1 files changed, 137 insertions, 0 deletions
diff --git a/unix-socket.c b/unix-socket.c
new file mode 100644
index 0000000..79800d8
--- /dev/null
+++ b/unix-socket.c
@@ -0,0 +1,137 @@
+#include "git-compat-util.h"
+#include "strbuf.h"
+#include "unix-socket.h"
+
+#define DEFAULT_UNIX_STREAM_LISTEN_BACKLOG (5)
+
+static int chdir_len(const char *orig, int len)
+{
+	char *path = xmemdupz(orig, len);
+	int r = chdir(path);
+	free(path);
+	return r;
+}
+
+struct unix_sockaddr_context {
+	char *orig_dir;
+};
+
+static void unix_sockaddr_cleanup(struct unix_sockaddr_context *ctx)
+{
+	if (!ctx->orig_dir)
+		return;
+	/*
+	 * If we fail, we can't just return an error, since we have
+	 * moved the cwd of the whole process, which could confuse calling
+	 * code.  We are better off to just die.
+	 */
+	if (chdir(ctx->orig_dir) < 0)
+		die("unable to restore original working directory");
+	free(ctx->orig_dir);
+}
+
+static int unix_sockaddr_init(struct sockaddr_un *sa, const char *path,
+			      struct unix_sockaddr_context *ctx,
+			      int disallow_chdir)
+{
+	int size = strlen(path) + 1;
+
+	ctx->orig_dir = NULL;
+	if (size > sizeof(sa->sun_path)) {
+		const char *slash;
+		const char *dir;
+		struct strbuf cwd = STRBUF_INIT;
+
+		if (disallow_chdir) {
+			errno = ENAMETOOLONG;
+			return -1;
+		}
+
+		slash = find_last_dir_sep(path);
+		if (!slash) {
+			errno = ENAMETOOLONG;
+			return -1;
+		}
+
+		dir = path;
+		path = slash + 1;
+		size = strlen(path) + 1;
+		if (size > sizeof(sa->sun_path)) {
+			errno = ENAMETOOLONG;
+			return -1;
+		}
+		if (strbuf_getcwd(&cwd))
+			return -1;
+		ctx->orig_dir = strbuf_detach(&cwd, NULL);
+		if (chdir_len(dir, slash - dir) < 0)
+			return -1;
+	}
+
+	memset(sa, 0, sizeof(*sa));
+	sa->sun_family = AF_UNIX;
+	memcpy(sa->sun_path, path, size);
+	return 0;
+}
+
+int unix_stream_connect(const char *path, int disallow_chdir)
+{
+	int fd = -1, saved_errno;
+	struct sockaddr_un sa;
+	struct unix_sockaddr_context ctx;
+
+	if (unix_sockaddr_init(&sa, path, &ctx, disallow_chdir) < 0)
+		return -1;
+	fd = socket(AF_UNIX, SOCK_STREAM, 0);
+	if (fd < 0)
+		goto fail;
+
+	if (connect(fd, (struct sockaddr *)&sa, sizeof(sa)) < 0)
+		goto fail;
+	unix_sockaddr_cleanup(&ctx);
+	return fd;
+
+fail:
+	saved_errno = errno;
+	if (fd != -1)
+		close(fd);
+	unix_sockaddr_cleanup(&ctx);
+	errno = saved_errno;
+	return -1;
+}
+
+int unix_stream_listen(const char *path,
+		       const struct unix_stream_listen_opts *opts)
+{
+	int fd = -1, saved_errno;
+	int backlog;
+	struct sockaddr_un sa;
+	struct unix_sockaddr_context ctx;
+
+	unlink(path);
+
+	if (unix_sockaddr_init(&sa, path, &ctx, opts->disallow_chdir) < 0)
+		return -1;
+	fd = socket(AF_UNIX, SOCK_STREAM, 0);
+	if (fd < 0)
+		goto fail;
+
+	if (bind(fd, (struct sockaddr *)&sa, sizeof(sa)) < 0)
+		goto fail;
+
+	backlog = opts->listen_backlog_size;
+	if (backlog <= 0)
+		backlog = DEFAULT_UNIX_STREAM_LISTEN_BACKLOG;
+	if (listen(fd, backlog) < 0)
+		goto fail;
+
+	unix_sockaddr_cleanup(&ctx);
+	return fd;
+
+fail:
+	saved_errno = errno;
+	if (fd != -1)
+		close(fd);
+	unix_sockaddr_cleanup(&ctx);
+	errno = saved_errno;
+	return -1;
+}