fix(dockerfile): handle quoted and space-containing ARG default values

Change ARG_LINE_PATTERN from \\S+ to .+ so values with spaces are fully
captured, and strip surrounding quotes before storing the default.

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

Author: a-oren

src/main/java/io/github/guacsec/trustifyda/providers/DockerfileProvider.java

@@ -50,7 +50,7 @@ public final class DockerfileProvider extends Provider {
       Pattern.compile("^FROM\\s+", Pattern.CASE_INSENSITIVE);
 
   private static final Pattern ARG_LINE_PATTERN =
-      Pattern.compile("^ARG\\s+([A-Za-z_][A-Za-z0-9_]*)=(\\S+)", Pattern.CASE_INSENSITIVE);
+      Pattern.compile("^ARG\\s+([A-Za-z_][A-Za-z0-9_]*)=(.+)", Pattern.CASE_INSENSITIVE);
 
   private static final Pattern VAR_REF_PATTERN =
       Pattern.compile("\\$\\{([^}]+)}|\\$([A-Za-z_][A-Za-z0-9_]*)");
@@ -144,7 +144,12 @@ static List<String> parseAllFromImages(Path dockerfile) throws IOException {
       String trimmed = line.trim();
       var argMatcher = ARG_LINE_PATTERN.matcher(trimmed);
       if (argMatcher.find()) {
-        argDefaults.put(argMatcher.group(1), argMatcher.group(2));
+        String val = argMatcher.group(2).trim();
+        if ((val.startsWith("\"") && val.endsWith("\""))
+            || (val.startsWith("'") && val.endsWith("'"))) {
+          val = val.substring(1, val.length() - 1);
+        }
+        argDefaults.put(argMatcher.group(1), val);
         continue;
       }
       var fromMatcher = FROM_LINE_PATTERN.matcher(trimmed);

src/test/java/io/github/guacsec/trustifyda/providers/Dockerfile_Provider_Test.java

@@ -188,6 +188,36 @@ void resolves_arg_substitution_with_bare_syntax() throws IOException {
       assertThat(images).hasSize(1).containsExactly("ubuntu:22.04");
     }
 
+    /** Verifies that double-quoted ARG default values are unquoted before resolution. */
+    @Test
+    void resolves_arg_with_double_quoted_value() throws IOException {
+      var dockerfile = TEST_MANIFESTS.resolve("arg_double_quoted/Dockerfile");
+
+      List<String> images = DockerfileProvider.parseAllFromImages(dockerfile);
+
+      assertThat(images).hasSize(1).containsExactly("ubuntu:22.04");
+    }
+
+    /** Verifies that single-quoted ARG default values are unquoted before resolution. */
+    @Test
+    void resolves_arg_with_single_quoted_value() throws IOException {
+      var dockerfile = TEST_MANIFESTS.resolve("arg_single_quoted/Dockerfile");
+
+      List<String> images = DockerfileProvider.parseAllFromImages(dockerfile);
+
+      assertThat(images).hasSize(1).containsExactly("ubuntu:22.04");
+    }
+
+    /** Verifies that ARG values with spaces are captured fully when quoted. */
+    @Test
+    void resolves_arg_with_spaces_in_quoted_value() throws IOException {
+      var dockerfile = TEST_MANIFESTS.resolve("arg_value_with_spaces/Dockerfile");
+
+      List<String> images = DockerfileProvider.parseAllFromImages(dockerfile);
+
+      assertThat(images).hasSize(1).containsExactly("ubuntu:22.04");
+    }
+
     /** Verifies that ARG without default value causes the FROM line to be skipped. */
     @Test
     void skips_arg_substitution_without_default_value() {

src/test/resources/tst_manifests/dockerfile/arg_double_quoted/Dockerfile

@@ -0,0 +1,4 @@
+ARG BASE_IMAGE="ubuntu:22.04"
+FROM ${BASE_IMAGE}
+
+RUN echo hello

src/test/resources/tst_manifests/dockerfile/arg_single_quoted/Dockerfile

@@ -0,0 +1,4 @@
+ARG BASE_IMAGE='ubuntu:22.04'
+FROM ${BASE_IMAGE}
+
+RUN echo hello

src/test/resources/tst_manifests/dockerfile/arg_value_with_spaces/Dockerfile

@@ -0,0 +1,5 @@
+ARG LABEL="my app label"
+ARG BASE_IMAGE=ubuntu:22.04
+FROM ${BASE_IMAGE}
+
+LABEL description=${LABEL}