[Content] Throw on relative image usage (#5648)

* chore: add rel image error plugin

* deps: mdast, mdast types

* chore: add rel image throw to mdx

* refactor: doc rel image path plugin

* fix: respect experimental flag in md remark

* chore: changeset

* deps: remove mdast package

* fix: resolve contentDir from config

* fix: apply MDX plugin after user plugins

* fix: stub out contentDir

1 files changed, 19 insertions, 0 deletions

diff --git a/packages/integrations/mdx/src/utils.ts b/packages/integrations/mdx/src/utils.ts
index 60a50c85a..e803dc300 100644
--- a/packages/integrations/mdx/src/utils.ts
+++ b/packages/integrations/mdx/src/utils.ts
@@ -95,3 +95,22 @@ export function handleExtendsNotSupported(pluginConfig: any) {
 		);
 	}
 }
+
+// Following utils taken from `packages/astro/src/core/path.ts`:
+
+export function isRelativePath(path: string) {
+	return startsWithDotDotSlash(path) || startsWithDotSlash(path);
+}
+
+function startsWithDotDotSlash(path: string) {
+	const c1 = path[0];
+	const c2 = path[1];
+	const c3 = path[2];
+	return c1 === '.' && c2 === '.' && c3 === '/';
+}
+
+function startsWithDotSlash(path: string) {
+	const c1 = path[0];
+	const c2 = path[1];
+	return c1 === '.' && c2 === '/';
+}