1 files changed, 94 insertions, 0 deletions
diff --git a/libcoopgamma_connect.c b/libcoopgamma_connect.c
new file mode 100644
index 0000000..d6c931c
--- /dev/null
+++ b/libcoopgamma_connect.c
@@ -0,0 +1,94 @@
+/* See LICENSE file for copyright and license details. */
+#include "common.h"
+
+
+/**
+ * Connect to a coopgamma server, and start it if necessary
+ * 
+ * Use `libcoopgamma_context_destroy` to disconnect
+ * 
+ * SIGCHLD must not be ignored or blocked
+ * 
+ * @param   method  The adjustment method, `NULL` for automatic
+ * @param   site    The site, `NULL` for automatic
+ * @param   ctx     The state of the library, must be initialised
+ * @return          Zero on success, -1 on error. On error, `errno` is set
+ *                  to 0 if the server could not be initialised.
+ */
+int
+libcoopgamma_connect(const char *restrict method, const char *restrict site, libcoopgamma_context_t *restrict ctx)
+{
+	const char *(args[6]) = {COOPGAMMAD};
+	struct sockaddr_un address;
+	char *path;
+	int saved_errno;
+	int tries = 0, status;
+	pid_t pid;
+	size_t i = 1;
+
+	ctx->blocking = 1;
+
+	if (method) args[i++] = "-m", args[i++] = method;
+	if (site)   args[i++] = "-s", args[i++] = site;
+	args[i] = NULL;
+
+	path = libcoopgamma_get_socket_file(method, site);
+	if (!path)
+		return -1;
+	if (strlen(path) >= sizeof(address.sun_path)) {
+		free(path);
+		errno = ENAMETOOLONG;
+		return -1;
+	}
+
+	address.sun_family = AF_UNIX;
+	stpcpy(address.sun_path, path);
+	free(path);
+	if ((ctx->fd = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
+		return -1;
+
+retry:
+	if (connect(ctx->fd, (const struct sockaddr *)&address, (socklen_t)sizeof(address)) < 0) {
+		if ((errno == ECONNREFUSED || errno == ENOENT || errno == ENOTDIR) && !tries++) {
+			switch ((pid = fork())) {
+			case -1:
+				goto fail;
+
+			case 0:
+				/* Child */
+				close(ctx->fd);
+#if defined(__GNUC__)
+# pragma GCC diagnostic push
+# pragma GCC diagnostic ignored "-Wcast-qual"
+#endif
+				execvp(COOPGAMMAD, (char *const *)(args));
+#if defined(__GNUC__)
+# pragma GCC diagnostic pop
+#endif
+				perror(NAME_OF_THE_PROCESS);
+				exit(1);
+
+			default:
+				/* Parent */
+				if (waitpid(pid, &status, 0) < 0)
+					goto fail;
+				if (status) {
+					errno = 0;
+					goto fail;
+				}
+				break;
+			}
+			goto retry;
+		}
+		goto fail;
+	}
+
+	return 0;
+
+fail:
+	saved_errno = errno;
+	close(ctx->fd);
+	ctx->fd = -1;
+	errno = saved_errno;
+	return -1;
+}