fix(providers): strip all leading flags from Dockerfile FROM lines

The parseFromImage function previously only stripped a single --flag
token using a regex. Dockerfile syntax allows multiple flags before
the image reference. Replace the single regex with a loop that skips
all leading --flag tokens.

TC-4977

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Assisted-by: Claude Code

Author: a-oren

src/providers/oci_dockerfile.js

@@ -42,13 +42,14 @@ export function parseFromImage(manifestContent) {
 	for (const line of lines) {
 		const trimmed = line.trim()
 		if (/^FROM\s+/i.test(trimmed)) {
-			// Extract image ref: FROM [--platform=...] image [AS name]
-			const withoutFrom = trimmed.replace(/^FROM\s+/i, '')
-			// Skip optional --platform flag
-			const withoutFlags = withoutFrom.replace(/^--\S+\s+/, '')
-			// Take only the image part (before AS alias)
-			const parts = withoutFlags.split(/\s+/)
-			lastFrom = parts[0]
+			// Extract image ref: FROM [--flag=val ...] image [AS name]
+			const tokens = trimmed.replace(/^FROM\s+/i, '').split(/\s+/)
+			// Skip all leading --flag tokens (e.g. --platform=linux/amd64)
+			let i = 0
+			while (i < tokens.length && tokens[i].startsWith('--')) {
+				i++
+			}
+			lastFrom = tokens[i] || null
 		}
 	}
 	if (!lastFrom) {

test/providers/oci_dockerfile.test.js

@@ -59,12 +59,18 @@ suite('testing the Dockerfile/Containerfile data provider', () => {
 			expect(parseFromImage(content)).to.equal('nginx:alpine')
 		})
 
-		/** Verifies that --platform flags are skipped when parsing FROM lines. */
+		/** Verifies that a single --platform flag is skipped when parsing FROM lines. */
 		test('handles --platform flag', () => {
 			const content = 'FROM --platform=linux/amd64 ubuntu:22.04\n'
 			expect(parseFromImage(content)).to.equal('ubuntu:22.04')
 		})
 
+		/** Verifies that multiple flags before the image reference are all skipped. */
+		test('handles multiple flags before image', () => {
+			const content = 'FROM --platform=linux/amd64 --some-flag=value ubuntu:22.04 AS base\n'
+			expect(parseFromImage(content)).to.equal('ubuntu:22.04')
+		})
+
 		/** Verifies that image references with digests are parsed correctly. */
 		test('handles image with digest', () => {
 			const content = 'FROM httpd@sha256:abc123\n'