+	return ret;
+}