discover: Add devpath resources

Add a generic resource type, to handle "dev:path"-style file references.

This creates a duplicate of is_prefix_ignorecase, which we'll switch
over to later.

Signed-off-by: Jeremy Kerr <jk@ozlabs.org>

1 files changed, 113 insertions, 0 deletions

diff --git a/discover/resource.c b/discover/resource.c
new file mode 100644
index 0000000..917a6dc
--- /dev/null
+++ b/discover/resource.c
@@ -0,0 +1,113 @@
+
+#define _GNU_SOURCE
+
+#include <assert.h>
+#include <stdbool.h>
+#include <string.h>
+
+#include <url/url.h>
+#include <talloc/talloc.h>
+
+#include "device-handler.h"
+#include "resource.h"
+#include "paths.h"
+
+static int is_prefix_ignorecase(const char *str, const char *prefix)
+{
+	return !strncasecmp(str, prefix, strlen(prefix));
+}
+
+struct devpath_resource_info {
+	char	*dev, *path;
+};
+
+static struct discover_device *parse_device_string(
+		struct device_handler *handler, const char *devstr)
+{
+	if (is_prefix_ignorecase(devstr, "uuid="))
+		return device_lookup_by_uuid(handler, devstr + strlen("uuid"));
+
+	if (is_prefix_ignorecase(devstr, "label="))
+		return device_lookup_by_label(handler,
+					devstr + strlen("label="));
+
+	return device_lookup_by_name(handler, devstr);
+}
+static void resolve_devpath_against_device(struct resource *res,
+	struct discover_device *dev, const char *path)
+{
+	char *resolved_path = join_paths(res, dev->mount_path, path);
+	res->url = pb_url_parse(res, resolved_path);
+	res->resolved = true;
+}
+
+struct resource *create_devpath_resource(void *ctx,
+	struct discover_device *orig_device,
+	const char *devpath)
+{
+	struct devpath_resource_info *info;
+	char *pos, *devstr, *path;
+	struct resource *res;
+	struct pb_url *url;
+
+	res = talloc(ctx, struct resource);
+
+	pos = strchr(devpath, ':');
+
+	/* do we have a "://" scheme separator? */
+	if (pos && pos[1] && pos[1] == '/' && pos[2] && pos[2] == '/') {
+		url = pb_url_parse(res, devpath);
+
+		if (url->scheme != pb_url_file) {
+			/* not a file? we're ready to go */
+			res->resolved = true;
+			res->url = url;
+		} else {
+			/* we've been passed a file:// URL, which has no device
+			 * specifier. We can resolve against the original
+			 * device */
+			resolve_devpath_against_device(res, orig_device,
+					url->path);
+			talloc_free(url);
+		}
+		return res;
+	}
+
+	/* if there was no device specified, we can resolve now */
+	if (!pos) {
+		resolve_devpath_against_device(res, orig_device, devpath);
+		return res;
+	}
+
+	devstr = talloc_strndup(res, devpath, pos - devpath);
+	path = talloc_strdup(res, pos + 1);
+
+	/* defer resolution until we can find a suitable matching device */
+	info = talloc(res, struct devpath_resource_info);
+	info->dev = devstr;
+	info->path = path;
+
+	res->resolved = false;
+	res->info = info;
+
+	return res;
+}
+
+bool resolve_devpath_resource(struct device_handler *handler,
+		struct resource *res)
+{
+	struct devpath_resource_info *info = res->info;
+	struct discover_device *dev;
+
+	assert(!res->resolved);
+
+	dev = parse_device_string(handler, info->dev);
+
+	if (!dev)
+		return false;
+
+	resolve_devpath_against_device(res, dev, info->path);
+	talloc_free(info);
+
+	return true;
+}